Nuts, cereals, seeds and legumes proteins derived emulsifiers as a source of plant protein beverages: a review

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Nuts, cereals, seeds and legumes proteins derived
emulsifiers as a source of plant protein beverages:
A review
Sadia Qamar, Yady J. Manrique, Harendra Parekh & James Robert Falconer
To cite this article: Sadia Qamar, Yady J. Manrique, Harendra Parekh & James Robert
Falconer (2019): Nuts, cereals, seeds and legumes proteins derived emulsifiers as a source
of plant protein beverages: A review, Critical Reviews in Food Science and Nutrition, DOI:
10.1080/10408398.2019.1657062
To link to this article: https://doi.org/10.1080/10408398.2019.1657062
Published online: 03 Sep 2019.
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REVIEW
Nuts, cereals, seeds and legumes proteins derived emulsifiers as a source of
plant protein beverages: A review
Sadia Qamar, Yady J. Manrique, Harendra Parekh, and James Robert Falconer
School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
ABSTRACT
Milk beverages derived from plant-based protein have attracted the interest of consumers and
researchers as a health-promoting functional food. It can also be considered as a substitute for
animal milk due to various allergy concerns associated with dairy milk. The plant-based emulsions
are directed to prevent diet-related chronic diseases including diabetes, cardiovascular, obesity
and other disorders due to the presence of healthy long-chain unsaturated fatty acids as com-
pared to bovine milk. Further, associations between nutritional contents (vitamins, minerals and
low fat) and pharmacological properties of plant-based protein may have extra beneficial effects.
The review aims to summarize the four different groups of plant sources (nuts, cereals, seeds and
legumes) used for the preparation of plant-based milk beverages. In addition, it also provides a
detailed review of the general characteristics and functional properties of these plant sources.
Physicochemical composition, protein and fats quality, functional properties, effect of heat and
high-pressure treatment is also provided in detail. It also covers fats digestibility, protein stability,
protein solubility and digestibility. Furthermore, the effect of processing, possible comparative
study and potential applications in healthcare have been discussed.
KEYWORDS
Nuts; cereals; seeds;
legumes; plant protein
stability; digestibility; plant
beverages; milk.
Introduction
For the maintenance of human health and regulation of
physiological needs, food plays an important role. The
human body gets essential bioactive compounds, nutritional
contents and minerals from foods. In general, dairy products
are considered as nutritive food, balanced and healthy diet
for both infants and adults. There are various health issues
associated with dairy products such as, lactose intolerance
and cow milk allergy. These issues are usually divided into
four groups, namely chemical (contaminates from the envir-
onment), physical (during handling of milk), biological (tox-
ins and allergic sensitization) and other issues (religious and
ethical concerns) (Iacono et al. 2008). Therefore, vegan-
friendly products or dairy-alternative beverages are in great
demand and interest to food industry marketers. The pro-
tein-based emulsified products are derived from four sec-
tions of plants, including nuts, legumes, cereals and seeds.
The nut-based beverages (e.g. almond emulsified prod-
ucts) are commonly available in the market. Due to the
presence of a high amount of phosphorus, potassium and
calcium in these products, they are used as an alternative
source of milk. Moreover, their nutty taste, creamy texture,
fatty acid composition and medical benefits also attract the
peoples. From the other three sections of plant protein,
emulsified products are entirely derived from the rice, soy
and oat. The beany flavor of these emulsion does not attract
the consumers enough to want to buy the plant protein
emulsified products. Therefore, peoples are looking for other
plant protein sources for dairy-alternative beverages.
Cereals are also a good source of polyphenols, antioxi-
dants, calcium, dietary fiber, lipids, protein and starch. Rice
protein is considered highly valuable due to hypocholestero-
lemic (reduce plasma cholesterol level) and hypoallergenic
(lower risk to any allergic reactions) properties with a bland
taste, colorless and high amount of essential amino acids
(Chrastil 1992; Revilla et al. 2009). After cereals, legumes are
the second most consumable source of the human diet.
They are an economical source of proteins and other valu-
able nutritional contents. Pea seed contains two major
globulin proteins (vicilin and legumin), high content of
lysine and has a well-balanced profile of amino acids (Grac¸a,
Raymundo, and de Sousa 2016). Chickpea proteins is also a
suitable source of dietary protein due to the presence of a
lower amount of anti-nutritional factors and high bioavail-
ability of essential amino acids. Additionally, several bio-
logical activities for chickpea protein hydrolysates have been
reported such as reduction of antigenic activity and angio-
tensin I-converting enzyme inhibition (Zhang et al. 2011).
Processing is the most important step to increase the
shelf life and stability of plant-based beverages. Pressure and
heat treatment are most commonly used to minimize the
microbial load and food poising risk of plant-based bever-
ages (McKinnon et al. 2009). Heat treatment does not alone
CONTACT Sadia Qamar s.qamar@uq.edu.au; James Robert Falconer j.falconer@uq.edu.au School of Pharmacy, The University of Queensland, Brisbane,
QLD 4072, Australia.
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CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION
https://doi.org/10.1080/10408398.2019.1657062

ensure the microbiological safety of the emulsified product.
Additionally, processing can cause some adverse effects on
the quality of protein-based beverages such as denaturation
of protein and changes in color. Therefore, the effect of
processing on the protein structure and emulsifying proper-
ties of a plant-based emulsion is discussed in this litera-
ture review.
Plant-based protein emulsion
Plant-based protein emulsion is an immiscible mixture of
either oil in water or water in oil. In every emulsion there
are two phases, a dispersed and continuous. Figure 1 illus-
trates the most possible types of plant-based protein emul-
sion phases. Generally, due to interfacial film-forming
abilities and amphiphilic nature, food proteins are good at
stabilizing oil-in-water emulsions. Mostly there are two types
of emulsion single layer (Figure 1b) and double layer
(Figure 1a). Single-layer emulsion mainly contains, single
dispersed phase and single continuous phase. Whereas, dou-
ble layer emulsion contains two or more dispersed phases
and only a single continuous phase (Yahaya Khan
et al. 2014).
For the production of emulsion from a plant source,
plant material is typically subjected to different processing
steps. The first step includes wet grinding to make a
paste of the nut, legume, cereal or seeds followed by mix-
ing the paste with enough quantity of water to extract
the emulsion. The emulsion is then subjected to hom-
ogenization followed by heat and pressure treatment. Due
to multiple factors including quality of material, microbio-
logical shelf-life, processing treatment and various electro-
static interactions there tends to be phase separation (i.e.
cracked) overtime via creaming, flocculation and/or
coalescence (Figure 2). Inherently these factors make the
emulsion thermodynamically unstable (Dhakal et al. 2014).
Quality of any emulsion can be obtained by these specific
properties. The main characterization of emulsion includes
physicochemical, functional, sensory and proximate com-
positional properties and their modifications (in the color,
viscosity, physical stability and particle size of the pro-
duced beverage).
The stability of emulsion is highly reliant on different
parameters such as emulsion processing conditions (hom-
ogenization pressure), solvent conditions (pH, temperature
and salts), protein characteristics (surface reactivity, solubil-
ity, protein concentration, size and conformation), distribu-
tion, phase volume ratio, continuous phase viscosity, droplet
size of liquid and their surface tension properties
(Avramenko, Low, and Nickerson 2013). There is a possibil-
ity of food-borne bacterial pathogens in untreated raw plant
beverages. Thus for commercialization, sterilization, exten-
sion of shelf life, maintaining the nutritional contents,
improving the quality, textural and organoleptic properties
plant-based beverages are subjected to different processing
treatments. The most possible processing treatment of plant-
based beverages is presented in Table 1.
Possible sources of plant-based
beverages/emulsions
Several beverages are available in the market derived from
cereals, nuts, legumes and seed or a combination of plant
sources as an alternative to dairy milk. The potential plant-
based protein source beverages can be categorized into
four parts:
Figure 1. Schematic representation double layer (A) and single layer (B) emulsion (Yahaya Khan et al. 2014).
2 S. QAMAR ET AL.

Nuts (almond, walnut and hazelnut)
Legumes (pea, chickpea, lentil and soy)
Seeds (hemp, sesame seed, pumpkin seed and water-
melon seed)
Cereals (rice, oat, millet and barley)
The physicochemical composition, protein and fat quality
and functional properties of the studied plant-based bever-
ages are discussed below:
Plant-based beverages from nuts and their benefits
Nuts derived from the tree such as almonds, walnuts or pis-
tachios are recommended as a part of a healthy diet due to
their nutritional profile. They contain a variety of proteins,
phytochemicals, essential micronutrients and fatty acids (Del
Gobbo et al. 2015). Recent research studies show the strong
associations between consumption of nuts and a lower risk
of cardiovascular diseases, diabetes and cancer (Fischer and
Clei 2013; Wu et al. 2015). Consumption of a reasonable
amount of nuts does not result in weight gain, although it
contains a higher amount of fats (Jackson and Hu 2014).
Nut consumption also reverses the metabolic syndrome and
adiposity risk (O’Neil, Fulgoni, and Nicklas 2015). Different
studies have reported the health-promoting effects of unsat-
urated fatty acids in nuts. Tree nuts can significantly
contribute to a daily intake of different micronutrients such
as tocopherols, vitamin B complex and carotenoids (Bolling,
McKay, and Blumberg 2010). Nuts can fulfill the dietary
intake of bioactive contents. For example, more than 57%
and 79% of the recommended daily intake/100 g (RDI) of
thiamin and pyridoxine can be obtained from Pistachios.
Almonds provide 119% of the riboflavin RDI. Pistachios and
walnuts contain rich amount of c-tocopherol. Additionally, a
significant amount of a-tocopherol is found in hazelnuts
and almonds (Stuetz, Schl€ormann, and Glei 2017).
Hazelnuts are also a good source of other phenolic contents
such as quercetin, sinapic acid, epicatechin, p-hydroxy ben-
zoic and gallic acid (Maleki, Khodaiyan, and Mousavi 2015).
There is a wide variety of nut-based beverages in the
form of emulsified products. Due to the presence of a high
amount of phosphorus, potassium and calcium in almond
and hazelnut emulsified products, they are used as an alter-
native source of milk for celiacs, pregnant women and
Lacto-intolerant individuals (Luengo 2009). These beverages
are also suitable for peoples suffering from heart conditions
as it contains low cholesterol, saturated fats and low sodium
content (Miraliakbari and Shahidi 2008). It is also reported
that obesity-related diseases can also be treated to a certain
extent with almond beverages (Chen, Lapsley, and
Blumberg 2006).
Physicochemical composition
Almond milk is one of the most researched product among
nut-based beverages. The consumption of almond milk is
relatively high among the various nut-based beverages due
to the nutty taste, creamy texture, fatty acid composition
and health benefits. The physicochemical composition of
almond beverages as described in Table 2. The composition
of plant-based beverages greatly depends on the raw mater-
ial used for preparation. The fat, protein, carbohydrate and
fiber content are reported to be approximately 3.40, 1.70,
4.50 and 1.25 g per 100 mL of almond milk with 1:3 nut to
hot water ratio (Alozie Yetunde and Udofia 2015). The
same study also reports the mineral composition per 100 mL
of almond milk as zinc (4.58 mg), iron (1.40 mg), sodium
(6.38 mg), potassium (65.33 mg), magnesium (42.05), phos-
phorus (75.20 mg) and calcium (13.10 mg) (Alozie Yetunde
and Udofia 2015). Another study, used un-split small-sized
pistachio nuts for the preparation of pistachio milk (1:5 ratio
Figure 2. Schematic representation of oil in water emulsion instability behavior
during storage (the small black circles represents oil drop while large white
circles represent water drops.
Table 1. Possible processing units for plant-based beverages.
Sterilization treatment Processing unit Intensity Plant-based beverages References
Thermal High-temperature short time
pasteurization
(HTST) process
72
C for 15–20 sec Almond beverages (Amador-Espejo et al. 2015;
Hotrum et al. 2010)
(Dhakal et al. 2014)
(Ferragut et al. 2011)High pasteurization process 80–90
C for 15 sec Almond and soy milk
Ultra-high temperature
(UHT) process
135–150
C for 1–4 sec Almond and soy milk
Pressure High-pressure
processing (HPP)
58,000–87,000 psi or
400–600 MPa, at chilling or
room temperature
Almond and Walnut emulsion (Balasubramaniam, Farkas,
and Turek 2008)
Pressure with thermal Ultra-high-pressure
homogenization (UHPH)
Up to 200 MPa, 75
C Almond (Briviba et al. 2016) (Qin
et al. 2013)
High-pressure thermal
processing (HPTP)
Up to 800 MPa pressure and
above 60
C heating.
(Devi et al. 2015)
CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION 3

for nut: hot water) as a substitute for animal source milk
(Shakerardekani, Karim, and Vaseli 2013). They studied the
effect of processing conditions (making paste, pH, blending
time and milling roasted kernels) on compositional parame-
ters such as total soluble solids, total dry matter, fat, and
protein. The study shows processing of pistachio milk at pH
8.5 forms a stable emulsion with total soluble solid
(3.9
Brix), dry matter (10.3%), total fats (5.8%) and total
protein (4.0%) Nut based beverages are an excellent source
of vitamins as antioxidants. Almond milk is a good source
of vitamin B1 and B2 as antioxidants (Briviba et al. 2016),
alpha-tocopherol and vitamin E (Sethi, Tyagi, and Anurag
2016). Hazelnut beverage is also a potential source of phyto-
chemicals, especially lipid-soluble phenolic and antioxidant
(vitamin E) (Alasalvar et al. 2003; Singhal, Baker, and
Baker 2017).
Protein and fats quality
Types of protein
Almond seed contains a variety of proteins. The protein and
fat composition of the almond beverage are presented in
Table 3. By using two-dimensional electrophoresis tech-
nique, there have been approximately 188 different proteins
has been detected in almond seed (Li and He 2004). Fasoli
et al. (2011) also investigated 132 types of proteins in
almond milk. Amandine is the major almond protein and
accounts for 65–70% of total soluble proteins (Wolf and
Sathe 1998). Amandine protein originally belongs to the 11S
globulin family. It is a hexamer protein and it’s every mono-
mer contains two polypeptides (20–22 kDa basic subunit and
40–42 kDa acidic subunit) (Zhang et al. 2016). The major
protein in walnuts is glutelin (70.11%) with other minor
proteins being prolamin (5.33%), globulin (17.57%), and
albumin (6.81%) (Sze-Tao and Sathe 2000). The charge
repulsion, net charge, structure and the size of the protein
largely contribute to the solubility of the protein.
Additionally it’s a function of various environmental factors
such as, operating temperature, pH and state of the solution
(Pelegrine and Gasparetto 2005).
Protein solubility
The solubility of protein can be defined as the concentration
of protein present in the aqueous phase in relation to the
total quantity of protein balance between solid and aqueous
phases (Pelegrine and Gasparetto 2005). Zhang et al. (2016)
studied the effect of dry-heat (100–400
C), moist heat
(60–100
C), autoclave sterilization (dry flour and flour with
phosphate-buffered saline (PBS) and high pressure
400–580 MPa on dry flour and flour with BPS) treatments
on solubility of almond protein isolates (API) in hot water
in the ratio 1:9. The recovery of relative protein remained
constant for dry heat treatment between 100 and 200
C for
10 min. While, after 250
C (10 min) the recovery of protein
starts to decrease with no noticeable protein at 400
C. In
case of moist heat (at 100
C) and high-pressure treatments
to Pbs lower recovery and no loss of relative protein were
observed. Autoclaved samples show little changes to the
API. This study also explored the solubility of API during
high-pressure treatment in the presence of water and
observed a reduction in protein solubility). Dhakal et al.
(2014) also determined the solubility of almond milk (1:9
ratio for nuts to hot water) during thermal and pressure
treatment. An increase in pressure, decreased the solubility
Table 2. Physicochemical composition of plant-based beverages.
Parameters Almond oil bodies/emulsion Rice emulsion Soy emulsion References
Total solids 22.75 ± 0.22% — 8.20 ± 0.45% (Gallier, Gordon, and Singh
2012; Sivanandan, Toledo,
and Singh 2010)
The volume-weighted
average diameter
of particles
3.47 ± 0.13 lm 6.64 ± 0.00 lm 3.18 ± 0.59 lm (Durand, Franks, and Hosken
2003; Gallier, Gordon, and
Singh 2012; Sivanandan,
Toledo, and Singh 2010)
The surface-weighted average
diameter of particles
2.62 ± 0.12 lm 2.52 ± 0.00 lm 1.02 ± 0.03 lm (Durand, Franks, and Hosken
2003; Gallier, Gordon, and
Singh 2012; Sivanandan,
Toledo, and Singh 2010)
Specific surface area 2.28 ± 0.10 m2
/g — — (Gallier, Gordon, and
Singh 2012)
Vitamin A and b-carotene 5 IU/100 g vitamin A and
3 lg/100 g b-carotene
0.00 vitamin A 1 mg/100 g vitamin A (Maguire et al. 2004; Walstra
et al. 2005).
vitamin E 0.45 mg/g lipid 0.00 0.85 (Jensen 2002; Maguire
et al. 2004)
Vitamin C (mg/100 g) 0.00 0.00 6.00 (Gallier, Gordon, and
Singh 2012)
Thiamin (mg/100 g) 0.20 0.18 0.87 (Viturro et al. 2010)
Riboflavin (mg/100 g) 1.14 0.06 0.87 (Vanga and Raghavan 2018)
Niacin (mg/100 g) 11 2.15 1.62 (Vanga and Raghavan 2018)
Vitamin B6 (mg/100 g) 1.2 0.11 0.38 (Vanga and Raghavan 2018)
Folate, DFE (mg/100 g) 44 7 375 (Vanga and Raghavan 2018)
Vitamin B-12 (mg/100 g) 0.00 0.00 0.00 (Vanga and Raghavan 2018)
Vitamin D (mg/100 g) 0.00 0.00 0.00 (Vanga and Raghavan 2018)
Carbohydrates (g/100 g) 21.55 81.68 30.16 (Vanga and Raghavan 2018)
Fibers (g/100 g) 12.50 2.80 9.30 (Vanga and Raghavan 2018)
Total sugars (g/100 g) 4.35 — 7.33 (Vanga and Raghavan 2018)
4 S. QAMAR ET AL.

of almond milk protein while, thermal processing did not
significantly affect the protein solubility.
Protein stability
High pressure and thermal treatments bring some changes
to the conformation of the almond protein. Results obtained
from confocal laser scanning microscopy (CLSM) suggest
aggregation of the almond milk (1:9 ratio for nuts: hot
water) particles when subjected to thermal and pressure
treatments. Moreover, a high proportion of the large size of
aggregates and increase in viscosity was observed with the
increase in temperature. Whereas, homogenization notably
reduced the particle size and improved the whiteness index,
clarity, particle size and surface charge of almond milk
Bernat et al. (2015).
Types of fats
A number of studies have investigated the chemical compos-
ition of almond lipids (Miraliakbari and Shahidi 2008).
Sphingolipids, phospholipids, tocopherol, and phytosterols
(mainly a-tocopherol) are among the almond lipids
(Maguire et al. 2004) (Table 3). In almond milk, these lipid
bodies are low in molecular weight and mainly contains
oleosins. In addition, the phospholipid monolayer is entirely
covered with oleosins that prevent its hydrolysis by phos-
pholipases (Dhakal et al. 2014). Oleosins also helps to stabil-
ize oil bodies from coalescence as reported by Huang
(1994). Furthermore, it helps to equilibrate the polyunsatur-
ated fatty acid and mono-unsaturated fatty acids ratio,
which define the suitability of the products for people with
heart syndromes (Falagan 1994). According to Gallier et al.
(2010), more than 400 different fatty acids have been discov-
ered in bovine milk. However, in almond milk only 1% of
the total lipids contain long-chain fatty acids with a high
level of unsaturation (Table 3). Fasoli et al. (2011) also
reported that almond milk contains a small amount of
unsaturated fat compared to cow milk. The high antioxidant
content in almond lipids is considered useful to maintain
cholesterol within a suitable range and thereby reduces the
risk of heart disease (Fraser et al. 2002; Jenkins et al. 2008;
Tey et al. 2011).
Functional properties
Different studies investigated the functional properties of
plant-based protein beverages. These properties may vary
based on the source of proteins, their storage, processing
Table 3. Protein and fat quality of plant-based beverages.
Parameters Almond oil bodies/emulsion Rice emulsion Soy emulsion References
Fat globules size Smaller Larger Smaller (Sivanandan, Toledo, and
Singh 2010)
Cholesterol 0.02–0.03 mg cholesterol/g
almond lipid
0.00 0.00 (Viturro et al. 2010; Walstra
et al. 2005)
Phospholipid composition Phosphatidylethanolamine,
phosphatidylinositol,
phosphatidic acid and
phosphatidylcholine
— — (Gallier, Gordon, and
Singh 2012)
Unsaturated long-chain
fatty acids
87.8% 0.2 g/100 g 11.25 g/100 g (Forrest 1978; Gallier, Gordon,
and Singh 2012)
Short-chain (with 4–12
aliphatic tails) and
saturated fatty acids
C4:0 Butyric acid, C17:0
Margaric acid, C16: 1n7-cis-
9-Palmitoleic acid, C16:0
Palmitic acid, C18:0 Stearic
acid, C18: 1n9c Oleic acid,
C18:1n7c Vaccenic acid,
C18:2n6c Linoleic acid,
C20:0 Arachidic acid,
C20:n9-cis-11-Eicosenoic
acid, C18:3n6-cis-6,9,12-
Gamma linolenic acid,
short-chain fatty acid
(C4–C14), medium-chain
fatty acid (C15–C17), long-
chain fatty acid (C18–C22),
poly-unsaturated fatty acid,
saturated fatty acid, and
mono-unsaturated
fatty acid.
0.2 g/100 g short-chain and
0.11 g/100 g saturated
fatty acids
4.40 g/100 g short-chain and
2.88 g/100 g saturated
fatty acids
(Gallier, Gordon, and Singh
2012; Jensen 2002;
Miraliakbari and
Shahidi 2008)
Proteins (g/100 g) 21.15 6.81 36.49 (Chen, Lapsley, and Blumberg
2006; Forrest 1978)
Major proteins Amandine (70% of the total
soluble proteins)
Glycinin and b-conglycinin
are major proteins (about
70%), whereas probable thiol
protease minor
protein (2–3%)
(Tomatsu et al. 2013; Viturro
et al. 2010)
Sterols b-Sitosterol, stigmasterol and
campesterol
— — (Jensen 2002; Miraliakbari
and Shahidi 2008; Viturro
et al. 2010)
Total sterols 19.5 mg/100 g milk — — (Gallier, Gordon, and
Singh 2012)

and production treatments. These factors can be related to
either from molecular characteristics (distribution between
hydrophilic and hydrophobic moieties, flexibility and con-
formational stability) or from external influences (tempera-
ture, ionic strength, and pH level) (Bucko et al. 2015).
Protein functionality is a complex topic because it deter-
mines the behavior of protein in the emulsion. In many
cases binding properties, solubility and pH altered the func-
tionality and structure of the protein. Therefore, research
needs to be done to gain a better understanding of func-
tional properties, and to develop methods that can be scaled
into industrial levels.
Effect of pH
The effect of pH on the functional properties of API (1:5
ratio for nuts: acetone) had been determined by Sze-Tao
and Sathe (2000). The study reported high emulsion activity
index and oil absorption capacity (3.56 g/g) for API at pH
8.2 as compared to soy protein isolates (2.93 g/g). Functional
properties of defatted cashew nut protein concentrate
(CNPC), isolates (CNPI) and defatted powder (DCNP) have
been evaluated by Sze-Tao and Sathe (2000). Overall, a
decreasing trend was observed in the functional properties
of all selected samples as the pH decreased. CNPI has rela-
tively higher least gelation capacity, foam stability, emulsify-
ing stability index and water and oil absorption capacities
than CNPC and DCNP. Whereas, bulk density and emulsi-
fying activity index were lower in CNPI compared to CNPC
and DCNP (Ogunwolu et al. 2009). In another study, the
effect of pH on functional properties of walnut protein iso-
late (WPI), concentrate (WPC) and defatted walnut flour
(DFWF) (with 1:10 ratio for flakes: water) were also deter-
mined by Mao and Hua (2012). Results showed that com-
paratively, WPI had better functional properties than WPC
(with 1:20 ratio of flour: aqueous alcohol) (represented in
Figure 3).
Effect of heat treatment
For the intake of quality protein, it is very important to
determine the behavior of processed protein in food formu-
lations. Homogenization decreases the particle size of an
almond and hazelnut milk (with 8:100 ratio for nut: water)
resulting in a fine emulsion. However, heat treatment causes
protein denaturation and increases flocculation and coales-
cence, fat globules and particle size but did not affect
f-potential (Bernat et al. 2015). Effect of heat processing on
functional properties (including foaming and emulsifying
capacities, oil and water absorption and solubility) of cashew
nut kernels protein isolates (150 g of defatted flour in 1.5 l of
water) was examined by Neto et al. (2001). They observed
an improvement in the foaming ability (at pH 7 and 8) and
oil and water absorption capacities of heat-treated samples,
although the solubility and emulsifying capacity of raw
cashew nuts were greater at and above isoelectric point pH.
Effect of high-pressure treatment
During UHPH processing various physical phenomena (tur-
bulence, cavitation, shear, and collapse) arises through the
high-pressure treatment which leads to better dispersion
capacity as it produces strong interaction among macromo-
lecules in the aqueous phase and reduces the fat globule
size. Additionally, it breaks microbial cells therefore, it is
considered as a valuable technique from a hygienic point of
view (Briviba et al. 2016). Ferragut et al. (2011) explored the
colloidal stability and hygenicity of almond milk after
UHPH treatment. UHPH treatment produced a finer emul-
sion with improved colloidal stability and considerably
reduced the microbiological spores and total counts com-
pared to heat-treated (UHT and pasteurised) and unpro-
cessed (control) samples. Similarly in another study the
effect ultra-high-pressure homogenization (UHPH, 200 and
300 MPa) with various inlet temperatures (55, 65 and 75
C),
ultra-high-temperature (UHT, 142
C, 6 s) and pasteurization
(90
C, 90 s) on microbiological, chemical (hydroperoxide
index) and functional (hydrophobicity, particle size distribu-
tion and dispersion stability) properties of almond beverages
(with 0.06–0.12% almond protein, 4% w/w almond in water)
was determined by Valencia-Flores et al. (2013). The results
of microbiological and functional properties suggested high-
pressure treatment produced good quality (zero bacterial
load after 20 days’ incubation period at 30
C) and highly
stable almond beverages compared to pasteurization.
Recently, walnut protein isolates (10 fold suspension of
defatted walnut flour with deionized water, w/v) was used
for the determination of functional and physicochemical
Figure 3. Functional properties of walnut protein isolate (WPI), concentrate (WPC) and defatted walnut flour (DFWF) (Mao and Hua 2012).
6 S. QAMAR ET AL.

properties after high hydrostatic pressure treatment
(300–600 MPa for 20 min) (Qin et al. 2013). It was found
that high HHP treatment partially denatured the protein
and decreases the emulsion stability. Also significant modifi-
cation in the functional properties (emulsifying activity, sur-
face hydrophobicity, free sulfhydryl content and solubility)
and foaming capacity of walnut protein isolate emulsion
was observed.
Nut-based beverages also contain numerous colloidal
substances. On the processing, the colloidal dispersion of
nut-based beverages undergo some irreversible changes
which can alter the physical appearance. Recently, Dhakal
et al. (2014) investigated the effect of pressure (450 and
600 MPa at 30
C) and thermal treatment (72 and 85
C at
0.1 MPa) on the color of almond milk. Thermal treatment
did not show any significant changes in the color of
almond milk compared to raw almond milk. However,
during pressure treatment, the greenness and lightness val-
ues at 450 MPa increased. But, the intensity of color did
not increase with the further increment of pressure. In
another study, an improvement in the whiteness index and
clarity of almond and walnut milk (with 8:100 ratio for
nut: water) was observed after homogenization (Bernat
et al. 2015).
Protein digestibility
Absorption and digestibility are important parameters of
protein. The quality of protein is ranked on the basis of
amino acids composition and its digestibility criteria.
Protein cannot be considered as useful if it is non-digest-
ible or digested poorly. Sze-Tao and Sathe (2000) com-
pared the digestibility and functional properties of almond
protein isolates (API) with soy protein isolates (SPI) (1:5
ratio for nuts: acetone). From in vitro digestibility measure-
ments, it was observed that API was easily digestible and
hydrolyzed by pepsin. In comparison to SPI, API has less
viscosity, better oil absorption capacity and emulsion activ-
ity index.
An improvement in the in vitro digestibility of walnut
protein emulsion after high hydrostatic pressure (HHP)
treatment (300–600 MPa for 20 min) was observed by Qin
et al. (2013). In another study, El-Aal, Hamza, and Rahma
(1986) evaluated the in vitro digestibility of the apricot
kernel protein isolates by using trypsin or pepsin and pep-
sin-pancreatin system and found digestibility was quite low
with trypsin or pepsin while relatively higher in the pepsin-
pancreatin system.
Fats digestibility
Lipid digestibility of almond emulsion, oil and nuts via
using magnetic resonance spectroscopy in rats had been
investigated by Gallier et al. (2014). A higher rate of fatty
acid digestibility in almond milk was observed (92.2%) com-
pared to tween-oil almond emulsion (88.7%) and whole
almonds (91.0%).
Plant-based beverages from legumes and
their benefits
Legumes belong to the Leguminosae plant family and con-
sidered the world’s most significant source of food. Legume-
based proteins are gaining more importance as they provide
different desired functional properties such as fat-absorbing,
gelling, water binding, and emulsifying properties (Grac¸a,
Raymundo, and de Sousa 2016). Soya is a predominant leg-
ume-based beverage as it is a good alternative to enhance
the technological performance and nutritional properties of
animal-based foods. One of the most prominent plant pro-
tein sources is pea seeds, which is widely available on a
commercial scale. Pea proteins show similar properties like
soybean proteins (Grac¸a, Raymundo, and de Sousa 2016).
Pea contains a high amount of lysine and amino acids and
contains about 20–25% total protein contents (Schneider
and Lacampagne 2000). Pea seeds also exhibit promising
functional properties such as emulsifying, foaming and gel-
ling (T€om€osk€ozi et al. 2001). Chickpea is also another
important legume that is a good source of protein (Zhang
et al. 2011). Concentrates and protein isolates extracted
from chickpea have been used for the preparation of bread,
cheese, and different products of meat (Clemente et al.
1999). Furthermore, lentils (Lens culinaris M.) are a popular
source of plant-based proteins that belongs to the legume
family that provide more than 21–31% (w/w) protein con-
tent (Joshi et al. 2011). From a nutritional perspective,
legumes contain an adequate amount of different contents
such as protein, vitamins, and minerals, they contain more
than two to three times protein content compared to cereals
grain (Olalekan and Bosede 2010).
Physicochemical properties
Legumes are a good protein source and able to support oil-
water emulsion (Caygill, Jones, and Ferber 1981). The physi-
cochemical composition of five different legumes (black
gram, pigeon pea, chickpea, cowpea and mung bean) has
been analyzed and used for the preparation of emulsion.
From among the selected legumes, mung bean contains
higher amount of moisture (102.0 g/kg), cowpea contains a
higher quantity of crude protein (256.0 g/kg), ash content
(37.0 g/kg) and protein dispersibility in whole seed (74.5%)
and chickpea had high crude fiber (99.0 g/kg) and oil
(20.1 g/kg) with a high percentage of protein dispersibility.
However, milk (with 1:4 ratio of seed and water) obtained
from cowpea contains high protein contents (44.9 g/kg), ash
(8.3 g/kg) and total sugars (17.7 g/kg) while mung bean milk
had a high ratio of moisture (884.0 g/kg) and carbohydrates
(44.3 g/kg). From the mineral composition study, cowpea
milk has high potassium (12.7 g/kg) and phosphorus (5.07 g/
kg), mung bean milk has high zinc (0.38 g/kg) and chickpea
milk has high sodium (0.72 g/kg) and calcium (0.88 g/kg)
(Caygill, Jones, and Ferber 1981). The physicochemical com-
positional analysis of chickpea hydrolysates (CPH) and pro-
tein isolates (CPI) per 100 g of dry matter show that both
CPH and CPI has polyphenols less than 0.1 g; CPH has high
protein (91.8 g N Â 25) and ash content (5.5 g) while CPI

has higher fat content (1.0 g), total fiber (2.1 g), total sugar
(0.2 g) (Clemente et al. 1999). Normally soy milk contains
2.9% total carbohydrates, 0.5% total ash contents, 2.0% total
fat and 3.5% protein (Ikya et al. 2013). The physicochemical
composition of soy milk is also presented in Table 2.
Types of protein
The amino acid composition of chickpea, cowpea and mung
bean milk (1:4 ratio of seed to water) was determined by
Caygill, Jones, and Ferber (1981). Which shows chickpea
milk has a high content of threonine (238.0 g/kg N), glycine
(231.0 g/kg N), alanine (258.0 g/kg N) and arginine (566.0 g/
kg N). Cowpea milk is rich in lysine (430.0 g/kg N), phenyl-
alanine (348.0 g/kg N), methionine (151.0 g/kg N) and histi-
dine (176.0 g/kg N) while mung bean milk contains good
quality isoleucine (310.0 g/kg N), leucine (504.0 g/kg N),
tyrosine (201.0 g/kg N), valine (347.0 g/kg N), asparagine
(714.0 g/kg N), serine (371.0 g/kg N), glutamine (1124.0 g/kg
N) and proline (240.0 g/kg N). The amino acid composition
of CPI and CPH was investigated by Clemente et al. (1999)
and Sanchez-Vioque et al. (1999) who obtained high level of
glutamic acid and aspartic acid for both CPI and CPH com-
pared to other amino acids. Ladjal-Ettoumi et al. (2016)
investigated the protein profile of lentil, chickpea and pea
protein isolates (1:10 ratio of flour to water) by using SDS-
PAGE. The molecular weight of polypeptide subunits lies
between 27 and 75 KDa that are attributed to vicilin and
legumin constituents. Among legumes, chickpea is an
important source of dietary protein with high bioavailability
of essential amino acid. The essential amino acid in chickpea
protein hydrolysates (CPH) show different biological activ-
ities including reduction of antigenic activity and angioten-
sin I-converting enzyme (ACE) inhibition (Zhang
et al. 2011).
In another study, legume-based milk of pea, chickpea,
lupine, mung bean, soy, lentil bean and faba bean (10%
flour in water) showed a high level of the most essential
amino acid (Sosulski, Chakraborty, and Humbert 1978). Soy
protein isolates contains two types of protein, including
major whey protein (composed on kunitz trypsin inhibitors
(KTI, 20 kDa), lectin (33 kDa), b-amylase (61.7 kDa) and lip-
oxygenase (LOX, 102 kDa)) and minor globulin protein
(c-conglycinin) (Nishinari et al. 2014). Tomatsu et al. (2013)
isolated eight novel inhibitory peptides from processed soy
milk and prepared enhanced inhibitory active (ACE) proc-
essed plant source milk compared to regular soya milk for
the patients with hypertension. These inhibitory peptides are
WNPR (IC50, 880.0 lM) from Palmate-like pentafoliata 1
parent protein, LEPP (IC50, 100.1 lM) from inositol phos-
phate kinase parent protein, VNP (IC50, 32.5 lM) from
dihydrodipicolinate synthase parent protein, IAV (IC50,
27.0 lM) from glycinin G1 parent protein, LHPGDAQR
(IC50, 10.3 lM) from b-conglycinin b subunit parent pro-
tein, FVP (IC50, 10.1 lM) from D-myo-inositol 3-phosphate
synthase parent protein, WHP (IC50, 4.8 lM) from phytase
parent protein and FFYY (IC50, 1.9 lM) from nitrate trans-
porter NRT1–5 parent protein.
Protein solubility
In legumes, the functional and emulsifying properties greatly
depend on the method used in the manufacture of the pro-
teins as they have a low tendency to adsorb at the oil-in-
water (O/W) emulsion. Cepeda, Villaran, and Aranguiz
(1998) investigated the enzymatic hydrolysis and protein
solubility of faba bean isolate obtained by freeze-dried and
spray drying during emulsion preparation (1:4 ratio of faba
bean to water). They observed higher solubility of protein
obtained by the spray drying method that influenced the
resulting emulsion properties. Clemente et al. (1999) found
that chickpea protein isolate (CPI) can be used for the for-
mation of chickpea protein hydrolysates (CPH) as it has
good solubility and high protein quality compared to the
starting material (CPI). Ashraf et al. (2012) evaluated the
effect of microwave treatment on the functional properties
protein solubility of a legume isolate (red bean flour) and
their blends (2 g flour in 40–100 mL water). Microwave
treatment for a short time (50 sec) significantly enhanced
the solubility of protein and functionality (foaming and
emulsifying capacities, oil binding and water holding) of leg-
ume isolates. But long term exposure (300 sec) of legume
paste diminished the protein quality of processed food.
Hefnawy (2011) also determined the effect of microwave
treatment on lentils paste (1:10 ratio for seed: water) and
found an improvement in the solubility of the protein con-
tent. Lee, Ryu, and Rhee (2003) determined the effect of dif-
ferent temperature (25, 50 and 75
C) pH (2–12) and NaCl
concentration (0.1–1.0 M) on the protein solubility of soy
protein isolates, concentrates and flour. With the increase in
pH and salt concentration, the protein solubility of isolates,
concentrates and flour of soy significantly decreases due to
protein damage. However, heat treatment did not bring any
significant changes on the soy protein solubility.
Protein stability
Ladjal-Ettoumi et al. (2016) determined the thermal stability
of chickpeas (CPI), pea protein (PPI) and lentil (LPI) pro-
tein isolates (1:10 ratio for flour: water). The thermal stabil-
ity was higher for CPI compared to PPI and LPI. A similar
trend was observed with a disulfide bond (SS) and free sul-
phahydryl group (SH) contents of protein fraction profile.
Chickpea isolates contain a high amount of SS and SH (20.2
and 59.7 mmol/g) compared to pea protein isolates (14.7
and 45.1 mmol/g) and lentil protein isolates (7.5 and
31.0 mmol/g). Koberstein-Hajda and Dickinson (1996) also
determined the effect of primary lipophilic emulsifier (Span
80) and secondary hydrophilic emulsifier (sodium caseinate)
on the protein stability of faba bean protein isolates emul-
sion. Results show that emulsions prepared from unmodified
faba bean protein isolates were stable.
The effect of protein concentration, pH and temperature
on the protein stability of soy protein isolates had been
studied by Petruccelli and Anon (1995). Increase in protein
8 S. QAMAR ET AL.

concentration, pH (from acidic to alkaline) and temperature
(50–100
C) increases the viscosity of emulsion and favored
the aggregation of the protein. In another study, the poly-
peptide conformation of soy protein isolates, 7S and 11S
globulins (b-conglycinin and glycinin) at acidic, neutral and
alkaline media were determined by using SDS-PAGE pattern
(Mauri and A~non 2006). At neutral pH (pH 8), high
molecular weight protein (94,000 KDa) of SPI was aggre-
gated. However, at 11 and 2 pH values, high molecular
weight protein from 7S and 11S globulins were aggregated
(represented in Figure 4).
Types of fats
The distribution and stability of fat in homogenized legume-
based milk containing pea, chickpea, lupine, mung bean,
soy, lentil bean and faba bean (10% flour in water) com-
pared to cow and skim milk was investigated by Sosulski,
Chakraborty, and Humbert (1978). They observed homogen-
ization uniformly distributed the fat content in legume-
based milk compared to cow milk. After storage (24 h) the
amount of fat content in the upper layer increases in con-
trast to the lower layer. However, the quantity of fat in both
layers of legumes milk (10% flour in water) were almost
similar to the cow milk. Soy milk is considered good for
cardiovascular health due to the presence of polyunsaturated
and monounsaturated fatty acid. The most abundant bio-
active components in soy milk are phytosterols and isofla-
vone which are responsible for the cholesterol-lowering
properties of soy milk (Sethi, Tyagi, and Anurag 2016).
Table 3 also presented the fatty acid composition of
soy milk.
Effect of pH, ionic strength and emulsion prepar-
ation method
Zhang et al. (2009) studied the emulsifying properties of
chickpea protein isolate (1:10 ratio for flour: water) as a
function of ionic strength, pH, percentage of oil and protein
concentration. The study found a positive effect of increas-
ing pH and ionic strength on the hydrophobicity and emul-
sifying activity index (EAI), Figure 5.
Chang et al. (2015) observed the emulsifying properties
(emulsion stability, droplet size, rheology, interfacial tension,
solubility, hydrophobicity and surface charge) of canola, len-
til, soy and pea protein isolates (1:10 ratio for flour: Tris-
HCl pH 7 buffer). The results revealed that, at pH 3.0, pH
7.0 and at the isoelectric point all selected protein samples
formed a stable emulsion with better interfacial rheological
properties observed at pH 3.0. In addition, lentil protein was
considered the most promising alternative to soy protein
due to their high hydrophobicity, solubility and surface
charge at pH 3.0.
The effect of pH on functional properties (Z¸ potential,
creaming index, flocculation index (FI) and coalescence
index (CI)) of lentil (LP), chickpea (CP) and pea protein
(PP) isolates (1:10 ratio for flour to water) was determined
by Ladjal-Ettoumi et al. (2016). All selected protein isolates
had shown almost the same trend in the change of zeta (Z¸)
profile from 30 to À40 by changing the pH (2–8). The
results of creaming index showed that relatively CP had
higher creaming index (73.3%) as compared to LP (58.3%)
and PP (46.1%). However, LP has shown high FI (4.4%) as
compared to CP (1.7%) and PP (3.6%) at pH 7. Whereas,
PP had high CI (76.2%) as compared to CP (66.3%) and LP
(39.8%) at 4.5 pH.
In another study, the effect of protein concentration
(0.5–2%, w/v) and ionic strength on the emulsifying proper-
ties of lentil, chickpea and pea protein isolates (1:10 ratio
for flour: water) was also evaluated by Ettoumi, Chibane,
and Romero (2016). The results show a high protein con-
centration (2%), the best emulsifying properties in term of
droplet size distribution was observed with lentil and chick-
pea. While, all proteins show best creaming stability at the
lowest protein concentration of 0.5%. Overall, results suggest
LP emulsion was more stable as compared to other two leg-
ume proteins. However, in terms of ionic strength, it was
noticed that all proteins were more sensitive with increasing
concentration of NaCl.
Liang and Tang (2014) explored the effect of protein con-
centration (0.25–3.0 g/100 mL) on pea protein emulsion pre-
pared at pH 3.0 from PPI (93.0 g protein per 100 g powder).
PPI emulsion had shown best Pickering stabilization with
the diameter of the particles of 134–165 nm. It was noticed
that, the PPI emulsion with a concentration of 0.2 g/100 mL
had very small size of particles (135 nm) and low creaming
index as presented in Figure 6. Whereas, no creaming index
of emulsion occurred after 2.0 g/100 mL concentrations
because at higher concentrations flocculated drop-
lets formed.
Zhang, Jiang, and Wang (2007) investigated the effects of
pH, calcium and sodium chloride on chickpea protein iso-
lates (CPI) (1:10 ratio for flour: water) gelation properties.
The results show that, under acidic conditions, the ionic
strength of dispersions had a direct association with gelation
properties of CPI, while at pH 7.0 elastic parameters of CPI
decreased. It was also found that the gel strength of CPI at
Figure 4. SDS-PAGE profile of SPI and 7S and 11S globulin (Mauri and
A~non 2006).

pH 3.0 was stronger in CaCl2 treated samples compared to
NaCl treated samples.
The effect of emulsion preparation method on the emul-
sifying (creaming stability, EAI-ESI, stability indices/emul-
sion activity and emulsion capacity) and functional
properties (droplet size, interfacial tension, protein solubility
and hydrophobicity/surface charge) of four different legumes
isolates (1:10 ratio for flour:water) including, pea (PPI), len-
til (LPI), faba bean (FbPI) and chickpea (CPI) protein iso-
lates (produced by isoelectric precipitation) had been
evaluated by Karaca, Low, and Nickerson (2011). The results
showed functional and emulsifying properties of all selected
legumes were significantly affected by the method of isolate
production. PPI prepared through isoelectric precipitation
had shown the highest value of surface hydrophobicity.
While LPI prepared through salt extraction method had the
highest emulsion capacity (EC is inverse phenome, at which
oil is emulsified by protein). However, selected legumes pre-
pared through both methods formed stable emulsions with
smaller droplet sizes, high surface charges and displayed
high EAI-ESI results.
Heating is commonly used as a processing treatment to
modify the functional properties of food products. One
study (Palazolo, Sobral, and Wagner 2011) investigated the
stability of emulsion created by using soy protein isolate
(56% total protein). The emulsion was created by mixing
soy flour and water in the ratio 1:10 and were subjected to
pasteurization and sterilization. Stability of oil-in-water
emulsion of soy protein isolates increased after thermal
processing and generate higher surface hydrophobicity with
smaller oil droplet size. In addition, heat treatment also
improves the oil freeze-thawing stability of soy protein oil-
in-water emulsion (Palazolo, Sobral, and Wagner 2011).
Heat treatment (95
C for 30 min) on the emulsifying prop-
erties of pea protein isolates (1:10 ratio for flour:water)
show excellent emulsifying abilities in term of creaming sta-
bility, hydrodynamic diameter, protein adsorption percent-
age and aggregation of protein compared to untreated pea
protein samples (Peng et al. 2016). McCarthy et al. (2016)
investigated the effect of micro-fluidisation, homogenization,
ultrasonication and thermal treatment on PPI (with 82%
protein). It was reported that microfluidisation and hom-
ogenization reduce the droplet and particle size and make
the most uniform emulsion. ultrasonication (50
C) treat-
ment also produce stable and uniform the droplet size emul-
sion but it increases the viscosity of emulsion. However,
protein aggregation and gel formation occurred during
thermal treatment at 71 and 79
C.
Effect of high-pressure treatment
The effect of high-pressure (up to 250 MPa for 20 min) and
temperature (up to 80
C for 2 min) on the emulsifying
properties of faba bean protein (including 11S
globulin (95%) and 15S globulin (5%)) system containing
Figure 5. Effect of pH (A) and ionic strength (B) on the emulsifying index of chickpea protein (Zhang et al. 2009).
Figure 6. Effect of protein concentration on particle size and creaming index of PPI (Liang and Tang 2014).
10 S. QAMAR ET AL.

k-carrageenan (k-CAR) and sulfated polysaccharides i-carra-
geenan (i-CAR) at pH 8.0 were determined by Galazka,
Dickinson, and Ledward (1999). High pressure and tempera-
ture treatment lead to substantially large droplets with
decreasing emulsion stability and emulsifying efficiency.
However, the presence of i-CAR resulted in a significant
increase in creaming stability, best stability and smallest
droplets in fresh emulsions.
Soy is commonly used for the preparation of plant pro-
tein beverages, but due to the complex protein structure of
soy, limited information is available on the emulsifying and
functional properties of soy protein (Liu, Lee, and
Damodaran 1999; Yao, Tanteeratarm, and Wei 1990). The
effect of high pressure treatment (200–600 MPa) on the
emulsifying activity index of 11S and 7S globulins and pro-
tein isolates (1: 5 ratio for flour:water) of soy (at pH 6.5 and
7.5, and 0.25–0.75% concentration) were determined by
Molina, Papadopoulou, and Ledward (2001) and presented
in Figure 7. A study has shown that at 400 MPa 7S globulin
and SPI had shown higher EAI value. While, 11S globulin
shown higher EAI at 200 MPa.
Chitra et al. (1995) investigated the in vitro digestibility of
three legumes protein - mung bean, chickpea and pea with
high protein content whose digestibility varies in the range
67.2% to 72.2%, 65.3% to 79.4% and 60.4% to 74.4% respect-
ively. Previously it was suggested that different home proc-
essing techniques such as steaming, frying, parching,
roasting, boiling, fermentation, sprouting, soaking and
decortication of chickpea hydrolysates increase the protein
digestibility and remove anti-nutritional factors (Clemente
et al. 1999). The same study also reveals that after heat treat-
ment the percentage of amino acids (including leucine, tyro-
sine, arginine, lysine, cysteine, and methionine) decreased.
The ratio between essential amino acids and total amino
acids decreased in heat-treated chickpeas hydrolysates to
39.3% from 95.0%. Additionally, the highest reduction was
observed with amino acids lysine (13.2%) and cyst-
eine (15%).
Ulloa, Valencia, and Garcia (1988) observed increased
digestibility during in vivo digestibility study of infant for-
mula with chickpea proteins concentrates and suggest it can
be animal milk alternative for children’s with the compro-
mised gastrointestinal condition. Soy formula is widely used
across the world to feed millions of infants. SPI and SPC
were used for the determination of in vivo digestibility. The
study presents slightly high protein digestibility of soy pro-
tein isolates (89.6%) as compared to soy protein concen-
trates (87.7%) (Hsu et al. 1977). The in vitro digestibility of
SPI nutritional beverage and SPI low hydrolysis samples
were also estimated by (Pinto, Lajolo, and Genovese 2005).
SPI nutritional beverage (93.0%) shown relatively higher in
vitro digestibility in comparison with SPI low hydrolysis
samples (76.0%).
Fats digestibility
Full fat soy meal with linoleic and oleic acids as dominant
fatty acids, 6.13% phospholipids, 0.51% monoacylglycerols,
1.87% diacylglycerols, 0.77% free sterols, 2.14% free fatty
acids, 86.72% triacylglycerols and 1.68% steryl esters in
19.25% total lipids were given to the Penaeus monodon for
the determination of lipid digestibility of full fat soy meal.
The digestibility coefficients for soy lipids including total
phospholipids was 63.82%, free sterols were 61.24%, free
fatty acids was 69.42%, triacylglycerols was 96.09% and
steryl esters was 27.37% (Merican and Shim 1995).
Plant-based beverages from seeds and
their benefits
Seeds have immense economically and biological importance
with high oil content, protein and starch reserves. Seeds are
commonly utilized to manufacture value-added food prod-
ucts. For example, seed isolates can be used in different
nutritional supplements and as functional ingredients in
various food products (El-Adawy and Taha 2001). From an
industrial point of view, hempseed is considered the most
beneficial because of the storage proteins legumin (67–75%)
Figure 7. Effect of pressure treatment on the emulsifying index of SPI (A), 7S globulin (B) and 11S globulin (Molina, Papadopoulou, and Ledward 2001).

and albumin (25–37%) with good digestibility properties
and no protease inhibitors. Melon and pumpkin are very
popular seeds used as a snack (El-Adawy and Taha 2001).
Another seed that is a cheap source of essential proteins is
sesame seed. Among the top thirteen oil seeds, sesame seed
is recognized as the most valuable oil seeds with nutty-flav-
oured, which produce 90% of global edible oil (Bamigboye,
Okafor, and Adepoju 2010). It contains phytochemicals spe-
cifically phenolic antioxidants and fiber. Sesame based prod-
ucts are a source of high protein with low carbohydrate,
which is considered suitable for diabetes patients. In com-
parison with casein, the ratio of arginine and lysine acids is
0.67 in the globulin fraction (67.3%) of a sesame seed, which
is considered more suitable for cholesterol metabolism.
Defatted sesame food consists of different bioactive compo-
nents such as lignan glycosides with sesamolinol, pinoresinol
and sesaminol glucosides. The hydrophilic components of
sesame products show neuroprotective, anti-carcinogenic
and anti-oxidative activities. Sesame seed also contains
flavonoid contents and these flavonoids have strong
hypoglycemic and hypolipidaemic activity (Das and
Bhattacharjee 2015).
The physicochemical composition of hemp seed protein iso-
lates (HPI) and hemp meal (1:20 ratio for Hemp seed meal:-
water) show that they contain about 89.0 and 50.2% total
protein, 5.0 and 6.7% moisture, 2.3 and 3.2% ash and 3.7
and 39.9% of other contents (Tang et al. 2006). Elleuch
et al. (2007) performed the comparative study on the physi-
cochemical composition of sesame seed paste (after roasting
and dehulling) and raw sesame seed. The study showed
lower amounts of protein and oil but higher quantities of
polyphenol, ash and dietary fiber in sesame seed paste. In
another study Kajihausa, Fasasi, and Atolagbe (2014) investi-
gated the effect of sprouting, soaking and boiling time on
nutritional content and proximate composition of sesame
seed flour. Sprouting and soaking decreased the nutrient but
increased the protein and moisture content while boiling
reduce both these content greatly.
The physicochemical composition of fatted and defatted
orange seed flour isolates has been determined by Akpata
and Akubor (1999). Physicochemical composition showed
high moisture (6.25%), crude fat (54.8%), crude protein
(3.15%), crude fiber (7.0%) and ash content (2.85%) in
undehulled orange seed flour compared to dehulled orange
seed flour. Similarly, the functional properties and proximate
composition of beniseed or sesame seed flour were also eval-
uated by (Egbekun and Ehieze 1997). Results show defatting
increased mineral contents, carbohydrates, crude fiber, ash
and crude protein.
Types of protein
In any food system, the structure and amount of protein
play a very important role in the formation of novel food
formulations. Malomo and Aluko (2015) determined the
structural properties (circular dichroism, intrinsic fluores-
cence, and gel electrophoresis) of salt-soluble globulin (GLB)
and water-soluble albumin (ALB) proteins in hemp seed iso-
lates (1:10 ratio of Hemp seed to water). Structural proper-
ties showed GLB contains a higher amount of hydrophobic
residues and aromatic contents compared to ALB. Recently,
Girgih et al. (2014) identified approximately 23 short-chain
(65 amino acids) peptides in hemp seed protein hydrolysate
(HPH) by using reverse-phase HPLC and tandem mass
spectrometry. These peptides also possess antihypertensive
and antioxidant activities. In another study, HPI (1:20 ratio
for seed: water) was also used for the evaluation of struc-
tural (amino acid composition) properties in comparison
with soy protein isolate (SPI) (Tang et al. 2006). The amino
acid composition in one gram of HPI protein contains lysine
(43.3 mg), phenylalanine (49.6 mg), cysteine (1.7 mg),
methionine (14.5 mg), leucine (69.0 mg), isoleucine
(41.5 mg), valine (51.8 mg), tyrosine (38.2 mg), proline
(47.2 mg), alanine (47.0 mg), threonine (47.6 mg), arginine
(103.2 mg), histidine (29.3 mg), glycine (41.7 mg), serine
(54.0 mg), glutamic acid (168.1 mg) and aspartic acid
(98.0 mg). The study also suggested that HPI contains a
comparatively higher quantity of essential amino acids
which are sufficient to feed 2 to 5-year-old children (accord-
ing to FAO/WHO). Additionally, the essential amino acid
content in hemp are sufficient for the consumption of
humans and more valuable as compared to soybean.
Achouri, Nail, and Boye (2012) extracted a selective frac-
tion of protein from sesame seed isolates by using ammo-
nium sulfate and sodium chloride and found three different
polypeptide bands (11S, 7S, and 2S) in sesame seed protein.
Comparison of functional properties of sesame seed protein
isolates with soy protein isolates yielded greater foaming and
emulsifying properties with sesame protein isolates.
Protein solubility
Minimum protein solubility of hemp protein isolate (HPI)
and hemp seed protein meal (HPM) (1:20 ratio for hemp
seed: water) was observed at pH 4.0 and 3.0 and protein
solubility increased with the increase of pH. From structural
composition (amino acid composition) it was shown argin-
ine/lysine (Arg/Lys) ratio was higher in HPI (5.52%) com-
pared to HPM (3.35%). While higher quality emulsion
properties were shown by HPM compared to HPI-formed
emulsions (Malomo, He, and Aluko 2014).
The effect of enzymatic hydrolysis (using pepsin and
alcalde) on the solubility of on pumpkin seed protein iso-
lates (PSPI), as a function of ionic strength (0–1 mol/dm3
NaCl) and pH (3–8) was determined by Pericin et al.
(2008). Also, PSPI was used to obtain the hydrolysates. The
lowest solubility of protein isolates was observed at pH 5.
Comparatively the solubility of hydrolysates was higher than
isolates of pumpkin seed (Bucko et al. 2015). The effect of
different pH regions on the solubility of pumpkin seed iso-
lates has also been determined by Rezig et al. (2013). The
solubility of pumpkin seed isolates is highly varied in differ-
ent pH regions, solubility increases with increase in pH
12 S. QAMAR ET AL.

reaching maximum (70–80%) at pH value above 7. Another
study showed maximum solubility (91%) of pumpkin seed
globulins at 3.99% NaCl concentration and pH 7.69 (Pericin
et al. 2008).
Protein stability
In various studies, it has been reported that food proteins
which cause a severe type of allergenic reactions can be
altered by processing. Processing techniques can modify the
food proteins structure via changing covalent interactions
between the components of food or through aggregation
and unfolding of proteins (Raikos 2010). The effect of ther-
mal processing (dry roasting, microwave heating, and boil-
ing), high pressure (100–500 MPa) and pH on sesame
protein isolates antigenic properties were investigated by
Achouri and Boye (2013). Microwave treatment showed
decreasing behavior of antigenic properties. However, from
ELISA response, it was shown that high-pressure treatment
at all pH values markedly reduces the allergenicity.
Types of fats
The most common fatty acids in hemp seed isolates and oil
are stearidonic acid, a and c-linolenic acid and oleic acid
(Malomo, He, and Aluko 2014). In hemp seed isolates the
fat reservoirs are most valuable because it contains several
essential polyunsaturated fatty acids (omega-3 a-linolenic
acid and linoleic), vitamins (vitamin E) and essential lipid-
soluble antioxidant (Kriese et al. 2004). Melon (Citrullus sp.)
and pumpkin (Cucurbita sp.) seed isolates are also a rich
source of fats (37.8–45.4%). The fatty acid composition has
shown that pumpkin seed has higher monounsaturated fatty
acids (20.8%), total saturated fatty acids (23.5%), oleic acid
(20.4%), palmitoleic acid (0.44%) and myristic acid (0.17%).
While paprika seed have higher polyunsaturated fatty acids
(67.8%), total unsaturated fatty acids (82.5%), linoleic acid
(67.8%) and palmitic acid (13.8%) and watermelon seed
have higher linolenic acid (0.35%), stearic acid (10.2%)
(El-Adawy and Taha 2001).
The structural analysis of pectin obtained from pumpkin
seed isolates showed mainly of a-1,4-D-galacturonic acid
(Cui and Chang 2014). The pumpkin seed isolates and oil
have various bioactive components and unsaturated fatty
acids. These components have several human health benefits
such as diuretic and anti-inflammatory properties. They also
help to reduce a certain type of cancer, cholesterol level and
free radicals (Bucko et al. 2015).
Effect of pH and ionic strength
Recently defatted hemp seed protein meal (HPM) and hemp
protein isolate (HPI, 1:20 ratio for hemp seed: water) were
used to investigate the effect of protein concentration and
pH on functional and structural properties of the resulting
emulsion (Malomo, He, and Aluko 2014). From results, it
was found that HPI had better foaming capacity at pH 3.0
and functional properties were dependent on the
confirmation of protein. In another study (Tang et al. 2006)
the effect of pH on the fat and water holding capacity of
HPI was compared with SPI. The results revealed that fat
holding capacity and surface hydrophobicity of both SPI
and HPI (1:20 ratio for seed: water) were similar but the
water holding capacity was slightly better for SPI. The emul-
sion stability and activity were considerably higher for SPI
as compared HPI. However an increase in pH from 3 to 8
significantly reduced the functional properties of both HPI
and SPI.
The effect pH and NaCl concentration on functional
properties, solubility and protein content of sesame seeds
(Kenana 1 cultivar) protein isolate were investigated by
Khalid, Babiker, and Tinay (2003). All emulsifying proper-
ties including, foam stability, foaming capacity, emulsion
stability, emulsifying activity, and capacity were greatly
affected by the concentration of NaCl and pH, especially
very sensitive at high salt concentration and acidic environ-
ment. In an alkaline environment (pH 9) dispersible and
highly viscous behavior of protein isolate was observed with
a bulk density of0.71 gm/ml, oil holding capacity of 1.50 ml
oil/g and water holding capacity of 2.10 ml H2O/g.
Bucko et al. (2015) evaluated the effect of ionic strength
(m ¼ 0.0–1.0 mol/dm3
NaCl) and pH (3.0–8.0) on emulsify-
ing, interfacial and functional properties (solubility) of
pumpkin seed isolates PSPI (with 94.3 g protein per 100 g
seeds). The effect of Ionic strength with pH 5 on PSPI at
pH 5–8 was very slight or insignificant while at pH 3 was
very prominent. Furthermore, with the increase in pH and
salt concentration, the interfacial properties and surface
pressure of PSPI were increases progressively. However, the
most stable emulsion of PSPI, regardless of added salt con-
centration, was obtained at pH 8.
Emulsifying properties of fatted and defatted flour of
orange seeds have been determined previously by Akpata
and Akubor (1999). Results showed water absorption cap-
acity for defatted samples was 240% and undefeated for
samples were 220% while the oil absorption capacity was
84% and gelation concentration ranges between 10 and 12%
(w/v). The foaming capacity, emulsion stability and emul-
sion activity were higher for full-fat orange seed flour than
defatted orange seed flour. Similarly, in another study by
Egbekun and Ehieze (1997) investigated the emulsifying
properties (nitrogen solubility, emulsion capacity, bulk dens-
ity, oil and water absorption, stability and foam capacity) of
defatted and full-fat beniseed. Results showed significantly
better functional properties in defatted flour of beniseed
compared to full-fat samples.
The effect of processing (light, storage, and heating) on the
oxidative stability of the hemp seed oil-in-water emulsions
was also explored by (Raikos, Konstantinidi, and Duthie
2015). The study showed light and thermal exposure can
enhance the lipid oxidation rate but did not significantly
affect the stability of emulsion during storage (at 4
C
for 10 days).

Effect of enzymatic hydrolysis
The emulsifying properties of enzymatically obtained raw
pectin fraction from pumpkin seed isolates (a-amylase and
cellulose with pronase) were studied by Cui and Chang
(2014). The protein content in pumpkin pectin treated with
pronase reduced significantly compared to untreated sam-
ples resulting in a loss of emulsifying properties in water
and oil mixture compared to untreated samples. Horax et al.
(2011) extracted protein content from bitter melon seed iso-
lates using 1.3 M NaCl at 9.0 pH and compared the emul-
sions of bitter melon seed isolates (BMSPI) and Soy protein
isolate (SPI). It was found that surface hydrophobicity was
higher in BMSPI than in SPI. The denaturation of the pro-
tein in BMSPI occurred at a higher temperature (113.1
C)
compared to SPI (78.0 and 94.8
C) and the solubility of SPI
at pH 7 was higher (86.7–90.1%) compared to BMSPI
(62.0–67.5%). The foaming stability, foaming capacity, and
emulsifying activity was lower for BMSPI compared to SPI.
The amino acid composition and in vitro digestibility of
hemp protein isolates (HPI) and soy protein isolate (SPI)
was determined by Ejeta, Hassen, and Mertz (1987). The
results showed a higher amount of essential amino acids
and improved protein digestibility for HPI (88–91%) com-
pared to SPI (71%). The various hemp protein products
were used for the determination of protein digestibility
(83.5–97.6%) and various biological values of protein includ-
ing total amino acid score (0.50–1.19%) and protein effi-
ciency ratio (0.62–1.00%) (House, Neufeld, and Leson 2010).
El-Adawy and Taha (2001) evaluated the in-vitro protein
digestibility of watermelon, pumpkin, and paprika seed iso-
lates. From results, it is clear that paprika seeds contain a
higher amount of total essential amino acids and lysine
compared to pumpkin seeds. While pumpkin seeds had
greater in-vitro protein digestibility (90.0%) as compared to
watermelon seed (87.9%) and paprika seed (72.7%).
Plant-based beverages from cereals and
their benefits
Cereals mainly consist of barley, oats, rice and sorghum.
They are also a member of the monocotyledonous grass
family. Cereals contain several micronutrients such as carbo-
hydrates, proteins, and fats. These micronutrients are essen-
tial for human growth. They also provide a significant
amount of calories (70%) and proteins (50%) (Zhou et al.
2013). Food products derived from cereals (especially whole
grains) have shown potential against different diseases such
as type 2 diabetes, coronary heart disease and some specific
type of cancer (Montonen et al. 2003). Furthermore, cereals
are also a good source of different vitamins, minerals, and
some essential micronutrients to maintain optimum health
level. In cereals, the use of rice protein is more prominent
because of their bland taste, color and presence of essential
amino acids (Chrastil 1992). In Table 4, the common types
of nutrients in cereals (including different minerals, vita-
mins, and micronutrients) and their concentration
are presented.
The physicochemical composition of cereals based milk and
beverages (including oat and rice) are dependent on the raw
material and fortification used for the preparation of bever-
age (Outi Elina M€akinen et al. 2016). From the physico-
chemical composition of defatted rice bran and rice bran it
was found that they have 62.94 and 43.73% carbohydrates,
7.43 and 8.57% ash contents, 7.31 and 8.58% moisture, 5.96
and 26.59% total fats and 15.59 and 12.45% total protein
(Wang et al. 2015). Recently the effect of combining rice
protein hydrolysates (DH ¼ 7.8%) with a nonionic surfac-
tant (Tween 20) on antioxidant activity of rice emulsion had
been determined by Cheetangdee and Benjakul (2015). They
observed that combining rice protein hydrolysates with
tween 20 systems had good antioxidant activity in rice emul-
sions compared to hydrolysates alone. The study on the
physicochemical composition of rice milk is also discussed
in Table 2.
Sorghum beverages are also considered as ideal choice
because of valuable dietary fibers, minerals and bioactive
compounds. The physicochemical composition of 100 g sor-
ghum flour shown that it contains 66.6 g carbohydrates,
3.4 g total ash, 9.1 g total fiber, 2.4 g lipids and 18.5 g total
protein. Study also presented that emulsion obtained from
sorghum flour (35 g flour into 250 mL water) had 23.3 g car-
bohydrates, 1.2 g total ash, 3.2 g total fiber, 0.8 g lipids and
6.5 g total protein (Queiroz et al. 2018).
Types of protein
Among cereals, oats protein is also considered valuable. The
total protein contents in oats are ranged between 12 and
24% with a higher ratio of globulins and albumins. Specially
globulins account 70–80% of total oat protein (Nesterenko
et al. 2013). The globulin protein from oat has 3 main
Table 4. Proximate composition of nutrients in Cereals.
Contents Concentration References
Magnesium and zinc Up to 20% (Zhou et al. 2013)
Carbohydrate 30–40% (Zhou et al. 2013)
Iron 30–40% (Zhou et al. 2013)
Riboflavin and niacin 20–30% (Zhou et al. 2013)
Proteins approximately 10–15% (Saulnier et al. 2007)
Starch approximately 60–70% of the grain (Saulnier et al. 2007)
Non-starch polysaccharides 3–8% of the total (Saulnier et al. 2007)
14 S. QAMAR ET AL.

fractions 3S, 7S and 11S (54 kDa molecular weight with
22 KDa basic subunits and 32 KDa acidic subunits). The
amino acid composition in 100 g oat protein shown valine
(5.2–5.7 g), tryptophan (0.8–0.9 g), threonine (3.3–3.7 g),
lysine (4.1–4.5 g) leucine (7.4–7.7 g), isoleucine (3.8–4.1 g)
and histidine (2.1–2.9 g) (M€akinen et al. 2017). In sorghum
protein, aromatic amino ranges and sulphur-containing
amino acid ranges around 82.0 and 28.0 mg/g. While the
total amino acid is mainly based on valine (53.0 mg/g), tryp-
tophan (11.0 mg/g), threonine (33.0 mg/g), lysine (22.0 mg/
g), leucine (140.0 mg/g), isoleucine (40.0 mg/g), histidine
(24.0 mg/g) (Taylor and Taylor 2017).
Wang et al. (2015) analyzed the protein fractions from
the rice bran based on their purity (P) and protein extrac-
tion rate (PER). They also determined the amino acid com-
position in these protein fractions. Rice bran protein was
divided into 2 main sections of a protein named as rice
bran protein fractions (RBPF) and concentrated rice bran
protein (CRBP). CRBP had shown 68.44% P and 49.39%
PER. Further, RBPF was divided into four section including
glutelin (with 70.28% P and 23.40% PER), prolamin (with
45.23% P and 5.54% PER), globulin (with 78.46% P and
30.74% PER) and albumin (with 65.65% P and 34.39%
PER). The amino acid composition of these fractions shows
that 100 g fraction of CRBP had a higher content of aspartic
acid (11.96 g). Glutelin had a high amount of isoleucine
(3.99 g), methionine (2.49 g), valine (7.51 g) and serine
(5.53 g). Prolamin had a larger quantity of phenylalanine
(7.52 g), tyrosine (6.14 g), leucine (11.57 g), cysteine (3.02 g),
alanine (6.43 g) and glutamate (17.99 g). Globulin fraction is
rich with arginine (10.82 g) and histidine (4.42 g). While
albumin showed a high value of proline (4.79 g), lysine
(6.62 g), glycine (5.78 g) and threonine (4.41 g). In another
study, the rice protein was isolated from Australian rice
flour and used for the determination of structural properties.
The main rice protein fractions were prolamin (2.7%), albu-
min (6.0%), globulin (15.0%) and glutelin (75.0%) (Agboola,
Ng, and Mills 2005). Recently, the complete proteome of
rice milk had been performed by (Manfredi et al. 2017). 158
protein species were identified by isoelectric focusing and
distributed into different classes as an oxidoreductase
(10.0%), hydrolase (16%), enzyme modulator (14%) and
nucleic binding (22%) protein class (as presented in
Figure 8).
Protein stability
The rice and oat milk have poor protein stability due to the
presence of high starch content. Previously, to improve the
stability of the protein in rice and oat milk different enzym-
atic treatment has been used (Sethi, Tyagi, and Anurag
2016). Runyon et al. (2015) used asymmetric flow field-flow
fractionation (AF4) method to separate monomeric proteins
from b-glucan polysaccharides in oats flour paste and eval-
uated the effect of thermal treatment on the stability and
structural conformation of this protein. They observed that,
the total percentage of soluble protein, ratio of monomeric
to aggregated protein and globulin hexamer proteins were
greatly decreased after heat treatment. From cation exchange
chromatography and SDS-PAGE analysis, it was confirmed
that heat treatment reduced amino acid residues and select-
ively eliminate the protein bands associated with the prola-
min and albumin protein fractions insoluble proteins of oats
flour paste. The effect of temperature on the stability of rice
protein isolates (RPI) with 92.0% protein was monitored by
(Nesterenko et al. 2013) who observed the denaturation of
RPI at 83.4
C.
Protein solubility
Agboola, Ng, and Mills (2005) also evaluated that in rice
protein isolates, the major contaminant is starch (around
90%). Compared to protein, starch easily solubilized in water
and lower the protein content in an emulsion. Therefore, to
improve the solubility of rice protein isolates enzymatic
hydrolysis treatment can be used. The effect of pH on the
solubility of rice bran isolate (92.0% protein) was estimated
by (Wang et al. 1999). They observed pH 10 was the most
ideal condition in term of protein solubility. While, at pH
(almost near to isoelectric point) poor solubility occurred.
Oat protein concentrates also show poor solubility and
various chemical modifications have been used to enhance
the protein solubility that includes succinylation, acetylation
and enzymatic hydrolysis (Nesterenko et al. 2013). Xu et al.
(2016) also determined the effect of enzymatic hydrolysis on
structural properties and solubility of rice glutelin emulsion.
The structural analysis showed that hydrolysis of protein
increased solubility and flexibility while, altered the surface
hydrophobicity and changed the molecular weight of pro-
tein. From the various degree of hydrolysis of glutelin (0.5%,
2.0%, and 6.0%) solubility of emulsion increased with
decreasing hydrolysis.
Elkhalifa, Schiffler, and Bernhardt (2005) investigated the
effect of fermentation (by the traditional Sudanese method)
on the solubility and stability of sorghum protein isolates.
The protein solubility and stability of sorghum protein
Figure 8. Rice milk protein according to their protein class (Manfredi
et al. 2017).

isolate constantly increased with fermentation. In another
study effect of germination of sorghum on the protein solu-
bility index were determined by Elkhalifa and Bernhardt
(2010) who observed an increase in protein solubility index
in germinated samples compared to un-germinated sor-
ghum samples.
Types of fats
The fatty acid composition of rice-based beverage show, they
are rich with c-oryzanol, bsitosterol and phytosterols with
anti-inflammatory, anti-diabetic, hypertension and lowers chol-
esterol properties (Biswas et al. 2011). The major fatty acids in
rice bran are linoleic acid (30–35%), oleic acid (40–50%) and
palmitic acid (12–18%) (Ramezanzadeh et al. 2000). The fat
composition of rice milk is also presented in Table 3. In the
previous study, the effect of storage on the fatty acid compos-
ition of oat milk had been studied. Study shows that long
term storage (around 1year) did not bring any significant
changes in fatty acid composition (linolenic, linoleic and oleic
acid) of iron-enriched oat milk (Zhang et al. 2007).
Effect of pH
Emulsifying properties of rice proteins was investigated pre-
viously under different pH conditions. Under acidic condi-
tions rice protein shows good emulsifying properties
compared to neutral conditions (Romero et al. 2012; Xu
et al. 2016). The effect of surfactant on the emulsifying
properties and stability of rice protein hydrolysates emulsion
was examined by Xu et al. (2016). 6 who observed an
increase in the stability of emulsion with the use of nonionic
surfactant (Tween 20) compared to control emulsion (rice
protein hydrolysates alone).
Wang et al. (2015) also determined the effect of pH on
the rice bran protein foaming ability and emulsifying activity
index (EAI). Foaming ability increased progressively for all
fractions of rice bran protein with the increase in pH (from
pH 4 to 12). While in the case of EAI, slightly decreased in
EAI was noticed from pH 4 to 6 but further increase in pH
(from 8 to 12) increases the EAI.
The effect of salt/sugar and pH on the functional proper-
ties of rice protein concentrates (RPC) with 55.0% protein
were analyzed by Chandi and Sogi (2007). They found that
emulsifying capacity and foaming stability were greatly
dependent on the added concentration of salt/sugar and pH.
Around 5–15% concentration of sugar considered ideal con-
dition for both emulsifying capacity and foaming stability.
In another study it was found that, increase in pH (from 3.0
to 9.0) progressively increases the EAI (27.6–45.3 m2
/g) but
decrease the emulsion stability index (110.0–76.9 min) of oat
protein concentrates emulsion (Guan et al. 2007)
In the previous study the effect of heat treatment on the
emulsifying properties of rice protein was determined by
Tang and Ma (2009). Such as moderate heating significantly
improved the functional properties (solubility, foaming and
emulsifying activity) of vicilin-rich rice protein isolates.
However high heating medium reduces these properties.
The effect of boiling, dry heating and microwave treatment
on rice bran protein isolates (RBPI) functional properties
were determined by Khan et al. (2011). High emulsion sta-
bility (46.9%) and foaming capacity were observed in dry
heated RBPI. Microwave treated RBPI show good foaming
stability (74.0 min). While boiling increase the emulsion
activity (59.1%) of RBPI.
Effect of enzymatic hydrolysis
Enzymatic treatments are used to improve the extraction
processes and emulsifying properties of the emulsion.
Figure 9. Protein digestibility of alkaline extracted (AE-RP) and enzyme-assisted micro fluidized (EM-RP) (Xia et al. 2012).
16 S. QAMAR ET AL.

Previously various hydrolysis (with proteolytic enzymes)
(Nieto-Nieto et al. 2014) and enzymatic treatment (succiny-
lation, acetylation, deamidation with acids) had been used to
enhance the protein yield, emulsifying properties and solu-
bility of oat protein isolates (Mirmoghtadaie, Kadivar, and
Shahedi 2009; Mohamed et al. 2009).
Jiang et al. (2015) tried to improve oat protein isolates
functionality by enzymatical deamidation (via food-grade
protein-glutaminase) at low salt concentration and neutral
pH conditions. This study also determined the effect of this
processing method on emulsifying properties, solubility, and
structure of oat proteins. After processing solubility of pro-
tein increased and emulsion has longer stability with more
uniform oil droplet particle size as well as the secondary
structure of oat protein became more flexible or increase
(from 55.1% to 70.4%) in the a-helix structure was observed
as compared to untreated samples. In another study, Xu
et al. (2016) investigated the effect of enzymatic hydrolysis
on the emulsifying properties of rice glutelin emulsion.
Enzymatic hydrolysis improves the surface hydrophobicity
of emulsion.
Study shows the protein efficacy ratio (PER) of oat milk and
rice milk was studied by M€akinen et al. (2016). A study
showed PER was ranged around 45.0–60.0% for oat milk
and 54.0% rice milk, respectively (M€akinen et al. 2016). The
protein digestibility for oat protein is approximately 85.0%
(M€akinen et al. 2017). The protein digestibility of sorghum
flour is ranging between 88.6–93.0% and heat treatment
reduce it to 45.3–56.7% (Duodu et al. 2003).
Various studies have been determined the nitrogen
digestibility of bran rice protein concentrates. The protein
digestibility of rice protein concentrates with 33–38% pro-
tein (obtained by wet alkaline extraction method) were
89.6% (Connor, Saunders, and Kohler 1976). In another
study, the in vitro protein digestibility of rice bran concen-
trates obtained through freeze-dried method was between
61.2 and 86.0% and for roller dried rice bran concentrates
was between 87.5 and 96.0% (Prakash and Ramaswamy
1996). The in vitro nitrogen digestibility of alkaline extracted
(AE-RP) and enzyme-assisted micro fluidized rice protein
(EM-RP) was also determined by Xia et al. (2012). The %
digestibility after 120 min with pepsin hydrolysis was 35.98%
for AE-RP and 68.22% for EM-RP (as represented in
Figure 9).
Conclusion
In this review, four different parts of plant protein source
(nut, legume, seed, and cereal) have been discussed. Plant-
based emulsions are rich in a variety of quality nutritional
content such as minerals, vitamins, proteins, fats, high quan-
tity of unsaturated fatty acid and phytochemicals. Utilization
of emulsion prepared from plant protein (such as almonds)
also have some additional benefits including nutty taste and
healthy wellbeing. In this review, the benefits, chemical
composition, protein and fat quality and functional proper-
ties of plant protein have been summarized. Processing plays
an important role in the quality of these emulsions, as it
brings extensive changes in the conformation of protein
structure (aggregation or folding and unfolding). Therefore,
the effect of various processing treatment and technological
interventions on the behavior of protein and other quality
parameters of plant-based beverages are also discussed. A
plant protein derived emulsions cannot be considered as an
ideal alternative beverage to animal protein source milk due
to lack of nutritional contents (essential fatty acids) and
some allergic responses. But, they can fulfill the diet require-
ments for the growth of users having allergies or any other
issues with animal-derived protein. Further study is also
required on the new edible plant protein sources and the
effect of processing on the quality of protein.
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18 S. QAMAR ET AL.

Nuts, cereals, seeds and legumes proteins derived emulsifiers as a source of plant protein beverages: a review

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