This document summarizes a study that aimed to use specific physicochemical parameters to design the physical properties of cakes by replacing sucrose with various sugar replacers. The study investigated how sugar replacement affected flour pasting behavior, cake batter rheology, thermal transitions during baking, and final cake properties. Key findings included correlations between physicochemical parameters like the volumetric density of effective H-bonding sites and measures of cake volume, crumb texture, moisture content and color. Formulations containing the amino acid glycine showed some deviations from trends, likely due to Maillard browning reactions.

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UNIVERSITE LIBANAISE
Faculté d’Agronomie
Département des Sciences et Technologie des Aliments
Rapport-Rhéologie
Préparé par : Mohammad DOGHMAN (4295)
Lyna ABOU ABBASS (3677)
Ranya HELLANY (3687)
Présenté à : Dr Ali BASSAL
2023-2024
Introduction:

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The passage discusses the challenges associated with reducing sugar content in food products,
particularly in sweet bakery items, to address health concerns related to obesity. Health
organizations recommend limiting free sugar intake to 10% of total daily energy, but in several
European countries, sugar contributes significantly more (15-25%). The food industry is urged to
reformulate products by lowering free sugar content, but sugar replacement is challenging due to
its multifunctional role in food. Sweet bakery products, especially cakes, pose difficulties in
mimicking the structure and texture controlled by sugar. The passage highlights the importance
of precise sugar replacement in achieving optimal rheological behavior during baking. The study
aims to use specific physicochemical parameters to design the physical properties of cakes,
demonstrating their control over flour pasting behavior, cake batter rheology, and biopolymer
phase transitions. The approach involves replacing sucrose with sugar replacers from different
classes, offering new opportunities beyond traditional sweeteners with potential gastrointestinal
side effects.
Theoretical background for quantitative description of sugar
functionality in bakery applications
Effective number of H-bonding sites in sugar solution controlling phase transition of starch
and proteins
In baking, the cake batter emulsion transforms into a solid sponge through the action of gases,
starch gelatinization, and protein interactions. The pr g white proteins can be described by an
adapted FloryHuggins theory for biopolymer melting according to :
Φw,eff is the volumetric density of effective H-bonding sites available in the solvent (i.e. the
water-sugar mixture) for interaction with biopolymers. χp,eff is the FH solvent-biopolymer
interaction parameter.
R is the universal gas constant. The effective interaction parameter χp,eff in
equation (1) is computed from :
𝜒𝑝,𝑒𝑓𝑓 = 𝜒0 + (𝜒1 − 𝜒0)(1 − Φ𝑤,𝑒𝑓𝑓2)
where χ0=0.5 is the interaction parameter of fully hydrated biopolymers (which is assumed to hold
universally for all biopolymers), while χ1 is the interaction parameter if the biopolymer is in the
dry state. χ1 is specific for each biopolymer.
Role of sugars in controlling flour pasting behaviour
From the NOH,s of sugars and sugar replacers, NOH,s/vs is obtained where vs is the molar
volume of the plasticizer. The NOH,s/vs parameter is an intrinsic property of the plasticizer,
which represents the number of H-bonding sites effectively available for intermolecular
interactions within the molar volume of a sugar. We have recently shown that NOH,s/ vs
controls the swelling behaviour of starch, as it controls peak viscosity and final viscosity

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obtained by rapid viscous analysis. In presence of mixtures of plasticizers, NOH,s/vs is
computed from:
where Φs is the volume fraction of each plasticizer in the mixture. Here, we suggest that
NOH,s/vs will also control the pasting behaviour of wheat flour.
Effect of sugars and sugar replacers on water activity
The water activity (aw) of sugar solutions for individual compounds and mixtures has been
described based on the Flory-Huggins Free Volume theory (FHFV) , including polyols
and amino acids following on: ln𝑎𝑤= ln(Φ𝑤)+ (1 − 1/𝑁𝑠)(1 − Φ𝑤) + 𝜒𝑠(1 − Φ𝑤)2
+ 𝐹(Φ𝑤)
where Ns is the ratio of molar volumes of solute versus water (νs/νw), χs is the Flory-Huggins
interaction parameter of the solute with water and φw is the volume fraction of water. F(Φw)
accounts for structural relaxation in the glassy state and the changes in hydrogen bonding
between water and polymer in the semi-dilute regime.
as we recently reported also for mixtures of sugars and sugar replacers included in this study .
The value of ΔCp,s is dependent on the class of plasticizers as previously reported ,this
equation assumes that the interactions between sugars (and sugar replacers) is about zero.
Materials:
o The authors used wheat flour, sugar, egg, margarine, baking powder, and various sugar
replacers (xylitol, FOS, L-proline, and glycine) to prepare cake batters. They also used a
TA Instruments Q200 DSC, a TA-Instruments Discovery HR-2 rheometer, a TA-XT2i
Texture Analyzer, and a Minolta CR310 Color Meter for the analyses.
o The physicochemical properties of these ingredients were reported in Table 2.
Methods:
Moisture sorption behavior of sugar replacers: o Moisture sorption of FOS: The authors
measured the moisture sorption of fructooligosaccharides (FOS) at 25 °C using a
gravimetric method. They fitted the experimental data with a Flory-Huggins-Fraser-
Vrentas (FHFV) model to estimate the interaction parameter of FOS with water (χs). The
results were compared with previous data for xylitol, sucrose, glycine, and L-proline.
o Physicochemical parameters of sugars and sugar replacers: The authors calculated
three physicochemical parameters for sucrose and four sugar replacers: xylitol, glycine,
L-proline, and FOS. These parameters are: the number of H-bonding sites effectively
available for intermolecular interactions within the molar volume of a sugar (NOH,s/vs),
the volumetric density of effective H-bonding sites available in the solvent (Φw,eff), and
the volume averaged interaction parameter of the sugars with water (χeff)23
.

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Cake batter preparation o The authors used a multi-stage mixing method to prepare cake
batters with different sugar compositions, based on a reference recipe with 244 g of each
of the four main ingredients: flour, sugar, egg and margarine. The batters were baked in a
deck oven for 60 min at different temperatures. Baking tests were performed in duplicate
for each variation.
o Studied variations in sugar composition: The authors studied 10 formulations with 50%
sucrose replacement and a sucrose reference. The sucrose was replaced by different
combinations of xylitol, FOS, L-proline and glycine. The sugar reduced samples were
coded based on the sugar replacers used and the value of Φw,eff, a physicochemical
parameter that represents the volumetric density of effective H-bonding sites available in
the solvent. NOH,s/vs and χeff, were computed from the cake formulations. o The
authors constructed a state diagram for cake baking based on Φw,eff and predicted the
effects of sugar replacement on the phase transitions during baking.
Cake batter formulation: o replacement: Sucrose was replaced by 50% using sugar
replacers from three different classes of compounds: xylitol (polyol), an oligofructose, L-
proline and glycine (amino acids).
o Formulations: The formulations included single sugar replacers or complex mixtures of
2–3 replacers. The sugar compositions were designed to modulate the physicochemical
parameters Φw,eff , NOH,s/vs and χeff , which are related to the phase transitions and
moisture sorption of the cake batter. o Code: The sugar reduced samples were coded
based on the sugar replacers used (F=FOS, G = Glycine, P = L-Proline and X = Xylitol)
followed by the value of Φw,eff computed from the formulation. For example, F_0.480
means a sample with FOS as the only replacer and Φw,eff = 0.480. Rapid Visco
Analysis (RVA):
o A method to measure the pasting properties of flour suspensions in different sugar
solutions.
o Flour suspensions preparation: Flour suspensions of 8% dry matter were prepared with
different sugar compositions and subjected to a time-temperature profile in an RVA
instrument. o Viscosity parameters: The viscosity of the flour suspensions was
expressed as centipoise (cP) and the pasting temperature, peak viscosity, final viscosity,
breakdown and setback were determined ,The results were analyzed as a function of
NOH,s/vs. Thermal transitions in cake batter by differential scanning calorimetry
(DSC):
o The authors used DSC to measure the melting temperatures of starch and proteins in
different cake batters with varying sugar compositions. o They found that these
temperatures were significantly affected by the volumetric density of effective H-bonding
sites available in the solvent (Φw,eff), except for the formulations containing glycine.
They also found that the melting temperatures were linearly related to Φw,eff, which
confirmed their previous studies based on the Flory-Huggins theory for biopolymer
melting.
Cake baking:

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o Author baked the cake batters in a convection oven at 180 ◦C for 30 min. The cakes were
cooled and stored at room temperature for further analysis.
o Dynamic mechanical thermal analysis of dough: The paper performed dynamic
mechanical thermal analysis of dough samples without baking powder using a rheometer.
The samples were oscillated at a frequency of 1 Hz and heated from 20 ◦C to 120 ◦C. The
data retrieved from this experiment were the storage modulus, the tan δ, and the onset
temperature of structure formation.
Cake volume and specific volume: o The authors measured the volume of the cakes using a
rapeseed displacement method and calculated the specific volume as the ratio of cake volume
to cake weight. They found that cake volume was controlled by Φw,eff, the volumetric
density of effective Hbonding sites available in the solvent1
. A high Φw,eff resulted in an
early structure setting during baking and a low volume, while a low Φw,eff resulted in a late
setting and a high volume. o The authors measured the volume of the cakes using a rapeseed
displacement method and calculated the specific volume as the ratio of cake volume to cake
weight. They found that cake volume was controlled by Φw,eff, the volumetric density of
effective Hbonding sites available in the solvent1
. A high Φw,eff resulted in an early structure
setting during baking and a low volume, while a low Φw,eff resulted in a late setting and a
high volume.
Crumb instrumental texture, moisture content and water activity:
The authors measured the crumb texture using a texture analyzer and performed a texture
profile analysis (TPA). They found that crumb hardness was also affected by Φw,eff, but
crumb cohesiveness was a non-linear function of NOH,s/vs, the number of H-bonding
sites effectively available for intermolecular interactions within the molar volume of a
sugar4
. They also measured the moisture content and water activity of the crumbs and
found that they were linear functions of χeff, the volume averaged interaction parameter
of the sugars with water.
Crumb colour:
The authors measured the crumb colour using a colour meter and reported the L*, a*, and
b* values. They found that crumb colour was mainly affected by the presence of glycine,
which enhanced browning by Maillard reactions.
Crumb instrumental texture, moisture content and water activity:
o The authors measured these properties of cake crumbs the day after baking using
different methods and instruments. o Effects of sugar composition: The authors found
that sugar replacement resulted in significant changes in crumb aw, texture and colour.
They also found correlations between these properties and the physicochemical parameters
of the sugar mixtures (Φw,eff, NOH,s/vs and χeff). Effects of glycine:
The authors observed that glycine-containing formulations deviated from the general trends
and showed lower springiness, cohesiveness and resilience, as well as higher aw and
browning. They attributed this to the high reactivity of glycine in Maillard reactions and its
effect on protein denaturation. Statistical analysis:

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The authors used ANOVA, Tukey’s test, correlation analysis and regressions to test the
significance and relationships of their data.
Sorption isotherm of FOS
The sorption data obtained in the aw range from 0 to 0.95 could be well described by the FHFV
model . The physicochemical parameters used in the model are glycine ,L-proline , sucrose,FOS .
The highest value of χs among the sugars and sugar replacers in this study indicated that the FOS
was the least hygroscopic among the plasticizers used.
RVA
The pasting properties of cake flour are influenced by sugar and sugar replacer compositions,
affecting pasting temperature and paste viscosity. The gelatinization and pasting temperature of
wheat starch in sugar solutions are regulated by Φw,eff.
The paste viscosity of wheat starch in sugars and sugar replacers solutions is controlled by NOH,
s/v of the sugar mixture. The viscosity parameters are regulated by the ratio of non-H-bonded
atoms to bonded atoms, except for mixtures with glycine, due to challenges in determining Tg.
DSC of cake batters
To identify the changes in starch gelatinization and protein denaturation, an analysis of cake
batters using DSC was conducted.
The second endothermic event involves starch gelatinization and egg denaturation, with sugar
types influencing melting temperatures. Φw,eff accurately predicted Tpeak and Tonset for
complex cake batter systems. The study confirms previous research on denaturation of egg white
proteins and gelatinization of starch in sugar-containing solutions, with glycine formulations
showing deviations from expected results.
Rheology cake batters during temperature sweep
The DMTA technique was used to investigate the thermo-mechanical behavior of the various
batters. The method reveals dough elastic properties (G' and tan δ) influenced by phase
transitions. G' decreases initially as temperature rises, mainly due to fat melting and batter
softening. Sugars affect rheology before structure formation.. However, there were no
connections found between G'min and the physicochemical parameters Φw,eff, NOH,s/vs, and
χeff.
Sugar replacement formulations affect G' and tan δ at 95 ◦C, affecting batter rheology and
biopolymeric network formation. Higher G'95◦C/G'min ratios indicate thermal sensitivity,
impacting cake texture. The study suggests that the solvent properties, specifically the
watersugar mixture, significantly influence the behavior of biopolymers within the batter matrix
and its rheology.
Cake volume
The use of sugar substitutes led to variations in the appearance, structure, and volume of the
cakes . The cake made with xylitol (sample X_0.505) had the smallest volume (p < 0.05), while
the one made with FOS had the highest volume (p < 0.05). The cake volume for all variations

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was influenced by Φw,eff . Cakes containing glycine were well described by linear regression,
resulting in an early structure setting during baking and a smaller volume, contrary to previous
observations. . In contrast, a delayed structure setting resulted in a larger cake volume.
Leavening agents and thermal expansion of gas bubbles above 50°C cause expansion, while
protein aggregation and starch swelling prevent it. Delayed structure setting during baking
increases cake volume.
Cake crumb properties
Sugar substitution significantly impacted cake moisture, texture, and color, with xylitol resulting
in higher crumb hardness. Original cake had higher bounce, stickiness, and shape recovery. The
bounce, stickiness, and ability to recover shape were closely related to each other. Additionally,
the moisture content of the crumb varied significantly depending on the recipe, with xylitol
resulting in the lowest values and FOS in the highest (p < 0.05). Crumb color and hardness were
significantly impacted, especially in formulations with glycine, which were darker and had
increased red color space. The crumb's stickiness and glycine variations were not directly related
to NOH,s/vs, and moisture content was attributed to changes in χeff.
Discussion:
The study's main hypothesis is that the effects of sugar replacement on baking and cake
properties are governed by specific physicochemical parameters: Φw,eff, χeff, and NOH,s/vs.
Xylitol and FOS are used as sugar replacers with opposite properties compared to sucrose.
Different formulations are designed to cover a range of physicochemical properties, and results
show that these parameters effectively describe the physical properties of cakes. The study
explores the use of amino acids (L-proline and glycine) as potential alternatives to polyols for
sugar replacement, with L-proline showing promise. The physicochemical parameters
successfully describe various functionalities of dissolved sugar, and their applicability is
demonstrated in predicting and controlling cake properties during baking. The study also
investigates starch behavior, rheology, and pasting properties, showing that Φw,eff can be
utilized to optimize cake volume and crumb softness. Overall, the findings support the study's
theoretical approach for designing cake properties through sugar replacement and composition
manipulation.
Conclusion:
This study establishes that three physicochemical parameters—Φw,eff, NOH,s/vs, and χeff—
play a critical role in governing the rheology, thermosetting behavior of sugar-replaced cake
batters, and the resulting physical properties of cakes. These parameters, computable directly
from initial formulations, allow for the systematic design of cake properties without the need for
a trial-and-error approach. By matching these parameters with the reference product, similar
instrumental texture and structural properties can be achieved with a substantial reduction in
sucrose, replacing it by at least 50%. The study proposes a forward-looking strategy that
separates texture design from nutritional composition, enabling the creation of bakery products
with significantly reduced sugar content while incorporating health-promoting ingredients like

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dietary fibers. The researchers aim to extend these principles to other compounds and broader
reformulation targets, even beyond 50% sugar replacement. A companion paper demonstrates the
control of both physical and sensory properties in sugar-replaced biscuits using the same
physicochemical parameters.