The document provides an overview of fruit juice concentrates, detailing the processes used for concentrating fruit juice, including evaporative, membrane, and freeze concentration methods. It highlights the advantages, such as microbiological stability and improved flavor retention, as well as disadvantages like potential nutrient loss and high operational costs. Additionally, it discusses various drying techniques for fruit juices and concentrates, emphasizing methods like spray drying and freeze drying for preserving quality and extending shelf life.

1. Fruit Juice Concentrates
Aakash Gill
B.Tech Dairy Technology
ICAR - National Dairy Research Institute
Karnal, Haryana

2. • Fruit Juice : 8 – 16 % TS
• FJ Concentrate : a product obtained from partial
removal of moisture from fruit juice
• Used in production of
(a) reconstituted fruit juice
(b) fruit juice beverages
(c) fruit juice powders
Introduction

3. • Advantages:
1. Microbiological stability
 Reduced water activity (aw)
 Increased shelf life
 Lesser undesirable changes
2. Ease of handling of Fruit Juice Powder
3. Economy in packaging, transportation
and distribution of the finished product
Introduction

4.  Evaporative concentration under vacuum
 Membrane concentration :
Nanofiltration
Ultrafiltration
Reverse osmosis
Microfiltration
 Freeze concentration
Methods

5. • Multiple effect vacuum evaporators
• High vacuum (29 inHg)
• Low evaporation temperature (58-60°C) – much lower than
the boiling point of the juice
• Economical method of fruit juice concentration
Thermal Evaporation

6. Concentration method Specific type
Vacuum pan – Tubular Climbing film
Falling film
Recirculation Single stage and one pass
Five stages and single pass
Plate Three stages and single pass
Agitated film Single stage
Centrifugal Single stage
Types Of Evaporators Used

7. • Loss of much volatile flavoring compounds as well as
nutrients
• Requires use of fining agents, enzymes and centrifugation for
juice clarification
• High temperature promotes oxidation of compounds in the
juice, which may result in chemical alteration of the aroma
and flavor compounds.
Disadvantages

8. • For such juices,
special evaporators
having agitators are
used
• Serum Concentration
Process :
Conc. Of Pulpy or Cloudy Juice
FOULING
• Formation of burnt layer
• Concentration becomes
difficult
• Retardation of heat transfer
• Overall Heat Transfer
coefficient (U) reduces
Juice ---------- > Pulp ( Solid Phase) + Serum (Liquid Phase)
ConcentrationMixing
Centrifugation

9. • Cold, gentle and selective
concentration procedure
• Two distinctive steps, viz.,
I ) ice crystallization and
II) ice separation from
the concentrate phase
are involved.
Freeze Concentration
STAGE I
 Direct contact crystallizer
 Indirect contact crystallizer
STAGE II
 Presses
 Filtering centrifuges,
 Wash columns
 any combination of the above.

10. • Less energy is needed to freeze
a unit of water.
• The low process temperature
prevents undesirable chemical
and biochemical reactions
(minimum color change, non
enzymatic browning and
vitamin losses).
• As vacuum is not involved, the
losses of low boiling flavor and
aromatic esters are completely
avoided
• Better flavor profile.
Advantages and Disadvantages
• Major problem is the loss of
soluble solids of the juice in the
separated ice.
• The final concentration of the
concentrated juice is as low as
40-55% dry matter, due to
steep increase in the viscosity
of ice concentrated mixture.

11. • As the concentration increases, concomitant increase in
viscosity retards water crystallization.
• In such process, the ice crystals are separated out at the end
of each cycle .
• The remaining concentrate after separation are fed to the
succeeding crystallizing compartments.
• In theses compartments, ice crystals are separated at
different levels of concentration and viscosity.
Multistage Freeze Concentration

12. • Usage:
• Clarification the juice by
means of ultrafiltration
and microfiltration
• Concentration by means
of nanofiltration and
reverse osmosis
• Ultrafiltration : performs
clarification and
fractionation
• Reverse Osmosis :
performs concentration
• Papplied > Posmotic
• Pressure forces out the
water from the juice
Membrane Processing
ADVANTAGES OF UF
 Desirable quality
 Greater Speed
 Single step clarification and
refining
 Lower energy consumption
 Increased flavor and aroma
retention
ADVANTAGES OF RO
 Considerable amount of aroma
retention at a cost competitive
with evaporation
 No undue loss of solids.
 Concentration without phase
change or thermal damage

13. • Initially, the fruit juice is passed through Ultrafiltration system to
remove suspended solids
• The UF permeate is directed to an RO system to simultaneously
concentrate the flavor and aroma compounds, sugars and amino
acids for eventual reconstitution to single strength juice.
• This allows for concentration of orange juice to levels of ~ 42oBrix.
On commercial scale up to 45-55 Brix can be achieved.
Combined UF and RO

14. • Nearly complete removal of moisture
• Purpose:
-enhances storage stability,
-minimizes packaging requirements
- -reduces transport weight
• Drying preserves the fruit juice by
significantly reducing water activity (aw)
which inhibits microbial growth.
Drying Of Fruit Juices

15. • Sun/Solar Drying
• Fluidized bed dryers
• Spray dryers
• Contact dryers
• Foam drying
• Vacuum and freeze drying
Methods of Drying

16. • It involves drying of fruit and fruit
juices by utilizing the heat energy
radiated by sun
• Using solar drying techniques can
lead to poor quality and product
contamination
• It takes more drying time
• Gives low economy
• More nutrition loss due to heat
damage to heat sensitive
constituents in the product
Sun/Solar Drying

17. • Some fruit or vegetable powders are produced from
juices, concentrates, or pulps by using a spray drying
technique.
• Dry powders can be directly used as important
constituents of dry soups, yogurt, etc.
• The drying is achieved by spraying of the slurry into an
airstream at a temperature of 138°C to 150°C and
introducing cold dry air either into the outlet end of the
dryer or to the dryer walls to cool them to 38°C– 50°C.
• The most commonly used atomizers are rotary wheel
and single fluid pressure nozzle
Spray Drying

18. Spray Dryer
Simplified Diagram of a Spray Dryer

19. • A wide range of fruit and vegetable powders can be dried,
agglomerated, and instantized in spray drying units
• These dryers are specially equipped with an internal static
fluidized bed, integral filter, or external vibrofluidizer
• Bananas, peaches, apricots, and to a lesser extent citrus
powders are examples of products dried by such techniques.
• Spray drying of soluble fruit powders and convective drying of
fruit and vegetables reduces the thermoplasticity of particles
and product hygroscopicity.
• They also eliminate the need for adding stabilizers which may
adversely affect the sensory properties of the final product.
Spray Drying (contd.)

20. • Foam mat and foam spray drying are two foam drying methods.
• Foam mat dried fruit or vegetable powders have fewer heat
induced changes in color and flavor than conventional spray dried
or drum dried products.
• It yields product with lower density than that of a conventional
dryer.
• The product density is about equal to the density of instantized or
agglomerated powder.
• A stable gas-liquid foam is a prerequisite.
• Glycerol monostearate, solubilized soya protein, and propylene
glycol monostearate are the typical additives for the fruit and
vegetable foam formulation from juice or pulp.
Foam Drying

21. • Foam mat drying involves drying a thin layer (0.1–0.5 mm) of
the stabilized foam in air at 65°C–70°C for a few minutes, as
the foam structure decreases drying time to about one-third.
• The foam is spread on perforated floor craters as the
airstream is forced through the bed.
• A continuous belt tray dryer or a modified spray dryer can be
used.
• Good quality tomato, apple, grape, orange, and pineapple
powders can be produced by this technique.
• Optimal initial concentration of feed solids is in the range of
30% for tomato and 55% for orange.
Foam Drying

22. • There are two main stages in the freeze drying process:
• (a) freezing of the food, when most of the water is converted
into ice
• (b) sublimation, when the bulk or all of the ice is transferred
into vapor under very low pressure or high vacuum.
• In some cases, additional final drying, in the same or other
equipment, is necessary.
• Cabinet or tunnel batch type dryers are typically used with
pressures in the range 13.5–270 Pa.
Freeze Drying

23. • Juice
and Powder formation
Freeze Drying

24. • Bananas, oranges, strawberries, peaches, plums, tomato fruit
juices are processed by freeze drying.
• The advantage of freeze drying over other methods of drying
is the superior quality of the product.
• Little or no shrinkage occurs.
• The dry product has a porous structure and a color almost as
fresh as that of the raw material.
• The only disadvantage of this process is the high equipment
and operational cost.
• The dried fruits can be powdered for the purpose of juice
making
Freeze Drying (contd.)

25. • Especially for low pH fruit juices (like lime, lemon juices) mild
pasteurization is sufficient to have the desired shelf life.
• However, for higher pH fruit juices over and above stringent
pasteurization, chemical preservatives (i.e. salts of sorbic acid
or benzoic acids) may be used, where permitted by laws.
• The main purpose is to prevent fermentation from occurring
during the refrigerated or even ambient temperature storage.
• Sterilization of the fruit juice by Incan (retort) or by Ultra high
treatment (UHT) followed by aseptic packaging can help in
extending the shelf life for months even under ambient
storage conditions
Preservation of Concentrates