Fruit juice concentrates

The concentration of fruit juice involves significant removal of moisture. This process is beneficial for product preservation, utilization, storage, distribution and transportation. For more useful presentations, visit my blog at aakashgill1.wordpress.com

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 (a w ) 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) Concentration Mixing 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 P applied > P osmotic 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 (a w ) 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

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