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Fruits and Vegetables Processing Technology
- 1. FET-427 Fruits and Vegetables Processing Technology
- 2. Contents 1. Fruits, vegetables & their products Vegetables General properties, composition, classification Structural features Activities of living system
- 3. Fruits, vegetables & their products Fruits properties, classification Ripening Fruit Harvesting Fruit beverages Fruit quality
- 4. Contents 2. Storage of vegetables and fruits Packaging Handling and transmits of fresh fruits and vegetables Methods for prolonging storage life Modified gas storage Problems- Packaging & transportation Refrigeration- methods, Problems
- 5. Contents 3. Dehydration of fruits and vegetables Sun drying Mechanical Dehydration Quality control Storage of dehydrated fruits and vegetables Intermediate moisture fruits and vegetable products
- 6. Contents 4. Fruit and vegetable juices Preparation of- fruit syrup Squashes and cordials Nectars Fruit juice concentrates
- 7. Contents 4. Fruit and vegetable juices Packaging and storage of juices and concentrates Quality control Modern method of fruit juice making
- 8. Unfermented and Fermented Fruit Beverages Synthetic drinks- Water 88% Total Carbohydrates 12% Provide 48 K-cal Fruit based drinks Vitamins (A, B and C) Minerals (iron, calcium) Provide more calories
- 9. Fruit beverages easily digestible highly refreshing thirst-quenching appetizing nutritionally superior
- 10. Fruit beverages Groups Unfermented beverages Fermented beverages
- 11. Fruit beverages Unfermented beverages do not undergo alcoholic fermentation example: natural & sweetened juices, RTS, nectar, cordial, squash, fruit juice concentrate, fruit juice powder etc.
- 12. Fruit beverages Fermented beverages undergo alcoholic fermentation by yeast Example: wine, champaigne, port, perry, muscat, cider Notes: Muscat- fortified wine Port- red wine Champaigne- sparkling wine black/ white grape Pear- fermented pear
- 13. Fruit beverages Unfermented beverages Preparation and preservation i) Selection of fruit ii) Sorting and washing iii) Juice extraction iv) Deaeration v) Straining or filtration vi) Clarification vii) Addition of sugar viii) Fortification ix) Preservation x) Bottling
- 14. i) Selection of Fruit Fully ripe fruits Over ripe and green fruits adversely affect the quality ii) Sorting and washing Diseased, damaged or decayed fruits are rejected Dirt or spray residues are washed with water or dilute HCl iii) Juice extraction By crushing and pressing Methods differs from fruit to fruit Some require heat processing for breaking up the tissues Citrus fruits require light pressure in a juice extractor Rind should be completely removed Finally, the juice is strained Equipment should be acid proof Copper and iron vessels- react with fruit acids-blackening of products Machines and equipments made of aluminium, stainless steel Juices not exposed to air- spoil color, taste
- 15. iv) Deaeration Air is present on the surface/ dissolve in juice Juice is subjected to a high vacuum Process- deaeration, equipment- deaerator Expensive method Notes: Reduce level of dissolved oxygen from juice- cause chemical oxidation. v) Straining or filtration Juices contain suspended matters Adversely affect the quality of juice Strained through a thick cloth/sieve-improves appearance some juices retain cloudy/pulpy appearance Grape/apple juice & lime juice cordial- clear appearance
- 16. vi) Clarification Complete removal of all suspended material Related to the overall quality of the juice Methods- A. Settling B. Filtration C. Freezing D. Cold storage E. High temperature F. Chemicals G. Enzymes
- 17. A. Settling Chemical preservative is added Juice is stored in a carboy/ barrel Very slow Example- lime juice stored for 3-6 months with 700 ppm sulphur dioxide B. Filtration Remove all fine and colloidal suspensions Strained juice is forced through a filtering medium Colloidal suspension clog the filter- filter aid are used (0.1-0.2) C. Freezing Pasteurized juice is frozen at -180 C Stored for 4-7 days at room temp. Costly method D. Cold storage Used for grape juice Stored at -2 to -30 C for one month
- 18. E. High temperature Heated at 820 C for about one minute- colloidal material coagulates & settles down Cooled & passed through filter press F. Chemicals Fining agents such as- a) Gelatin- coagulate the colloids and the precipitate settles down b) Albumen- solution mixed with the juice, heated to about 910 C (complete coagulation of albumen) Notes: Gelatin- Electrostatic action betn positively charged gelatin & negatively charged colloids (pectins, gums, proteins etc.) Hydrogen bond betn the phenolic group of juice and the peptide group of the gelatin molecule. c) Casein- 2% solution mixed with the juice, fruit acid precipitate the casein (settles down with other particles) d) Mixture of tannin and gelatin- juice+ tannin+ gelatin solution allowed to stand for 18 to 24 hours, suspended matter coagulate and settle down G) Enzymes Pectic enzymes (Pectinol, Filtragol) destroys pectin, pectin settles down with other materials. Notes: Pectins responsible for keeping other materials in suspension, Heat 770 C 30 min. After filtering the juice is heated to stop enzymes
- 19. vii) Addition of sugar Sweetened the juice Acts as preservative Added directly/ as a syrup (made by dissolving sugar in hot water) viii) Fortification Vitamins, ascorbic acid (antioxidant) & beta-carotene (orange color) are added enhance nutritive value Improve taste, texture, color Replace nutrients lost in processing Ix) Preservation Fruit juices, RTS and nectars- Pasteurization Chemical preservative Fruit juice concentrates- Heating, freezing or adding chemicals x) Bottling Bottles washed with hot water 1.5-2.5 cm head space sealed
Editor's Notes
- Muscat- fortified wine Port- red wine Champaigne- sparkling wine black/ white grape Pear- fermented pear
- Reduce level of dissolved oxygen from juice- cause chemical oxidation
- Syrup- made by dissolving sugar in hot water Fortification with vitamins ascorbic acid –antioxidant, beta-carotene- orange color