Juice Processing Techniques Quiz

Fruits Processing

• Fruits are versatile, used in puddings, pies, jellies, salads, appetizers, snacks, soups, enhancing meat and fish flavors.
• Citrus fruits have thick skins, aromatic oils, and segmented flesh. They are rich in Vitamin C. Common citrus fruits are oranges, grapefruits, lemons, limes, tangelos, and tangerines. Flavor ranges from sweet oranges to tart lemons.
• The sweetness of fruits comes from fructose.
• Tropical fruits are named for growing conditions, including figs, dates, kiwis, mangos, bananas, papayas, pomegranates, passion fruit, pineapple, and coconuts.
• Bananas are high in nutrients and ripen during transport.

Vegetables

• Vegetables include leaves, stems, roots, tubers, seeds, and flowers, they have lower sugar content than fruits.
• Examples of vegetables include celery (petioles), lettuce (leaves), cucumber (immature fruit), carrots (roots), Onions (bulbs), and white potatoes (tubers).

Principles of Food Preservation

• Prevention/delay of microbial decomposition:
  • Keeping out microorganisms (asepsis)
  • Removing microorganisms (filtration)
  • Hindering growth and activity (low temperature, drying, anaerobic conditions, chemicals, antibiotics)
  • Killing microorganisms (heat, radiation)
• Prevention/delay of self-decomposition:
  • Destroying or inactivating enzymes (blanching)
  • Preventing chemical reactions (oxidation, antioxidants)
• Preventing damage by insects, animals, or mechanical causes

Fruit Based Products

• Liquids: Juices, concentrates, cordials, nectar, smoothies, fruit tea, wine, vinegar, oil.
• Solids: Canned/ dehydrated products, fruit leather, chips, powder, candies, frozen fruits, tutti frutti, jam, jelly, marmalade, chutney, tomato pulp/puree, sauces, ketchup.
• Semi-Solids: Ice cream, other sweet products.

Fruit Juice Technologies

• Fruit juices are obtained by pressing or diffusion of cellular juices from fruit.
• Concentrated fruit juices are produced by removing a substantial portion of the water content through vacuum evaporation or fractional freezing.

Fruit Based Juices

• Juices: Pure fruit juice with nothing added.
• Nectars: Normally contain 30% fruit solids, drunk immediately after opening.
• Squashes: Contain at least 25% fruit pulp, mixed with sugar syrup, diluted to taste with water, may contain preservatives.
• Cordials: Are crystal-clear squashes.
• Syrups: Are concentrated clear juices with high sugar content.

Categorize the Fruit Juice

• Processing method (with or without pulp)
• Ingredients (natural, mixed)
• Method of use (drink immediately or requires dilution)

Technological Steps for Fruit Processing

• Washing (thorough washing before/after sorting)
• Sorting (remove decayed fruit)
• Crushing (grapes & berries)
• Grinding (apples & pears)
• Disintegration (tomatoes, peaches, mangoes, apricots)

Enzyme Treatment

• Crushed fruit mass is treated with pectolitic enzymes (2-8%) at 50°C for 30 minutes to improve extraction yield, juice color, and taste.

Heating

• Heating (optional step) is used for some fruits to facilitate pressing, fix color, and cause protein coagulation.

Pressing

• Pressing is crucial to extract the juice

Diffusion

• An alternative step for juice extraction. Carried out discontinuously or in batteries at water temperatures of 80-85°C.

Juice Clarification

• Centrifugation (separating particles) and enzyme treatment (clarifying). This operation is carried out in centrifugal separators at 6000-6500 RPM.

Filtration

• Clarified juice is filtered using kieselgur and bentonite as additives.

De-Tartarization

• Removing potassium bitartrate from raisin juice using 1% calcium lactate or 0.4% calcium carbonate.

Pasteurization

• Juice can be pasteurized for temporary preservation using continuous equipment, then stored in drums or receptacles. Conditions are 75°C in a continuous stream.

Preservation by Freezing

• Preservation using-30°C, after preliminary de-aeration, storage at -15 to -20°C.

Preservation under CO2

• 1.5% CO2 pressure, proceeded by CO2 decompression for filling, and aseptic filling in receptacles.

Canning of Fruit

• A method of preservation where cooked or uncooked food is sealed in tin-plated and lacquered steel cans, then sterilized by heat treatment under pressure in a retort.
• Fruit pulp is prepared from selected varieties of fully ripened fruits and processed (washed, pulped, deseeded, centrifuged, homogenized)
• Then they are thermally processed, filled hot, maintained sterility, and cooled.
• Fruits are canned in slices, rings, and cubes along with sugar syrup.

Canning of Vegetables

• Similar to fruit canning, but vegetable canning uses brine solution for filling materials.
• Thorough cleaning and slicing are required.
• Vegetables don't need lacquered cans.

Problems During Canning

• Swell: Causes by CO2 or microorganisms; discolored, offensive odor. Food unfit.
• Hydrogen Swell: Bulging from hydrogen gas; food is usually free of harmful microorganisms but unfit.
• Springer: Mild swell; food is typically fit for consumption.
• Flipper: Normal appearance can become deformed when struck; possibly an early form of swell
• Flat Sour: Caused by thermophilic bacteria in non-acidic foods; unpleasant sour odor, higher acidity than normal.
• Leakage: Defective seaming, nail holes, excessive pressure, corrosion, or mechanical damage cause leaks.
• Breathing (Breather): Tiny leaks let air in and destroy the vacuum without affecting micro-organisms. May cause rusting.
• Bursting: Excess pressure caused by food decomposition; loss of the canned product.

Pickling

• Preserving fruits/ vegetables using 5%-10% salt solution (brine).
• Salt prevents spoilage, allows lactic acid bacteria to grow, converting natural sugars into lactic acid.
• The fermentation process takes weeks, eventually resulting in 1% acidity in the product.
• Spices and edible oils are used in pickle-making, improving flavor and inhibiting undesirable microflora.

Jam and Jelly

• Converting fruit pulp into jam and jelly.
• Preserving fruit by adding considerable sugar to lessen the water content, preventing microbial growth.
• Fruit is mashed/sliced, mixed with sugar and simmered until it reaches a gel-like consistency.
• Fruit pulp (with added pectin) is boiled to a gel at 103-105°C.

Problems During Jam & Jelly Preparation

• Cloudy/foggy jelly: Due to non-clarified fruit extract or using immature fruits.
• Weeping/syneresis: Exudation of fluid from the gel due to excess acid, too little sugar, insufficient pectin, or premature gelation.
• Failure of jellies to set: From lack of acid or pectin, or too much sugar. Can involve insufficient cooking of the fruit; poor pectin extraction.
• Formation of crystals: From adding too much sugar.
• Stiff/tough jelly: Caused by overcooking or by too much pectin or too little sugar.
• Growth of molds: Food contamination from improper sterilization.

Squashes

• Sweetened fruit juices with a minimum of 25% fruit juice (by volume), as per Indian Standards.
• Mixed with water (1:3 ratio). Contains preservatives and flavorings for improved taste and longer shelf life.

Tomato Products

• Tomato Juice: Extracted from tomatoes.
• Tomato Puree/Paste: Pulped & concentrated tomatoes.
• Tomato Sauce: Tomato purée or paste with added ingredients.
• Tomato Ketchup: Tomato pulp, spices, salt, vinegar.
• Tomato Chutney: Tomato product, spices, and other ingredients.
• Tomato Soup: Canned tomato product mixed with other materials to make a soup.
• Tomato Chili Sauce: Tomato product, spices, and chili peppers.

Sauces

• Prepared from the pulp of tomatoes or other fruits/vegetables.
• Typically contain 15% total solids, with 1.2% acidity and 3% preservatives
• Includes tamarind, pumpkin, chili, and soya sauces.

Ketchup (Preparation)

• Selecting and cleaning ripe tomatoes.
• Preparing pulp by crushing and cooking.
• Adding spices, salt, vinegar, and other ingredients.
• Cooking the pulp to a consistent texture.
• Removing the spice bag, and extracting flavors from the spices.

Tomato Puree

• Tomato pulp with no skin and seeds, containing at least 8.37% salt-free tomato solids.
• Concentrated further to 12% solids to become heavy tomato puree.
• Packaged in glass bottles or cans

Chemical Preservatives

• Used to retard or inhibit the activity of microorganisms, including fermentation, spoilage, and decomposition of food.
• Class 1: Common salt, sugar, dextrose, spices, vinegar, and ascorbic acid.
• Class 2: Benzoic acid (and its salts), SO2 and salts of sulphuric acid, nitrates, ascorbic acid (and its salts), propionic acid and its salts, and lactic acid and its salts.

Other Preservation Methods

• Preservation by oil: Preventing microbial growth (e.g., pickles).
• Preservation by fermentation: Microorganisms ferment carbohydrates into alcohol or organic acids; maintaining keeping quality of products depends on the presence of alcohol, acetic acid, and lactic acid.
• Preservation by by carbonation: Dissolving CO2 in water or beverages, providing a distinct taste. Supplementing the effect of acidity (suppressing pathogenic bacteria) with 0.005% sodium benzoate.
• Preservation by Antibiotics: Using certain metabolic products of microorganisms as preservatives (e.g., nisin)

Home Assignment

• List value-added products available in the market for specified fruits.
• Draw a processing flow chart for each product. (e.g., Mangoes, bananas, pineapples, guavas, avocados, durian, strawberries, oranges, cherries, passion fruit, apples, grapes, wood apples, papayas)