Juice Processing Techniques Quiz

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Questions and Answers

What is the primary aim of de-tartarisation in raisin juice processing?

To enhance color retention

To improve flavor stability

To eliminate potassium bitartrate (correct)

To increase sugar content

At what temperature is pasteurization typically performed in the continuous stream method?

65°C

95°C

85°C

75°C (correct)

What type of filtration additive can be used in press-filters during the filtration of clarified juice?

Sodium bicarbonate

Activated charcoal

Cornstarch

Kieselgur (correct)

Which operation is carried out at a speed of 6000 to 6500 RPM in the context of juice processing?

Centrifugal separation (A) Signup and view all the answers

What is the concentration of CO2 pressure used for preservation in juice processing?

1.5% (D) Signup and view all the answers

During pasteurization, what is the temperature the juice reaches before cooling, if there is no pre-pasteurization?

68°C (B) Signup and view all the answers

What is the storage temperature range for juice preservation by freezing?

-15 to -20 °C (C) Signup and view all the answers

What is the recommended duration for rapid pasteurization of juice?

10-60 seconds (A) Signup and view all the answers

What is one method of preventing the growth of microorganisms in food?

Filtration (D) Signup and view all the answers

What is blanching primarily used for in food preservation?

Kill harmful microorganisms (D) Signup and view all the answers

Which fruit product is created from pressing the juice out of fruits?

Fruit juice (C) Signup and view all the answers

What is the minimum percentage of fruit juice required in ready-to-drink fruit juice (RTS)?

10 percent (A) Signup and view all the answers

What is the main advantage of using antioxidants in food preservation?

Prevent oxidation (B) Signup and view all the answers

How are fruit juice powders primarily preserved for use in drinks?

Dehydration and freeze-drying (A) Signup and view all the answers

What type of food preservation technique does killing microorganisms by heat or radiation fall under?

Destruction (D) Signup and view all the answers

Which of the following is NOT considered a semi-solid fruit product?

Fruit juice (A) Signup and view all the answers

What distinguishes jam from jelly?

Jam is made from fruit pulp, whereas jelly is prepared from clear fruit extract. (D) Signup and view all the answers

Which of the following statements about concentrated juices is true?

They are defined as juices that have had a major portion of their water content removed. (C) Signup and view all the answers

What is the primary difference in the composition between nectars and pure fruit juices?

Nectars must contain at least 25% fruit pulp mixed with sugar syrup. (C) Signup and view all the answers

Which type of product is prepared by alcoholic fermentation of fruit juice?

Fermented fruit (B) Signup and view all the answers

What is the minimum percentage of tomato solids that ketchup must contain?

12% (D) Signup and view all the answers

How are pickles primarily preserved?

Common salt or vinegar (B) Signup and view all the answers

Which of the following is NOT a characteristic of squashes?

They contain 30% fruit solids. (A) Signup and view all the answers

What is the characteristic feature of marmalade?

It consists of jelly with suspended shreds of peels. (A) Signup and view all the answers

What is the minimum percentage of solids in heavy tomato puree?

12% (D) Signup and view all the answers

Which type of chemical preservative primarily retards the activity of microorganisms?

Class-2 preservatives (B), Class-1 preservatives (D) Signup and view all the answers

Which chemical preservative is best suited for controlling moulds rather than bacteria?

Potassium Meta bisulphate (KMS) (C) Signup and view all the answers

Which product is not suitable for using KMS as a preservative?

Phalsa juice (B), Jamun juice (C) Signup and view all the answers

What is Sodium Benzoate derived from?

Benzoic acid (A) Signup and view all the answers

Which of the following is NOT classified as a Class-1 preservative?

Sodium Benzoate (C) Signup and view all the answers

What is the primary effect of chemical preservatives on food?

Inhibit fermentation (B) Signup and view all the answers

What is a potential issue when using KMS in packaging?

It acts on tin containers (B) Signup and view all the answers

What is the final sugar concentration achieved when mixing 45% orange juice and 5% sugar syrup?

15% (C) Signup and view all the answers

Which of the following is a necessary step in the canning process of fruit?

Cutting and de-stoning the fruit (B) Signup and view all the answers

What is the primary filling material used in the canning of vegetables?

Brine solution (B) Signup and view all the answers

Why do vegetables require lacquered cans less frequently than fruits during canning?

Vegetables have lower acidity (C) Signup and view all the answers

At what temperature does effective sterilization during canning typically occur?

Greater than 100°C (B) Signup and view all the answers

Which of the following is NOT a step in the preparation process of canning fruit?

Fermentation (A) Signup and view all the answers

What role does the ripening of fruits play in the canning process?

To enhance flavor and sweetness (D) Signup and view all the answers

During which stage of canning is thermally processing the food important?

After filling (A) Signup and view all the answers

What is the purpose of enzyme clarifying in juice processing?

To decrease the juice's viscosity and facilitate filtration (A) Signup and view all the answers

How long can heating treatments for pectolitic enzyme preparations last at room temperature?

2 to 6 hours (D) Signup and view all the answers

At what temperature should the enzyme preparation heating not exceed?

50° C (C) Signup and view all the answers

What role does sticking play in juice processing?

It generates flocculation of particles through tannins (C) Signup and view all the answers

What is the main benefit of using diffusion for juice extraction?

It can be performed at high temperatures to help extract juice (C) Signup and view all the answers

Which of the following is NOT a method for clarifying juice?

Boiling (D) Signup and view all the answers

What substance is used in the sticking process to achieve flocculation?

Food grade gelatine (C) Signup and view all the answers

Which of the following steps is NOT mentioned as part of juice extraction processes?

Fermentation (C) Signup and view all the answers

Study Notes

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)

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Description

Test your knowledge on essential techniques in juice processing, including pasteurization, filtration, and preservation methods. This quiz covers various operations and standards in the production of clarified juice and its storage. Perfect for students and professionals in food science and technology!