Q1. The bitterness of orange juice can be prevented by ______.

1. Using pectic enzymes
2. Raising the pH
3. Adding ascorbic acid
4. Both A and B

ANSWER: D. Both A and B

• Explanation – The major bitter component of navel oranges is limonin. Excessive extraction of bitter fractions from the rag and pulp during orange juice reparation should be avoided. Raise the pH to greater than 4.0 to avoid the production of limonin di lactone. Pectic enzymes are used. The enzymes cause the dispersed colloids to coagulate, and the bitter principles are precipitated along with them. Centrifugation after stirring the juice with dry polyamide granules. However, ascorbic acid loss of up to 25% has been documented.

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Q2. _______ is one of the processes used to reduce or avoid detrimental phenomena in fruit and vegetables without a sensorial and nutritional quality loss.

1. Osmotic dehydration
2. Washing
3. Freezing
4. Sun drying

ANSWER: A. Osmotic dehydration

• Explanation: Osmotic dehydration is one of the methods for reducing or avoiding harmful effects in fruits and vegetables while maintaining sensory and nutritional quality. Before using traditional drying methods, osmotic dehydration involves placing fruit pieces in contact with sugar syrup to remove 30-50 percent of the water by weight. This suppresses the action of polyphenol oxidase and reduces the loss of volatile flavour compounds during dehydration.

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Q3. The factors affecting the osmotic drying process include?

1. Size & shape
2. Temperature
3. Type of osmotic agent
4. All of the above

ANSWER: D. All of the above

• Explanation – Size and form, kind of osmotic agent, the concentration of the osmotic solution, temperature, food to solution ratio, time, pressure, agitation of the osmotic medium and food pieces, Ca fortification of fruits and vegetables, and other parameters all impact the osmotic drying process. A saturated glucose or sucrose solution, 60oBrix glucose or isomerized glucose-fructose syrups, sucrose (70%)-glycerol (65%) 1:1, and ethanol were utilized as osmotic agents.

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Q4. ________ are the typical additives for the fruit and vegetable foam formulation from juice or pulp.

1. Glycerol monostearate
2. Solubilized soya protein
3. Propylene glycol monostearate
4. All of the above

ANSWER – D. All of the above

• Explanation:  The common additions for the fruit and vegetable foam formulation from juice or pulp include glycerol monostearate, solubilized soy protein, and propylene glycol monostearate. Foam mat drying entails drying a thin layer (0.1–0.5 mm) of stabilized foam in the air for a few minutes at 65°C–70°C since the foam structure cuts drying time in half.

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Q5. Combined UF and RO allows for concentration of orange juice to levels of?

1. ~ 35⁰Brix
2. ~ 42⁰Brix
3. ~ 47⁰Brix
4. ~52⁰Brix

ANSWER: B. ~ 42⁰Brix

• Explanation: To remove suspended particulates, the fruit juice is first run through a UF system. The UF permeate is pumped into a RO system, which concentrates the taste and fragrance chemicals, carbohydrates, and amino acids in preparation for reconstitution into single-strength juice. This permits orange juice to be concentrated to 42⁰Brix levels. Up to 45-55⁰Brix can be reached on a commercial basis.

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