Q1. __________ involves the replacement, in full or in part of the losses incurred during processing.

1. Enrichment
2. Restoration
3. Fortification
4. Enhancement

ANSWER – B. Restoration

• Explanation: Restoration is the whole or partial repair of losses caused during processing. When we heat or concentrate orange juice or other citrus juice via thermal processing, some of the nutrients, such as vitamin C and other antioxidants, are destroyed. After the processing, ascorbic acid or vitamin C from natural sources might be added to compensate for the loss caused by the processing.

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Q2. What is the range of the production capacity for pilot/laboratory-scale freeze dryers?

1. 1 to 10 kg
2. 2 to 10 kg
3. 1 to 20 kg
4. 2 to 20 kg

ANSWER: D. 2 to 20 kg

• Explanation: Freeze-drying, also called lyophilization or cryodesiccation, is a low-temperature dehydration method that involves freezing the product, reducing the pressure, and then sublimating the ice. This is in contrast to most traditional methods of dehydration, which use heat to evaporate water. The rehydrated product’s quality is outstanding thanks to the low processing temperature. When solid materials, such as strawberries, are freeze-dried, the shape of the result is preserved. The freeze drier on the pilot/laboratory scale can freeze-dry batches of 2 to 20 kg of frozen goods.

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Q3. Which of the following is not a freeze-dehydration-related process?

1. Freeze concentration
2. Liquefaction
3. Sublimation
4. Condensation

ANSWER: B. Liquefaction

• Explanation – Pre-freezing, freeze concentration, condensing, and defrosting are all freeze-drying processes. Sublimation is a type of freeze-drying in which a substance is converted from a solid to a gas without passing through the liquid phase. Liquefaction is not a part of the freeze-dehydration process, which is the conversion of a substance from a solid or gaseous state to a liquid state.

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Q4. Which of the following affect the temperature of collapse in a freeze-drying process?

1. Moisture content and pore size
2. B. Moisture content and bulk density
3. Moisture content and solute concentration
4. Moisture content and true density

ANSWER – C. Moisture content and solute concentration

• Explanation: When a product is cooked to a specific temperature, it changes its bulk density. Collapse is the term for this transformation. It happens as the concentrated phase’s mobility rises. The temperature at which the meal collapses is determined by the moisture content and solutes present.

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Q5. The rate of heat transfer in freeze-drying depends on the ________ and ________ of the ice layer.

1. Thickness and Thermal conductivity
2. Thickness and Temperature
3. Thermal conductivity and Pressure
4. Temperature and Thermal diffusivity

ANSWER: A. Thickness and Thermal conductivity

• Explanation: The rate of heat transmission in the freeze-drying process is influenced by the thickness and thermal conductivity. The rate of heat transfer is determined by the ice layer’s thickness and thermal conductivity. The thickness of the ice thins out as it dries, and the rate of heat transfer rises. Variations in the rate of freezing affect ice crystal size and hence pore size in the dried product, and thus can be predicted to influence the pace of drying and the features of the dried product, particularly its reconstitutability.

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