This set of Fruits Processing Multiple Choice Questions & Answers (MCQs) focuses on “Blanching of Fruits”.
1. What is the purpose of blanching?
a) Stops enzyme actions
b) Prevent reduction reaction
c) Removes bruises
d) Improves metabolism
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Explanation: Blanching stops enzyme actions which otherwise cause loss of flavor, color and texture. In addition, blanching removes some surface dirt and microorganisms, brightens color and helps slow vitamin losses. It also wilts greens and softens and makes them easier to pack.
2. What are the disadvantages of blanching?
a) Stops enzyme actions
b) Prevent reduction reaction
c) Leaching of nutrients
d) Improves metabolism
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Explanation: One of the main disadvantages of hot water blanching is that it leaches the micro nutrients from the product. Therefore it affects the nutritional quality of the product. Water soluble vitamins are leached especially from citrus fruits.
3. What is the temperature for blanching?
a) 160°C
b) 150°C
c) 100°C
d) 1200°C
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Explanation: Small vegetables and fruits that contain less surface area are blanched very quickly. It takes less than few minutes. But the big fruits and vegetables require more blanching time. Blanching as a unit operation is a short time heating in water at temperatures of 100°C or below.
4. What are the effects of blanching?
a) Protein denaturation
b) Loss of color
c) Modifying texture
d) Protein denaturation, loss of color and modifying texture
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Explanation: the main purpose of blanching for fruits and vegetables is to remove the peel from the surface of the product. It also alters the texture. It also inactivates the polyphenolase enzymes. The blanching results in tissue cells damage, denaturation of protein and color loss due to the heat treatment.
5. What happens if blanching of fruit is not done before freezing?
a) Faded or dulled coloring
b) Increased shelf life
c) Decreased moisture content
d) Protein denaturation
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Explanation: Blanching helps fruits keep their vibrant colors and retain nutrients. It also stops the enzymes that would lead to spoilage. Therefore if blanching is not done before freezing, it results in faded or dulled coloring, as well as off flavors and textures.
6. Which of the following factors influences blanching time?
a) Size
b) Relative humidity
c) Pressure
d) Relative humidity and pressure
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Explanation: Blanching time is the total time taken by the product for inactivating the poly phenol oxidase. It depends on the type of fruit or vegetable. The size of the pieces of food plays an key role. Blanching temperature depends on the method of heating system.
7. Are these statements about the blanching true?
Statement 1: Blanching reduces the numbers of contaminating microorganisms on the surface of foods.
Statement 2: Blanching also softens vegetable tissues to facilitate filling into containers.
a) True, False
b) True, True
c) False, True
d) False, False
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Explanation: Blanching reduces the numbers of contaminating microorganisms on the surface of foods Blanching also softens vegetable tissues to facilitate filling into containers and removes air from intercellular spaces. It increases the density of food and assists in the formation of a head-space vacuum in cans.
8. Steam blanching has poor uniformity of heating in the multiple layers of food.
a) True
b) False
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Explanation: In conventional steam blanching, there is often poor uniformity of heating in the multiple layers of food. The time and temperature combination required to ensure enzyme inactivation at the center of the bed. But this results in overheating of food at the edges. Therefore loss of texture and other sensory characteristics takes place.
9. What is the limitation of hot water blancher?
a) Risk of contamination by thermophilic bacteria
b) Risk of contamination by mesophilic bacteria
c) Does not maintains the pH
d) Does not maintains the flavor
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Explanation: The limitation of hot water blancher is there is risk of contamination by thermophilic bacteria.it has higher cost for water treatment and effluent treatment. But the hot water blancher has a very good efficiency than steam blancher.
10. Which of the following is added to retain chlorophyll during blanching?
a) Sodium carbonate
b) Potassium nitrate
c) Sodium metabisulphite
d) Potassium metabisulphite
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Explanation: Blanching brightens the color of some foods by removing air and dust on the surface and thus altering the wavelength of reflected light. Sodium carbonate or calcium oxide is often added to blancher water to protect chlorophyll. It helps in retaining the color of green vegetables.
11. Which of the following is added to retain firmness during blanching?
a) Sodium carbonate
b) Calcium chloride
c) Sodium metabisulphite
d) Potassium metabisulphite
View Answer
Explanation: One of the purposes of blanching is to soften the texture of fruits to aid in filling of containers prior to canning. Calcium chloride is therefore added to blancher water. It forms insoluble calcium pectate complexes and thus maintains firmness in the tissues.
Sanfoundry Global Education & Learning Series – Fruits Processing.
To practice all areas of Fruits Processing, here is complete set of 1000+ Multiple Choice Questions and Answers.
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