Food Processing &Preservation, Quiz – 15


Q. The damage in texture of strawberries tomato during freezing storage is due to 

  • Formation of small ice crystals
  • Formation of large ice crystals
  • Protein denaturation
  • All of the options

Answer: b)

Formation of large ice crystals in strawberry and tomato freezing causes its texture loss due cell wall rupture during thawing.

Q. The microorganisms which grow at freezing temperatures are known as _____________

  1. Psychrotrophs
  2. Thermotrophs
  3. Mesotrophs
  4. None of the options

Answer: a)

Organisms called psychrotrophs, also known as psychrotolerant, prefer cooler environments, from a high temperature of 25 °C to refrigeration temperature about 4 °C. They are found in many natural environments in temperate climates. They are also responsible for the spoilage of refrigerated food.

Q. The rate of freezing depends upon 

  1. Agitation
  2. Type of refrigerant used
  3. Size of food package
  4. All of the options

Answer: d)

All the above mentioned factors enhance the rate of freezing size of package or surface area of food is directly proportional to rate of freezing.

Q. In this type of freezing method the food comes in air contact

  1. Blast freezer
  2. Immersion freezer
  3. Single plate freezer
  4. Slush freezer

Answer: a)

The air blast freezer is one the oldest and commonly used freezing equipment due to its temperature stability and versatility for several product types. In general, air is used as the freezing medium in the freezing design, either as still air or forced air. Freezing is accomplished by placing the food in freezing rooms called sharp freezers. Still, air freezing is the cheapest way of freezing and has the added advantage of a constant temperature during frozen storage, which allows usage for unprocessed bulk products like beef quarters and fish.

However, it is the slowest method of freezing due to the low surface heat transfer coefficient of circulating air inside the room. Freezing time in sharp freezers is largely dependent on the temperature of the freezing chamber and the type, initial temperature, and size of product (Desrosier and Desrosier 1977).

An improved version of the still air freezer is the forced air freezer, which consists of air circulation by convection inside the freezing room. However, even modification of the sharp freezer with extra refrigeration capacity and fans for increased air circulation does not help control the air flow over the products during slow freezing. 

There are a considerable number of designs and arrangements for air blast freezers, primarily grouped in two categories depending on the mode of process, as either inline or batch.

Q. The major reason for deterioration in partially frozen food is due to

  • Hypotonic solution of remaining water
  • Hypertonic solution of remaining water
  • Isotonic solution of remaining water
  • All of the options

Answer: b)

Hypertonic solution which remains in frozen food also after freezing which deteriorate the food.

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