ICAR AICE-JRF/SRF Principles of Food Science & Food Preservation: practice questions

Question 1 · hard

If Q10 for a deterioration reaction is 3, by what factor does the rate rise when temperature goes from 20 °C to 40 °C?

1. 6
2. 9
3. 3
4. 27

Question 2 · hard

Why does one mole of sodium chloride depress water activity about twice as much as one mole of sucrose in the same water?

1. It has a molar mass about six times greater than that of sucrose
2. It dissociates into two ions, roughly doubling the number of solute particles
3. It binds water covalently while sucrose binds none of the water
4. It raises the vapour pressure of the water above the solution at the same temperature

Question 3 · hard

What is hysteresis in moisture sorption?

1. Water activity always equals moisture content divided by one hundred
2. The isotherm moves to higher aw when temperature rises, at the same moisture content, in all foods
3. The monolayer value equals the moisture at an aw of exactly 0.5 for every food
4. Adsorption and desorption isotherms differ, so moisture at a given aw depends on direction

Question 4 · hard

Why do high-temperature short-time processes give better quality for the same microbial kill?

1. At high temperature microbes die instantly and quality reactions stop entirely
2. Quality reactions have a smaller z value than microbial death, so quality improves when heated
3. Microbial kill has a smaller z than most quality losses, so it speeds up more with temperature
4. High temperature removes oxygen, which is the only cause of quality loss

Question 5 · hard

Why is fish intended to be eaten raw often required to be frozen before sale?

1. Freezing kills parasites such as anisakid nematodes
2. Freezing destroys histamine already formed in the flesh
3. Freezing kills all bacteria and viruses present in the fish
4. Freezing removes heavy metals from the fish tissue

Question 6 · hard

Why does temperature fluctuation in frozen storage harm ice cream and frozen foods?

1. Small crystals melt and refreeze onto larger ones, coarsening texture
2. It causes the fat to turn into protein during each thaw cycle
3. It sterilises the food, removing desirable cultures
4. It converts starch into sugar, making the food sweeter

Question 7 · hard

Which hazard can arise from a poorly controlled fermentation of protein-rich foods such as fish sauce or cheese?

1. Benzene from benzoate and vitamin C
2. Biogenic amines such as histamine
3. Acrylamide from starch
4. Trans fats from hydrogenation

Question 8 · medium

Why is sodium iron EDTA used to fortify high-phytate flours?

1. It turns flour white, hiding the bran colour
2. It adds no iron but blocks phytate completely
3. Its iron stays well absorbed despite phytate
4. It is the cheapest form of iron available anywhere

Question 9 · hard

Why is iron the most difficult nutrient to add to foods?

1. Iron is toxic at any level and so can be added only in trace amounts
2. Iron is destroyed completely by cooking, so none reaches the consumer
3. Iron is volatile and evaporates from the food during storage
4. Well-absorbed forms spoil the food; inert forms are poorly absorbed

Question 10 · hard

Why can processing rarely improve the quality of a poor raw material?

1. Processing always destroys all quality, so raw material does not matter
2. Processing adds back all nutrients and flavours lost in the field
3. Poor raw material becomes good after heating to 121 °C
4. Processes preserve existing quality; they cannot remove all defects