Mock questions 2 GXSL

How much ice do you need in order to cool (0°C) 10 kg of fish at an initial temperature of 30°C? (Use: Cpf = 0.8 kcal/kg °C, Latent heat of fusion of ice = 80 kcal/kg)

• 2.0 kg

• 3.0 kg

• 4.0 kg

• 5.0 kg

The following fish species will be transported using separate insulated styrofoam boxes to a nearby landing site. Given the same mass of fish (10 kg), the same latent heat of fusion (79.7 calories per gram), and the same initial temperature of 25 degrees Celsius, which fish species will require more ice?

• S. longiceps

• N. japonicus

• M. rosenbergii

• T. albacares

How much energy is needed to freeze 2 kg fish to -30°C with an initial temperature of 25°C. The specific heat of water is 1 calorie/gram °C, the latent heat is 80 cal/g. Provide final answer in kilocalories unit (kcal).

• 241

• 315

• 108

• 50

The following statements correctly describe how spoilage is affected by temperature, EXCEPT:

• At low temperatures, microorganisms have a slower growth rate in the logarithmic phase.

• At low temperatures, microorganisms have a faster induction period or lag phase.

• Refrigeration depresses enzymatic activity and but not enzymatic stability.

• Spoilage is linearly related to storage temperature.

• Low-temperature preservation depresses molecular mobility and slows down biological processes.

Which of the following statements CORRECTLY describe low-temperature preservation?

• If done properly, frozen products will have a longer shelf life but requires more energy input than drying method.

• If done properly, freezing removes the necessity for cold-chain transport and processing of products.

• If done properly, refrigeration allows for a permanent preservation method resulting in products with an indefinite shelf life.

• If done properly, refrigeration can significantly improve the initial quality of the product.

Which of the following INCORRECTLY differentiates chilling and freezing as forms of low-temperature preservation methods?

• Chilling methods are cheaper and requires less technical skills than freezing.

• Frozen products can be stored for a longer period than chilled products.

• Chilling results in nutrient leaching while frozen fish are prone to dehydration.

• Chilling lowers water activity in the fish muscle while freezing inactivates microbial growth through low temperatures.

The following are advantages of direct icing, EXCEPT:

• It prevents surface dehydration and reduces weight losses.

• Its raw material is widely available and cheap.

• It increases the heat transport between fish and ice surfaces through convection.

• It has a high latent heat of fusion so that it is capable of removing large amount of heat while it melts.

Suppose 3 tonnes of fish (3,000 kg) are to be cooled from 24°C to -1°C and a 3:1 ratio of fish to seawater is used. The weight of ice required (in kilograms) is: (Use: Latent heat of fusion of ice = 80 kcal/kg, Specific Heat of fish and water = 1 kcal/kg °C)

• 1250

• 1500

• 1750

• 2000

The following statements correctly describe the different methods of storing fish in ice, EXCEPT:

• Bulking allows the layering of fish and ice and is the method usually used in the hold of fishing boats.

• Fish are stored belly side down in the shelfing method.

• Small milkfish are stored using the shelfing method and the boxing method for big, yellowfin tuna.

• In the tropics, ice to fish ratio used for bulking method is 1:1.

Which of the following statements INCORRECTLY describe the Thermal Arrest Period (TAP)?

• Fast passage through TAP results in few, large crystals than can break the cell walls.

• Fast passage through TAP prevents salts and enzymes from concentrating at a higher level, preventing autolysis.

• More than 65% of the energy extracted in freezing occurs during this stage.

• Little or no drop in temperature is occurring.