Week11C2 : cold processing

Question 1

How does the cold processing work to increase the shelf life

Answer 1

doesn’t kill microbes or denature enzymes but it slows the rate of deterioration of food.

Question 2

What is the temperature of common refrigerators

Answer 2

below 4˚C or 40˚F.

Question 3

What are the variable that needs to be controlled in refrigeration

Answer 3

1. high RH
2. Good air circulation
3. Temperature
4. Gas atmopsheres

Question 4

T or F : freezing results in change in the sensory qualities

Answer 4

False not if it is done properly

Question 5

What other kitchen appliance has improved the convenience of frozen foods

Answer 5

microwave

Question 6

T or F : the freezing point of food products is 0˚C

Answer 6

false

Question 7

Complete : dissolved solutes results in freezing point ____

Answer 7

depression

Question 8

What is the temperature of the eutectic point for most foods?

Answer 8

-50˚C

Question 9

What is the common commercial temperature of freezing

Answer 9

-18˚C

Question 10

What is the eutectic point

Answer 10

the temperature at which the residual and the solutes water co-crystallize.

Question 11

At commercial temperature _____ of the water in a food products is in the crystalline state

Answer 11

99%

Question 12

Why does frozen product can continue to deteriorate?

Answer 12

because some water is still available for chemical reactions

Question 13

What are the changes that can occur in frozen foods ?

Answer 13

1. reduction in solubility
2. Denaturation of proteins
3. change in pH
4. Destruction of sensitive emulsion

Question 14

What is the reason of the formation of crystals in ice cream?

Answer 14

reduction in the solubility of lactose with water

Question 15

Why is there denaturation of protein in frozen foods

Answer 15

because the remaining salt or acids are concentrated in frozen food and that can have an impact on the peptide bonds.

Question 16

Why can’t you put mayo in the freezer?

Answer 16

because it will loose the emulsion

Question 17

Why can’t you put coke in the freezer

Answer 17

because of the loss of gas solubility.

Question 18

Why does the water expands in the freezer?

Answer 18

because of its hydrogen bonding.

Question 19

Slow freezing produces ____ crystals while fast freezing produces _____ ice crystals

Answer 19

larger

smaller

Question 20

Complete : as _____ increases, the rate of freezing increases

Answer 20

airflow

Question 21

____ the temperature differential and faster is the rate of freezing

Answer 21

Higher

Question 22

What is the freezing point of liquid nitrogen?

Answer 22

-198˚C

Question 23

what percentage of the food product cost is due to freezing?

Answer 23

10%

Question 24

what are the fluctuating temperature of freezers?

Answer 24

-22˚C to -12˚C

Question 25

Subjecting milk to temperatures >100°C for ~1 second using direct steam injection is ……

Answer 25

UHT

Question 26

A container that is made of cardboard, aluminum foil and plastic and that is formed on-site is ……

Answer 26

tetra brick

Question 27

The decrease of the freezing point of a solvent on addition of a non-volatile solute is ……

Answer 27

freezing point depression

Question 28

Fast freezing produces …… ice crystals

Answer 28

large

Question 29

Production (freezing) represents …… of the total cost of frozen products.

Answer 29

10%

Question 30

According to the U.S. National Institute of Standards and Technology, liquids of gases that have boiling points below -180 °C are referred to as ……

Answer 30

cryogenic liquids

Question 31

…… °C is the accepted temperature financially and commercially to store frozen products.

Answer 31

-18

Question 32

What the boiling point of cryogenic liquids?

Answer 32

Below -180˚C