Refrigeration and Freezing MIDTERM Flashcards
Low temperature storage slightly above freezing is invariably referred to as
It retards all forms of deterioration whether they are in the guise of physiological changes, enzymic changes or those induced by microbiological factors.
Cold Storage
The mans firsts refrigerator
Natural Caves
Wells, Springs and streams is also found to be effective
Requirements of food refrigeration
Constant temparature
Air circulstion
Control of the relative humidity
is necessary to avoid dehydration of products and to remove heat given off by the food and the heat that leaks through the walls of the refrigerator.
Air circulation
is necessary because the difference in vapor pressure of the refrigerator and that of the food causes the removal of moisture form the unpacked food.
Control of the relative humidity of the refrigerator
is a section of refrigerator with high relative humidity which would keep vegetables from wilting and fruits from shrinking.
The hydrator or crisper
lowers the temperature of food to solidify water content into ice crystals, inhibiting microbial growth and enzymatic activity, which cause spoilage
Freezing
preserves the fresh color, flavor and palatability of fruits, vegetables, meat, fish and poultry better than canning or any other method of food preservation.
Freezing
Methods of freezing
Slow or sharp freezing
Quick freezing
is considered the Father of Frozen Foods.
Clarency Birdseye
refers to freezing in cold room maintained at -5 to – 20 degree F. From 12 to 72 hours may be required to complete the freezing process.
Slow or sharp freezing
Since solidification is obtained as temperature drops from 32 degree to 25 degree F this range of temperature
zone of maximum crystal formation
freezing food for a short time, generally 30 minutes or less.
Quick freezing
This is a recent technique in the processing of fruits and vegetables. It consists of drying fruit or vegetable to about 50 percent of its original weight and volume. The partially dried materials is then frozen and stored at 0 degree F.
Dehydrofreezing
There are several types of home freezing equipment.
- Ice cube compartment
- Combination refrigerator- freezer
- Food freezer
It should be used only for storage of already frozen foods. Average temperature is 10 – 20 degree F
Ice cube compartment
Has 2 compartments: a frozen food compartment and an unfrozen food storage compartment.
This provides storage of frozen food for longer periods of time.
Combination refrigerator- freezer
Food freezer 2 types
Chest or horizontal freezer
Upright or vertical freezer
opens upward and is wide more than it is tall. The main problem of this type is the inaccessibility of foods at the bottom of the freezer.
Chest or horizontal freezer
occupies less floor space than the chest freezer.
Upright or vertical freezer
