Difference between revisions of "AY Honors/Food - Freezing/Answer Key"
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==6. Quick freeze a vegetable for easy pouring.== | ==6. Quick freeze a vegetable for easy pouring.== | ||
==7. Why is salt not put in vegetables to be frozen?== | ==7. Why is salt not put in vegetables to be frozen?== | ||
| − | + | Salt lowers the freezing point of water from its normal temperature of {{units|0°C|32°F}} to {{units|-21°C|-6°F}}. Most food freezers operate at {{units|-18°C|0°F}}, which is higher than the freezing point of salt water. If food to be frozen contains enough salt, it will not freeze in a regular freezer. If it contains only a little salt, the freezing point will be lowered, but not by as much. Even a small amount of salt will prevent it from quick-freezing. | |
==8. Freeze some peaches in light syrup and also some in orange or pineapple juice. What is the reason for using ascorbic acid in the syrup and not in the fruit juice? Why is ascorbic acid used in freezing peaches?== | ==8. Freeze some peaches in light syrup and also some in orange or pineapple juice. What is the reason for using ascorbic acid in the syrup and not in the fruit juice? Why is ascorbic acid used in freezing peaches?== | ||
Revision as of 22:57, 17 April 2007
1. Define the following terms:
- a. Blanching
- Blanching is a food preparation process wherein the food substance, usually a vegetable or fruit, is plunged into boiling water, removed after a brief, timed interval and finally plunged into iced water or placed under cold running water (shocked) to halt the cooking process.
- b. Quick freeze
- Quick freezing is used to quickly freeze perishable food items. In this case, water contained inside the food items is subjected to temperatures well below its melting/freezing point {{inits|0°C|32°F). This causes the water inside the foods to freeze in a very short period of time.
- c. Freezer burn
- Freezer burn is a condition that occurs when frozen food has been damaged by ice crystals, due to air reaching the food. It is generally caused by non-airtight packaging. Freezer burn often results in change of texture and discoloration of the affected food. It appears as grayish to brown leathery spots on the food. Although freezer burn affects the quality of food, it does not make it unsafe or unhealthful to eat.
2. What kinds of containers can be used for freezing foods?
Plastic containers work the best. Metal containers also work well. The important considerations are that the container be food-safe, air-tight, and not be damaged by freezing.
3. What are the essential things to be considered when selecting vegetables or fruits for freezing?
First check the quality, then wash thoroughly. Make sure the fruit or vegetable has no salt (or any other freezing-preventing material) on it, then when you freeze the fruit/vegetable make sure that is is not bumped or squished.
4. How do you thaw frozen vegetables for the table? How do you thaw frozen fruits for the table?
- Vegetables:
- Fruits:
5. Freeze two vegetables (corn and another of your choice), then prepare and serve for sampling.
6. Quick freeze a vegetable for easy pouring.
7. Why is salt not put in vegetables to be frozen?
Salt lowers the freezing point of water from its normal temperature of 0°C
to -21°C. Most food freezers operate at -18°C, which is higher than the freezing point of salt water. If food to be frozen contains enough salt, it will not freeze in a regular freezer. If it contains only a little salt, the freezing point will be lowered, but not by as much. Even a small amount of salt will prevent it from quick-freezing.
