3.2 Dehydration
Objectives
- To apply the principles of dehydration to home methods of drying.
- To properly store dehydrated food.
- To rehydrate or otherwise prepare dehydrated food for consumption.
Laboratory Problems
- Pretreat, dry, store and serve some commonly dehydrated fruits and vegetables.
- Observe the characteristics of various dried fruits.
General Laboratory Directions
This lesson is divided into two laboratory periods several weeks apart, with short assignments during the week following the first laboratory.
Preparation Day
Pretreat assigned fruit or vegetable according to specific directions below to control enzymatic deterioration.
Carrots or Onions
Wash and trim. Cut into ⅛-inch slices, then pretreat if directed. Steam blanch by spreading vegetable in a thin layer in steamer. Steam until hot in center, approximately 3 to 3 ½ minutes.
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- no treatment.
- steam blanching.
Apples
Wash, peel, core, and cut into ⅛-inch rings. Immediately drop into assigned pretreatment solution and soak for 10 to 15 minutes.
-
- no treatment.
- 1 tsp. salt in 1 pint water.
- 2 tsp. ascorbic acid in 1 pint water.
Peas
No treatment.
- Drain and dry fruits and vegetables. Spread one layer of cheesecloth on dehydrator racks. Spread food in a single layer on racks. Set temperature of dehydrator at 140o-150oF. Dry until vegetable slices are brittle (3-6 hours) and fruit slices are leathery and pliable (6-8 hours).
Label a Ziploc bag for each dehydrated sample as follows:
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- Name of Product, treatment used, section number, and student initials
- Let food stand in a large loosely covered container for a week, stirring each day, to allow moisture to equilibrate.
- Place in small air-tight containers and store in a cool place.
Evaluation Day
Prepare food according to specific directions. Record your observations on the chart.
Carrots
Rehydrate by soaking for 20 minutes or more in enough water to cover. Add more water if necessary to keep carrots covered. Cook carrots as if they were fresh in a small amount of soaking water.
Apples
Dehydrated apple slices may be eaten as they are, or they may be rehydrated and cooked. Add enough water to cover fruit and soak for 1 hour or more. Add more water if necessary to keep fruit covered. Simmer fruit in soaking water until tender.
Observations and Explanations
Type of Treatment Before Drying | Appearance | Texture | Flavor |
---|---|---|---|
Carrots, No Pre-treatment | |||
Carrots, Steam-Blanched | |||
Apples, No Pre-treatment | |||
Apples, Salt | |||
Apples, Ascorbic Acid |
Observe the characteristics of various dried fruits:
Dried Fruits | Appearance | Texture | Flavor |
---|---|---|---|
Apples | |||
Apricots | |||
Currants | |||
Dates | |||
Figs | |||
Peaches | |||
Prunes | |||
Raisins | |||
Partially cook in a large amount of boiling water to inactivate enzymes or to facilitate peeling.