Q. Rehydration tests for the dried sample?
• gain knowledge about the sensory changes that take place during the dehydration of the samples, and
• learn about the effectiveness of different drying techniques.
Rehydration tests for the dried materials are important as they give idea about the percentage water in the rehydrated material, rehydration ratio and coefficient of rehydration. However, no standard method for testing these are available, although are developed by the plants where the daily evaluation of quality of dried products is made.
Sample: Culture or dehydrated carrots or dehydrated cauliflower or dehydrated
cabbage. (Take any 3 dried sample).
Beakers - (6)
The following procedure for measuring rehydration is suggested by the US
Department of Agriculture. Follow these steps and carry out the activity.
1) Weigh 2-10 g of the dry material (sample) in six beakers of 500 ml capacity.
2) Add 80-150 ml of distilled water*
3) Cover each beaker with watch glass, bring to a boil within 3 min on an electric heater/burner and continue boiling for 5 minute.
4) Filter through whatman no. 4 filter paper and drain excess water until the drip from the funnel has stopped.
5) Remove the sample from the funnel and weigh in a weighed petri dish.
6) Set the sample aside for conducting quality tests.
7) Rehydrate six other 10 g samples, boiling two for 10 minutes, two for 20 minutes, and two for 30 minutes.
8) Boiling should be carried out carefully for proper rehydration of samples.
9) Now record your observations and do the calculations as stated herewith.