5 Determination of gel consistency
 

 

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Materials and Reagents

 

95% Ethanol

0.025% thymol blue

0.2N KOH

13 x 100 mm culture tubes

Water bath

Ice cold water

Graph paper

 

Composition of reaction mixtures

 

A. 0.2N KOH solution

Dissolve 1.12g KOH in 100ml of distilled water

 

Procedure

 

1.  Place 100 mg rice powder (12% moisture) in 13 x 100 mm culture tubes

2.  Wet the powder with 0.2 ml 95% ethanol containing 0.025% thymol blue.

3.  Shake the tube and add 2.0 ml of 0.2N KOH immediately and disperse the mixture.

4.  Cover the tubes with glass marbles and place for 8 minutes in a boiling water bath.

5.  Remove the samples, keep at room temperature for 5 min, and then cool in ice cold water for 15 minutes.

6.  Lay tubes horizontally over a ruled paper graduated in millimeters and measure the length of the gel from the bottom of the test tube after 30 - 60 minutes.

 

Gel consistency is classified as given below.

 

Category

Consistency, mm

Soft

61-100

Medium

41-60

Medium hard

36-40

Hard

26-35

 

 

 

 

 

 

 

Cagampang, G.B., CM. Perez and B.O. Juliano (1973). A gel consistency test for eating quality in rice. J. Sci. FoodAgr., 24:1598 -1594.