IRRI SERVICE LABORATORIES
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The time required for cooking rice grains is determined by gelatinization temperature. The degree of spreading of six head rice grains soaked in 10 ml of 1.7 % KOH after 23 hours at room temperature (25 ± 5 °C) is measured and a score of 1-7 is given, depending on the intensity of swelling and spreading, 1 as having no reaction and 7 being mostly dissolved. An alkali spreading value corresponds to the following gelatinization temperature:
1-2 high (74.5 to 80 °C)
3 intermediate high
4-5 to intermediate (70 to 74 °C)
6-7 low (< 70 °C)
Note: For gelatinization temperature determination by ASV, the sample weight required is at least 3 g of head rice placed in a paper bag. In order to keep the integrity of the customers' samples, senders are requested to place them in secure plastic boxes.
Juliano BO. 2010. Screening for grain quality in the rice breeding program. Grain Quality of Philippine Rice. p. 12
Little RR, Hilder GB, Dawson EH. 1958. Differential effect of dilute alkali on 25 varieties of milled white rice. Cereal Chem. 35:111-126
Sreenivasulu, N. (2018). Rice Grain Quality: Methods and Protocols. New York, NY: Humana Press.