Rice grains cook dry, are less tender, and become hard upon cooling. Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 1 : What are the three chemical characteristics of milled rice that determine quality? Gelatinization temperature determines the time required for cooking the rice Gel consistency measures the tendency of the cooked rice to harden on cooling. High amyclose content? Rice grains cook dry, are less tender, and become hard upon cooling. Low-amylose content? Rice grains cook moist and are sticky

FREQUENTLY ASKED QUESTIONS (FAQs) Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 1 : What are the three chemical characteristics of milled rice that determine quality? FREQUENTLY ASKED QUESTIONS (FAQs) What are the specific physicochemical tests used to determine the cooking and eating qualities of rice? Alkali test Amylose test Gel consistency test Kernel elongation test Aroma test

FREQUENTLY ASKED QUESTIONS (FAQs) Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 1 : What are the three chemical characteristics of milled rice that determine quality? FREQUENTLY ASKED QUESTIONS (FAQs) Why is endosperm appearance a major breeding consideration? The appearance of milled rice is important to the consumer, which makes it also important to the producer and the miller. The consumer prefers rice with a clear endosperm and pays a premium rice for it, even though capacity disappears during cooking and does not affect eating quality. Grain with opaque areas in the endosperm, caused by the loose packing of the starch and protein particles, breaks more readily during milling than clear grain, greatly reducing its market value.

FREQUENTLY ASKED QUESTIONS (FAQs) Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 1 : What are the three chemical characteristics of milled rice that determine quality? FREQUENTLY ASKED QUESTIONS (FAQs) Of what importance are grain length, shape and endosperm appearance to the breeder? Most breeders attempt to estimate the milling behavior of pedigree selections n the basis of grain length and shape and on endosperm appearance. Grain traits that contribute to increased breakage, singly and in combination with other traits, include grain length, excessively slender or bold shape, partial flatness, and appreciable white belly.

FREQUENTLY ASKED QUESTIONS (FAQs) Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 1 : What are the three chemical characteristics of milled rice that determine quality? FREQUENTLY ASKED QUESTIONS (FAQs) How does the limited association of gelanization temperature and amyclose content help the breeders? It allows the breeders, in certain cases, to use the simple gelatinization temperature test to estimate the amylose content, which is considerably more difficult to measure directly.

FREQUENTLY ASKED QUESTIONS (FAQs) Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 1 : What are the three chemical characteristics of milled rice that determine quality? FREQUENTLY ASKED QUESTIONS (FAQs) How is gelatinization temparature related to the physical cooking properties of rice? Gelatinization temperature directly affects the physical properties of the starch granule, which in turn influences the quality ratings of cooked rice. Rice with a high gelatinization temperature becomes excessively soft and tends to disintegrate when overcooked. Under standard cooking procedures, this type of rice tends to remain undercooked. It requires more water and time to cook than those with low or intermediate gelatinization temperature. Thus, gelatinization temperature correlates positively with the time required to cook rice. Soaked milled rice of high gelatinization temperature elongates less during cooking than rices with low or intermediate gelatinization temperature.

FREQUENTLY ASKED QUESTIONS (FAQs) Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 1 : What are the three chemical characteristics of milled rice that determine quality? FREQUENTLY ASKED QUESTIONS (FAQs) Why test for gel consistency? Varietal differences in gel consistency exist among varieties of similar high amylose content (more than 25%). The gel consistency test separates the high-amylose rices into three categories: very flaky rices with hard gel consistency (length of gel = 40 mm or less) flaky rices with medium gel consistency (length of gel = 41 to 60 mm) soft rices with medium gel consistency (length of gel > 61 mm).

FREQUENTLY ASKED QUESTIONS (FAQs) Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 1 : What are the three chemical characteristics of milled rice that determine quality? FREQUENTLY ASKED QUESTIONS (FAQs) Why should paddy rice be stored for at least 4 months after harvest before tasting panels evaluate promising lines? Aging increases water absorption and volume expansion during cooking, resulting in a more flaky cooked rice than freshly harvested grains.

If then Amylose content is high, Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 2 : Why is amyclose content important and how is it measured? If then Amylose content is high, the rice grains will show high volume expansion (not necessarily elongation) and a high degree of flakiness. The rice grains cook dry, are less tender, and become hard upon cooling. Amylose content is low, the rice grains will cook moist and sticky.

CLASSIFICATION RANGES Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 2 : Why is amyclose content important and how is it measured? CLASSIFICATION RANGES 10-20% amyclose content is classified as Low 25% amyclose content is classified as Intermediate. Intermediate amyclose rice is preferred in most rice-growing areas of the world except where low -amyclose japonicas are grown. 20-30% amyclose content is classified as High                                                                                                                                                                                                             

Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 3 : Why is gelatinization temperature important and how is it measured? Gelatinization temperature determines the amount of time it takes for a particular variety of rice to cook.

Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 3 : Why is gelatinization temperature important and how is it measured? Low Varieties with a gelatinization temperature below 70°C. Most Japonica varieties have a low gelatinization temperature. Intermediate Varieties with a gelatinization temperature between 70°C – 74°C. Most tropical Indica varieties have intermediate or low gelatinization temperature. High Varieties with a gelatinization temperature greater than 74°C. If GT is very high, then the rice will become excessively soft and disintegrate when overcooked. It will also require more cooking and water than rice with a lower GT.

If then Classification Length of gel (mm) Course : Grain Quality Module 6 : Determining the Chemical Characteristics of Milled Rice Lesson 4 : Why is gel consistency important and how it is measured? Hard and soft gel consistencies Gel consistency If then Gel consistency is hard, the cooked rice tends to be less sticky. Harder gel consistency is associated with harder cooked rices and this feature is particularly evident in high-amylose rice. Gel consistency is soft, the cooked rice has a higher degree of tenderness. This is a preferred characteristic Classification Length of gel (mm) Hard 27-35 Medium Hard 36-40 Medium 41-60 Soft 61-100