Cereals processing technology

80 Cereals processing technology
Chemistry and Technology. Other books on rice have been edited by Hoseney, 10
Juliano, 13 Luh, 18,19 and Marshall and Wadsworth. 21 This chapter presents recent
developments in rice production, including rice grain quality, rice cultivation,
genetic modification, processing issues and future trends.
5.2 Rice grain quality indicators
The most important factors that plant breeders consider in developing new rice
varieties are grain quality and yield. The term ‘grain quality’ has many meanings
and is perceived differently depending on end use, field of interest,
specialization and ethnic background. In marketing, appearance is of foremost
importance as a quality characteristic; rice millers emphasize milling quality;
food manufacturers emphasize processing quality; and consumers demand a
widely divergent array of cooking and eating qualities.
Quality in rice may be categorized into four broad areas: (a) milling quality;
(b) cooking and processing quality; (c) nutritive quality; and (d) specific
standards for cleanliness, soundness, and purity. 32 All four categories are
important in judging the suitability of rice for a specific use. The quality
characteristics desired vary considerably, being ultimately related to final
consumer acceptance of each rice product. Boiled rice prepared in homes and
institutions constitutes by far the greatest consumption pattern. Other important
uses include: rice flours, parboiled rice, quick cooking rice, canned rice, frozen
rice, breakfast rice cereals, baby foods, fermented rice products, rice snack
foods, wine and vinegar, and many others. 19
Characteristics that influence rice quality include those under genetic control
and those independent of genetic control, such as purity and cleanliness. These
latter characteristics are primarily a function of handling and storage, and as
such, are described thoroughly in United States Standards for Rice 30 and in the
Rice Inspection Handbook. 31
Modern rice breeding programs continually refine and improve genetic
characteristics influencing quality to obtain the most desirable product. Breeding
and selecting for desirable milling, eating and processing qualities in hybrid
selections, breeding lines, and new varieties are essential components of
responsible varietal improvement programs conducted by the US Department of
Agriculture, and state agricultural stations in Arkansas, California, Louisiana,
Mississippi and Texas. New varieties developed in these programs meet required
industry standards for milling, cooking, eating, and processing quality before
release for commercial production. 1,32,33
A major factor influencing rice quality is the environment in which the plants
are grown. Once a new variety is released for commercial production, it spreads
to wherever it can be produced advantageously compared to currently grown
varieties. Consequently, before release, new varieties are tested agronomically
and for quality over their likely production area. Tests are carried out in rice
performance nurseries in each rice-producing state. These trials permit