This study evaluated the characteristics of rice starch and protein obtained by a fast alkaline extraction
method on rice flour (RF) derived from broken rice. The extraction was conducted using 0.18% NaOH at
30 C for 30 min followed by centrifugation to separate the starch rich and the protein rich fractions. This
fast extraction method allowed to obtain an isoelectric precipitation protein concentrate (IPPC) with 79%
protein and a starchy product with low protein content. The amino acid content of IPPC was practically
unchanged compared to the protein in RF. The proteins of the IPPC underwent denaturation during
extraction and some of the starch suffered the cold gelatinization phenomenon, due to the alkaline
treatment. With some modifications, the fast method can be interesting in a technological point of
view as it enables process cost reduction and useful ingredients obtention to the food and chemical
industries.
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1. Introduction
Rice (Oryza sativa L.) is a cereal that grows on and is consumed
on every continent. This cereal is mainly composed of starch and
minor amounts of protein, lipid, fiber, minerals, vitamins and phenolic
compounds. Besides starch, which is the major constituent of
milled rice at about 90% of the dry matter, also proteins (6.3–7.1%),
lipids (0.3–0.5%) and fibers (0.2–0.5%) are found in the rice endosperm
(Juliano, 1993).
Broken grain is a by-product obtained from the processing of
milled rice. Broken rice is used for the industrial production of rice
flours with different features. Furthermore, in recent years, ingredients
derived from rice and milled rice have been the basis for
the development of new foods. Rice starch, rice protein, rice syrup
and rice dextrin have growing applications. Rice starch is composed
of tiny granules with a narrow size distribution making
them ideally suited as a cosmetic dusting powder, a textile stiffening
agent, and a fat mimetic in foods. In addition, rice starch causes
minimal allergic