Rice starches protein content

Depending on the relative amylopectimamylose ratio found in the rice, the starch can exhibit a variety of gelatinized textures and strengths, as well as resistance to acid. Overall, there are several basic factors that affect starch performance. These factors, which include rice variety, protein content, method of starch production and modification, are described below. 

Our group has used twin-screw extrusion to produce many texturized whey-fortified puffed snacks. Whey protein has been blended with barley flour, com meal, rice flour, and wheat starch prior to extrusion, leading to corn puffs with a protein content of 20% instead of the usual 2% (Onwulata et al., 2001a). 

Lim, S. T, Lee, J. H., Shin, D. H., Lim, H. S. (1999). Comparison of protein extraction solutions for rice starch isolation and effects of residual protein content on starch pasting properties. Starch, 51, 120-125. 

In the preparation of starch from rice, a product known as rice sludge or rice slump is left as a residue. The dried product has a crude protein content of about 280 g/kg DM and low crude fibre and oil contents, and is suitable for ruminants and pigs. 

Mutations of SSIIa have been observed in wheat and rice.208 In wheat, each of the three wheat genomes were mutated to entirely eliminate expression of the SSIIa gene product, Sgp-1 protein in one line 209 the result was reduced starch amounts and an altered starch structure. In rice, two classes of starch have been found. In Indica rices, the starch is of the long chain variety, while in Japonica, it is of the short chain variety.208 Genetic analysis showed that the mutation in Japonica rice led to a loss of starch synthase II.209 Thus, in higher plants, it seems that loss of SSII activity in dicots and SSIIa activity in monocots have the same results with respect to reduced starch content, due to a lowered amount of amylopectin and altered amylopectin chain size distribution. Thus, these genes may have the same function in starch biosynthesis. 

The traditional koji process may be considered the archetype of SSF. Koji is a generic Japanese name for starters used in a variety of fermentations its functional importance lies in its high content of various amylolytic and proteolytic enzymes which can catalyze the degradation of starches and proteins to soluble products capable of subsequent fermentation by yeasts or bacteria. A variety of raw materials are used in the production of kojis but, typically, steamed rice is inoculated with spores of an Aspergillus oryzae strain and incubated under carefully controlled conditions of temperature and humidity [7]. 

Cereal-based foods are the most important source of nutrients for mankind (FAO 2009). Table 17.1 summarizes the contribution of the most important foods to the average human diet. Cereals continue to be the primary sources of energy, due to the high starch content, protein, dietary fiber, B-vitamins, and minerals. The majority of diets are based on one particular cereal grain as the main substance in most countries around the world. The cereals most widely consumed are rice, wheat, and maize, mainly by inhabitants of Asia, Europe-United States-Canada, and Latin America, respectively. In Africa, maize, sorghum, and millets are widely cultivated in order to produce grains for the manufacturing of many traditional foods (Chapter 16). 

---