Common rice starches

RVA curves compare commercial rice starch prepared by traditional alkali methods and rice starches prepared by the mechanical method. In the case of common rice starches, the onset of pasting appears to occur earlier (at lower temperature) and the final cooled viscosity appears to be lower for the starches prepared using alkaline conditions. The latter differences may be due to either rice type or the effect of alkali on granules. In the case of waxy rice starches, mechanically produced starches, in... 

Rice starch applications are normally discussed in terms of common and waxy types and are specified that way in Table 13.4. A 10% solution of a common rice starch, when sheered and gelatinized simultaneously, produces a product that resembles a solid shortening in texture. The waxy rice starches do not produce this same texture however, they too have been used very effectively for fat replacement due to a fat-like mouthfeel when blended with other food products. Waxy rice starches also tend to resist oil uptake when used in batters for fried foods. Most applications of rice starch may be attributed to one or more of the characteristics already discussed that are unique to rice starch. 

The functionality of rice starch depends on the amylose amylopectin ratio. Differences among rice starches made from long-, medium- or short-grain rice are insignificant relative to the amylose content. Rice starches made from common rice tend toward higher peak, cooked and cooled viscosities, as well as paste textures that are short and pasty. The texture of waxy rice starch pastes tends to be long and stringy (Table 13.3). 

Rice starch from common rice contains 0.3%-0.4% lipids, while waxy rice contains considerably less (0.03%). Complexes of these lipids are not easily removed from the starch, and are presumably responsible for the lack of paste clarity and the difficulty in clarification of starch hydrolyzates. 

Com, tapioca, potato and wheat starches are the most commonly used starches in the US and Europe. In the US, 95% of the starch is made from corn, an amount representing 3.4% of the total com crop, excluding that wet-milled to make sweeteners (see Chapter 22) and alcohol11124 (see Chapter 2). In Europe, about 60% of the starch produced is made from com and about 20% each from potato and wheat.12 In select regions, rice, sorghum, arrowroot, sago and other starches are also used. The relative utility of these starches in foods is a function of differences in viscosity, stability to... 

The vapourization of the solvent (including v/ater). A dough which contains glutinous rice starch and is charged into a tube, shrinks slowly as it dries and creates a gap especially if it is in a metal tube, even when the tube is less than 3 in internal diameter. During the manufacture of small pieces like igniters this is important. It is a common rule to decrease the amount of solvent in a composition as far as possible. When the composition feels to be rather wet, it contains 2 3% solvent or water. A composition like this is most unlikely to shrink, when it is formed into a mass under high pressure. 

The so-called Pepsina porei is either the calcium precipitate obtained as described in the first part of the above method, or, more commonly, the mucous membrane of the stomach of the pig, scraped off, dried, and mixed with rice-starch or milk-sugar. 

Starch is obtained from cereals, from leguminous and other seeds, from potatoes and other tubers, and from certain roots. The starches which are most commonly used are those of wheat, maize, rice, potatoes, sago, manioc and maranta. 

As would be expected from the results of studies on model systems, it has been found that foods with a high starch or sugar content may form genotoxic substances, but at a much lower level than meats or fish. Spingarn et al (65) showed that several common foods, in addition to beef, contained mutagens active for TA98 in the presence of S9 (Table V) Pariza et al. (66) found mutagenic activity in basic fractions of chicken broth, beef broth, rice cereal, bread crust, crackers, corn flakes, toast and cookies. 

Outside of the use of cellulose for papermaking, starch is the most widely used plant-derived carbohydrate for non-food uses. Around 60 million tonnes of raw starch are produced per year for food and non-food uses. The US accounts for most of the world s production, utilising starch from maize, which accounts for over 80% of world production. The starch market in the US is driven by the large isoglucose sweetener market and now increasingly by the growing bioethanol market, which uses maize as a fermentation feedstock. Europe derives most of its starch from wheat and potatoes, which account for 8% and 5% of world starch production, respectively. The other main source of starch is cassava (tapioca), produced in South East Asia. Small amounts of oat, barley and rice are also exploited for starch production. Many edible beans are also rich in starches, but are not commonly exploited for non-food uses. 

Almost all the starches investigated contain some phosphorus.124-126 In addition to phospholipids, phosphorus is also commonly found in starch as monostarch phosphate esters.6,7 Inorganic phosphate is present in some starches.124-126 Monostarch phosphate esters and phospholipids have different effects on starch paste properties.133,135 Monostarch phosphate esters, found in potato, shoti and other starches,6,7,136-140 increase paste clarity and paste viscosity.79 Little phosphate monoester is found in cereal starch.121,124,141,142 Phospholipids, found in normal cereal starches (e.g. wheat, rice and maize) decrease paste clarity and viscosity.133 31P-nmr spectroscopy has... 

Both processes use starch (com, potato, rice, wheat, etc.) as the substrate. Com and potato starches are most commonly used. In both processes, the starch is hydrolyzed to a dextrose equivalent (DE) of 3 to 8 (see Chapter 21) prior to use.25 If liqui-faction/hydrolysis is not sufficient, retrogradation occurs. This limits the availability of substrate, resulting in low yields of cyclodextrins, and interferes with later recovery steps. If the starch is over-hydrolyzed, the disproportionation reaction dominates and yields of cyclodextrins are low. If an a-amylase is used to hydrolyze the starch, it must be inactivated by acidification, raising the temperature, otherwise, the yield will be greatly reduced. 

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