Rice kernels

DF Houston, T Iawasaki, A Mohammad, L Chen. Radial distribution of protein by solubility classes in the milled rice kernel. J Agric Food Chem 16 720-724, 1968. 

Non-tryptamines.—The structure (1) of a new bromo-indole derivative, isolated from an Australian sponge of the genus Iotrocha, has been elucidated and confirmed by synthesis.4 The indole-3-acetic ester of myo-inositol occurs in rice kernels (Oryza sativa) 5a this is the first reported occurrence of this ester in a plant other than maize (Zea mays). 

Rohrer, C.A. Siebenmorgen, T.J. 2004. Nutraeeutieal eoncentrations within the bran of various rice kernel thickness fraetions. Biosys. Eng. 88 453-460. 

Very few published examples of the genetic manipulation of terpenoid biosynthesis are available, but two interesting successes have been achieved in the area of terpenoid vitamins for example, the ratio of beneficial tocopherol (vitamin E) isomers in oilseeds has been altered by this means and increased P-carotene (a vitamin A precursor) in both rice kernels and rapeseed has been obtained by manipulating the carotenoid pathway [361]. 

Beriberi, a neurologic and cardiovascular disorder, is caused by adi etary deficiency of thiamine (also called vitamin B,). The disease has been and continues to be a serious health problem in the Far East because rice, the major food, has a rather low content of thiamine. This deficiency is partly ameliorated if the whole rice grain is soaked in water before milling some of the thiamine in the husk then leaches into the rice kernel. The problem is exacerbated if the rice is polished, because only the outer layer contains significant amounts ot thiamine. Beriberi is also occasionally seen in alcoholics who are severely malnourished and thus thiamine deficient. The disease is characterized by neurologic and cardiac symptoms. Damage to the peripheral nervous system is expressed as pain in the limbs, weakness of the musculature, and distorted skin sensation. The heart may be enlarged and the cardiac output inadequate. 

Cnossen, A.G., Siebenmorgen, T., Yang, W., Bautista, R. An application of glass transition temperature to explain rice kernel fissure occurrence during the drying process. Drying Technol, 19, 1661, 2001. 

Saikusa, T. 1994. Distribution of free amino acids in the rice kernel and kernel fractions and the effect of water soaking on the distribution. J. Agric. Food Chem. 42 1122-25. 

Thiamine was the first of the B vitamins to be identified, so it became known as vitamin B1. The absence of thiamine in the diet causes a disease called beriberi, which damages the heart and impairs nerve reflexes. In extreme cases, it causes paralysis. One major dietary source of vitamin Bj is the hulls of rice kernels (p. 1035). A deficiency is therefore most likely to occur when highly polished rice is a major component of the diet. A deficiency is also seen in alcoholics who are severely malnourished. 

Equation (20) is catalyzed by glutathione reductase (E.C. 1.6.4.2), a chloro-plast stromal enzyme (Foyer and Halliwell, 1976 Jablonski and Anderson, 1978) of wide distribution in plants (see Wirth and Latzko, 1978 for review), which has been purified to homogeneity fi-om rice kernels (Ida and Morita, 1971a,b) and spinach (Halliwell and Foyer, 1978). 

Figure 9.1.28 Rice kernel structure adapted from Orthoefer.

Milling of rice is different from that of some of the other cereals in that there is usually no grinding step to produce a powder. Milling involves removal of the hull and bran layers of the rough rice kernel (paddy). Hulled rice (brown rice) is composed of surface bran (6-7% by weight), endosperm (about 90%), and embryo (2-3%). Milling of brown rice uses abrasion and friction between kernels to produce polished or whitened rice, where some 8-10% of the mass (mainly bran) has been removed. 

Siebenmorgen, T.J. Yang, W. Sun, Z. (2004). Glass Transition Temperature of Rice Kernels Determined by Dynamic Mechanical Thermal Analysis. Transactions of the ASAE, Vol. 47, No.3, pp. 835-839. 

Figure 4A.16 Rice kernel structure. (Adapted from Orthoefer, Food Techno 1996,50(12).-62 taken from Ref 91)...

Tab. 2.1 Possible states for a given rice kernel (and related terminology). ...

Fig. 2.2 Six possible states for a broken or non-broken rice kernel (a) non-flssured, (b) superficially fissured, (c) deeply fissured. Note that types (b) and (c) can be combined.

Fig. 2.3 Variation in the normalized volume of cargo rice kernels during convective drying at 40-70°C. Data from Abud-Archila et al. (1999).

Fig. 2.7 Scheme of video acquisition of shrinkage and cracking of rice kernels during drying according to Abud-Archila et ai. (1999). 

There is much less information available in the literature on the tensile strength of rice kernels, probably because measurements under tension are more difficult to realize than measurements under compression. For uniaxial tension tests, the... 

Parboiling under carefully controlled process conditions can enhance the tensile strength and tensile modulus of elasticity of rice kernels. Saifet ol. (2004) found that parboiling increased the maximal tensile strength by almost four to five times compared to that of raw rice. 

There are several published papers dealing with the modeling of stress cracks in a rice kernel induced by drying. Two complementary approaches are usually used ... 

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