Rice bran enzymes

The rice bran phytochemicals and antioxidants have a profound influence on the induction of antioxidant enzymes at the cellular level and control hpid peroxidation at the cellular level. 

Myo-inositol is one of the most biologically active forms of inositol. It exists in several isomeric forms, the most common being the constituent of phospholipids in biological cell membranes. It also occurs as free inositol and as inositol hexaphosphate (IP6) also known as phytate which is a major source from food. Rice bran is one of the richest sources of IP6 as well as free inositol. Inositol is considered to belong to the B-complex vitamins. It is released in the gastrointestinal tract of humans and animals by the dephosphorylation of IP6 (phytate) by the intestinal enzyme phytase. Phytase also releases intermediate products as inositol triphosphate and inositol pentaphosphate. Inositol triphosphate in cellular membrane functions as an important intra- and intercellular messenger, that merits its value as a nutritional therapy for cancer. 

Tocotrienols present in rice bran inhibit the liver microsomal enzyme HMGCoA reductase (Qureshi and Qureshi, 1992), the key enzyme involved in the endogenous synthesis of cholesterol, and this helps to lower the circulating cholesterol. Inhibition of another enzyme, ACAT (Acyl coenzyme A acyl transferase), by y-oryzanol results in lowered LDL-C synthesis and enrichment... 

The fiber of rice bran products, especially the RiceMucil is helpful in maintaining normal gastrointestinal and colon health (Tomlin and Read, 1988). It helps in bowel regularity. Patients with irritable bowel syndrome, inflammatory bowel disease and colitis get excellent relief with RiceMucil . As has been mentioned in the earlier part of this chapter, the fiber of rice bran is non-bloating and lactose free, and the acidic environment the fiber creates during the fermentation of undigested food improves colon health and induces all the healthy enzymes and fnendly bacteria to proliferate (Folino et al, 1995 Life Sciences News Letter, 1999). It has been scientifically demonstrated to have an excellent nutritional support for gut and colon health. 

MANORAMA R (1993) Hcpatic Drug Metabolizing Enzymes of Rice Bran Oil Fed Rats. Ph D. Thesis submitted to Osmania University, Elyderabad, India. 

When Rhizopus sp. 26R was cultivated in the solid substrates without addition of rice bran but composed of only wheat bran and rice husk at the ratio of 18 2. The pectinase activity from the culture was approx. 25-35 unit/ml within 2 days and the production remained constant for 4 days (Figure 3). One gram of raw starch from cassava tuber, 1 g of pectin or 0.5 g of yeast extract was added to the solid substrates in order to induce higher activity of the enzsrme. The results showed that either 1 g raw cassava starch or 1 g pectin that was added to the 20 g solid substrates increased the enzyme activity to 1.7 and 2.4 times, respectively (Figure 3). The production of pectinase in soHd substrates with wheat bran and rice husk could be enhanced with the addition of raw cassava starch and pectin. 

Addition of rice bran to the solid substrates to make the ratio of wheat bran, rice bran and rice husk to 9 9 2 helped increasing the activity of pectinases from Rhizopus sp. 26R as shown in Figure 4. The activity of the enzyme was approx. 4.3 times higher. Moreover, either 1 g of pectin or 0.5 g of yeast extract did not help increasing of the enzyme production. In contrary, the enz5mie activity was decreased 2.6 times to that of the former one. Addition of raw cassava starch to the substrates did no effect to the enzyme production (data not shown). 

Different ratios of the solid substrates, wheat bran, rice bran and rice husk, were done and the activity of the pectinases was compared in Figure 5. The mixture of wheat bran, rice bran and rice husk in the ratios of 9 9 2 or 6 12 2 appeared to be two of the best composition ratios for growth of the fungus and the pectinase production.The ratio of 6 12 2 was selected for the enzyme production since rice bran was cheaper than wheat bran and locally obtained. 

Figure 6,7 and 8 showed the results of the pectinase activity when produced in the solid substrates containing wheat bran, rice bran and rice husk in the ratio of 6 12 2. The highest activity obtained when the strain was grown on the solid substrates with 58 % initial moisture content, pH adjusted to 5.7 and incubation temperature was at 32°C. Under these conditions, the highest activity of the enzyme that could be obtained from Rhizopus sp. 26R was ca. 700 units of enzyme activity per gram of solid substrates. 

Addition of rice bran to the mixture of wheat bran and rice husk was the best substrates for the fungal pectinase production. The solid substrates that composed of wheat bran, rice bran and rice husk at the ratio of 6 12 2 was selected to be the best since rice bran are easily found in South-east Asian countries. Addition of either raw cassava starch or pectin as inducer is not needed. On the otherhand, pectin even inhibited the activity of the enzyme as well as that reported by Elegado and Fujio (6). 

Unstabilized bran and polish have been used almost exclusively for animal feed, due to the bitter flavor that develops from the lipolytic action of enzymes on the oil found in them. However, development of a thermal process that inactivates the lipases has resulted in a stabilized rice bran product that is suitable for the food industry. The impressive nutritional qualities of the oil, fiber, carbohydrate and proteins of rice bran have made it a valuable food material. Removal of fiber from the bran by physical K,J7or enzymic1819 processes produces a milk-like product having desirable nutritional and functional properties. The nutritional composition of the rice bran milk product described by California Natural Products has been shown to match the nutritional requirements of an infant formula. Originally, the anti-nutritional factor of the residual phytates was of concern. However, as of 2005, phytase enzymes are suitable for use to break down these phytates. 

Lipases liberated from the testa and the cross cells promote rapid hydrolysis of the oil, and therefore, it should be extracted within hours of milling. Attempts have been made to upgrade oil with 30% free acid by reaction with glycerol and the enzyme Lipozyme Mucor miehei lipase) followed by neutralization. The major acids in rice bran oil are palmitic (12-18%, typically 16%) oleic (40-50%, typically 42%), and linoleic acid (29 2%, typically 37%). The oil contains phospholipids ( 5%), a wax that may be removed and finds industrial use, and unsaponifiable matter including sterols, 4-methylsterols, triterpene alcohols, tocopherols, and squalene among others. 

Rice bran contains active enzymes (30). Germ and the outer layers of the caryopsis have higher enzyme activities. Some enzymes that are present include a-amylase, p-amylase, ascorbic acid oxidase, catalase, cytochrome oxidase, dehydrogenase, deoxyribonuclease, esterase, flavin oxidase, a and p-glycosidase, invertase, lecithi-nase, lipase, lipoxygenase, pectinase, peroxidase, phosphatase, phytase, proteinase, and succinate dehydrogenase. 

As expanders cook within 20 seconds, they counteract the activity of troublesome enzymes, such as lipase in rice bran (40) and urease in soybean (41). The short time between enzyme activation and inactivation destroys the enzyme before it has time to cause damage. An expander is even more effective than the horizontal, atmospheric pressure cookers described earlier. 

Rice bran protein, hydrolyzed Definition Hydrolysate of rice bran protein derived by acid, enzyme, or other method of hydrolysis Uses Antistat in cosmetics Hydrolyzed rice protein CAS 94350-05-7 97759-33-8 EINECS/ELINCS 305-224-5... 

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