Enzymatic polishing of rice – A new processing technology

A novel processing technology was developed to polish rice in a more selective way with the help of xylanase and cellulase enzymes. The enzymes are produced from Aspergillus sp. and Trichoderma sp., respectively. Brown rice was soaked in water at 35 °C for 24 h to attain a saturated moisture level of 35.5 g/100 g, which leads to an increase in GABA concentration to 27 mg/100 g of rice. Enzymatic treatment was done for 2 h at 50 °C. The enzymes acted upon the non-starch polysaccharides of the bran layers releasing their monomeric sugar constituents, as detected through HPLC. Enzyme degraded surface structure of the rice grain was also studied by Scanning Electron Microscopy. Crude oil and crude fibre content of brown rice was reduced by 16 g/100 g and 20 g/100 g, respectively, through enzymatic treatment over brown rice.