Impact of bio-processing on rice

Abstract

The usual way of preparing rice is boiling, thermal process that gives it a lower digestibility as compared to instantiation, extrusion or expandation. Having in view this fact, the possibility to biotechnologically improve the boiled rice digestibility was investigated in a laboratory study. In this respect, boiled rice was solid state fermented using a strain of Saccharomycopsis fibuligera, an amylase producing yeast originating from ragi. Fermented rice was then analyzed from the point of view of its content in easily assimilable sugars, protein, amino-acids,
phosphorus and vitamins from B group. Biochemical analyses revealed that the fermented rice has a ten times higher content of reducing sugars than boiled rice, due to starch hydrolysis, while chromatographic studies proved that the fermented rice contains glucose, maltose, maltotriose and maltotetrose that are easily assimilable carbohydrates. Fermented rice has a protein content that is two times higher than that of boiled rice because it contains the yeast biomass, and is enriched in vitamins from B group (B1, B2, and B6) that are synthesized by the yeast. Inorganic phosphorus present in rice doubles its concentration in fermented rice, which means that phosphorus bioavailability is increased. The sensorial profile of boiled rice is also improved by fermentation. This study proves the possibility to have a processing method which is relatively cheap, practical and of which the resulting product has good nutritive qualities and does not pose safety problems due to pure culture utilization as starter.