Simultaneous recovery and purification of rice protein and phosphorus compounds from full-fat and defatted rice bran with organic solvent-free process.

We studied a process that enables simultaneous recovery of protein and phosphorus compounds from rice bran. Phosphorus substances in full-fat and defatted rice bran such as phytic acid and inorganic ions were solubilized under acidic conditions in the first step. After that, inorganic and/or organic phosphate salts were recovered in insoluble form under weak alkaline conditions. Furthermore, protein fractions obtained after phosphorus compounds had been removed were solubilized under alkaline conditions. After solubilization, protein fractions with high content were recovered by isoelectric precipitation (IP) followed by electrolyzed water treatment (EWT). The highest protein content (52.3 w/w%) was attained when machine defatted rice bran was treated through the process. Energy-dispersive X-ray spectroscopy (EDX) and inductively coupled plasma atomic emission spectrometry (ICP-AES) analyses demonstrated efficient desalting from the protein fractions by EWT and higher phosphorus contents (15.1-16.4 w/w% P) in the phosphorus fractions compared with commercial phosphate rock. In addition, no heavy metal ions in either protein or phosphorus fractions were detected. These results suggest that the newly developed process is suitable for practical recovery of highly concentrated protein and phosphorus compounds from rice bran without enzymes or chemicals such as organic solvents, buffering agents, and surfactants.

Fermentative l-(+)-lactic acid production from non-sterilized rice washing drainage containing rice bran by a newly isolated lactic acid bacteria without any additions of nutrients.

A newly isolated lactic acid producing bacterium Lactobacillus rhamnosus M-23, from a rice washing drainage storage tank was found to produce l-(+)-lactic acid from a non-sterilized mixture of rice washing drainage and rice bran without any additions of nutrients under the simultaneous saccharification and fermentation (SSF) process. The maximum lactate yield attained was 59 g/l with a productivity of 1.23 g/l/h and a product optical purity of 95% corresponding to a conversion of 0.85 g of lactic acid per gram of sugar equivalent.

Effect of enzymatic treatment on sedimentation and flocculation abilities of solid particles in rice washing drainage and its relationship with protein profiles.

In this research, the protein participation that occurs with the flocculation and sedimentation phenomena caused by adding enzymes to solid particles derived from rice washing drainage and the electrostatic properties of the solid particle surfaces was examined. As seen in the results, adding protease to rice washing drainage decreased the protein content, strengthened the negative surface electron charge, and decreased the isoelectric point (IEP) value of the solid particles. In addition, about 25% of the proteins in the rice washing drainage still remained after enzyme treatment. Moreover, due to the enzyme treatment, specific and gradual degradations of 10, 13, and 16kDa of prolamin and 20-22kDa of gluterin basic subunit, both categorized in the basic protein group, were observed in an SDS-PAGE analysis. These results suggest that the flocculation and sedimentation of solid particles in rice washing drainage occur as a result of the formation of the IEP-dependent strengthening of the negative surface electron charge on the solid particle surface.

Bioethanol production from rice washing drainage and rice bran.

Bioethanol production from rice washing drainage and rice bran derived from a rinse-free process of rice manufacturing was established using the combinations of an enzymatic procedure and an ultra-sonic procedure of rice washing drainage for a sample pre-treatment. The maximum ethanol concentration was attained at 6.2% (v/v).