PREVENTION OF SECONDARY SEDIMENTATION OF RICE VINEGAR

Sediment formation of rice vinegar was studied to maintain vinegar qua lity for a longer period. The main component in the sediment was prote in. The browning component of the sediment was extracted with a chloro form-methanol solvent and was mainly attributed to the hydrolysates of rice, koji and enzymes used in the fermentation process. Perfect prev ention of the sediment formation in rice vinegar was attained by ultra -filtration with a membrane cutting off at molecular size up to 13000. The sediment preventive activity of many substances (polysaccharides, synthetic high molecular compounds, adsorbents and coagulants) were t ested, and it was found that an addition of xanthan gum, carboxy methy l cellulose (CMC) and sodium polyacrylate to vinegar was useful. An ad dition of bentonite was also effective at 80-degrees-C. Xanthan gum, C MC and sodium polyacrylate dissolved in vinegar may act as stabilizer for the prevention of the secondary sediment. Ultra-filtration and ben tonite-treatment could only remove the sediments from rice vinegar and it was presumed that no artificial materials were remained in rice vi negar obtained from ultra-filtration and bentonite-treatment. From the above results, the ultra-filtration process and bentonite treatment a t 80-degrees-C were found to be favorable in maintaining rice vinegar quality against the secondary sedimentation.