Rice hull ash adsorbent performance under commercial soy oil bleaching conditions

Rice hull silica and a rice hull carbon ash were evaluated as adsorbents for the soy oil bleaching process under commercial temperature and pressure conditions. Their performance in adsorbing pigment, phospholipid, free fatty acids, and peroxides was compared with that of a commercial bleaching clay and silica hydrogel. With the exception of phospholipid binding, rice hull‐derived adsorbents were ineffective. Rice hull silica showed potential as a phospholipid adsorbent but was not as effective as the synthetic silica hydrogel on an adsorbent weight basis. However, it was a superior adsorbent when the data were expressed as adsorbate bound per unit surface area. The low surface area of the rice hull silica limits its commercial viability. It may have value in areas of the world where rice hulls are plentiful and an inexpensive phospholipid adsorbent is required for oil processing. Research is in progress to increase the surface area of rice hull silica for commercial oil processing.