Biocatalysis for rice bran valorization

The use of biocatalysis for the conversion of biomass into value added products is rapidly growing. We report here the application of biocatalytic processes to the valorization of rice bran oil and protein. Because of the large amount of rice produced annually, by-products of rice milling, such as rice bran (ca. 70 kg/tonn of rice), are plentiful and readily available. Although rice bran is a rich source of highly nutritional proteins (10-16%), lipids (15-22%), carbohydrates (34-52%), and a number of micronutrients (e.g. vitamins, minerals, antioxidants, and phytosterols), it is currently under-utilized. The aim of this work is to exploit the protein and the oil fraction of rice bran by using a biotechnological approach to obtain high-added value products. Rice bran protein (RBP) are valuable because they contain essential amino acids and are hypoallergenic. However, the heterogeneous and complex nature as well as the poor solubility of RBP due to strong aggregation and/or extensive disulfide bond cross-linking are limiting factors in their utilization as food ingredients. A biocatalyzed process based on the use of proteases, also in combination with carbohydrate-hydrolyzing enzymes, was developed to solubilize RBP and to enhance the extractability of the entrapped protein components. On the other hand, rice bran oil (RBO) is characterized by a high free fatty acids (FFA) content. This feature makes RBO unsuitable for processing into edible oil; however, it can be a valuable feedstock for the production of chemicals. In fact, a significant number of high-value products require FFA in their manufacturing. RBO was submitted to a preparative lipase-catalyzed hydrolysis affording pure FFA in a moderate yield. This work is supported by Fondazione Cariplo (RiceRes Project, 2014-0558)