Rice straw as a valuable source of cellulose and polyphenols: Applications in the food industry

Abstract

Background: Rice plants generate a large amount of straw after harvesting, which is currently managed mainly by incineration or used as animal bedding, animal fodder or wrapping of materials during transport. Other technological uses, such as the production of energy and biofuels, pulp and paper production or construction materials have also been described. However, due to the current European Union (EU) restrictions, alternatives for waste management must be sought. Valorisation of rice straw is aligned with the Sustainable Development Goals agenda set by the EU, since interesting biocompounds have been described in their composition and, after a successful extraction and purification, they can be used in various sectors. Scope and approach: This review gathers the most relevant works related to the valorisation of rice straw. It focuses on polyphenolic extracts and cellulose derivatives obtained by different extraction techniques, either conventional or innovative. In addition, the different applications that these compounds have in the field of food and nutrition sciences are summarized. Key findings and conclusions: Polyphenols and cellulose fractions have shown their viability to be extracted from rice straw, showing great potential as antioxidants in the food sector or as nutritional components in the development of new food or packaging materials, respectively. In conclusion, the valorisation of rice straw as a rich source of valuable compounds has been demonstrated, which currently generates serious environmental and human problems due to difficulties in its management and incineration, adding value to these underutilized residues and contributing to the circular bioeconomy concept.