Revalorization of rice bran as a potential ingredient for reducing fungal contamination in bread by lactic acid bacterial fermentation

Abstract

Rice bran (RB) is a by-product of the rice industry that reaches a waste of 63 million tonnes per year. In order to promote the development of the circular economy, it is important to revalorize the by-products generated by the food industry. Lactic acid bacteria (LAB) can ferment multiple substrates generating antifungal compounds such as organic acids, phenolic acids, or bacteriocins, so the use of LAB can be a good strategy for the revalorization of food industry by-products. In addition, RB can be a good substrate for the lactic acid bacteria fermentation due to its content of carbohydrates and nitrogenous compounds. This study explored the potential of incorporating RB into a lactic acid bacterial medium for antifungal bread ingredient development. We evaluated the in vitro antifungal activity and metabolite production of LAB-fermented RB media. L. plantarum H1 fermentation with 20 % RB demonstrated the most effective inhibition of fungal growth and antifungal metabolite production. This formulation was chosen for bread preparation without compromising dough and bread quality. The bread with 20 % fermented RB extended shelf life like the propionate control, with one day less for Penicillium commune and Aspergillus flavus-contaminated bread. The fungal population after seven days showed no significant differences compared to the propionate control. Additionally, aflatoxin levels significantly decreased in bread with 20 % RB, achieving a 96 % reduction, like the propionate control. This research not only extends the shelf life of commonly consumed foods but also reduces waste from this food industry's important by-product.