Exploitation of plant-derived food waste for valuable products using bioprocesses: a narrative review

Abstract

Globally, a million tons of plant-derived food waste are generated annually from various cultivation activities and agro-industrial manufacturing. When food waste decomposes, it releases methane gas that causes global warming. The exploitation of food wastes for valuable products provides an alternative approach to environmental protection. This paper aimed to review the exploitation of plant-derived food waste for valuable products and to evaluate different bioprocesses for optimum yields of the valuable products. This review study was conducted by using PubMed, ScienceDirect, and NCBI databases. A total of 169 publications were screened and 43 papers of high relevance were selected. Cereal wastes such as wheat straw, rice bran, root and tuber waste, and fruits and vegetable pomace contribute the most amounts to the total food waste worldwide. These wastes serve as renewable sources for bioactive production. Various fermentation processes involving enzymes, yeast, or bacteria were used to convert food waste into valuable products such as phenolics, flavonoids, dietary fibre, carotenoids, lignocellulose, phytosterols, tocotrienols, coumaric acid, oryzanol, citrulline, vitamins, and essential amino acids. Several bioprocesses and the optimization conditions for the maximum yield of valuable products were highlighted. In the production of xylitol from corn cobs using yeast (Debaryomyces hansenii), a higher yield (0.216 g xylitol/g xylose) was obtained through enzyme hydrolysate fermentation compared to acid hydrolysate fermentation (0.100 g xylitol/g xylose). In the production of fungal chitosan using solid-state fermentation, the yield was 3 folds higher (34.4 g/kg substrate) for soybean meals substrate than potato peels substrate (10.8 g/kg substrate). Plant-derived food waste serves as a renewable substrate for the production of health-promoting bioactive compounds through the optimization of various bioprocesses. The exploitation of plant-derived food waste for high-value products has significant implications for environmental impact, public health, and economic gain.