Enzyme-Assisted Transformation of Lignin-Based Food Bio-residues into High-Value Products with a Zero-Waste Theme: A Review

Increasing world’s population, rapid urbanization, and modern lifestyle results in enormous generation of food bio-residues and wastes from various agricultural, household, and industrial activities. Approximately one-third of the total food produced is lost/wasted every year, according to the Food and Agriculture Organization (FAO) that represents a significant threat to food systems sustainability and environment. Multi-faceted and state-of-the-art solutions are continuously being explored and executed by research scientists, food industries, and government/non-government organizations to address the social, economic, and environmental concerns, depleted fossil fuel resources and climate change. Discarded food waste and bio-residues are enriched with a plethora of high-value biomolecules, such as Carbohydrates, lipids, lignin-based molecules, and proteins. These compounds are thought to exhibit a vast economic potential for transforming into a range of revenue sources, such as biofuels, biopolymers, organic acids, enzymes, nutraceuticals, and functional sugars etc. Enzyme-assisted bio-transformations have been stepped up as a sustainable valorization way for the effective treatment of such food waste. This approach is capable of efficient conversion of lignin-based food bio-residues into a large number of high-value bioproducts and industrial commodities given excellent catalytic performance, eco-sustainability, process stability, and amenability to commercial utility. This review spotlights recent and state-of-art information about food waste as a growing environmental burden, current practices, and enzyme-based valorization approaches to convert food waste into marketable products, including biofuels, prebiotics, biodegradable plastics, sweeteners, bioactive compounds, rare functional sugars, biosurfactants, etc. Current challenges, conclusive remarks, and future bioeconomy prospects are also discussed to accomplish the target goals of sustainable industrial production along with food waste minimization. In conclusion, enzymes' deployment might constitute an eco-friendly and sustainable solution for food waste management by producing high-value products. Graphic Abstract