Agro-Waste as a Source of Functional Proteins: Extraction, Purification and Applications in Food and Nutraceutical Industries

Abstract

Agro-waste represents an abundant yet underutilized resource for sustainable protein recovery, offering potential applications in the food and nutraceutical sectors. This review consolidates recent advances in the extraction and purification of proteins from diverse agro-industrial byproducts, including cereal residues, oilseed cakes, fruit peels, and legume husks. Conventional methods such as alkaline and acid extraction remain cost-effective but often compromise protein functionality, while emerging green technologies—enzyme-assisted, ultrasound-assisted, and microwave-assisted techniques—show promise in enhancing yield and preserving bioactive properties. Purification strategies, including membrane filtration, chromatography, and precipitation, are critically compared with respect to scalability, cost, and impact on functional quality. The bioactive potential of agro-waste-derived proteins, particularly peptides with antioxidant, antimicrobial, and antihypertensive properties, underscores their nutraceutical relevance. However, challenges such as variability in raw materials, high operational costs, and lack of clinical validation hinder large-scale adoption. The discussion highlights the trade-off between protein yield and functionality, as well as the need for integrated, multidisciplinary approaches to optimize recovery systems. Within the framework of sustainability and circular economy principles, protein mining from agro-waste offers a dual advantage of value addition and waste minimization. Future research should focus on scaling up green technologies, standardizing quality assessment, and exploring regulatory pathways for commercial application. Overall, agro-waste proteins present a promising avenue toward sustainable food security and nutraceutical innovation.