Valorization of Food By-Products Employing Spectroscopic and Chemical Methods: Characterization and Applications of Functional Biomolecules

Background: Large quantities of by-products and waste materials are inevitably generated throughout food processing and manufacturing operations. Despite being consistently rich in high-value bioactive constituents — including polyphenols, dietary fiber, antioxidant compounds, and bioactive peptides — these by-products are frequently discarded without further utilization, representing a considerable loss of both nutritional and economic potential. Therefore, valorizing such byproducts constitutes a sustainable strategy for reducing food waste while generating added value across food, animal feed, and non-food industrial applications.

Aims: This review aimed to systematically and critically evaluate the current scientific literature pertaining to the characterization and valuation of bioactive compounds extracted from food by-products, with particular emphasis on the spectroscopic and chemical methods employed for their identification and quantification, and on their applications within food systems food systems.

Methods: A structured critical narrative review methodology was adopted for this study. A systematic literature search was conducted across three major academic databases—Scopus, ScienceDirect, and Springer—encompassing publications from 2015 to 2025. The initial search yielded 26,152 documents, from which 4,538 peer-reviewed research articles published in English language were identified. Inclusion criteria were applied to retain publications specifically describing the characterization of bioactive substances employing spectroscopic or chemical analytical methods, and reporting on their primary applications in food-related contexts.

Results: The reviewed literature consistently confirms that food by-products represent potential and underexploited sources of bioactive compounds with biological, technical, and nutritional properties. The integration of spectroscopic techniques — most notably Fourier-transform infrared spectroscopy (FTIR) and near-infrared spectroscopy (NIR) — with conventional chemical analytical methods has demonstrated considerable utility for the rapid and non-destructive characterization of bioactive molecules, quality evaluation, and authenticity verification of food by-product-derived materials. Applications of these compounds in food formulation, preservation, and active packaging have been increasingly documented in the literature; however, persistent challenges remain with respect to analytical standardization, comprehensive safety evaluation, and industrial-scale feasibility.

Conclusions: The valorization of food by-products through the combined application of spectroscopic and chemical analytical approaches presents substantial and scientifically exciting prospects for the development of sustainable, circular food systems. To fully realize the functional and commercial potential of food by-product-derived bioactive compounds, future research should prioritize the standardization of analytical protocols, the rigorous evaluation of safety and toxicological profiles, and enabling their industrial-scale deployment.