Valorization of animal and aquatic product processing side-streams: Upcycling into flavoring and functional ingredients.

The by-products of animal and aquatic product processing remain underutilized within the food industry. The present review focused on various processing methodologies, including enzymatic hydrolysis, thermal treatments, the Maillard reaction, and fermentation, to enhance the sensory and functional attributes of these by-products. Such techniques facilitate the transformation of proteins, carbohydrates, and other nutrients into distinctive flavor and bioactive compounds, thereby unlocking their potential as valuable seasonings and functional food ingredients. Key flavor compounds formed during processing include volatile compounds (VOCs) such as aldehydes, ketones, and pyrazines, as well as non-volatile compounds such as amino acids and peptides. Additionally, bioactive peptides with antioxidant, antihypertensive, and antimicrobial properties are generated, contributing to the functional value of these materials. The extraction of essential minerals, such as calcium, along with other bioactive components, was also examined herein. By emphasizing sustainable practices and efficient resource use, the present review provides insights into optimizing processing conditions to balance flavor enhancement with nutritional value retention and creation, thus supporting the valorization of animal and aquatic product side-streams and promoting a circular economy in the food industry.