Abstract
The valorization of agri-food by-products is a critical pathway toward building sustainable food systems, reducing waste, and advancing the circular economy. This review aims to identify recent advances, key challenges, and future perspectives in this field. We conducted a critical and systematic synthesis of 159 peer-reviewed studies (2019-2025) selected based on quality and thematic relevance from leading international databases. The analysis focuses on emerging technologies such as ultrasound-assisted extraction, microencapsulation, spray drying, lyophilization, deep eutectic solvents, and colloidal systems, emphasizing their efficiency in recovering bioactive compounds from agro-industrial by-products. Significant challenges include industrial scalability, economic feasibility, regulatory compliance, and consumer acceptance. This paper also discusses current applications in functional foods and nutraceuticals, outlining promising directions for the sector. Although challenges remain, the findings offer valuable insights for researchers, industry, and policymakers aiming to foster sustainable innovation and implement strategies aligned with circular economy principles.