Current food transformation processes must face the food waste issue by developing valorization processes to reintroduce by-products in the economic cycle and contribute to circular economy, generating social and economic value, and ensuring permanence of agricultural and rural activities. In the present paper, the results of a collaboration project between a regional agri-food cooperative and university are summarized. The project aimed to revalorize a series of vegetable wastes (carrot, leek, celery, and cabbage) from the fresh and ready-to-eat lines of the cooperative, by producing functional powders to be used as functional food ingredients. Vegetables residues were successfully transformed into functional ingredients by hot air drying or freeze-drying, and variables such as storage conditions and grinding intensity prior to drying were considered. Twenty-five vegetable powders were obtained and characterized in terms of physicochemical and antioxidant properties. Results showed that drying (mainly hot air drying) allowed obtaining stable powders, with very low water activity values, and a significantly increased functionality. Vegetable waste powders could be used in the food industry as coloring and flavoring ingredients, or natural preservatives, or either be used to reformulate processed foods in order to improve their nutritional properties.

Interest in high homogenization pressure technology has grown over the years. It is a green technology with low energy consumption that does not generate high CO₂ emissions or polluting effluents. Its main food applications derive from its effect on particle size, causing a more homogeneous distribution of fluid elements (particles, globules, droplets, aggregates, etc.) and favoring the release of intracellular components, and from its effect on the structure and configuration of chemical components such as polyphenols and macromolecules such as carbohydrates (fibers) and proteins (also microorganisms and enzymes). The challenges of the 21st century are leading the processed food industry towards the creation of food of high nutritional quality and the use of waste to obtain ingredients with specific properties. For this purpose, soft and nonthermal technologies such as high pressure homogenization have huge potential. The objective of this work is to review how the need to combine safety, functionality and sustainability in the food industry has conditioned the application of high-pressure homogenization technology in the last decade.

Food waste is a worldwide concern as it represents a constant threat to the environment and a serious operational problem for the food industry. The by-products of fruits and vegetables being a valuable source of bioactive compounds have the potential to be reused and reintroduced in the agri-food chain. This circular approach contributes to a sustainable production system. In this context, a collaborative project with the primary sector for the integral valorization of the waste generated in the fresh-processing vegetable lines of an agricultural cooperative is currently being developed, particularly focused on cabbage, carrot, celery, and leek. The objective of this project is to transform vegetable wastes into functional powdered ingredients and be able to use them in food formulations in order to improve the nutritional profile of foods, contributing to the development of sustainable healthy diets. Through an exhaustive bibliographic review, this research studies the influence of pretreatments, drying and in vitro digestion on the bioactive compounds of vegetable residues, with the aim of identifying the appropriate production parameters to achieve an adequate functional and physicochemical profile of the final powders.