SUSTAINABLE VALORIZATION OF AGRI-FOOD RESIDUES BY HIGH PRESSURE HOMOGENIZATION PROCESSING TO UNLOCK HIGH-ADDED VALUE INTRACELLULAR COMPONENTS

Residues from agri-food industry, including both by-products and wastes, often represent an environmental burden, either in terms of the impact of their use in low-added value products, or of their disposal. However, they also represent an opportunity to bring economic and social benefits, because still rich in valuable intracellular compounds, which can be efficiently valorized if adequately recovered. The present work addresses the use of wet milling by High Pressure Homogenization (HPH), as an efficient process to unlock high-added value intracellular components from plant-based agri-food residues through the mechanical disruption of vegetable cells. HPH processing has been tested in the valorization of different agri-food residues, such as tomato peels, coffee residues, and rice bran, primarily to increase the bioaccessibility of antioxidant compounds. The vegetable matrices were suspended in water, pre-milled and screened at 600 micron. Subsequently, the vegetable suspensions were processed by HPH, at pressures ranging between 100 and 200 MPa and for 1 - 5 passes. The results show that HPH processing causes a statistically significant increase in both supernatant antioxidant activity (related to the antioxidant compounds released in the aqueous phase upon HPH processing) and surface antioxidant activity (related to the antioxidant still bonded to the surface of cell debris). However, HPH-processed suspensions exhibited also other interesting features, suggesting their possible use not only as functional ingredients but also as thickening agents or stabilizers: (a) the content of soluble protein significantly increased, with a consequent higher surface activity of the vegetable suspension; (b) the fine cell debris resulting from the mechanical disruption of vegetable cells caused a measurable increase in the viscosity of the suspension.In conclusion, HPH processing of agri-food residues enables to unlock the high-added values components still remaining in the vegetable cells using a purely physical process and water as solvent, contributing to pursue the concepts of sustainable valorization and total use of the residue.