Food Functional Powders with Redox Capacity and Antioxidant Properties Obtained from Food Losses and Waste of Olive Oil Industry

Abstract

Food powders were produced from olive pomace (Coratina, COP, and Arbequina, AOP) using freeze-drying with maltodextrin (MD) and native corn starch (NS) as wall materials in varying proportions. Optical microscopy revealed that OP was partially recovered by MD and NS. COP presented a total polyphenol content (TPC) of 53.8 g GAE/kg; meanwhile, AOP was 31.9 g GAE/kg. Accordingly, powders obtained from COP presented higher TPC than those from AOP. NS allowed obtaining powders with higher TPC and antioxidant activity. The greatest encapsulation efficiency was achieved by using 15% MD, achieving values of 94.9% for COP and 89.4% for AOP. Hydroxytyrosol was identified as the predominant polyphenol in the powders. It was demonstrated that powders could be added to food formulations and withstand cooking temperatures up to 220 °C without suffering a significant thermal degradation. Chemometric analysis of MIR and NIR spectra evidenced that they are analytical techniques capable of differentiating OP varieties and wall material types, besides variations in OP concentration. Results derived from this study demonstrated that it is feasible to give added value to olive pomace, obtaining powders rich in antioxidants to be used as ingredients of functional foods.