GAMMA RADIATION AS A TOOL FOR AGRO-INDUSTRIAL WASTES MICROBIOLOGICAL SAFETY AND ITS EFFECT ON THE ANTIOXIDANT PROPERTIES EVALUATED BY IN VITRO TESTS AND MODEL SYSTEMS

Abstract

Peanut skins as well as the wine industry wastes are among the most known residues with antioxidant potential. However, information regarding their microbiological safety as well as their application in high lipid foods, e.g. vegetable oils and oil-in-water emulsion, is still lacking. The present study aims to evaluate the effects of gamma radiation (0.0, 2.5, 5.0, 7.5 and 10.0 kGy) in these agroindustrial wastes in relation to their microbiological safety, extracts yield from processes with water, ethanol and their mixtures, as well as their antioxidant activities measured in vitro, and in model systems (oils and their emulsions in water) both in soybean stripped oil free from synthetic antioxidants. Regarding their microbiological safety, Escherichia coli, Salmonella spp, yeast and mold, coagulase positive staphylococci are going to be investigated. Quantification and identification of polyphenols are going to be conducted by HPLC-DAD-ESI-MSn, antioxidant activity, by on-line HPLC-DPPH and on-line HPLC-ABTS. Ferrous ion chelating activity, hydroxyl radical scavenging activity, hydrogen peroxide scavenging activity, singlet oxygen inhibition, hypochlorous acid scavenging capacity and reducing power are going to be performed too. The oxidation status will be monitored by peroxide values, UV absorptivities and thiobarbituric acid reactive substances (TBARS). The identification and quantification of volatile compounds will be accomplished using solid phase micro-extraction (SPME) and gas chromatography-mass spectroscopy (GC/MS). Extracts identified as potential natural antioxidants will have their performance evaluated against those synthetic allowed by Brazilian legislation (TBHQ, BHA, BHT and alpha-tocopherol).