Use of Phenolic Extract from Peanut Skin as a Natural Antioxidant in Chia Oil-Based Mayonnaise ^†

Currently, the antioxidants (AOs) used in foods are mainly synthetic, often questioned on health grounds. So, the need for innocuous natural AOs has increased in last years. The peanut skin (PS) is an industrial by-product of low added value, but rich in bioactive phenolic compounds. In this study, the antioxidant capacity of a PS extract (PSE) was examined in a chia oil-based mayonnaise stored during six months (25 °C). The mayonnaise was made using chia oil (68% w/w) added with PSE (2 mg/g fat) and without any AO (control). For the storage test, 30 g were placed in 100 mL amber bottles and at 2, 4 and 6 months the oily phase was extracted (chloroform: methanol). Peroxide index (PI), acidity index (AI), K₂₃₂, K₂₇₀, p-Anisidine (pAnV) and TOTOX values were measured. Moreover, the presence of 2,4 heptadienal and 3,5-octadiene-2-one was analyzed by static headspace GC-MS. At the end of the assay, PI, AI, K₂₃₂, K₂₇₀, and pAnV for control and PSE mayonnaises were 74.7 and 13.4 meq O₂/kg oil; 2.4 and 2.0 mg KOH/kg oil, 10 and 3.55, 1.34 and 0.64, 3.7 and 0.98, respectively. The TOTOX value of the control was approximately six times higher than PSE mayonnaise. 2,4 Heptadienal and 3,5-octadiene-2-one were not detected at initial time but in the control treatment at the end reached 3.75 and 2.15 µg/g, respectively. Differently, in PSE mayonnaise, 3,5-octadiene-2-one was undetected and 2,4 Heptadienal was 0.83 µg/g. In conclusion, PSE represents a potential natural AO to preserve the oxidative stability of chia oil-based mayonnaise.