Effect of addition of basil essential oil on the OSI of PO
The induction period of PO without antioxidants and added with basil essential oil, before and after the frying process, is shown in Figure 1. As expected fresh samples showed longer induction a periods than after 5 d of frying. The fresh PO added with 200 ppm of basil essential oil showed the longest induction period with 26 h almost 3 times that observed for fresh PO without antioxidants (9 h). This is a valuable result, and an indicator of the high-potential antioxidant power of the basil essential oil at tributed to its active compounds: methyl cinnamate, linalool, and eucalyptol. Hernandez-Nava (2011) reported an induction period for PO added with 200 ppm of synthetic antioxidant TBHQ, while 7 h were achieved for PO added with a blend of 00 ppm of citric acid and 200 ppm ofTBHQ, and more than 32 h for PO added with a blend of 200 ppm of rosemary extract and l 200 ppm of TBHQ at the same Rancimat conditions (130 oC) These data support that the addition of basil essential oil leads to an f improvement on the oxidative stability of PO. having a larger in h duction period compared with synthetic antioxidant T separately as well as some natural/synthetic antioxidants mixtures, such as citric acid-t-TBHQ There is a complex dependence between induction period and lipid peroxidation rate during Rancimat test. OSI for basil essential z oil did not increase with the increase of concentration. The same behavior was reported by J (2010), who reported shorter induction times for oils added with 630 ppm of extract of leaves than those exhibited when the extract was added at 250 ppm. The between OSI and natural 2005) idants concentration can be nonlinear (Carelli and others due to some antioxidants that are consumed in chain termination reactions during Rancimat assay, but also, in other side reactions decreasing its efficacy at higher concentrations Danishlieva and Marinova, 1992), and consequently, causing a prooxidative effect in in vitro assays
Effect of the addition of basil essential oil to PO on oxidative rancidity
Figure 2 shows the PVs of the PO without antioxidants and added with basil essential oils at 2 concentrations. The PVs in suddenly in the 1st day offrying, and then, remained st