Fig. 1 illustrates pH changes in the chicken breast samples during the 16 day refrigerated storage period. The initial (day 0) pH of all fillets was 5.81; the pH, however, increased with different trends. Except for day one, the pH values of the control group were significantly different (p < 0.5) from those of other groups. Additionally, the mean of A-L 6 sample was higher than that of the control A, A-l 2 and A- l 4 groups (not significantly, p > 0.05) on days 4 and 8. pH values of chicken fillets (ranging from 5.72 to 6.13 during 16 days) were similar to those reported by Silva et al. (2002) and Mano et al. (1993). The increase in the pH of chicken breast fillets (Fig. 1) can be traced back to the accumulation of amines and ammonia compounds originated from microorganisms. Our results indicated that high LPOS, increased the pH of chicken…show more content… In other words, at primary stages, most hydroperoxides were transformed into secondary oxidation products which is different from Teets and Were research (Teets and Were 2008) where there was an increase in the POV levels during the first 2-3 days of experiment. These outcomes indicate that performing a successful study about the peroxide value requires at least two tests in the first four days. There is no evidence as to the effect of lactoperoxidase enzyme on the production of hydroperoxides, nor was there any significant difference between lactoperoxidase coating samples and control A fillets on days 0, 4, 8 and 16. As seen in Fig. 1, the pH of A-L 6 sample is near the neutral point on day 12 as opposed to other days. Khaksar et al. (2010) reported that the increase in the pH toward the neutral point provides an ideal condition for oxidation, hence the, higher levels of POV for A-L 2 and A-L 6 chicken fillets compared to control A and A-L
