Chitosan solution was prepared with 2 % (w/v) chitosan in 1% (v/v) acetic acid glacial. The solution was placed on a hot plate/magnetic stirrer for 6 h. The resultant chitosan-based coating solution was filtrated, through a Whatman filter paper No: 2, glycerol was added at 0.75 % (w/v), and stirred for more than 15 minutes. Two of the best concentrations, 60 and 90 mg mL−1 were prepared from freeze-dried IgY for S. putrefaciens and P. fluorescens respectively. After centrifugation (10000 ×g) for 30 min, the supernatant was collected and sterilized by ﬁltrating, through a 0.22 µm micro-ﬁlter. Finally, IgY was added to chitosan-based coating solution. The final coating solution was homogenized under aseptic …show more content…
Treated fillets were dried at 4 °C for 5 hours under aseptic conditions, and were placed in zip bags and kept in the refrigerator for 16 days (Ojagh, Rezaei, Razavi, and Hosseini 2010) (Table 1). Total fat was extracted, according to Bligh and Dyer on days 0, 4, 8, 12 and 16 of refrigerated storage (Bligh and Dyer 1959). Antioxidant evaluation of lycopene solutions by DPPH method
DPPH solution in methanol (24 mg mL-1) was prepared and 2 mL of this solution were added to 50 μL of different concentrations of lycopene. After one-hour incubation at room temperature in the dark, absorbance at 517 nm was measured, using a spectrophotometer (Pharmacia LKB Novaspec, Sweden) (Aminzare, Aliakbarlu, and Tajik 2015). Scavenging capacity of lycopene was calculated as follows:
(Radical Scavenging Activity) RSA% = [(Ablank - ASample ) / Ablank]×100
Free fatty acids (FFA) …show more content…
Fat was dissolved in 25 mL of the solvent (a mixture of chloroform and acetic acid). Then, 1 mL of saturated solution of potassium iodine was added, and kept in a dark environment for 10 minutes. After this time, 20 mL of distilled water and 1mL of starch solution (1.5%) were added.
The sample was titrated by 0.01 N Na2S2O3, until disappearance of the blue color. The amount of peroxide was calculated, using the following equation (Harold, Kirk, and Swayer 1981).
PV = (1000 (푉1-푉2) 푁) / V1
V1: volume of sodium thiosulfate solution, V2 volume of sodium thiosulfate, W: weight, N: normality of sodium thiosulfate solution
0.2 g of fat was mixed with 1 mL of BHT and 35 mL of C2HCl3O2. Then 100 mL of distilled water was added, 50 mL of distilled samples was collected to mix with 5 mL of TBA, and was placed for 1 hour in the water bath. The absorbance of the samples was measured at 532 nm, using a spectrophotometer (Pikul, Leszczynski, and Kummerow 1989).
TBA value = (Asample−Ablank)×50/200 PH