Gases within the sealed packages were sampled to determine the levels of CO2 and O2. Headspace sample (0.1mL) was withdrawn from each of the polystyrene trays using a syringe by piercing the trays with a fine hypodermic needle. The sampling hole was resealed with a patch of PVC adhesive tape, and the contents of the packages were used for subsequent quality analysis. The gas samples were then injected into a gas chromatograph (GC 2010, Shimadzu corporation, Japan). The GC was equipped with a split injector, (split ratio 5) a molecular sieve column (length 30 m, 0.35 I.D., RT-Msieve 5A, Restek Corporation, USA) and a TCD detector. Injection port temperature was maintained at 35 C. Initial column temperature was kept at 35 C for 5 min, then raised to 100 C at the rate of 100 C min1 and then held at this temperature for 5min. The TCD current and temperature was maintained at 90 mA and 110 C, respectively. Only O2 and N2 could be evaluated on the column used in the study. Based on observed O2 and N2 concentrations in the package headspace, actual concentrations of O2 and CO2 (%O2 and %CO2) were calculated using following equations: (Gupta et al., 2012).
%O2 = (Observed %O2/Observed %N2) 78.084 (1)
%CO2 = 100 [(Observed %O2/Observed %N2) 78.084 + 78.084 (2)
(Atmospheric composition of N2 taken as 78.084%)
Analysis was done in triplicates and concentrations of gases expressed as percentage.
Gases within the sealed packages were sampled to determine the levels of CO2 and O2. Headspace sample (0.1mL) was withdrawn from each of the polystyrene trays using a syringe by piercing the trays with a fine hypodermic needle. The sampling hole was resealed with a patch of PVC adhesive tape, and the contents of the packages were used for subsequent quality analysis. The gas samples were then injected into a gas chromatograph (GC 2010, Shimadzu corporation, Japan). The GC was equipped with a split injector, (split ratio 5) a molecular sieve column (length 30 m, 0.35 I.D., RT-Msieve 5A, Restek Corporation, USA) and a TCD detector. Injection port temperature was maintained at 35 C. Initial column temperature was kept at 35 C for 5 min, then raised to 100 C at the rate of 100 C min1 and then held at this temperature for 5min. The TCD current and temperature was maintained at 90 mA and 110 C, respectively. Only O2 and N2 could be evaluated on the column used in the study. Based on observed O2 and N2 concentrations in the package headspace, actual concentrations of O2 and CO2 (%O2 and %CO2) were calculated using following equations: (Gupta et al., 2012).%O2 = (Observed %O2/Observed %N2) 78.084 (1)%CO2 = 100 [(Observed %O2/Observed %N2) 78.084 + 78.084 (2)(Atmospheric composition of N2 taken as 78.084%)Analysis was done in triplicates and concentrations of gases expressed as percentage.
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