Measuring Oxygen Barrier Properties of Soybean Oil

Oxygen barrier property was measured by sodium thiosulfate titration [13 (link)]. First, 3 g of soybean oil was placed into 50 mL conical bottles of the same size. These conical bottles were then sealed with different composite membranes. One bottle without a membrane seal was designated as the blank group. All the films were subsequently placed in an incubator at 50 °C for 3 days, after which the peroxide value (PV) was measured. The peroxide value of the oil was determined in accordance with GB 5009.227. The PV was calculated using the following formula: $$PV=\frac{\left(V-V_0\right)\times c\times 0.1269}{m}\times 100$$
In the formula, PV is the peroxide value, g/100 g; V is the volume of sodium thiosulfate standard solution consumed by the sample, mL; V₀ is the volume of sodium thiosulfate standard solution consumed in the blank sample, mL; c is the concentration of sodium thiosulfate standard solution, mol/L; 0.1269 is the mass of iodine equivalent to 1.00 mL of standard titration solution of sodium thiosulfate, [c(Na₂S₂O₃)] = 1.000 mol/L; m is the sample mass, g; and 100 is the conversion factor.