Abstract
The thermoal oxidation rete of oil at 180°C was previously found proprtional to atmospheric oxygen in contrast to autoxidation of fats and oils at room temperature that could be retarded under an atmosphere containing less than 1% oxygen. Chicken nughetts were deepfried in high-oleic safflower oil and soybean under 2% or 20% oxygen and the quality of the frying oil and flavor of the nughetts were assessed periodically.
Based on acid and carbonyl values, content of polar compounds and other parameters, deterioration of deep-frying oil was efficiently retarded by frying under 2% oxygen. When residual tocopherol levels in the frying oil decreased to less than 10mg/100g (high-oleic safflower oil), 60mg/100g (soybean oil), oxidative deterioration was extensive. Foods deep-fried of low oxygen showed significantly better quality at 40h in soybean oil and 10h in high-oleic safflower oil, compared with the control. Lessening oxygen concentration by replacement with nitrogen gas would thus appear to improve the stability of deep-frying oil and of fried food quality.
