Influence of Phenolic Antioxidants on Changes in Quality Characteristics of Palm Olein during Intermittent Frying of Potato Chips

Abstract

Consumption of deep fried foods is continuously increasing because they are easily and quickly prepared, relatively cheap, with typical appealing flavor, golden brown color and have a crispy texture. In common practice, mostly the frying process is conducted again and again in the same oil. So this repeatedly heating of the same oil at high temperatures causes several deteriorative reactions such as oxidation, polymerization and thermal degradation. Among them oxidation is one of the major problems that affect the edible oils. The use of antioxidants is one of the easiest and cheapest method which my address this issue, especially in developing countries. In this study effectiveness of four different types of phenolic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tertiary butylhydroquinone (TBHQ) and vitamin E (tocopherol) against the changes in quality characteristics of palm olein during deep-fat frying (at 180 °C) of potato chips (for seven consecutive days) was compared at their five different concentrations i.e. 40 ppm, 80 ppm, 120 ppm, 160 ppm and 200 ppm and also with control. Potato chips were fried in palm olein containing different levels of these phenolic antioxidants. Fried oil samples were analyzed for three parameters such as peroxide value (POV), free fatty acid (FFA) contents and iodine value (IV). In general, BHA showed lowest rate of increase in POV and FFA at each concentration and day compared to control and three other antioxidants. The mean value of POV for BHA, TBHQ, BHT, Vit E and Control was 8.7144, 8.9924, 9.3094, 9.5964 and 9.8671 meq/kg respectively. Similarly, mean values of FFA for BHA, BHT, TBHQ, Vit E and Control were 0.1454, 0.1861, 0.1992, 0.2700 and 0.2998 % respectively. While in case of IV, BHA showed lowest rate of decrease in IV at each concentration and day compared to control and other three antioxidants. The mean value of IV for BHA, TBHQ, BHT, Vit E and Control was 50.154, 49.664, 49.615, 49.615 and 48.321 g/100g respectively. The sequence of effectiveness of antioxidants against oxidative deteriorations in palm olein during intermittent frying of potato chips at each concentration (40 ppm, 80 ppm, 120 ppm,160 ppm and 200 ppm) and day (day 1st to 7th) was BHA >TBHQ >BHT >Vit E >Control. Overall, BHA showed highest protection against oxidation at each concentration and day as compared to rest of the antioxidants, after BHA, TBHQ was most effective against the rate of oxidation at each level of concentration and day then rest two antioxidants, after TBHQ, BHT was on third position when compared to other antioxidants while Vit E was least effective antioxidant against the oxidation of oil. From the results of this research it can be concluded that BHA with the concentration level ranging from 160 ppm to 200 ppm could be used to improve the oxidative stability of palm olein during deep fat frying, due to its low cost, easy availability and high performance.