EFFECT OF GARLIC ON SOME QUALITY CHARACTERISTICS OF GROUNDNUT OIL REPEATEDLY USED FOR DEEP-FRYING.

Abstract

Deep frying is one of the most commonly used procedures for the preparation and manufacture of foods throughout the world, for both domestic and industrial food preparation procedures. During deep-frying, the oil is exposed to elevated temperatures in the presence of air and moisture. A number of chemical reactions, including oxidation and hydrolysis, occur during this time, as do changes due to thermal decomposition. The oil commonly used in deep-frying includes groundnut oil, canola oil, sunflower oil, palm olefin, soybean oil. The addition of antioxidants is the most commonly used form to retard lipid oxidation processes and extend the shelf life of oils and fats. Synthetic antioxidants such as BHT, BHA, TBHQ and PQ are reported to be health hazardous, and some are removed from the GRAS (generally recognized as safe) list and banned in many countries. Natural antioxidants are mainly polyphenolic compounds that help to stabilize oils and food, trapping free radicals and retarding oxidative processes. Garlic (Allium sativum L.) is known to contain natural antioxidants that can remove reactive oxygen species (ROS) and reduce lipid peroxides and low-density lipoprotein oxidation. The antioxidant properties of garlic compounds are allyl cysteine, alliin, allicin, and allyl disulfide. This study was conducted to determine the effect of garlic on some quality characteristics of repeatedly used groundnut oil. The initial phenolic content of the oil before frying was 677±2.83g GAE/g. At the end of the frying period, the total mean value for the phenolic content of the samples were 493±7.53g GAE/g, 407±3.43g GAE/g, and 346±4.44g GAE/g for Sample GS2 (7% garlic), Sample GS1 (4% garlic) and Sample GS0 (untreated groundnut oil) respectively. This research work is significant for decision –making and policy formulation in the food industry value chain in Nigeria. Keywords: Antioxidant, Deep-Frying, Garlic, Food Chain, Polyphenol.