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J Food Sci Technol (SeptemberOctober 2013) 50(5):868878 DOI 10.1007/s13197-011-0419-8
ORIGINAL ARTICLE
Oxidative stability of vegetable oils as affected by sesame extracts during accelerated oxidative storage
Adel A. Abdelazim & Awad Mahmoud &
Mohamed Fawzy Ramadan-Hassanien
Revised: 18 May 2011 /Accepted: 25 May 2011 /Published online: 10 June 2011 # Association of Food Scientists & Technologists (India) 2011
Abstract In vitro antioxidant activities and protective effects of sesame cake extract in stabilising sunflower and soybean oils were tested. Total phenolic, flavonoid and flavonol contents in the extract of sesame cake were 1.940.02 (mg gallic acid equivalent (GAE) g1 dry weight (DW)), 0.880.02 (mg quercetin equivalent (QE) g1 DW), and 0.400.02 (mg QE g1 DW), respectively. Protective effects of sesame cake extract in stabilizing sunflower and soybean oils were tested, compared to synthetic antioxidants, by measuring their peroxide values (PV), conjugated dienes (CD), conjugated trienes (CT), and p-anisidine value during accelerated storage. Results indicated that sesame cake extract exhibited stronger antioxidant activity than BHT and BHA. However, its antioxidant activity was less than that of TBHQ.
Keywords Sesame . Vegetable oils . Accelerated storage . Antioxidant activity. Oxidative stability
Introduction
Edible oils with higher levels of unsaturation, especially polyunsaturated fatty acids (PUFA), are more susceptible to
oxidation. Oxidation of oils modifies organoleptic properties and affecting the shelf life of the product (Lercker and Rodriguez-Estrada 2002). Lipid oxidation of oils not only produces rancid odours, unpleasant flavours and discoloration, but also decreases the nutritional quality. Many methods have been reported to measure the oxidative stability (OS) of edible oils. The oxidative stability of oils and fats with added antioxidants can be determined during storage under normal ambient conditions and packing. However, in general, oxidation take a long time to occur which is impractical for routine analysis. For this reason, accelerated oxidation tests or aging tests are conducted. Tests like Schaal oven test, Sylvester test and Swift test are used for testing accelerated oxidation at elevated temperatures (Mahuya et al. 2008; Ramadan 2008). Storage of oils at high temperatures has been employed for monitoring OS of oils. The extent of oxidation in oils has been frequently evaluated by measuring the peroxide value (PV). This index is related to the hydroperoxides, the primary oxidation products, which are unstable and...