مجله پژوهشهای علوم و صنایع غذایی ایران (Sep 2023)
Evaluation of Antioxidant Effect of Ethanolic Extract of Aloe Vera Gel on the Stability of Soybean Oil
Abstract
Introduction Oxidation of lipids results in changes that may affect the nutritional quality, wholesomeness, colour, flavour and texture of food. The aim of this study was to investigate the type and amount of phenolic compounds in ethanolic extract of aloe vera gel as a source of natural antioxidant and its effect on the oxidative stability of soybean oil.Using synthetic antioxidant due to the possibility of toxic and carcinogenic effects is limited. Thus, it is important to find an alternative to synthetic antioxidants by natural antioxidant. Different intrinsic and extrinsic factors may initiate the oxidation of lipids. The initial products of oxidation are tasteless and odorless and after degradation and production of secondary products, the off-flavors and off-odors will appeared in edible oils. This is a great concern in food industry, because it decreases the shelf life of food products. Free radicals are produced during chain reactions in lipid oxidation process. To avoid this, synthetic antioxidants are usually used which are sensible to heat and are hazardous to human health and may cause cancer. Polyphenols have antioxidant activity and absorb free radicals. Thus, the vegetable oils rich in polyphenols can affect human health. In this research, we aimed to investigate the application of natural extract of aloe vera gel as a natural antioxidant to avoid soy oil oxidation and to compare it with synthetic antioxidants.The rate of oxidation reaction can be delayed by adding antioxidants. Consumers today tend to use natural antioxidants instead of synthetics. The overall purpose of this study was to investigate the effect of adding ethanolic extract of aloe vera gel as natural antioxidant on improving the stability of soybean oil. Materials and Methods The compounds in ethanolic extract of aloe vera gel were determined using GC / MS. The antioxidant activity was evaluated by the method of DPPH. For this purpose, ethanolic extracts of aloe vera gel were added to soybean oil in four different concentrations (500, 1000, 1500, 2000 ppm) and peroxide value, acidity, thiobarbituric acid, total phenol, oxidative stability to Rancimat method, fatty acid profile and sensory evaluation were performed on soybean oil samples and compared with the control sample containing 120 ppm BHA and soybean oil sample without adding antioxidants during 30, 60 and 90 days of storage at 25 ° C. Results and Discussion The results showed that by increasing the concentration of aloe vera extracts from 500 to 2000 ppm, the oxidation rate decreases during 90 days of storage, the amount of peroxide, thiobarbituric acid and acidity of soybean oil containing 2000 ppm ethanolic extract of aloe vera gel was lower than the control sample containing 120 ppm BHA. The total phenol content and free radical scavenging and stability to oxidative degradation by Rancimat method in soybean oil sample containing 2000 ppm aloe vera ethanol extract was higher than soybean oil samples containing BHA120 ppm. Evaluation of sensory properties showed that no significant difference was observed between the sensory properties of the oil sample containing 2000 ppm ethanolic extract of aloe vera gel and the control soybean oil sample of BHA120 ppm. Conclusion Considering that the sample of soybean oil containing 2000 ppm ethanolic extract of aloe vera gel had higher phenol content and free radical scavenging and more antioxidant properties than the control sample, it did not differ significantly from the control sample. Qualitative and health properties were selected as the superior treatment. The results of this study showed that the ethanolic extract of aloe vera gel can be used as a natural antioxidant instead of conventional synthetic antioxidants in the oil industry and to prevent oxidative spoilage of the oil in a desirable way. Therefore, it might be employed as a natural antioxidant in foods, particularly those containing edible oils.
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