Chemistry
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Item Ethanolic extract of rice bran: a thermally stable preservative for edible oils and cake(2022) Seneviratne, K.P.; Anjali, N.V.P.; Senanayake, C.M.The purpose of this study was to evaluate the thermal stability of the rice bran extract (RBE) and analyze the effect of RBE on the shelf-life of sunflower oil and the quality characteristics and shelf-life of baked cake. The thermal stability of RBE was evaluated by a Rancimat test using sunflower oil. Properties such as moisture content, porosity, crumb density and pore area of cakes baked with RBE and the synthetic antioxidant butylated hydroxytoluene (BHT) were compared. Sensory properties such as taste, aroma, texture, color and overall acceptability of the cake samples were compared using a sensory panel test. The shelf-life of the cakes was evaluated by microbial counts and chemical methods. Thermally treated RBE and BHT for 2 h at 180 °C retained 75% of their initial capacity in protecting sunflower oil while RBE had a significantly higher protection factor (p < 0.05). Cakes baked with RBE received higher scores for taste, color and overall acceptability compared to control or BHT-added cake. BHT-added cake and RBE-added cake exceeded the aerobic plate count (APC) and yeast and mold count (YMC) on days 11 and 13 respectively, while the control cakes without added antioxidants exceeded the APC and YMC on day 7. Both BHT- and RBE-added cakes maintained hexanal levels below 5 mg/kg over 28 days while the control cake exceeded this level on day 21. The results suggest that RBE can be used as a natural food additive to improve the quality and shelf-life of baked foods and edible oils.Item Antioxidant and Nutritional Properties of Domestic and Commercial Coconut Milk Preparations(International Journal of Food Science, 2020) Karunasiri, A.N.; Gunawardane, M.; Senanayake, C.M.; Jayathilaka, N.; Senevirathne, K.N.The aqueous extract of scraped coconut kernel is known as coconut milk. Coconut milk preparations are also commercially available in the form of desiccated powders or liquids. While these various coconut milk preparations are heavily used in cooking in the Asian countries as a major source of dietary fat, limited studies have been conducted on their chemical and nutritional composition. In this study, we have determined the chemical composition and nutritional effects of both domestic preparations of coconut milk and the commercially available counterparts. The results indicate that the phenolic compounds of all coconut milk preparations provide protection against oxidative damage on lipids and inhibit oxidative damage of both proteins and DNA. The lipid profiles are not significantly affected by the consumption of the three coconut milk preparations despite their different fat contents.Item Protective Effect of Coconut Oil Meal Phenolic Antioxidants against Macromolecular Damage: In Vitro and In Vivo Study(Journal of Chemistry, 2020) Karunasiri, A.N.; Senanayake, C.M.; Hapugaswatta, H.; Jayathilaka, N.; Seneviratne, K.N.Coconut oil meal, a cheap by-product of coconut oil production, is a rich source of phenolic antioxidants. Many age-related diseases are caused by reactive oxygen species- (ROS-) induced damage to macromolecules such as lipids, proteins, and DNA. In the present study, the protective effect of the phenolic extract of coconut oil meal (CMPE) against macromolecular oxidative damage was evaluated using in vitro and in vivo models. Sunflower oil, bovine serum albumin (BSA), and plasmid DNA were used in the in vitro study, and thiobarbituric acid reactive substances (TBARS), protein carbonyl, and nicked DNA were evaluated as oxidation products. The inhibitory effect of CMPE against H2O2-induced macromolecular damage was evaluated using cultured HEp-2 cells. The results indicate that CMPE inhibits macromolecular damage both in vitro and in vivo. In addition, CMPE regulates redox status of HEp-2 cells under oxidative stress conditions by maintaining higher reduced glutathione levels. There was no significant difference in the expression of glutathione peroxidase in stressed and unstressed cells suggesting that CMPE regulates the cellular oxidative stress responses without affecting the expression of oxidative stress response genes. Oral feeding of Wistar rats with CMPE improves the serum and plasma antioxidant status without causing any toxic effects.Item Phenolic extracts of the leaves of Psidium guineense Sw. improve the shelf life of sunflower oil and baked cake and antioxidant status of Wistar rats(J Food Biochem, 2018) Senanayake, C.M.; Hapugaswatta, H.; Jayathilaka, N.; Seneviratne, K.N.The potential of the ethanolic extract of Psidium guineense Sw. leaves (PGLE) to protect food from oxidation was evaluated using sunflower oil and baked cake as food models. The nutritional quality of PGLE was evaluated by feeding Wistar rats with PGLE for 150 days. Psidium guineense Sw. leaves contain 195.25 ± 9.56 mg g–1 phenolic substances, 51% of which are o‐diphenols. Protection factor, the ability of Psidium guineense Sw. leaves to protect sunflower oil against oxidation (1.82 ± 0.13), was not significantly affected by heat treatment compared to BHT. Formation of oxidation products, peroxide and hexanal in PGLE‐ and BHT‐added cake was significantly lower (<5 ppm over 28 days) compared to control with no added antioxidants. Therefore, addition of PGLE improved the shelf life of sunflower oil and oxidative stability of baked cake. PGLE also improves the serum antioxidant capacity and inhibits lipid and protein oxidation in Wistar rats. Practical applications PGLE is a rich source of phenolic substances. Due to high antioxidant activity, pleasant sensory quality and high thermal stability, PGLE can be used to improve the shelf life of baked cake and edible oils. As PGLE also improves serum and plasma antioxidant properties without causing any toxicity, nutritional food supplements can be developed based on PGLE.Item Determination of thermal stabilities of guava leaf, coconut cake, rice bran and sesame cake extracts(Sri Lanka Association for the Advancement of Science, 2015) Senanayake, C.M.; Seneviratne, K.N.; Jayawardena, B.M.; Prasadani, W.C.