Evaluation of physicochemical parameters of edible oils at room temperature and after heating at high temperature

Abstract

Edible oils and fats are recognized as vital constituents of our daily diet and contribute significantly to the regulation of different body functions. Edible oil quality is largely determined by physicochemical characteristics and sensory evaluation due to its nature and processing procedure. The present study includes evaluation of different physicochemical parameters of soybean, palm, mustard and bran oil at room temperature and after heating at 180oC for 10 mins using different analytical methodologies. These properties were studied to evaluate the compositional quality of oils and also to investigate the effect of heating as it ultimately changes the physicochemical and sensory properties of the oil. Results revealed that there was a significant difference in physicochemical parameters among four types of oils before and after heating. Peroxide, free fatty acid and acid value were increased with the increase of temperature at 180oC. The iodine value was highest in soybean oil (133.17 mg/g), followed by mustard oil (110.59 mg/g) but was lowest in palm oil (46.18 mg/g). In addition, saponification value was found to be 187.1, 202.39, 191.38 and 181.6 mg/g in soybean, palm, mustard and bran oil, respectively. The study also indicated that the L*, a* and b* values of oil decreased significantly with heating temperature. However, sensory evaluation results also found that soybean oil and bran oil were more preferable to cooking than the other two oils. Taking consideration of all parameters the study concluded that soybean oil and bran oil had the superior quality to other samples.