Evaluation of different methods to monitor primary stage of oxidation of heat clarified milk fat (ghee)

Abstract

In the present study, weight gain, conjugated dienes (CD), kreis number, iodine value, free fatty acids (FFA) and peroxide value (by ferrous xylenol orange (FOX) method) were compared with sensory testing in monitoring the primary stage of oxidation in ghee. The latter used a nine-point hedonic scale for flavor. Six samples of ghee were stored at 80 °C and samples removed at 48-h intervals. Correlation coefficients of the test methods with flavor scores were weight gain −0.006, CD content 0.055, iodine value −0.016, FFA −0.066, Kreis number −0.260 and peroxide value (by FOX method) −0.624. Thus, highest coefficient of correlation was obtained for the peroxide value (by FOX method) method. The high correlations between the peroxide value and flavor data indicated that peroxide value (by FOX method) was the more suitable of the methods tested to monitor primary stage in oxidized ghee. Practical applications Ghee is a heat clarified milk fat and gaining popularity in the world. It is most valuable fat rich dairy products having nutritive and medicinal properties. Ghee deteriorates through oxidation when stored at ambient temperature. There are methods available for monitoring the primary stage of oxidation of ghee. However, no work so far carried out to compare these methods. The finding of this research will be very useful for selection of suitable method for monitoring primary stage of oxidation of ghee during storage.