EVALUATION OF THE OXIDATIVE THERMAL STABILITY OF FISH OIL WITH THE ADDITION OF PUMPKIN SEED OIL OR ROSEMARY EXTRACT

Abstract

The present study investigates the thermal stability of the commercial fish oil, rich in unsaturated fatty acids, and compares the sensory properties of pure fish oil with a mixture of fish oil and added rosemary extract (RE), as well as roasted and unroasted pumpkin seed oil, at a concentration of 5 %. All samples were monitored using FTIR spectroscopy to measure the specific absorptivity of conjugated dienes (CDs) and conjugated trienes (CTs), as well as the peroxide value. Additionally, GC/FID was employed to evaluate the oxidative degree of the fish oil and compare the antioxidative effect of roasted pumpkin seed oil, specifically in comparison to rosemary extract. For this purpose, the oil stability was optimized by comparing the oxidation levels of fish oils exposed to range of temperature, including 23°C, 50°C, 70°C, 90°C, and 110°C. This was done in the presence of a low percent of rosemary extract, unroasted pumpkin seed oil (UPSO), and roasted pumpkin seed oil (RPSO). Based on the obtained results, a clear difference is observed in the blended samples, particularly when roasted pumpkin seed oil is used. This difference is evident in the ultraviolet chemical parameters, fatty acid profile, and most notably in the optimized FTIR vibrational bands. The ratios of area peaks such as 3444/2854, 1745/2854 and 3010/2854 are considered important parameters for monitoring the chemical changes and lipid stability. All the chemical parameters confirm the possibility of enhancing the stability of fish oil by blending it with healthy pumpkin seedoil. The composition of pumpkin seed oil increases the stability of fish oil. Consequently, it is evident that pumpkin seed oil, known for its high healthy benefits, can successfully be used to improve the thermal and oxidative stability of fish oil lipids. The principal component analysis (PCA) was used to define clusters, which revealed a wide range of both chemically changed and unchanged samples. The application of FTIR spectroscopy as an alternative method provides excellent parameters for easy operation, affordability, and ecological considerations, making in an efficient tool for controlling the quality of edible oils.