Effect of processing and storage of Jameed on conjugated linoleic acid content and fat and cholesterol oxidation

The influence of Jameed processing and storage on fat and cholesterol oxidation, hydrolytic rancidity, and conjugated linoleic acid (CLA) was evaluated by determining peroxide value (PV), 7-ketocholesterol, free fatty acids content (FFAs) and total CLA. Three different sizes of Jameed pieces (ca. 50, 200 and 400 g balls) were used to investigate the influence of storage for 0, 1, 3, 5 and 7 months on the above lipid oxidation parameters. No significant (P>0.05P>0.05) effect of the Jameed processing steps on lipid changes was found with the exception of the sun drying steps, that caused an increase of PV, 7-ketocholesterol and FFA contents and a decrease in CLA content. This trend was also observed during storage of Jameed at room temperature and kept exposed to light and atmospheric air. The PV values of the 50, 200 and 400 g balls after 7 months of storage were 35.3, 19.4 and 20.4 meq O2 kg−1 of fat, that were 17, 11 and 12 times higher compared with the corresponding values of the fresh samples (1.9 meq O2 kg−1 of fat ). The 7-ketocholesterol of the tested samples increased from about 5.7 μg g−1 to 210, 120 and 125 μg g−1 for the 50, 200 and 400 g balls, respectively. FFA content increased remarkably during storage, from about 1.3 g kg−1 at the beginning of storage to 8.6 g kg−1 of fat after 7 months with no significant (P>0.05P>0.05) effect for the size of Jameed pieces on FFAs content. On the contrary, a decrease of about 43%, 26% and 26% of the original value (5.7 mg kg−1 of fat) in CLA content was found for the stored Jameed pieces of 50, 200 and 400 g, respectively.