Changes in Moisture, Fat, and Fat Oxidative Indicators of Meat during the Preparation of the Iranian Koobideh Kebab

Koobideh kebab (barbequed minced meat) is one of the most popular Iranian foods. Reduction in the water holding capacity (WHC) of meat during thermal processing makes the water and melted fat run out of the meat. The fat content of the final product depends on the proportion of the retained moisture and fat. Meanwhile, high temperature and the presence of oxygen and iron in meat may facilitate oxidative rancidity of the fat. This study aimed to determine changes in moisture, fat content, and fat oxidative indicators of minced meat during Koobideh kebab preparation. Minced meat was provided by the restaurant of Isfahan University of Medical Sciences, Isfahan, Iran. Meat was barbequed and 3 times of sampling were performed with intervals of at least one week. Moisture and fat contents were measured by the weight and Sox let methods, respectively. Petroleum ether and diethyl ether were used as two solvents to extract fat. After the vaporization of the solvents, the peroxide value (PV) and acid number of the extracted fat were determined by iodometry and oil titration using alcoholic potassium hydroxide (KOH), respectively. During the process of preparing Koobideh kebab, moisture decreased from 62.5% to 45.5%. Using diethyl ether as the extraction solvent, the total fat in the raw sample and final product were found to be 10.32% and 19.44%, respectively. The PV and acid number of the fat extracts of the final product were higher than the initial values in raw meat. A 127-232% increase in PV was seen at the final stage of cooking period. However, the difference was not statically significant due to a wide variation in the measured PVs in repeated experiments. In addition, the produced peroxide was far less to make the extracted fat unusable (below 5 meq/kg). No specific relation was detected between acid number of the extracted fats and various phases of Koobideh kebab preparation. Effect of different methods of cooking meat and fat oxidation in various studies carried out, is different. Follow-up study showed that changes in the peroxide oxidation of the fat is made of compacted meat. This problem may be related to the direct heat of the fire.