تاثير فرايند حرارتي و مدت نگهداري بر تركيب اسيدهاي چرب، ويژگي هاي ميكروبي، شيميايي و حسي در فراورده هاي حاوي 40 درصد گوشت قرمز تهيه شده از روغن هاي سويا و كانولا

Effect of cooking and length of storage on the fatty acid composition and microbial, chemical, and sensory properties of 40%-beef products prepared with soybean and canola oils

Background and objectives: No studies have been done in Iran so far on the fatty acid composition of meat products and the effect of various factors on it. This study investigated and compared the effects of length of storage period (45 days) and initial cooking (at 72 C) on the fatty acid composition of two types of heated 40%-beef products prepared with soya and canola oils. Materials and methods: Samples of the products were analyzed at 5 stages, namely, before cooking and on days 1, 15, 30 and 45 after cooking. Fatty acid composition of the products was determined using gas chromatography and flame ionization detector (FID). Chemical analysis (determination of peroxide value, free fatty content, and the thiobarbituric acid value) was carried out to assess the spoilage progression and fat content changes. Also, in order to investigate the role of microbial growth in spoilage, microbial tests including total psychrotrophic bacteria and Lactobacillus counts were done on the samples. Furthermore, for comparison of sensory properties of the two products, paired-preference test was used at the middle of storage period. Results: Significant differences were observed in the soya batch at the beginning of storage (day 1) with regard to linoleic acid, on day 15 with regard to palmitic acid, and on day 30 with regard to linolenic acid. On the other hand, in the canola batch on day 45 the contents of the following four fatty acids were statistically different: palmitic, stearic, linoleic and linolenic acids. Furthermore, in the canola batch, the linolenic acid content also increased significantly on day 30. Microbiological examinations showed lower counts in products containing soya oil, but the results of chemical experiments showed different trends in the 2 products. Finally, the canola batch had a higher sensory acceptance than the soya batch. Conclusion: Based on the findings, the product containing canola oil is the more desirable product as regards quality and resistance to spoilage. Thus, considering the higher sensory acceptance of the canola batch, soya oil, which is currently used widely in the cooking oil industry in Iran, can be substituted with canola oil.