| Xinjiang dry-cured beef is a tranditional meat product with strong ethnic characteristics. Currently, Xinjiang dry-cured beef is mainly hand-made by herdsmen or produced in individual workshopsrather than produced in industrial scale and standardized approachwhichinduced unstablequality and low turnover of the dry-cured beef. In this research, qualitative charateristics and volatile compouds of Xinjiang dry-cured beef were investigated, changes of quality of Xinjiang dry-cured beef during processing were determined, and influences of lipid oxidation to volatile flavour compouds were also analyzed. Hence, this study provided a theoretical basis for commercialization of the traditional process, standardized production and flavour quality control of Xinjiang dry-cured beef. The results were as follows:(1) Quality parameters of 30 market origined samples of Xinjiang dry-cured beef were investigated. The results showed that Xinjiang dry-cured beef was characterized by a low moisture content, high protein, low fat, moderate salinity food of a mean moisture content (59.50 g/100g), protein content (29.77 g/100g), fat content (3.92 g/100g), and NaCl content (4.36 g/100g). Xinjiang dry-cured beef had a higher pH and aw, was classified into perishable food. Microbial analysis showed that the total plate count reached 5.22×105 cfu/g, presence of coliforms, mould and yeast indicates a poor hygiene quality of products. Sensory quality was evaluated pleasant. Multiple linear regression analysis was used to establish the prediction models of overall acceptability by physicochemical variables, results were presented as follows:Overall acceptability= 6.354+0.091 x chewiness-0.013 x moisture content-0.3 x fat content+0.169x6* (R2=0.803, P<0.001)。(2) Volatile compounds of 30 market origined samples of Xinjiang dry-cured beef were analysed by SPME/GC-O-MS. A total of 86 volatile compounds were identified.73 volatile compounds were detected in Yili dry-cured beef,34 in Tacheng dry-cured beef and 26 in Altay dry-cured beef, respectively.51 volatile compounds, were detected only in Yili dry-cured beef,7 only in Tacheng dry-cured beef and 1 only in Altay dry-cured beef. These volatile compounds, including hexane, hexanal, heptanal,2-penty furan, I-octanal, nonanal and l-octen-3-ol were identified as characteristic flavor compounds of Xinjiang dry-cured beef. Lipid oxidation, spices, and amino acids degradation played a key role in the flavour formation of Xinjiang dry-cured beef.(3) The moisture content and aw decreased, while the protein content and the fat content increased during processing of Xinjiang dry-cured beef (P<0.05). The pH did not change significantly (P>0.05) during processing. Processing time affected L*, a*, and b*.(4) TBARS values increased during processing, and then showed an decrease during storage (P>0.05). Spearman’s correlations between TBARS values and the volatile compounds were analysed, and the following correlations were observed:strong positive correlation (P<0.01) to 2-ethyl-furan (r=0.879),2-pentyl-furan (r=0.878) and total furans (r=0.879); significant positive correlation (P<0.05) to hexanal (r=0.852), (Z)-4-heptenal (r=0.841), octanal (r=0.837),2,3-octanedione (r=0.833), (E)-2-decenal (r=0.828), 2-ethyl-l-hexanol (r=0.803), propanal (r=0.797), (E)-2-nonenal (r=0.796), and total aldehydes (r=0.776). During the processing period, the proportion of PUFA and MUFA decreased, while the proportion of SFA increased (P<0.05). The results showed that oxidation reactions mainly could be happened in the PUFA and MUFA.In addition to ketones compounds, the total content of other types of compounds changed significant (P<0.05). Aldehydes were the most abundant volatile compounds in the final product. At end of storage, alcohol became the major compounds in Xinjiang dry-cured beef. |
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