Studies On The Processing Improvement Of Dry-Cured Goose And Their Quality Variations

The dry-cured goose, also known as "salted goose" or "cured goose", is one of the traditional cured meat products in China; consumers love it because of its unique flavor and rich aroma. Earlier, dry-cured goose was produced by wet/dry salting and open-air drying in traditional hand cottage just in winter with a long processing cycle of almost 1-2 weeks. After improvements, the production cycle was shortened to 3 days by automated dry-cured production line, air supply, ventilation, cooling and dehumidification; and now it can also be produced in seasons other than winter. However, the processing of dry-cured goose lacked scientific explanation; particularly the impact of rapid curing of poultry products, which lead to poor quality, low productivity and reduced economic efficiency resulting into an overall slow development of dry-cured goose industry.By exploring quality variation of dry-cured goose and investigating the influences of tumble curing, this project was designed to optimize the production process, and to provide theories for standardization and modernization of the production of dry-cured goose.1. Exploring existing process of quality variation of dry-cured gooseThe basic quality of processing, protein degradation and lipid oxidation were studied; the results showed that PI remained low; FAAN/TN ratio increased considerably indicating that less protein peptide increased, FAA increased significantly, while the proteolysis was weak during processing of dry-cured goose. Arg, Thr, Glu, Leu and Ala were the most abundant FAA, while Asp, Leu, Tyr, Val, Ile, and Lys increased in the goose breast. Most of the FAA exceeded several times of their threshold level which might have important impact on the flavor of dry-cured goose.2. Effect of tumble curing on the quality of dry-cured gooseThis research was conducted to investigate the changes of the goose quality after the vacuum tumbling, and analyze the correlation between each index. The results showed that after tumbling, the pH significantly increased, L* and a* values, cooking loss, pressure loss and shear force were significantly decreased, while b* did not experience any significant change. The diameter of muscle fiber decreased significantly and sarcomere length increased significantly. The denaturation temperatures of three proteins measured by DSC reduced significantly. On NMR (nuclear magnetic resonance, NMR), the T23 disappeared after tumbling, T21 and T22 were significantly higher than before, and the proportion of T22 increased, as well. There was a high correlation between several indicators. The micro level, the distortion and degradation of Z line, reduction of muscle fiber diameter, increase in sarcomere length and changes in spatial structure of protein improved the tenderness and increased the water retention. Application of vacuum tumbling enabled to shorten the curing from 20 hours to 4 hours, saved pickling liquid, reduced labor intensity and increased economic efficiency.3. Optimization of tumble curing processIn this experiment, Yangzhou geese were used as raw materials. Optimization was performed by the L9 (34) orthogonal experiment using production rate, L* value and salt content as reference index. The parameters and conditions were optimized for production of dry-cured goose for further comparison with the usual factory product. The results showed that the optimum indices; liquid to meat ratio was 6:10, speed 11 r/min, tumbling 10 min and holding time 5 min, while the order of the factors was:liquid to meat ratio> tumbling time>speed. Under these conditions, the dry-cured goose had significantly higher quality than those produced by usual factory method.