Changes in Chemical-Physical Index and Microstructure During Dry-cured Duck Processing

The change of volatile compounds of two kinds of vinasse-cured ducks during processing

Vinasse-cured duck was processed by boiling, salting, and vinasse-dry-curing or vinasse-wet-curing. Volatile compounds, moisture contents, reducing sugars, and thiobarbituric acid reactive substances (TBARS) values during processing were determined. Reducing sugars decreased during boiling and increased after vinasse-curing. TBARS values increased throughout the processing. The volatiles of ducks during processing and vinasse-curing agents (dry vinasse and vinasse sauce) were 125 compounds. The first principal component (PC1) belonged to the flavor of cooked duck, whereas the second principal component (PC2) represented the flavor of yellow rice wine. The 66.49 and 29.61% of typical aroma of vinasse-dry-cured product were from dry vinasse and lipid oxidation, respectively, whereas the 75.58 and 21.89% of aroma of vinasse-wet-cured product were from vinasse sauce and lipid oxidation, respectively. Lipid oxidation products increased after boiling, whereas salting promoted their release. Compared with vinasse-wet-cured duck, vinasse-dry-cured product presented richer aroma of lipid oxidation and weaker flavor of vinasse-curing agents. Besides, protein denaturation which was caused by ethanol could influence the retention and release of flavor. In conclusion, two kinds of vinasse-curing methods influenced the characteristic volatiles of products and their generation during processing.

Optimization of Flavourzyme Hydrolysis Condition for the Preparation of Antioxidant Peptides from Duck Meat using Response Surface Methodology

The aim of this study was to optimize and characterize Flavourzyme hydrolysis conditions for the preparation of antioxidant peptides from duck meat, using response surface methodology. The results indicated that optimal Flavourzyme hydrolysis conditions for preparation of antioxidant peptides from duck protein were a temperature of 50.19°C, pH 5.45, and a reaction time of 1.03 h. Compared to non-hydrolyzed duck meat, Flavourzyme hydrolysis significantly improved the hydroxyl-radical scavenging, DPPH radical-scavenging, ferrous ion-chelating, reducing, and ABTS radical cation-scavenging activities of duck meat. Therefore, Flavourzyme can be regarded as an effective hydrolytic enzyme for the preparation of antioxidant peptides from duck meat.

The effect of adenosine 5'-monophosphate (AMP) on tenderness, microstructure and chemical-physical index of duck breast meat

BACKGROUND

Adenosine 5'-monophosphate (AMP) is often used in meat and poultry soups as a flavor enhancer (flavor modifier), or as food additives for specific nutritional purposes. Our previous research as well as evidence from others showed that actomyosin could be dissociated into myosin and actin by AMP in extracted muscle solution. However, there is no report available on the application of AMP to dissociate actomyosin and to improve meat tenderness. The objectives of this study were to evaluate the effect of AMP on duck meat tenderness and other quality traits and to explore the mechanism of the action of AMP on meat tenderness.

RESULTS

Duck breast muscle was treated with 0, 10, 20, 30, 40 mmol L(-1) AMP at 5 °C for 10 h and examined for shear force, microstructure, actomyosin dissociation, myofibril fragmentation index (MFI), pH, water content, cooking loss, CIE* color (L*, a*, b*), inosine monophosphate (IMP) and free amino acid (FAA) contents. Results showed that shear force, cooking loss, L* and b* of the muscles significantly decreased after AMP treatment (P < 0.05); actomyosin dissociation, MFI, pH, water content, fiber diameter, sarcomere length, IMP and ammonia significantly increased (P < 0.05); no significant change in a* or other FAA content was observed (P > 0.05), and muscle shrinkage in transverse and longitudinal directions were restrained after AMP treatment.

CONCLUSION

The results suggest that AMP could notably improve meat tenderness, and this effect was probably mainly through increasing muscle pH, promoting actomyosin dissociation and disrupting the Z-line; meanwhile, the conversion of AMP to IMP may contribute to the flavor of meat.

Optimization of the Tenderization of Duck Breast Meat by Adenosine 5'-Monophosphate (AMP) using Response Surface Methodology

This study aimed to characterize and optimize the tenderization condition of duck breast meat by adenosine 5'-monophosphate (AMP), with the aid of response surface methodology (RSM). The results showed that the optimal conditions for the tenderization of duck breast meat were at the NaCl concentration of 3.99 g/100 g, AMP concentration of 13.83 mmol/L, temperature of 15.32°C, and marinating time of 8 h. Compared with control duck breast meat, AMP combined with NaCl treatment demonstrated significant effects on improvement of meat tenderness and decrease of cooking loss. Such effects might be ascribed to the combination of a series of biochemical reactions, e.g. increase of muscle pH, dissociation of actomyosin and inhibition of meat shrinkage. Therefore, the mixture of AMP and NaCl could be regarded as an effective tenderization agent for duck breast meat.