Change of Peptides and Free Amino Acids Contents during Nanjing Dry-Cured Duck Processing
Abstract
In order to explore the relationship between the change of peptides and free-amino acid (FAA) and its unique flavour, Dry-cured duck samples of different processing phases were used to study the change of free-amino acid by High Performance Liquid Chromatography (HPLC) in this paper, meanwhile the trichloroacetic acid precipitation method for modeling use to establish the quantitative predicated peptides. The changes of small peptides and free amino acids in the process were studied. The results showed that the level and amount of proteolysis increased with the processing time at traditional technology, meanwhile the amount of peptides were positively correlated with FAA contents (R2=0.86).
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Introduction
Special flavor of cured meat product depended on special processing technology of different countries and regions, Monica Flores [1] and other scientists studied the flavor and sensory descriptions of correlation of Serrano ham of amino acids, peptides etc by HPLC and capillary electrophoresis and sensory analysis method. the flavor material with proportional combination could produce special dry pickled flavor characteristics. Ya-jun zhang etc[2] studied the relationship between protein degradation products and ham quality in jinhua ham. The analysis showed that the essential amino acid composition of proteins in jinhua ham made were more consistent with recommendation model and produced a large number of low molecular weight proteins and peptides after processing. The Nanjing dry-cured duck was a kind of traditional Chinese meat product, which was popular with consumers. However, the study on the mechanism of protein degradation in the processing of protein has not been reported.
Based on the different stages of processing in Nanjing dry-cured duck as the research object, the change of small peptides and free amino acid were determined during product process by HPLC, which provided theoretical basis for the modern control technology for Nanjing dry-cured duck.
Conclusion
During the different stages of processing in nanjing dry-cured duck, the content of small peptides showed a significant increase (P <0.05) at the beginning stage, then decreased in the dry pickled stage and finally increased and stabilized. By using HPLC analysis of the free amino acids, in addition to arginine, threonine, cysteine little be changed, the other kind of free amino acids concentration with the processing time had different degrees of increase, which was a flavor of glutamic amino acid could be risen highest. From the total amount of change, the free amino acid from the beginning of the raw materials to dry 5d could be continuously increased, and then could be slightly declined.