Flavor And Quality Grade Evaluation Of Three Main Dry-cured Hams In China By Multiple Fingerprints Technology

Dry-cured Ham is a kind of meat product made from back leg of pigs,after a sequential processing of curing, drying and fermenting. Jinhua ham is the most famous dry cured hams in our country, while xuanwei ham, rugao ham, anfu ham, xianning ham and enshi ham also belong to the local traditional pork products. Flavor is a key index of the quality of dry-cured ham that consisits of the taste and aroma. Fingerprint technique is the overall information of contour analysis technology that is associated with the development of modern analysis techniques. Generally speaking, fingerprint technology include spectrum technology(near infrared spectrum, infrared spectrum and nuclear magnetic resonance spectra), chromatography(gas chromatography, liquid chromatography) and bionic technology(such as electronic nose and electronic tongue), to provide more technical means for meat quality evaluation.The article evaluate flavor and quality of dry cured ham with different grades and years by fingerprints technology, which include fourier transform infrared spectroscopy(FT-IR), olfactometric fingerprint and tasteable fingerprint. The results are as follows:(1) The microwave assisted extraction followed by solvent assisted flavor evaporation(MAE-SAFE) was used to extract the volatiles from Chinese hams(jinhua ham, xuanwei ham and rugao ham). Extracts were analyzed by a comprehensive two-dimensional gas chromatography/high resolution-time of flight mass spectrometry(GC×GC/HR-TOFMS) and GC-MS. 163 compounds were identified by GC×GC/HR-TOFMS with an aid of the NIST08 library and accurate mass determination, and only 50 compounds were identified by GC-MS with the NIST08 library and retention index(RI). Among rhe identified compounds, decanal, pentadecanal, hexadecanal, 2-methyl-butyric acid, undecane and 2,6,10,14-tetramethyl pentadecane were not detected by GC×GC/HR-TOFMS but by GC-MS. But, the application of GC×GC/HR-TOFMS to detect volatiles in dry cured ham was successful. Because of its high resolution and power to conduct an accurate mass determination, the qualitative analysis of flavors has become more reliable and credible, and will facilitate the identification of other volatile compounds present in trace amounts. In the research, there were 169 compounds identified in total including aldehydes(21), ketones(12), nitrogen containing, sulfur-containing compounds(38), alcohols(34), acids(29), esters(15), phenol(5) and hydrocarbons(15). Many of the compounds were common to all dry cured hams, although unique volatile components to specific samples were also observed. The results represent the most detailed characterization of volatile constituents of Chinese hams reported to date.(2) E-nose, E-tongue and sensory evaluation were used to evaluate the aroma, taste profiles and flavor of jinua, xuanwei and rugao ham. PCA and SIMCA method were used to discuss the feasibility that E-nose can distinguish the different area, grade and years of ham. The experimental results show that, there exist certain differences in flavor, aroma and taste profiles among different hams. There are large differences between 1 year ham and other hams.The super jinhua ham has similar smell with guranteed jinhua ham, 2 years and 3 years of ham, resulting in different degrees of miscalculation in the SIMCA model.In the sensory evaluation experiments, the result of quantitative descriptive analysis showed that all the nine kinds of hams have obvious meaty, strong fatty, cured odor, and weaker sour and faint scent.(3) The hams had similar IR macro-fingerprints especially for the absorption bands of amide groups. Compared to X3 and R3, however, JT had a strong characteristic peak of lipids at 1745 cm-1, indicating that JT had the highest content of lipids. SD-IR spectra of the hams enhanced the spectral resolution and amplified the small differences, especially, suggesting that the hams had different profiles of lipids and proteins. Moreover, evident differences were observed in 2DCOS-IR spectra. In a word, it was demonstrated that the tri-step infrared spectroscopy could be applicable for discrimination of dry cured ham in a direct, rapid and holistic manner.