| The traditional processing technology of Cantonese Roast Duck (CRD) is barely up to meet the needs for the development of industrialization. In this context, the comparative study on flavor characteristics between traditional-charcoal and modern-electric roasted CRD is necessary; so was the tracking of flavor volatiles in CRD during the roasting procedure. Both the researches help in improving the flavor quality of industrial products of CRD, and in establishing the evaluation systems.Hereon, extracting methods of flavor volatiles were optimized in this paper, and then combined with GC/MS to conduct the qualitative and quantitative analysis on volatile flavor components in CRD during roasting. Emphases were put on the odor-active components (OACs) by odor activity value (OAV) calculation, along with principle component analysis (PCA). Flavor differences between charcoal roasted and electric roasted CRD were also evaluated by comparison of their OAC composition. The main results were listed as follows:1. Two-step of simultaneous distillation-extraction (SDE) was employed, with diethyl ether and methylene dichloride as the solvents, extracting for30min each. Fiber of75μm CAR/PDMS was selected in headspace solid-phase microextraction (HS-SPME), and the duck sample, mixing with6mL internal standard/saturated sodium chloride, was extracted under55℃by a magnetic stirring for60min. The RSDs of total content of flavor volatiles by the above two extracting methods turned out to be7.15%and8.95%.2. The most abundant components in traditional charcoal roasted CRD were hydrocarbons, followed by aldehydes, nitrogen-and sulfur-containing heterocyclics. Total content of flavor volatiles in charcoal roasted duck meet (CM) and skin (CS) have respectively reached58.52μ-g·g-1and72.88μg·g-1. While the proportions of hydrocarbons and aldoketones varied significantly. There were three principle components acquired separately from SDE and SPME data, consisting of48OACs, here the first principle components can effectively distinguish the OAC composition of CM from CS.3. In the roasting process of charcoal roasted CRD, the total content of flavor volatiles in CM increased from16.47μg·g-1to61.66μg·g-1, which increased from21.51μg·g-1to79.75μg·g-1in CS instead. The proportion of olefines decreased progressively, however, the nitrogen-and sulfur-containing heterocyclics were the opposite. Alcohols, acids and aldoketones, in large part, generated in I stage and got the highest content in II or III stage. But most of the nitrogen-and sulfur-containing heterocyclics and furans generated in II stage and got the highest content inIIIstage. Odor activities of most compound classes in CM were stronger than that in CS, which reached a higher level of odor activity after I and II, separately.4. The constituents of flavor volatiles in charcoal roasted (CM&CS) and electric roasted duck (EM&ES) were similiar. But as for total content, CM was9.66%-17.28%higher than EM, and CS was30.24%-40.13%higher than ES. Odor activities of most of the53OACs in charcoal roasted samples were stronger than that in electric roasted samples. PCA showed a high level of similarity between CM and EM in SDE data, while the difference between CS and ES in SPME data was also small.According to the experiment results and theoretical analysis, the far-infrared technology is an ideal alternative of traditional processing method. Though the special flavor of charcoal roasted CRD is basically reserved, the flavor quality waits for further enhancement. |
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