Study On Thermal Field Drying Processing Technology Of Traditional Roast Duck

Roast duck is a typical example of Chinese roast meat with a long history and great reputation all over the world. Traditional roast duck is divided into two types, namely, Gua Lu roast duck and Men LU roast duck, which are featured with bright ruddy color but not greasy texture after roasting by the fruit tree charcoal fire. However, hazardous substances, like PAHs, HCAs, etc., can be generated during the course of processing under high temperature. Meanwhile, apart from the residues in meat, these harmful substances are also absorbed by the fine particles in flue gas which will be emitted into the atmosphere. This study aimed to develop a thermal field drying processing method that enhances safety while detains the attractive color, pleasant flavor and delicious taste of traditional roast duck.Detailed research contents and results are summarized as follows:1 Research on the emission of PM2.5 in traditional roast duck fumes and heterocyclic amine, benzo(a)pyrene in traditional roast duckUsing vacuum-packed "Beijing roast duck" bought in Beijing market and roast duck produced by gas oven as the research samples, the contents of 12 kinds of heterocyclic amine in duck skin were detected by HPLC, while benzo(a)pyrene by UPLC. Flue gas was collected during the roast process with the concentration of airborne particulate matters detected afterwards. Results showed that the skin of "Peking Roast Duck" had the highest amount of benzo(a)pyrene at 4.25μg/kg, lower than the national standard of 5μg/kg and exceeding Germany standard of 1μg/kg; higher amount of 12 kinds of heterocyclic amine was detected in roasted duck made by gas oven, which was up to 49.95p.g/kg; average concentration of airborne particulate matters was 2020μg/m3, by gas oven,25.9 times higher than national air quality standard.2 Optimization of Maillard reaction conditions and processing technique for roast duckMaillard reaction on roast duck skin surface was explored by determination of surface temperature, surface water activity and the internal temperature during processing with a chart regarding temperature and water activity drawn to find out the most suitable conditions for roast duck drying processing technology, epidermal water activity between 0.955-0.965 duck surface temperature at 80-100℃ was the appropriate conditions. Using cherry valley duck as raw material and Zengxiangye as technical support, the optimal processing technology with the processing temperature of less than 120℃ was determined through orthogonal test, which is in line with the principles of the chart mentioned above. Quality analysis, like color and texture, was conducted on green manufactured roast duck after high-temperature sterilization. As for color, the red value was 12.16, with L*,a*,b* of 44.22,12.16,25.67, respectively; for texture, hardness value was 1658.98 g and the shearing force was 19.14N. Quality analysis was also conducted on three traditional roast duck, with a of 9.76,12.96,13.33, hardness value of 508.49g,659.19g,896.21g, shearing force of 7.90 N,8.36 N,11.09N, respectively. It is evident that there was no significant difference between the colors of traditional and drying processing roast duck, while the texture of drying processing roast duck was significantly superior to traditional roast duck.3 Research on determination of heterocyclic amine, benzo(a)pyrene in thermal field drying processing roast duck and volatile compoundsEvaluation of drying processing roast duck was conducted by testing the contents of 12 kinds of heterocyclic amines and benzo(a)pyrene as well as collecting the flue gas for airborne particulate matters under the optimized processing condition. Results showed that roast duck using drying processing technology had brighter color and better texture after high-temperature sterilization, with a significantly decreased mean level of airborne particulate matters of 156.67μg/m3. The residual amount of benz(a)pyrene was not detected, and the total amount of 12 kinds heterocyclic aromatic amine residues was a small percentage of traditional roast duck. Volatile compounds analysis showed that aldehydes were the most main compounds of roast duck,4-methyl-5-hydroxyethyl thiazole were the main compounds of drying processing technology roast duck, while that of traditional roast duck are characterized by pyrazines and furans.