液氮冷媒介质对速冻饺子冻裂率的影响

Effect of liquid nitrogen frozen on dumpling frost crack rate

研究饺子新型冻结技术,探索液氮速冻工艺对调理食品品质的作用规律。该文以饺子为研究对象,和面水面质量比、皮馅质量比、面粉品质、馅料配比、产品规格、冻结时间、冻结方式、冻结介质等诸多因素对饺子冻裂率都有重要影响。该试验以猪肉、香菇、大豆组织蛋白为饺子馅主要原料,研究了和面时的水面质量比、面团的静置时间、皮馅比、饺子在液氮池中的沉浸时间对饺子冻裂率的影响。结果表明:以上四因素对饺子的冻裂率都有不同程度的影响。和面水面质量比为56∶100、面团静置时间在10 min、皮馅质量比在1∶1.3、液氮池沉浸时间为40 s,制作好的饺子在立即速冻后的冻裂率为37%,感官评定得分为77.6。该研究为液氮沉浸速冻工艺在调理食品的应用提供了一定的理论参考。

In order to improve the quality of dumplings and explore the role of liquid nitrogen on regulating food quality, an experiment was conducted with dumplings as the research object, which was made of dough, meat and stuffing water. However, there were some differences in the water content, enthalpy and freezing rate in each component, therefore, and the dumpling-cracking rate itself was a complex manifestation, which in the meantime could also be affected by the quality of flour, ratio of raw materials and specifications etc. This study was aimed at understanding how the amount of water when kneading dough, the incubation time of the finished dough, the dumpling wrapper and meat stuffing ratio and the immersion time of dumplings in liquid nitrogen pool affected the cracking rate of the dumplings, which took pork, mushrooms and soy protein as the main raw material of dumpling stuffing. The result showed that the water amount of the flour had great influence on the gluten network formation of dumpling wrapper and dough processing characteristics. The dumplings from the same batch in the process of quick freezing tunnel method had far lower cracking rate than the liquid nitrogen freezing technology. Compared with freeze tunnel, being frozen in liquid nitrogen would have shorter freezing time and faster shaping time. Regardless of the water amount in dough, according to the water distillation principle, outer layer of wrapper would appear to be white powder layer, and the dumpling wrapper whiteness improved significantly （P〈0.05） when frozen in liquid nitrogen （fresh 83; frozen 85; liquid nitrogen 88）. Liquid nitrogen freezing method for food preservation and quality improvement is better than quick freezing tunnel method. Through the construction of the relationship between dough sensory and texture characteristics, the dough elasticity in industrial production could be expressed by texture determination, rather than relying on the subjective factors from experienced workers. Also in order to reduce or eliminate the dumpling-cracking rate, it could not only control the selection of the flour, the water addition and the dumpling wrapper and meat-stuffing ratio etc., but also control the selection of additives （single and combined）. Through market research, with the increase in air separation plants, liquid nitrogen production cost had been slashed, and the use of liquid nitrogen in the industrialized production of food would have good prospects. The result showed that there were some effects at different degree on dumpling cracking rate for the 4 factors above. The dumplings would have relatively low cracking rate （37%） and high quality （77.6） under mass ratio of water and flour was 56：100, less than 10 min incubation time of finished dough, 1：1.3 weight ratio of dumpling wrapper and meat stuffing and immersing in nitrogen pool for 40 s immediately after the dumplings were done. The study provides a theoretical reference for the application of liquid nitrogen on food process.