Study On Preparation Process Of Quick-frozen Pulled Noodles

The frozen cooked noodles were highly appreciated by consumers because of the convenience and good mouthfeel. In this paper, quick-frozen cooked pulled-noodles were made by extrusion and frozen equipment. The key process parameters such as amount of water, standing time, washing water temperature, freezing temperature and freezing time were researched on the noodles’ cooking quality and texture properties. On this basis, the effects of different kinds of food additives(edible alkali, edible gum, enzymes, emulsifiers, modified starch, gluten) on the quality of frozen pulled-noodles were analyzed, and the modifiers which could remarkably improve the quality of frozen pulled-noodles were selected. The impacts of storage conditions(frozen storage time, frozen thaw cycles) on quality of noodles were further studied. Changes of freezable water content and ultrastructural of the pulled-noodles before and after improving were compared to propose quality improvement mechanism. The results are as follows:Amount of water, water temperature, mixing time, holding time and sheeting times in dough-mixing process could significantly affect the texture properties and cooking quality of frozen pulled-noodles. The optimum amount of water to make quick-frozen noodles was 45%, suitable water temperature was 30℃, and the mixing time was 3min. Moreover, suitable sheeting times were 2, and the best holding time was 30 min.The wash water temperature of pulled-noodles before freezing was 8℃; Appropriate frozen temperature was-40℃; and under this temperature, the quality of frozen pulled-noodles was better when the final temperature was-18℃.The better modifiers to improve the quality of quick-frozen pulled-noodles were xanthan gum, guar gum, TG enzyme and gluten, and their optimum addition amount respective was 0.4%, 0.4%, 0.4% and 5%. Xanthan gum, guar gum and gluten mainly improved the hardness and tensile properties of quick-frozen pulled-noodles. The every indicator of quick-frozen pulled-noodles with the amount of 0.4%TG enzyme was better. And the sensory quality was significantly better than the control group.Compared with the control group, the internal network structure of quick-frozen pulled-noodles adding xanthan gum, guar gum, TG enzyme or gluten was more compact and the distribution of ice crystals was more uniform. And compared with the control group, the freezable water content of these products respectively was reduced 8.51%, 4.64%, 4.64% and 8.58%.With the extension of frozen storage time, the hardness and tensile distance of control group and pulled-noodles adding gluten had a larger degree of decline, and the cooking loss rate increased remarkably. After 30 d, the internal network structure of these two groups became loose, and larger voids were emergenced at the same time. With the growth in frozen storage time, the declined indicators of frozen pulled-noodles adding the xanthan gum, guar gum or TG enzyme were also concentrated in hardness, tensile strength and tensile distance. Compared with the control group, the cooking quality of quick-frozen pulled-noodles adding these three improvers was decreased significantly. The microstructure of these three groups after 30 d had a less severe damage and the structure was relatively compact.The freeze-thaw cycles mainly affected the hardness and cooking loss of quick-frozen pulled-noodles. With the increase in the times of freeze-thaw cycles, the hardness showed a decreasing trend and the cooking loss rate was increased whether it was in the control group or frozen pulled-noodles while modifiers were added. From the microscopic structure, the internal structure of the control group became loose and had the largest holes after three freeze-thaw cycles. When xanthan gum or guar gum was added, the structure of the quick-frozen pulled-noodles was better. The internal hole of the pulled-frozen noodles adding TG enzyme or gluten was relatively uniform. The effect of freeze-thaw resistance of TG enzyme and gluten on frozen noodles was better than that of xanthan gum and guar gum.