不同热处理方式对小麦粉特性及其蒸饼品质的影响

目前蒸饼的制作大多采用传统的半烫面工艺，工序较为复杂，为解决这一问题，该研究采用不同热处理方式（蒸汽处理、微波处理、干热处理）对小麦粉进行热处理，研究了不同处理方式对小麦粉的糊化特性、热机械学特性、微观结构等的影响，并将处理后的小麦粉添加到未处理的小麦粉中制成蒸饼，考察了所制得的蒸饼的水分分布、质构特性及感官品质。结果表明：3种热处理的适当处理时间都可以提高小麦粉的黏度和回生值；经干热处理和微波处理后的小麦粉的破损淀粉含量高于经蒸汽处理的小麦粉。3种热处理小麦粉的添加均可以提高面团的吸水率，蒸汽处理小麦粉的添加使面团耐揉性降低、蒸煮稳定性提高，微波和干热处理小麦粉的添加使面团的耐揉性和内部结构稳定性提高。适当处理时间的热处理小麦粉的添加可以提高蒸饼的结合水含量、硬度、弹性和咀嚼性等。其中，经蒸汽处理40 min、微波处理2 min和干热处理30 min后的小麦粉的添加制得的蒸饼有相对适中的强韧性、较高的结合水含量和感官评分。该研究结果表明添加热处理后的小麦粉代替传统的烫面工艺制作高品质蒸饼具有可行性，同时能够为蒸饼的工业化生产提供相应的基础数据和一定的理论指导。

Effects of different heat treatments on the quality of wheat flour and its steamed cakes

Steamed cakes can usually adopt as the traditional hot water dough. Among them, the boiled water and wheat flour are required to be fully mixed instantaneously for the uniform and stable quality of dough. The complex procedure has seriously hindered the large-scale production of steamed cake. It is particularly necessary to explore the suitable treatment for the industrial production of steamed cake. In this study, the steam, microwave and dry heat treatments were used to treat the wheat flour. A systematic investigation was implemented to explore the effects of different treatments on the gelatinization, thermal mechanical properties, and microstructure indicators of wheat flour. The processed wheat flour was also added into the untreated to make the steamed cake. The water distribution, texture and sensory quality of steamed cakes were investigated . The results indicated that three heat treatments caused the different degrees of binding between protein and starch in wheat flour, where free damaged starch was observed. The damaged starch content of wheat flour increased significantly (P<0.05) after microwave and dry heat treatments, compared with the untreated. Besides, the appropriate treatment time of three heat treatments improved the peak viscosity, through viscosity, final viscosity and retrogradation of wheat flour (P<0.05). The increase of peak viscosity indicated that the thermal stability of starch was enhanced in the wheat flour. The increase of retrogradation value means that the gel stability of wheat flour was enhanced. In terms of thermomechanical properties, the three types of heat-treated wheat flour were improved the water absorption and starch gelatinization in the mixed flour doughs (P<0.05); The steam treated wheat flour was reduced the kneading resistance of dough but improved the cooking stability (P<0.05); The microwave- and dry heat-treated wheat flour also increased the kneading resistance and stability of the internal structure in the mixed dough (P<0.05). The addition of three heat-treated wheat flour was significantly promoted the bound water content of steamed cakes, while also improving their hardness, elasticity, and chewiness P< 0.05). However, the addition of wheat flour with different heat treatments also shared the different effects on the firmness of steamed cakes. Especially, the firmness of steamed cakes made of wheat flour treated with steam was significantly reduced (P<0.05). The suitable treatment time was then screened out in each heat treatment, particularly for the high quality of steamed cake. An optimal combination of wheat flour treatment with 40-min steam, 2-min microwave and 30-min dry heat was achieved in the relatively moderate strength and toughness, high bound water content and sensory scores. It was feasible to produce the steamed cake with the high quality. The steamed cake was then prepared to add the heat-treated wheat flour, instead of the traditional hot water dough. The finding can also provide the basic data and theoretical foundation for the industrial production of steamed cake. The processing parameters can be adjusted in actual production, according to the product requirements. In addition to steamed cake, the heat-treated wheat flour can be expected to realize the industrial production of staple food products that made of hot water dough in future.