全麦粉对油炸面制食品脂肪含量的调控及其作用机制

Deep-frying is one of the food preparing methods, which is widely used to produce snack and instant foods. However, the fried foods have a relative high amount of oil content. For example, the average oil content of Sachima is 30-40%, which was higher than that of instant fried noodles (15-20%). It is well known that taking foods with high oil content are always associated with obesity, cancers and angiocardiopathy. Today consumers are much more concerned about health issues thus leading to a demand for lower fat foods. Lots of researches had been done to produce low oil content fried foods. These researches were focus on the modifying the frying process, coating in the material surface, and adding extra ingredients. Few researches had been reported about the effects of basic ingredients on the oil content. In our previous reports, we found that the oil content of fried Sachima sticks was reduced by 24.5%, when 75% refined wheat flour in the basic recipe for Sachima dry mix was replaced by whole wheat flour (WWF). However, the effects of WWF on oil content are still not clearly understood. In this research, the two traditional snack, Sachima and You-tiao, were taken as the study object. The effects of WWF on the oil content were investigated based on the previous studies. First, the effect of WWF on the dough properties was studied. The macroscopic, structural, and molecular changes of WWF components during deep-frying were further investigated, as well as the regularity and correlation between these changes and frying kinetics. The method for reducing oil content of traditional snack was established based on realizing the regulation mechanism, which would provide the theory basis and scientific guideline for the producing low-oil content healthy foods.

油炸食品的脂肪含量普遍较高，长期摄入会对人体健康造成威胁。目前已有较多降低油炸食品脂肪含量的相关研究，但还未见从油炸原料本身进行研究的报道。研究发现，当沙琪玛配料中75%的精制面粉被全麦粉替代时，其脂肪含量下降24.5%。谷物是油炸小吃/点心中最主要的原料，本项目以油条和沙琪玛为研究对象，用全麦粉替换其中的精制面粉，分析全麦粉对面团特性的影响；在揭示全麦粉中各组分在油炸过程中变化规律的基础上，阐述其对物料微观结构的影响；通过研究不同油炸阶段油脂吸收-水分蒸发之间关联度的变化，探讨全谷物对油炸工艺的影响；从组分的自身变化、对物料结构影响、对水分蒸发-脂肪吸收平衡度的影响等多个层次的分析，从定性/定量、宏观/微观等多个角度，找出全麦粉调节最终产品中脂肪含量的拐点；根据油炸过程中水分蒸发和油脂吸收的机理，研究油脂吸入的方法途径和条件，建立可能的调控机制，为生产健康低脂食品提供理论依据与科学指导。

项目以沙琪玛、油条和油炸方便面为研究对象，用全麦粉替换配方中的精制面粉，研究了全麦粉对面团特性及最终产品品质的影响，优化了三种全麦产品工艺；进而探讨了油炸过程中油脂吸收-水分蒸发之间的动态关系，初步明确了影响油炸食品含油率的作用机理。结果表明：全麦粉显著改善沙琪玛、油条和油炸方便面原料粉面团的粉质拉伸性质。全麦粉显著影响蛋白网络结构形成和淀粉糊化过程，改变产品的内外组织结构，也降低了沙琪玛、油条的含油率；沙琪玛总含油率在全麦粉替代率为75%时降低了24.48%；全麦粉替代率为100%时，油条的总含油量降低了42.60%。油炸动力学研究结果发现：油炸过程中水分蒸发与油脂吸收处于动态平衡状态，但全麦油炸食品的结构含油率和含水率的传质动力学系数均随着全麦粉取代率的增加而降低；低场核磁结果显示，全麦粉增加了沙琪玛中底物与水分的结合度而减少了底物与油脂的结合度。从整体结果分析得出，全麦粉一方面通过降低面团比容和改善内部结构来抑制脂肪吸收，另一方面，通过提高面团持水性来抑制水分蒸发和脂肪吸收。全麦粉粒径以及其中丰富的阿拉伯木聚糖显著影响最终产品的脂肪含量，深入开展相关研究可为健康油炸食品提供理论依据和技术支持。