Study On Quality Improvement Of Whole Wheat Dried Noodles

Whole wheat noodles are more and more popular because of their rich nutrition and convenient storage.However,the high content of dietary fiber leads to poor taste and poor texture quality of whole wheat noodles.Moreover,lipase and peroxidase will affect the storage stability of whole wheat flour.This paper firstly selects the appropriate bran stabilization process and bran particle size,then improves the quality of whole wheat noodles through the ultrasonic assisted resting process and the addition of xylanase,finally optimizes drying methods to further improve the quality of whole wheat noodles.Firstly,the effects of four stabilization method(microwave,NaCl assisted microwave treatment,infrared and NaCl assisted infrared treatment)on the bran's enzyme inactivation and bran fatty acid value were studied.The results show that the addition of NaCl has a certain synergistic effect on the enzyme activation effect of heat treatment.The four stabilization methods significantly reduced the fatty acid value of bran(p<0.05).Among them,the fatty acid value of bran treated with infrared and NaCl was significantly lower than that of infrared treatment group(p<0.05),which was reduced by 16.85%.Secondly,the effects of different particle size bran on the water distribution of whole wheat dough sheets,qualities and microstructure of whole-wheat noodles were studied.The Low field nuclear magnetic resonance(LF-NMR)results showed that as the bran particle size decreased,the content of strongly bound water decreased,the content of weakly bound water increased,and the content of free water decreased first and then increased.Moreover,the reduction of bran particle sizes could decrease the cooking loss of the noodles,increase the hardness,springiness,chewiness and tensile properties,and improve the sensory quality.The results of SEM and CLSM showed that the decrease in bran particle size could make the microstructure of whole wheat noodles more complete,and the starch was better encapsulated in the gluten network.In addition,the effect of ultrasonic assisted resting on the structure of whole wheat dough sheets and the quality of whole wheat noodles was studied.The results show that with the increase of resting time,the breaking force and extensibility of whole wheat dough sheets gradually increase.When the conventional resting time is 30 min,the breaking force and extensibility of whole wheat dough sheets reached the best,and the dough sheets under ultrasonic assisted resting reached the maximum value after 10 min,which shortens the resting time.The results of moisture distribution showed that ultrasonic resting accelerated the transition from strongly bound water to weakly bound water,and promoted faster and even distribution of moisture in the dough sheets.The GMP content increased during resting and the-SH content decreased.Ultrasound assisted resting accelerated the oxidation of free sulfhydryl groups.The breaking distance of whole wheat noodles at 10 minutes of ultrasonic treatment was significantly larger than that at 30 minutes of normal resting(p<0.05).There was no significant difference in the breaking force,hardness and chewiness of whole wheat noodles at 10 minutes of ultrasonic treatment compared with that at 30 minutes of normal resting(p<0.05).Moreover,the effect of xylanase on the quality of whole wheat noodles was studied.The addition of 0.02% xylanase significantly reduced the cooking loss and increased the hardness and chewiness of whole wheat noodles(p<0.05).The addition of xylanase increased the G'and G''of whole wheat dough,and reduced the disintegration value of flour.SEM results showed that the proper amount of xylanase could improve the continuity of noodle structure and the starch was better encapsulated in the gluten network.Finally,the drying characteristics of whole wheat noodles were studied,and the drying temperature and relative humidity of the three-stage drying zone were optimized to improve the quality of whole wheat noodles.The results show that the drying process of whole wheat noodles belongs to the reduced-speed drying section,and the three-stage drying method is suitable for whole wheat noodles.The temperature and humidity in different stages have different effects on the qualities of whole wheat noodles.The final reasonable drying parameters are: pre-drying: 30°C,85%,40 min;main drying: 60°C,65%,100 min;final drying: 30°C,50%,60 min.