| As a kind of coarse grain with the same origin as medicine and food,mung bean has high nutritional and medicinal value and has a long history of consumption in China.However,the amount of mung bean added to mung bean noodles on the market is low,and the overall nutritional enhancement effect of mung bean noodles is not obvious.Moreover,when mung bean is added to the product,due to the existence of its highly active oxidase,the product is prone to oxidative rancidity in the storage process,resulting in the loss of nutrients and the generation of toxic and harmful substances and undesirable flavor.Based on the above two problems,this study firstly compared the effects of two heat treatment methods(boiling and superheated steam)on the oxidase activity and physicochemical properties of mung beans;secondly,it investigated the effects of different mung bean flour(untreated and heat treated)additions on the quality of mung bean-wheat dough,determined the amount of mung bean flour added,and improved the edible quality of mung bean dried noodles by adding different proportions of gluten flour,and determined the amount of gluten flour added;Finally,to investigate the role of heat treatment of mung beans on the regulation of physicochemical properties,lipid storage stability and flavour during storage of mung bean hanging noodles.(1)In this study,mung beans were treated with boiling and superheated steam to determine the changes in basic physicochemical parameters,lipoxygenase(LOX)and peroxidase(POD)activities,total phenol and total flavonoid contents,pasting characteristics and functional properties.The results showed that the LOX activity was reduced by 98.13%and POD was not detected when the mung beans were treated with the boiling method for 80 s.Superheated steam treatment had little effect on enzyme activity of LOX and POD in mung bean.Both heat treatments had essentially no effect on the total phenolic content,while the total flavonoid content decreased slightly.After boiling,the pasting temperature,peak time,final viscosity and regeneration value of mung beans decreased and the disintegration value increased,resulting in significant changes in pasting characteristics(P<0.05),while no significant changes in pasting characteristics were observed after superheated steam treatment.The water absorption index,water solubility index and water and oil holding capacity of mung beans increased after boiling treatment;The water absorption index and water holding capacity did not change significantly after superheated steam treatment,while the water solubility index and oil holding capacity were significantly increased(P<0.05).In summary,mung beans treated in the boiling mode for 80 s gave the best results.(2)The effects of the addition of mung bean flour(untreated and boiled)on the mixing characteristics,tensile properties,protein secondary structure,moisture pattern,microstructure and noodle making results of mung bean-wheat dough were investigated separately.The results showed that the addition of both mung bean flours led to a significant decrease(P<0.05)in the peak midline height,peak midline time,peak midline integrated area,8 min bandwidth,dough pull-off force and pull-off distance of the mixes;a significant decrease(P<0.05)in theβ-fold,α-helical,disulfide and hydrogen bond contents,a significant increase(P<0.05)in the irregular curl,β-turn and sulfhydryl content of the dough proteins,and a significant decrease(P<0.05)in the hydrophobic The addition of mung bean flour led to the conversion of bound water to free water in the mung bean-wheat dough and increased water mobility;Microstructural observations also revealed that the addition of excess mung bean flour led to uneven distribution of starch and gluten protein in the dough and a significant decrease in the yield of the noodles(P<0.05).The addition of mung bean flour resulted in poorer dough quality,and the untreated group showed a more pronounced decrease in quality for the same amount of mung bean flour added.Finally,a 30%addition of mung bean flour was chosen to optimise the product by adding gluten.It was found that at 9%gluten addition,the sensory score and bending strength of the dried noodles reached their maximum,and their hardness,elasticity and chewiness were significantly higher after boiling(P<0.05),and the breaking distance and bending work were significantly higher(P<0.05).Similarly,all of the above indicators were better in the boiled treated group than in the untreated group.In summary,30%mung bean flour and 9%gluten flour additions were chosen to make the dried noodles for subsequent experiments.(3)The changes in LOX and POD activity,total phenol and total flavonoid content,lipid oxidation,colour,texture and sensory quality of the blank,untreated and cooked mung bean noodles during storage were investigated.The results showed that with the increase of storage time,the LOX enzyme activity of the blank noodles decreased,the POD activity increased and then decreased,while the LOX and POD activities of both mung bean noodles decreased;the total phenolic content of both mung bean noodles decreased significantly(P<0.05),the total flavonoid content of the blank noodles increased and then decreased,while the total flavonoid content of both mung bean noodles increased significantly(P<0.05);the acid value,peroxide value,malondialdehyde concentration and fatty acid value of the three noodles all decreased significantly(P<0.05),Acid value,peroxide value,malondialdehyde concentration and fatty acid value of all three noodles increased significantly(P<0.05),while acid value,peroxide value,malondialdehyde concentration and fatty acid value of untreated mung bean noodles increased 2.98,1.61,1.38 and 1.29 times more than those of blank noodles and 1.27,1.09,1.21 and 1.28 times more than those of boiled treated mung bean noodles after 8 weeks of accelerated storage.The L~*and b~*values of all three types of noodles decreased significantly(P<0.05),the brightness value decreased,the color of the noodles became darker,and the a~*value increased,and the L~*value of the untreated mung bean noodles decreased more significantly than that of the boiled treatment;the hardness,elasticity and chewiness of all three types of noodles decreased significantly after boiling,and the adhesion increased,and the elasticity,chewiness and reversibility of the boiled treated mung bean noodles decreased more slowly than that of the untreated mung bean noodles;the bending strength and breaking distance of all three types of noodles decreased significantly,and the untreated mung bean noodles decreased significantly.The bending strength and breaking distance of the three kinds of noodles decreased obviously.Compared with the other two kinds of noodles,the bending characteristics of the untreated mung bean noodles decreased more obviously.In conclusion,it was concluded that the boiling treatment of mung beans had an inhibitory effect on the lipid oxidation and quality deterioration of mung bean noodles.(4)The changes in flavour composition and relative content of blank,untreated and cooked mung bean noodles during storage were investigated.Compared with blank noodles,mung bean noodles,especially untreated mung bean noodles,had a faster bad smell and richer flavor substances.In the storage process of the three kinds of noodles,aldehydes were reduced,alcohols were increased,and acids were first increased and then decreased.The main aroma components of mung bean dried noodles with OAV≥1 were less,and the main aroma components of untreated and boiling mung bean dried noodles were significantly different,with hexanol,1-octen-3-ol and 2-pentylfuran as the main flavour substances being lower than those of untreated mung bean dried noodles.In conclusion,it was concluded that the boiling treatment of mung beans had improved the flavour deterioration of mung bean noodles during storage. |
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