| Pueraria lobata and adlay are food resources for both medicine and food promulgated by the Ministry of Health of China,and their nutritional value and medicinal value are extremely high.The resources of pueraria lobata and adlay in China are very rich,mainly fresh food and dried storage,with few deep-processed products and low added value.In order to improve the deep processing level of pueraria lobata and adlay,meet the demand of consumer market,and increase the variety of related products of pueraria lobata and adlay.Considering that noodles are one of our staple foods,but there are few high-value noodles in the current market,and pueraria lobata,adlay and wheat flour are complementary in nutrition,their combination can significantly improve the nutritional value of noodles.And pueraria lobata has high dietary fiber content,adlay contains high polysaccharide,and edible fungi are rich in various enzymes.If we can enzymatically hydrolyze pueraria lobata and adlay first,and then use edible fungi to ferment and convert it into small molecular substances that are easier to use,it can further enhance its nutritional value and give it a good flavor.Therefore,in this paper,adlay and pueraria lobata were used as combined raw materials for enzymatic hydrolysis.Then the nutrition and biological activity of pueraria lobata and adlay by different edible fungi were compared and analyzed,and the best edible fungus was selected to explore its effect on pueraria lobata and adlay.Finally,the fermentation solution of pueraria lobata and adlay was used instead of water as auxiliary material to prepare noodles with wheat flour.The texture,starch digestibility,antioxidant ability,biological activity and flavor of fermentation solution of pueraria lobata and adlay on noodles were also studied.A new type of high-value noodle prepared by fermenting pueraria lobata and adlay with edible fungus was obtained.The main conclusions are as follows:（1）The enzymatic hydrolysate of pueraria lobata and adlay fermented by Agrocybe aegerita,Pleurotus ostreatus,Coriolus versicolor,Ganoderma lucidum and Poria cocos was used to measure the contents ofγ-amino acid（GABA）,flavonoids,puerarin and sensory score.The results showed that the GABA content（49.36±2.14μg/m L）,flavonoid content（1.25±0.03 mg RE/m L）and puerarin content（78.77±1.14μg/m L）were the highest.To further explore the changes of physicochemical index and biological activity of Agrocybe aegerita to pueraria lobata and adlay during fermentation.The results showed that the fermentation of Agrocybe aegerita could significantly improve the nutritional value and biological activity of pueraria lobata and adlay.During the culture period of 0-7 days,the contents of total phenols,flavonoids,soluble protein,reducing sugar and crude polysaccharides reached the maximum on the 3rd or 4th day of fermentation,which were 242.86±8.38 mg GAE/100m L,140.67±4.14 mg RE/100m L,0.75±0.03 mg/m L,64.91±1.08 mg/m L and 9.67±0.12 mg/m L,respectively.Meanwhile,the antioxidant capacity and phenolic compounds of pueraria lobata and adlay fermented by Agrocybe aegerita also increased significantly.In addition,the content of coix,soluble peptide and GABA of pueraria lobata and adlay increased with the extension of fermentation time.On the 7th day,the content of GABA and soluble peptide were 62.41±0.59μg/m L and11.27±0.33 mg/m L,respectively,while the content of coix reached the highest value on the 5th day,which was 64.96%,209.61%and 32.7%higher than that of unfermented.During the whole fermentation process,the conversion of puerarin to aglycone in the fermentation solution of pueraria lobata and adlay slightly reduced the puerarin content from 79.57μg/m L to 72.87μg/m L.（2）On the basis of the previous chapter,it was selected that the fermentation solution of pueraria lobata and adlay fermented for 4 days had the highest nutritional value.This chapter explored the effects of 22%,32%,42%fermentation solution of pueraria lobata and adlay and 32%enzyme hydrolysate of pueraria lobata and adlay on noodle texture,starch digestion,noodle microstructure,noodle starch crystal short-range ordered structure,free sulfhydryl and disulfide bonds and protein secondary structure.The results showed that the addition of fermentation solution of pueraria lobata and adlay improved the hardness,adhesion and chewiness of noodles,but had no effect on noodle cohesion and elasticity.After adding fermentation solution of pueraria lobata and adlay,the content of noodle resistant starch increased from 3.20%to 4.71%,while the total starch content and rapid digestion starch content decreased from 75.94%to 67.84%and 41.39%to 28.85%,respectively.The predicted glycemic index（p GI）of noodles decreased from 83.42 to 71.17-64.55 by simulating the process of noodle starch digestion by starch hydrolysis kinetic model Cleav=∞(1--6)).The results of SEM,XRD and FTIR showed that 22%and 32%fermentation solution of pueraria lobata and adlay could promote the arrangement and aggregation of powder chain more easily,thus increasing the regularity of molecular aggregation and forming crystal structure,and the crystal region of noodle was intact.While the addition of 42%fermentation solution of pueraria lobata and adlay would lead to poor continuity of noodle network structure and rough noodle surface.It also showed that the fermentation solution of pueraria lobata and adlay could affect the aggregation and rearrangement of noodle gluten protein,and the ordered crystal structure of protein,polysaccharide and dietary fiber in the fermentation solution of pueraria lobata and adlay inhibited the enzyme activity to reduce the noodle starch digestibility.In addition,the addition of fermentation solution of pueraria lobata and adlay also increased the contents of free sulfhydryl and disulfide bonds in noodles,which were 3.27 times and 1.86 times higher than those of the control,respectively.The secondary structure of noodle protein is mainlyβ-fold andβ-turn.After adding different proportions of fermentation solution of pueraria lobata and adlay,β-fold andβ-corner increased by 27.83%43.07%and 27.84%43.97%,respectively.It promotes the cross-linking of covalent bonds between noodle proteins and strengthen the gluten network structure of noodles.（3）The effect of fermentation solution of pueraria lobata and adlay on the nutritional function and quality of noodles was studied.The results showed that after adding 0%-42%fermentation solution of pueraria lobata and adlay,the L*value and b*value of noodles decreased from 92.35 to 86.84 and 7.64 to 6.75,while the a*value increased from 2.23 to 2.86,and the noodle water absorption increased from145.62%to 212.23%.The noodle cooking loss decreased at first and then increased.After the addition of fermentation solution of pueraria lobata and adlay,the breaking rate of noodles in the five groups was 0,and there was no significant difference in stickiness and taste,but the color,tissue state and smoothness decreased,while the toughness and palatability increased significantly（P<0.05）.The total score of sensory quality of noodles increased at first and then decreased,and the total sensory score was the highest when the addition amount was 32%,which was 86.41.Compared with wheat noodles and enzyme hydrolyzed of pueraria lobata and adlay noodles,the contents of total phenols,flavonoids,puerarin,GABA and amino acids in fermented noodles were significantly increased,and increased with the increase of addition ratio.42%addition was higher than 32%and 22%.In addition,the scavenging ability of ABTS and DPPH free radicals was significantly enhanced.The contents of total phenols,flavonoids,puerarin,GABA and total free amino acids significantly improved the biological activity and nutritional value of noodles.In addition,87,84,84 and 82 volatile components were detected in N-22%,N-32%,N-42%and WN-32%noodles respectively,all of which were higher than those of N-0%sample（79volatile components）.The results showed that the addition of fermentation solution of pueraria lobata and adlay increased the contents of aldehydes,ketones,alcohols and esters in noodles,and these volatile components gave noodles a unique flavor.OAV value revealed that trans-2-nonanal,1-octene-3-ol,linalool,2,6-dimethylpyrazine and2-pentylfuran were the key flavor substances of noodles,which gave noodle mushroom flavor,coconut and peach flavor. |
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