| As a whole grain food,brown rice noodles are increasingly favored by consumers.However,brown rice retains the bran layer,resulting in high cooking loss and poor eating quality.Germination can stimulate endogenous enzymes in brown rice,change the structure and function of starch,protein,dietary fiber and other components,and produce γ-aminobutyric acid,polyphenols and other bioactive substances.These changes may affect the eating quality(cooking,texture,sensory and nutritional quality)and intestinal flora regulation(fermentation characteristics and flora structure)of brown rice noodles.Therefore,this paper aims to investigate the effects of germination on the eating quality of brown rice noodles and the regulation of intestinal flora,and provide a theoretical basis for the development of germinated brown rice noodles.Around the above objectives,this paper studies from three aspects.Firstly,the effect of raw material characteristics of germinated brown rice on the cooking and texture quality of rice noodles was investigated.Secondly,the effects of germination on the eating quality of brown rice noodles were studied.Finally,the effects of germination on the in vitro intestinal flora fermentation characteristics and flora structure of brown rice noodles were discussed.The main results are as follows :(1)Using eight varieties of germinated indica brown rice as raw materials,the relationship between raw material characteristics and the cooking and texture quality of rice noodles was constructed.The results showed that the raw material characteristics that significantly affected the cooking and texture quality of germinated brown rice noodles were amylose content,onset pasting temperature,peak pasting temperature,final pasting temperature and swelling power.Among them,amylose content was significantly negatively correlated with cooking loss,and significantly positively correlated with hardness and chewiness of germinated brown rice noodles.Considering the texture,cooking and sensory quality,Younian germinated brown rice was the most suitable for processing rice noodles,with the highest sensory score(73.6),the lowest broken rate(0%),the lower cooking loss(8.3%),moderate hardness(438.2g)and the highest chewiness(473.5 g).(2)The effects of germination on cooking,texture and sensory quality of brown rice noodles were analyzed by cooking time,cooking loss,broken rate,texture,appearance,smell and taste.The results showed that after germination,the cooking time,cooking loss,hardness,stickiness and chewiness of brown rice noodles decreased significantly by 42.34 s,1.77%,55.56 g,0.43 g·sec and 151.42 g,respectively.The bitterness value decreased significantly and the color deepened slightly.The effects of germination on the nutritional composition of brown rice noodles were investigated by measuring the in vitro digestibility of starch and the contents of dietary fiber,fat,protein,mineral elements,γ-aminobutyric acid and polyphenols.The results showed that after germination: the starch content of brown rice noodles decreased by 6.41 %,but the the final hydrolysis rate of starch(C∞)and expected glycemic index(eGI)increased by 5.95% and 8.15,respectively.The contents of dietary fiber,fat,γ-aminobutyric acid,free phenolic acid and bound phenolic acid were significantly increased by 2.59%,0.08%,17.97 mg/100 g,28.03 and 27.47 μg GAE/g DW;germination had no significant effect on the content of protein and most mineral elements in brown rice noodles.(3)The effects of germination on the fermentation characteristics and intestinal flora structure of brown rice noodles were investigated by the changes of pH,gas production,short-chain fatty acids(SCFAs)and intestinal flora at 48 h of intestinal flora fermentation in vitro.The results showed that germination had no significant effect on pH value,gas production and total SCFAs of brown rice noodles.Germination at the phylum level did not significantly change the total relative abundance of Firmicutes and Bacteroidetes(about 83%).At the genus level,germination did not significantly change the total relative abundance of two major short-chain fatty acidproducing bacteria,Megamonas and Bacteroides(about 77%),but reduced the relative abundance of Bacteroides.At the same time,germination inhibited the growth of Dialister and promoted the growth of Megamonas,Shigella and Bifidobacterium.In summary,germinated indica brown rice with the higher amylose content and lower onset pasting temperature is beneficial to improve the cooking and texture quality of rice noodles.Germination could further improve the eating quality of brown rice noodles and had no significant effect on its intestinal fermentation characteristics and flora regulation.In addition,the changes of pH,gas production and SCFAs production during the fermentation of germinated brown rice noodles and brown rice noodles were consistent with the prebiotics(fructooligosaccharides),which was beneficial to intestinal health. |
