Effects Of Wheat Bran Soluble Dietary Fiber And Insoluble Dietary Fiber On Dry White Noodles

Laboratory-made wheat bran soluble dietary fiber（SDF） was sieved after ultrafine grinding as a source of dietary fiber, dry white Chinese noodles was chosen as the SDF carrier to study the effects of wheat bran SDF on dry white noodles. Different proportion of SDF caused the wide-ranging effects of noodles such as noodle color, texture characteristics, sensory evaluation, moisture distribution, amount of hydrosulphonyl and disulfide bond. Combined with correlation analysis, the mechanism of wheat bran SDF on noodle quality impacts was discussed. Based on the original tests, discussed the impacts on noodle quality with 3% DF content. The main findings are as follows :（1）The high content of SDF caused noodle color darker. L* fell observably. And b* showed a trend of increase, even L* variation of noodles was slightly restrained after cooking. With the increase of the SDF content, the hardness and maximum shear force fell with the content less than 3%, increased observably with 3% SDF, then fell with 5% SDF. The gumminess and chewiness showed a similar trend, didn’t changed significantly with the content less than 3%, increased gradually with the content above 2%. The tensile strength fell slightly with 1% SDF, increased gradually with the content above 1%. The sensory value increased first and then decreased, 3% SDF noodle reached the top value. Correlation analysis showed that the SDF content and L* negative correlated significantly, the SDF content and texture values positively correlated significantly.（2）T₂₁ and T₂₂ decreased as SDF content increased. The SDF absorbed moisture competitively, reduced the liquidity of moisture in noodles effectively, benefited to noodle preservation. Correlation analysis showed that T₂₁ and T₂₂ had negative correlation significantly with the SDF content and texture values, had positive correlation significantly with L*.（3）SEM observation showed that the SDF improved noodle quality and uniformity. Noodle with 3% SDF had the best quality. Noodle structure got worse with 5% SDF, gluten protein was diluted. The result was consistent with noodle texture result.（4）By the addition of SDF,-SH content increased,-SS- content decreased. This may be because the phenolic aids in SDF had the oxidative crosslinking reaction with protein,-S-S- broke to produce-SH. Correlation analysis showed that-SH content had positive correlation significantly with the SDF content and texture values, had negative correlation significantly with L*, T₂₁ and T₂₂. The-S-S- content had negative correlation significantly with the SDF content, texture values（besides maximum shear force）, T₂₁ and T₂₂.（5）The SDF was light brown, IDF was light yellow. Therefore the effects of 3% DF on noodle color were L* to fell and b* increased. The influence caused by SDF was larger than IDF. The sensory values of noodle with 3% DF were higher than the control group,accepted by the market.（6）Compared with the control group, texture values of 3% DF noodle increased. The influence of noodle texture caused by SDF was larger than IDF. SEM observation showed that DF noodles had better quality and uniformity. The result was consistent with 3% DF noodle texture result.（7）The best content DF noodles were compared with control group, T₂₁ and T₂₂ decreased. So the DF was benefited to noodle preservation. This may be because DF had high water absorption capacity and well water holding capacity, contained the moisture migration of noodles, reduced the liquidity of moisture in noodles.（8）Compared with the control group, the –SH content of the best content DF noodle increased and-SS- content decreased. This may be because the ferulic in DF had crosslinking reaction with protein,-S-S- broke to produce –SH, changed the structure of protein, then protein conformation became loose.