Effects Of Protein And Dietary Fiber On Dry White Noodle

The objective of this research was to study the quality of dry whiteChinese noodle added with soybean flour, mungbean flour and soybean proteinisolated (SPI) as a protein source, with buckwheat flour, brown rice flour and wheatbran dietary fiber (WBDF) as a dietary fiber source. Effects of SPI and WBDF onnoodle color, cooking properties, structure qualities were studied in this paper.Comparing with the distribution of moisture, change of protein secondasry structureand transformation between disulfide bond (-SH) and hydrosulphoyl (-S-S-) toanalysis effect mechanism.The main experimental results are as follows:1. The brightness of dry noodle reduced with content of soybean flour andmungbean flour increasing, content of mungbean flour and brightness of dry noodlehad a extremely significant negative correlation. The brightness of dry noodleincreased and changes of red was small, which was not significant correlation addedwith SPI. Effect of the color of dry noodle was small added with soybean flour,mungbean flour and SPI, and the variation coefficient was less than5%. With thecontent of buckwheat flour and WBDF increasing, the brightness of dry noodlereduced, red of dry noodle increased, the variation coefficient was large andcorrelation was significant. The brightness and red of dry noodle with brown riceflour increased and correlation was not significant. The result showed that factorsaffecting dry noodle color not only included content of protein and dietary fiber, butalso ash, amylase and the color of flour, there were crucial factors.2. With content of soybean flour, mungbean flour and SPI increasing, cookingloss and absorption of noodle increased, correlation between structure of cookednoodle and protein content was not significant; absorption of noodle reduced andcooking loss of noodle increased with content of buckwheat flour, brown rice flourand WBDF increasing, and the correlation between structure of cooked noodle anddietary fiber content was negative. The result showed that protein and dietary fibermade the network structure of dry noodle unfold and cooking quality reduced.3. The correlation of bending strength, bending distance of dry noodle andcontent of soybean flour, mungbean flour and SPI were negative, elastic modulus andloss modulus reduced with content increased; The correlation of bending strength,bending distance of dry noodle and content of buckwheat flour and WBDF weresignificantly negative, elastic modulus and loss modulus reduced with contentincreased. Therefore, due to the three-dimensional network structure of glutenproteins of dilution, resilience of dry noodle reduced.4.T21and T22of dry noodle added with SPI increased first and then decreased,with content of WBDF increased, T21increased and T22decreased, and thedifferences were significant. But the correlation of T21and T22of dry noodle andstructure qualities were negative. The result showed that SPI weakened the trend ofcombination of moisture and protein-starch network structure; Due to the strong hydrophilic of WBDF, dry noodle had formed a part of illiquid combined water, buttransformation of moisture was less effected on the qualities of dry noodle.5. With content of SPI increased, hydrosulphonyl content of dry noodlevolatility increased and disulfide bond content volatility decreased, the correlation ofcontent and noodle structure qualities was not significant. With content of WBDFincreased, hydrosulphonyl and disulfide bond content decreased linearly, and thecorrelation of content and noodle structure qualities was significant. Result showedthat SPI and WBDF effected on the transformation between hydrosulphonyl anddisulfide bond, destroyed the network structure of gluten.6. with content of SPI and WBDF increased, percentage of characteristic peakin protein secondary structure, include Anti-parallel β-sheet, aggregated strands,β-strand, α-helix, β-sheet, extension and intramolecular coupling, were significantlydifferent, the correlation of percentage and structure of dry noodle was significant.Result showed that adding a small amount of SPI and WBDF weakened thehydrogen bonding between three strands of protein chain and intramolecularinteraction, the content of disordered structure of protein increased.Therefore, properties changes of dry noodle added with SPI and WBDF wasmainly due to composition of protein secondary structure and transformation ofhydrosulphonyl and disulfide bond content.