Study On Key Production Technology Of Special Flour For Raw Wet Noodles

Raw wet noodles（RWNS）have a unique chewy texture and wonderful flavor,which have been favored by many people.However,short shelf-life and darkening limit the industrialization development of RWNS,which could be attributed to the microbial loads in wheat flour and wheat properties.This study focused on the key production technology of special flour for RWNS with three aspects:screening and blending of different varieties of wheat flour,low-microbial processing technology and flour improvers usage,which was intended to promote the industrialization development of RWNS by decreasing the microbial loads of wheat flour and inhibiting the darkening of RWNS.Firstly,different varieties of wheat flour used for producing special flour for RWNS were screened and blended.The relationship between 13 different varieties of wheat flour properties（color,protein and starch property,dough rheological characteristics,pasting property,solvent retention capacity and endogenous enzymes activity）and RWNS quality（lightness,texture and sensory quality）was investigated.The results of correlational analysis indicated that there was a significant negative correlation between protein,glutenin macropolymer,ash content in flour and L*of RWNS（P<0.05）.SDS sedimentation index was significantly positively with（35）L*of RWNS after storing for 24 h（P<0.05）.The content ratio of glutenin to gliadin was significantly negatively correlated with the cohesiveness of cooked noodles（P<0.05）.The solvent retention capacity of lactic acid in flour was significantly positively correlated with the chewiness and sensory evaluation of cooked noodles（P<0.05）,and the lipoxygenase activity of flour was significantly positively correlated with the hardness,gumminess and chewiness of cooked noodles（P<0.05）.13 different varieties wheat flour were divided into 3 clusters.The protein quality and dough rheological character of the third cluster of wheat flours（Canadian wheat 1 and 2）were better than the others,which was related to the best edible quality of the cooked noodles.The lightness of the dough sheet made by the second cluster of wheat flours（Australian standard wheat and French white soft wheat）was significantly higher than that made by other flours,which gave the best appearance to RWNS.Australian standard wheat flour and Canadian wheat 1 flour were blended at a ratio of 10:3,which could be used to make the RWNS with the best appearance and edible quality.This blending ratio was used as the formula of special flour for RWNS.Secondly,the tempering technology for the production of low-microbial special flour for RWNS was studied.The antimicrobial capacity of tempering by plasma-activated water（PAW）and its effects on flour properties were investigated.After being tempered by PAW activated for 40 min,the total plate count in wheat bran was decreased by 68.85%,60.91%and 27.27%compared with tempering by reverse osmosis water（P<0.05）.The dough rheological characteristics of straight-grade flour had no significant change after the treatment of PAW.However,protein polymerization in low-and straight-grade flour was observed.The SDS extractable protein and free sulfhydryl content in low-and straight-grade flour significantly decreased（P<0.05）,while the protein subunit distribution in wheat flour had less change.Moreover,the peak,trough and final viscosity of straight-grade flour decreased significantly（P<0.05）.The polyphenol oxidase activity in bran and low-grade flour significantly decreased by24.26%and 41.27%（P<0.05）,lipase activity decreased by 12.90%and 18.07%（P<0.05）,and lipoxygenase decreased by 27.74%and 31.42%（P<0.05）.The polyphenol content in wheat bran was also significantly reduced（P<0.05）.Finally,effects of improvers in special flour on RWNS were studied.The effects of enzymes and phosphates on darkening inhibition in RWNS were evaluated.The formation of dark spots in RWNS was effectively inhibited by transglutaminase（TG）and hexose oxidase（HOX）,which was less than that of RWNS added with LA.The RWNS with 0.2%TG possessed the best appearance,its L*₂₄significantly increased from 75.94 to 78.06（P<0.05）,and the number and total area of dark spots reduced by 82.35%and 84.75%（P<0.05）.0.2%TG could also reduce the cooking loss and improve the hardness,chewiness and tensile force of RWNS.For three phosphates（tetrasodium pyrophosphate,sodium hexametaphosphate and sodium tripolyphosphate）,0.3%sodium hexametaphosphate（SHMP）performed best on darkening inhibition in RWNS,which elevated the L*₂₄ to 77.93（P<0.05）,decreased the（35）L*,dark spots number and area by 14.0%,89.88%and 84.56%,respectively（P<0.05）.Moreover,the cooking loss and adhesiveness of RWNS increased as the dosage of three phosphates was increased.0.2%TG and 0.3%SHMP could inhibit the polyphenol oxidase activity in flour by52.40%and 40.73%.Compared with using a single additive,the compound improver（0.2%TG+0.3%SHMP）could further elevate the L*₀ in RWNS,reduce the dark spots area and significantly improve the color,appearance and sensory scores of cooked noodles（P<0.05）.