Study On The Effect Of Emulsifier On Quality Of Moisture Fresh Noodle During Shelf-life

Fresh noodle is considered to have good taste,unique flavor,mechanical production can maintain the original quality of traditional handmade noodle,but noodle is prone to abnormal flavor,texture hardened and other quality deterioration phenomenon during shelf life.In order to study changes of quality and the key technologies to keep quality of fresh noodle during shelf life,parameters of quality change in fresh noodle during the shelf life was analyzed by using the texture analyzer,differential scanning calorimetry,low field nuclear magnetic resonance,X-ray diffraction and electron microscopy from the dynamic changes of water molecules and starch molecules in fresh noodle during the shelf life.Besides,the rule of quality change and the mechanism of emulsifier on keep quality in fresh noodle were studied.research shows:1.Fresh noodle's tensile properties were as examined object,the result showed that the stretching distance and the tensile force were the largest,elasticity was the best,when SSL was added 0.2%and ?-CD was added 0.1%.The TPA experiment showed that the hardness was increased,the cohesion became smaller,and the chewiness became larger of the fresh noodle during the storage;The hardness and cohesiveness were decreased and the cohesion was increased of fresh noodle by SSL and ?-CD(P<0.05).2.Two aging peaks was found in the DSC experiment,aging temperature was roughly 50?60? of peak ? and aging temperature is roughly 90?120? of peak ?;The aging enthalpy became larger of fresh noodle during storage;Emulsifier reduced the aging enthalpy and recrystallization melting temperature of fresh noodle;There was no significant change in peak ? when the fresh noodle was deproteinized,and the aging enthalpy and recrystallization melting temperature were increased significantly in peak ? when the fresh noodle was degreased(P<0.05).The results showed that the emulsifier inhibited the formation of amylose-lipid complex and formed a new complex,inhibited starch crystallization.The moisture distribution in micro structure of fresh noodle added emulsifier was more smooth than the CK group.3.Fresh noodles were stored for seven days at 4?,their bound water content(A21)and immobilized water content(A22)were decreased gradually,and free water content(A23)was increased gradually;SSL and ?-CD increased bound water content and immobilized water content(P<0.05)and decreased free water content(P<0.05).In addition,SSL and ?-CD reduced the relaxation time T2 of fresh noodle after storage for 7 days,reduced moisture migration,and the effect of SSL and ?-CD was different significantly(P<0.05).4.Investigated by X-ray diffraction,the change of crystallie patterns occurring in fresh noodle was from V to B+V patterns by SSL and ?-CD,and the crystalline peak intensity became lower,the crystal area was smaller.The result showed that the starch crystallinity of fresh noodle was reduced by emulsifier,a complex was formed between emulsifier and amylose,which was changed the crystallie patterns and inhibited the crystallization of starch,and inhibited the retrogradation of resh noodle during shelf life.Investigated by SEM,the structure was found to be rough with gap of fresh noodle;The particle size and number were increased of fresh noodle after seven days for storage;SSL and P-CD made smooth surface,enhanced the gluten structure,reduced clearance,and reduced the number of crystals by combining,with starch molecules.5.Significant differences were observed in the T1 and T2 of the water molecules in the samples added SSL.The T2 relaxation time of the water molecules in the fresh noodle stored for seven days at 4? were shortened by SSL(P<0.05),and the chemical exchange between the proton and the starch exchangeable proton was reduced in the NMR analysis.In addition,the chemical exchange between water protons and starch exchangeable protons was reduced,and the hydrogen bonds interaction of starch and bound water was stronger,water flow was decreased;free water penetrated into the interior of the starch granules.The results show that emulsifiers improve the texture parameters of the fresh noodle during shelf life,reduce the rate of increase of starch aging enthalpy and inhibit the migration of water,strengthen the starch-water interactions,and reduce the degree of starch crystallization by the action of starch and protein,inhibit the aging of fresh noodle and raise the quality.