| Instant wet noodles as a kind of noodles without deep-frying,fresh and moisturizing and smooth texture,with balanced nutrition,time-saving and convenient features,and its unique charm to lead the new trend of fast food,but the moisture content of industrially produced instant wet noodles is high,and during storage is prone to starch retrogradation thus increasing the hardness of instant wet noodles,taste decline,easy to break and other phenomena.At present,the quality of instant wet noodles is generally improved by changing the materials and adding exogenous additives to inhibit the retrogradation of starch in instant wet noodles,while the quality of instant wet noodles is less studied by changing the processing methods and combining exogenous additives with processing methods.Therefore,in this study,the effects of three kinds of exogenous additives on the storage quality of instant wet noodles at 4°C were used to optimize the type and amount of exogenous additives,and the correlation between starch properties and the storage quality of instant wet noodles was analyzed;The effects of different processing methods including boiling(Boi),steaming(Ste),boiling & steaming(Sboi)and microwave(Mic)on the storage quality of instant wet noodles were studied,and the processing methods for delaying starch retrogradation in instant wet noodles were clarified.Based on the above research results,the optimal exogenous additives were combined with the processing methods to study their effects on the storage quality and starch retrogradation of instant wet noodles after0,2,4,6,8,16 and 30 days of storage,and to explore the mechanism of delaying starch retrogradation in instant wet noodles.The specific research results are as follows :The effects of different exogenous additives on the storage quality of instant wet noodles were studied.The results showed that emulsifiers and biological enzymes improved the color of dough sheets.Sodium stearoyl lactate(SSL),guar gum(GG)and β-amylase(β-AMS)improved the elastic modulus and viscous modulus,deformation resistance and recovery ability,and strengthened the gluten network structure of the dough sheet.Emulsifier and hydrophilic gel significantly improved the cooking quality of instant wet noodles.Among them,0.20 % SSL and 0.40 % sodium carboxymethyl cellulose(CMC)had the best improvement effect,and the cooking loss rate decreased significantly from 5.18 %of the blank group to 3.00 % and 2.99 %,respectively.The improvement effect of biological enzyme preparation was not significant.0.40 % monoglyceride(GMS),0.30 % GG and0.001 % xylanase(XY)significantly reduced the increase of hardness,improved the elasticity of instant wet noodles,and improved the texture characteristics of instant wet noodles.The hardness increase of 0.30 % GG was the lowest,which was significantly reduced from 71 % of the control to 9.43 %.Emulsifier and hydrophilic colloid significantly improved the tensile properties of instant wet noodles.Compared with the control,0.10 %SSL and 0.30 % xanthan gum(XG)increased the tensile strength of instant wet noodles by47.87 % and 78.46 %,respectively.According to the comprehensive evaluation,the highest comprehensive score of instant wet noodles with 0.30 % GG was 0.90.The effects of different exogenous additives on the physicochemical properties and gel properties of starch and their correlation with the quality of instant wet noodles were studied.The results showed that GG and XY significantly reduced the breakdown value,setback value,retrogradation and turbidity during storage.The setback value were reduced by 9.5%and 10.7%,respectively,which delayed the short-term retrogradation of starch.The starch solubility and swelling power of GMS and GG were significantly lower than those of the control.GMS,GG and XY significantly reduced the hardness of starch gel,and the increase of GG was the smallest,reduced by 48% as compared with the control.The correlation analysis showed that there was a significant positive correlation between the solubility of starch and the cooking loss rate of instant wet noodles,a significant positive correlation between the swelling power and the dry matter water absorption rate of noodles,and a highly significant positive correlation between the cooking loss rate of instant wet noodles,a positive correlation between the peak viscosity of starch and the water absorption rate and cooking loss rate of instant wet noodles,a highly significant positive correlation between the final viscosity of starch and the hardness of instant wet noodles,and a highly significant positive correlation between the absorbance and coagulation characteristics of starch and the hardness of instant wet noodles.The results of the effects of different processing methods on the storage quality of instant wet noodles showed that the moisture content of Boi instant wet noodles was significantly higher than that of Ste,Sboi and Mic.The results of low field nuclear magnetic resonance showed that compared with Boi,Ste,Sboi and Mic significantly increased the content of combined water in instant wet noodles and decreased the free water content,indicating that these three processing methods inhibited the conversion of combined water to free water and improved the water holding capacity of the system.After 8 days of storage at4°C,the water holding capacity of Ste,Sboi and Mic increased by 11 %,14.5 % and 19.4 %respectively compared with Boi.SEM showed that the microstructure of the convenient wet surface of Ste,Sboi and Mic was more uniform and dense than that of Boi.With the increase of storage time,the structure of the instant wet noodles was more dense and there were holes.The holes of the instant wet noodles of Ste,Sboi and Mic were small,continuous and evenly distributed.The setback value of Ste and Sboi instant wet noodles decreased significantly from 676.5 c P of Boi to 396.0 c P and 641.5 c P,indicating that the processing method of Ste and Sboi delayed the retrogradation of starch.The lowest re-cooking loss rate was 1.14 %.The Sboi method significantly reduced the increase in hardness and improved the elasticity and tensile properties of the convenient wet noodles.The Sboi significantly reduced the increase in hardness from 64.36 % to 4.36 %.The effects of exogenous additives and processing methods on the storage quality of instant wet noodles and the mechanism of delaying retrogradation were studied.The results showed that the hardness of instant wet noodles increased significantly during storage,and the elasticity,breaking force and breaking distance decreased significantly.After 30 days of storage,the hardness of Boi,Boi-G,Sboi and Sboi-G increased by 85.13 %,49.02 %,51.87 % and 38.74 %,respectively.Sboi-G significantly reduces the increase of hardness and improves the elasticity and tensile properties.After 16 days of storage,the strongly combined water contents of Boi-G,Sboi and Sboi-G were significantly higher than those of Boi Sboi-G effectively inhibited the conversion of combined water to free water and improved the overall water holding capacity of the system.XRD showed that the diffraction peak appeared near 17 ° during the storage of the instant wet noodles,which was transformed into B-type crystal.The short-range ordered structure and relative crystallinity of the instant wet noodles increased significantly during storage,and the relative crystallinity of Sboi-G decreased significantly from 8.79 % of Boi to 7.01 %.SEM shows that the addition of GG can make the hole smaller and the structure more uniform and continuous.DSC results showed that Boi-G,Sboi and Sboi-G significantly reduced the retrogradation enthalpy of instant wet noodles.The retrogradation kinetic equation showed that the nucleation mode of Boi,Boi-G,Sboi and Sboi-G instant wet noodles was instantaneous nucleation,and Sboi-G instant wet noodles was instantaneous nucleation.In summary,exogenous additives and processing methods can delay the retrogradation of instant wet noodles,thereby improving the storage quality of instant wet noodles.Among them,the Sboi-G method has the most significant effect on delaying starch retrogradation. |
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