| Cassava vermicelli has a broad market prospect due to its advantages such as raw material price and transparent color.However,there are problems with poor chewability and high surface adhesiveness of cassava vermicelli,and existing research and improvement methods could not meet their requirements for improving hardness and tensile strength.There was also no systematic research on the surface adhesiveness mechanism of cassava vermicelli,which has limited the application of cassava vermicelli in the field of cold vermicelli.Therefore,this paper aimed to improve the chewing characteristics and reduce the surface adhesiveness properties of cassava vermicelli,and studied the effects and mechanisms of corn starch,xanthan gum(XG),and heat-moisture treatment(HMT)on the quality of cassava vermicelli.The main conclusions are as follows:Firstly,increased the hardness of cassava vermicelli by adding corn starch.The results showed that the hardness of vermicelli was proportional to the amount of corn starch added,and the final determination was that the amount of corn starch added was 30%(w/w).Compared with the sample without corn starch added,the hardness of vermicelli added with30%(w/w)corn starch increased by 111.94%,tensile strength increased by 45.55%,the surface adhesiveness decreased by 19.18%,cooking loss decreased by 39.24%,and rehydration rate decreased by 28.55%.After adding corn starch,the yield of vermicelli decreased due to the breakage of the strips during the flour leakage process.Adding 0.1%(w/w)XG increased the breaking elongation of the short ripening time vermicelli by 102.23%,improved the breaking condition of the vermicelli,and increased the yield of the vermicelli.At the same time,compared with the samples without XG,the texture quality and cooking quality of vermicelli added with 0.1%(w/w)XG had little change.Secondly,the surface adhesiveness of cassava vermicelli was reduced by HMT.The determined HMT process condition was to treat the vermicelli at 100°C for 1 hour at a moisture content of 26%(w/w).Under this condition,the surface adhesiveness of the HMT vermicelli was reduced by 71.12% compared to the control.The HMT process also improved the texture,cooking quality,and sensory quality of the vermicelli.Compared with untreated vermicelli,under the final optimized conditions,the hardness,tensile strength,cooking loss,rehydration rate,and total sensory acceptance of the HMT vermicelli were increased by39.36%,24.00%,69.56%,19.89%,and 45.45%,respectively.Thirdly,the mechanism of improving the quality of vermicelli by blending raw materials was studied.The results showed that corn starch improved the retrogradation characteristics of the mixed flour,enhanced the gel network structure of vermicelli,and thus improved the chewiness of vermicelli.After the addition of corn starch,the viscosity of the composite flour changed slowly with the increase of temperature,which led to the slow ripening and insufficient elasticity of the vermicelli during the flour leakage process,resulting in the occurrence of breakage.XG counld interact with free amylose to form a complex,increasing the viscosity of the system and reducing the paste formation temperature.The pasting temperature of XG plus corn starch system was 10.1°C lower than that of corn starch alone,and the pasting temperature of XG plus cassava starch system was 1.7°C lower than that of cassava starch alone.Therefore,the addition of XG improved the viscosity and elasticity of vermicelli within a shorter ripening time,thereby improving the yield of vermicelli.Lastly,the mechanism of HMT action of vermicelli was analyzed.The research showed that the proportion of short chain starch microcrystals,crystal layer thickness,and crystallinity in vermicelli significantly increased after HMT,which indicated that the double helix structure of starch was prolonged during hydrothermal treatment,resulting in an increase in crystal layer thickness and starch crystallinity,leading to a significant improvement in the thermal stability of starch.After HMT,the cooking loss decreased,and the proportion of short chain starch increased,indicating that HMT caused more entanglement of medium and long chains.At the same time,after HMT,the mesh size of starch gel decreased,and the short-range order increased,which reduced the fluidity of starch molecules and inhibits the exudation of starch molecules during the cooking process of vermicelli,thus reducing the surface adhesiveness of vermicelli. |
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