| Ablmoschus manihot gums（AMG）is a relatively rich renewable natural hydrophilic colloid,with strong swelling rate and excellent water retention,but also shows weak gel characteristics.The properties of the compound of AMG and polysaccharides have not been reported,which limits the development and application of AMG as a novel gel material.In order to expand the application range of AMG,AMG was added to konjac gum（KGM）and the properties of its compounds were studied.In order to further expand the application scope of AMG and reflect the significance of combining KGM and AMG,KGM and AMG was added to potato starch vermicelli to explore their influence on the quality of potato starch vermicelli,and High-amylose corn starch（HACS）was further added to improve the quality of vermicelli.This study can provide a reference for expanding the application range of AMG,improving the gelability of KGM and improving the quality of potato starch vermicelli.The results of this study are as follows:（1）Effects of AMG addition and salt ions on the properties of KGM and AMG composite gels:compared with pure KGM,AMG addition resulted in a significant increase in the Zeta potential absolute value,hardness,springiness and cohesiveness of the system（p<0.05）.The hardness（386.46 g）,springiness（0.99）and cohesiveness（0.85）of the composite gels were maximum when AMG was added at 2%（w/v）.The results of rheological properties indicated that the composite of KGM and AMG was a new type of non-covalent gel.The addition of salt ions(Na+,Ca2+and Mg2+)decreased the Zeta potential absolute value,hardness,springiness,resilience and storage modulus of the composite gel,and the absolute value,hardness,springiness,resilience and storage modulus further decreased with the increase of salt ion concentration or salt ion valence.（2）Effect of the compound addition of KGM and AMG on the performance of potato starch vermicelli:compared with pure potato starch vermicelli,the compound addition of KGM and AMG reduced the breakage rate of vermicelli from 50%to 0%and the cooking loss from 5.35%to 3.08%,and increased the total sensory score from 14.0 to 20.9,which meant the compound addition of KGM and AMG could improve the cooking quality of vermicelli and sensory quality.Compared with alum vermicelli,the combined KGM and AMG vermicelli had similar breakage rate and boiling loss as alum vermicelli,but the overall sensory evaluation was lower than alum vermicelli（5.0 points for elasticity and 22.2 points for total score）due to poor elasticity（3.5 points for elasticity and 20.9 points for total score）.Compared with pure potato starch vermicelli and alum vermicelli,KGM and AMG composite vermicelli had higher tensile strength,hardness,whiteness and resistant starch content.（3）Process optimization of KGM,AMG and HACS composite potato starch vermicelli:to further improve the quality of vermicelli,HACS was added to the potato starch vermicelli,and the addition levels of KGM,AMG and HACS were optimized by single-factor test and orthogonal test with the evaluation indexes of breakage rate,cooking loss and sensory evaluation.The results showed that the optimal addition levels of KGM 0.75%,AMG 0.75%and HACS 15%（w/w）.Compared with pure potato starch vermicelli（50%breakage and5.35%steaming loss）and alum vermicelli（0%breakage and 3.02%steaming loss）,the composite vermicelli made at this optimal addition level had the lowest breakage（0%）and steaming loss（1.46%）,and the sensory score of composite potato vermicelli（total score 23.2）was close to that of alum vermicelli（total score of 22.2）.In addition,the composite vermicelli at this optimum addition level had higher tensile strength,hardness,whiteness and resistant starch content compared to pure potato starch vermicelli and alum vermicelli.（4）Effects of KGM,AMG and HACS on the properties of potato starch gels:this part of the study aimed to explore the mechanism of KGM,AMG and HACS affecting the quality of potato starch vermicelli through the characterization of starch gel properties.The results showed that the addition of HACS alone reduced the cohesion and cohesion of potato starch gel,and increased the content of amylose leakage.When KGM and AMG were compounded,the hardness of starch gel could be further increased,and the content and coagulation of amylose leakage could be reduced.Infrared spectroscopic analysis of the gel showed that the addition of KGM,AMG and HACS alone or in combination could blueshift the absorption peak at 3383 cm-1.The result indicated that HACS improved the quality of potato starch vermicelli by increasing the amylose content of the system and increasing the rejuvenation effect,and KGM and AMG enhanced the network structure strength of the starch system through hydrogen bonding with starch molecules,thereby improving the quality of potato starch vermicelli. |
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