| Dietary fiber has benefits such as stabilizing blood sugar after meals,lowering cholesterol,and reducing the risk of diet-related metabolic disorders.Resistant starch(RS)can be utilized by microorganisms in the colon as a dietary fiber to produce butyric acid.The beneficial effects of RS on human health are more pronounced than those of common dietary fiber.Vermicelli is a traditional starch-based food with a very high percentage of carbohydrates and low RS content.Therefore,resistant vermicelli prepared by adding resistant starch is being explored as a new low-calorie food.In this study,pea starch was treated with three different modifications,pullulanase(PUL),combined enzymatic treated-regeneration and sodium tripolyphosphate/sodium trimetaphosphate crosslinking,to prepare RS2,RS3 and RS4 types of pea resistant starch,respectively.Secondly,starch gels were prepared by adding different contents of RS2,RS3 and RS4 resistant starch,and the effects of resistant starch on the pasting properties of starch and the multiscale structure of the gels were also investigated.Thirdly,resistant pea starch vermicelli was prepared and the cooking characteristics of the vermicelli were evaluated.Finally,the improvement of the quality of RS2 type resistant starch vermicelli by the addition of xanthan gum(XG),sodium alginate(SA)and XG-SA combination was investigated.The results are as follows:(1)In this study,pea starch was treated with three different modifications,pullulanase(PUL),combined enzymatic treated-regeneration and sodium tripolyphosphate/sodium trimetaphosphate crosslinking,to prepare RS2,RS3 and RS4 types of pea resistant starch,respectively.The prepared RS2,RS3 and RS4 contained significantly higher resistant starch content,relative crystallinity and particle diameter.The RS content was 40.79%,88.55% and 91.86%,respectively.RS3 contained the highest amylose content and relative crystallinity of 63.13% and 42.64%,respectively.RS4 showed the best thermal stability with the lowest weight loss of 65.72%.(2)The effects of resistant starch on the pasting properties,textural properties and multiscale structure of starch gels were examined and compared.The experimental results showed that the paste viscosity and fluidity of gel of RS2 increased significantly(P <0.05)with increasing PUL;while RS3 and RS4 showed the opposite trend.The addition of resistant starch did not change the crystalline structure,but the relative crystallinity increased significantly(P < 0.05).Different resistant starches had different effects on the amylose content(AM)and amylopectin(AP)length distribution of the gels.The highest amylose content of 47.30% was obtained when the RS2 sample was treated with pullulanase at a concentration of 300 U/g;the lowest amylose content with 25% of RS4 was 33.86%.And there was a significant correlation(P < 0.05)between the textural properties of the gels with the AM and the average chain length of AP,respectively.By studying the effect of the addition of resistant starch on the gel properties,it provides the theoretical basis and foundation for the subsequent preparation of resistant vermicelli and exploration of the effect of resistant starch on the quality of vermicelli.(3)Effects of adding different levels of resistant starch on the cooking characteristics of pea starch vermicelli were investigated and compared.The results showed that RS3 vermicelli had the best resistant digestibility and significantly reduced the in vitro hydrolysis rate of the vermicelli with increasing addition.The sample containing 25%RS3 had the lowest hydrolysis rate,which was reduced by 12.15% compared with the nature starch vermicelli.This was followed by containing 15% RS3 and 20% RS4,both of which showed a 10.12% reduction in hydrolysis rate.The results showed that the addition of resistant starch significantly reduced the rate of rupture,improved the swelling,thermal stability and hydrolysis resistance of the vermicelli(P < 0.05).This indicated that the resistant starch significantly reduced the digestibility of the vermicelli while improving the quality of the vermicelli.None of the vermicelli containing RS3 rupture during cooking,showing excellent cooking quality.RS4 resistant starch significantly improved the thermal stability of the vermicelli and increased with the increase of RS4content(P < 0.05).The experimental results provide data and technical support for the development of RS2,RS3 and RS4 resistant starch vermicelli with different contents.(4)This study evaluated the impacts of xanthan gum(XG),sodium alginate(SA),and XG-SA complex formulations on the pasting,rheology,structural properties,amylose content,and in vitro digestibility of debranched pea starch(DBPS)treated with pullulanase.The addition of polysaccharides increased the viscosity of DBPS,and the fluidity of the DBPS gels was enhanced.The amylose content and relative crystallinity(RC)of the XG-added samples decreased.In contrast,the RC of SA and XG-SA samples increased from 38.34% and 40.97% to 40.48% and 47.64%,respectively.Additionally,the resistant starch content in vermicelli added with 0.5% of XG,SA and XG-SA increased from 30.14% to 33.68%,41.28% and 39.76%,respectively.Meanwhile,compared with the positive control with alum addition,the vermicelli containing polysaccharides did not rupture during cooking process and significantly improved swelling and thermal stability(P < 0.05).However,the addition of XG and SA individually increased the cooking loss rate of vermicelli.Overall,the compound formulation with 0.5% xanthan gum and 0.5% sodium alginate added can be used instead of alum in enzymatic pea vermicelli.The results provide experimental data and technical support for the development of DBPS vermicelli with XG,SA and XG-SA and a theoretical basis and new insights about DBPS and polysaccharide applications in food and materials.This study provided insights into the preparation of resistant vermicelli.Meanwhile,it was verified that the addition of resistant starch reduced the in vitro digestibility of vermicelli and had good cooking quality.The feasibility of applying resistant starch to vermicelli is confirmed,providing experimental data and technical support for the production of resistant vermicelli. |
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