挤压处理对豌豆淀粉的流变特性和体外消化率的影响

Effect of Extrusion Treatment on Rheological Properties and in Vitro Digestibility of Pea Starch

目的:研究挤压条件(豌豆淀粉水分质量分数:25%、35%、40%、45%和55%;剪切温度:50、60、70、80℃和90℃;螺杆转速:100、120、140、160r/min和180r/min)对豌豆淀粉的体外消化率和流变特性的影响。方法:采用体外消化法测定了豌豆淀粉的水解度,并通过稳态剪切实验、频率扫描实验和温度扫描实验测定了豌豆淀粉的流变特性。结果:挤压后水解度和慢消化淀粉(slowly digestible starch,SDS)相对含量增加,抗性淀粉(resistant starch,RS)相对含量降低;在水分质量分数为25%的条件下(螺杆转速140r/min、剪切温度70℃),SDS相对含量最高,为34.41%;在螺杆转速为180r/min时(水分质量分数40%、剪切温度70℃),RS相对含量最低,为10.49%。粒径与SDS相对含量和稠度系数K呈显著正相关(P<0.05),相关系数分别为0.60和0.61。挤压的豌豆淀粉溶液为假塑性流体;在频率和温度扫描实验中,储存和损耗模量随豌豆淀粉挤压损坏程度增加而增加。结论:挤压后的豌豆淀粉结构增强并表现出弹性凝胶特性。因此,挤压工艺可能通过影响豌豆淀粉的体外消化率和流变性能来改善食品的功能性和品质。

This study investigated the influence of different extrusion conditions including pea starch moisture content(25%,35%,40%,45%and 55%),barrel temperature(50,60,70,80 and 90℃)and screw speed(100,120,140,160 and 180 r/min)on the in vitro starch digestibility and rheological properties of pea starch.Hydrolysis degree(HD)was measured using an in vitro digestion model,and rheological properties were determined through steady shear test,frequency sweep test and temperature sweep test.The results showed that after extrusion treatment,HD and the relative content of slowly digestible starch(SDS)increased whereas the relative content of resistant starch(RS)decreased.The maximum relative content of SDS of 34.41%was obtained under the following extrusion conditions:moisture content 25%,barrel temperature 70℃and screw speed 140 r/min.When screw speed increased to 180 r/min with moisture content 40%,barrel temperature 70℃,the relative content of RS reached the minimum value of 10.49%.Particle size was positively correlated with SDS relative content and consistency coefficient(K value)(r=0.60 and r=0.61,P<0.05).The extruded pea starch suspension was pseudoplastic.In frequency and temperature sweep tests,storage and loss moduli increased with the degree of starch damage increasing caused by extrusion.The results showed that the extruded pea starch exhibited enhanced structure and elastic gel properties.Therefore,extrusion can affect the in vitro starch digestibility and rheological properties of pea starch,thereby improving food functionality and quality.