真空微波干燥过程中南瓜果胶性质变化与质构的关系

Relationship between Pectin Properties and Texture of Pumpkin during Vacuum Microwave Drying

为了明确真空微波干燥过程中脱水果蔬果胶性质变化对质构的影响,实验以南瓜为原料,采用不同微波强度进行处理,分析脱水南瓜硬脆度和微观结构,以及果胶含量、酯化度和单糖组成等性质的变化之间的关系。结果表明:微波强度为9 W/g时,南瓜获得较大的脆度和适中的硬度,孔状结构均匀。随着微波强度的升高,南瓜水溶性果胶(WSP)含量先减少后增加,螯合性果胶(CSP)含量先增加后减少。微波处理后南瓜果胶分子链断裂,分子量减小。随微波强度的升高,南瓜中不饱和半乳糖醛酸(UG)含量、果胶酯化度呈现先升高后降低的趋势,微波强度为9 W/g时,UG含量较高,达到10.54 mg/g。综合分析,真空微波干燥过程中UG含量是影响南瓜硬度的主要因素之一,酯化度和WSP含量影响其脆度和多孔结构的形成。

In order to find out the effect of pectin property change on texture during microwave vacuum drying(MVD),pumpkin were used as raw materials and treated with different microwave power.The hardness,crispness,microstructure,pectin content,esterification degree and monosaccharide composition of dehydrated pumpkin were analyzed.The results showed that when the microwave power was 9 W/g,pumpkins obtained higher crispness,moderate hardness and uniform pore structure.With the increase of microwave power,the content of water-soluble pectin(WSP)of pumpkin decreased first and then increased,and the content of chelating pectin(CSP)increased first and then decreased.After microwave treatment,the molecular chains of pumpkin pectin were broken and the molecular weight decreased.With the increase of microwave power,the content of unsaturated galacturonic acid(UG)and pectin ester degree in pumpkin increased first and then decreased,when the microwave power was 9 W/g,the content of UG was higher,reaching 10.54 mg/g.In summary,UG content is one of the main factors affecting the hardness of pumpkin during MVD,and the degree of esterification and WSP content affect the formation of its crispness and porous structure.