破碎温度对番茄浆流变性质与果胶分子结构的影响

Effect of Breaking Temperature on the Rheological Properties and Pectin Molecular Structure of Tomato Pulp

对在不同破碎温度下所得番茄浆的动态流变性质以及果胶物质相对分子质量的分布和大小进行了研究 .结果表明 :随着破碎温度的增加 ,番茄浆中果胶物质的平均相对分子质量增加 .但当破碎温度为 90℃时 ,果胶物质的平均相对分子质量却有所下降 .在 80℃和 85℃破碎时 ,番茄浆具有相当大的贮能模量 ,而在 75℃和 90℃破碎时 ,贮能模量值较小 .贮能模量值对振荡频率具有一定的依赖性 ,故番茄浆表现出弱凝胶特性 .贮能模量G′和损耗模量G″交汇点的位置随着破碎温度的升高向低频区移动 .这说明破碎温度越高 ,大分子物质被保留得愈多 ,体系呈较强的弹性 ;破碎温度越低 ,体系中大分子物质被保留得越少 。

The rheological properties, the size and distribution of pectin molecular weight of tomato pulps broken at different temperatures were investigated. The average molecular weight of pectic substances in tomato pulps increased with the increasing breaking temperatures, while the value decreased when tomato was broken at 90 ℃. Dynamic shear data revealed that tomato pulps broken at 80 ℃ and 85 ℃ had relatively high storage moduli. The values were lower when tomatoes were broken at 75 ℃ and 90 ℃. Storage modulus was dependent on oscillatory frequencies to some extent. Therefore the pulps exhibited weak gel properties. The positions of crossover point of storage moduli and loss moduli moved toward low frequencies with the increase of breaking temperature. It reflected that the higher the temperature was, the more macromolecular substances were retained in tamato pulp, and the more obvious was the elastic properties, and vice versa .