This research examines changes to the functional (solubility, emulsifying and foaming) properties of pea protein isolate when complexed with commercial citrus pectin of different structural attributes. Specifically, a high methoxy (P90; degree of esterification: 90.0%; degree of blockiness: 64.5%; galacturonic acid content 11.4%) and low methoxy (P29; degree of esterification: 28.6%; degree of blockiness: 31.1%; galacturonic acid: 70%) pectin at their optimum mixing ratios with pea protein isolate (4:1 pea protein isolate to P90; 10:1 pea protein isolate to P29) were assessed at the pHs associated with critical structure forming events during the complexation process (soluble complexation (pHc), pH 6.7 and 6.1; insoluble complex formation (pHϕ1), pH 4.0 and 5.0; maximum complexation (pHopt), pH 3.5 and 3.8; dissolution of complexes, pH 2.4 and 2.1; for admixtures of pea protein isolate–P90 and pea protein isolate–P29, respectively). Pea protein isolate solubility was improved from 41 to 73% by the presence of P90 at pH 6.0 and was also moderately increased at pH 4.0 and pH 5.0 by P90 and P29, respectively. The emulsion stability of both pea protein isolate–pectin complexes was higher than the homogeneous pea protein isolate at all critical pHs except pHopt as well as pHc for pea protein isolate–P29 only. P90, with the higher level blockiness and esterification, displayed better foaming properties at the maximal complexation pH when complexed with pea protein isolate than pea protein isolate–P29 or pea protein isolate alone. However at pHϕ2, pea protein isolate–P29 admixtures produced foams with 100% stability, increasing pea protein isolate foam stability by 85%. The enhanced functionality of pea protein isolate–pectin complexes based on the type of pectin used at critical pHs indicates they may be useful biopolymer ingredients in plant protein applications.

中文翻译：

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不同程度的果胶酯化和封闭性对豌豆分离蛋白-果胶复合物功能行为的影响

本研究考察了豌豆分离蛋白与不同结构属性的市售柑橘果胶复合后的功能（溶解性、乳化性和起泡性）特性的变化。具体而言，高甲氧基（P90；酯化度：90.0%；块状度：64.5%；半乳糖醛酸含量11.4%）和低甲氧基（P29；酯化度：28.6%；块状度：31.1%；半乳糖醛酸: 70%) 果胶与豌豆分离蛋白的最佳混合比（4:1 豌豆分离蛋白对 P90；10:1 豌豆分离蛋白对 P29）在与复合过程中关键结构形成事件相关的 pH 值下进行评估（可溶性络合 (pHc)，pH 6.7 和 6.1；不溶性复合物形成 (pHφ1)，pH 4.0 和 5.0；最大络合 (pHopt)，pH 3.5 和 3.8；复合物溶解，pH 2.4 和 2.1；分别用于豌豆分离蛋白-P90 和豌豆分离蛋白-P29 的混合物）。豌豆分离蛋白的溶解度在 pH 6.0 时因 P90 的存在而从 41% 提高到 73%，并且在 pH 4.0 和 pH 5.0 时，P90 和 P29 也分别适度增加。在所有临界 pH 值下，两种豌豆分离蛋白-果胶复合物的乳液稳定性均高于均质豌豆分离蛋白，除了 pHopt 和仅豌豆分离蛋白 P29 的 pHc。与豌豆分离蛋白-P29 或单独的豌豆分离蛋白相比，P90 具有更高的块状和酯化水平，在与豌豆分离蛋白复合时，在最大复合 pH 下表现出更好的发泡性能。然而，在 pHφ2 时，豌豆分离蛋白-P29 混合物产生的泡沫具有 100% 的稳定性，豌豆分离蛋白的泡沫稳定性提高了 85%。