Surface activity of ultrahigh methoxylated pectin of different size. (April 2021)

• Record Type: Journal Article
• Authors: Hua, Xiao; Liu, Jinran; Guan, Shuyi; Tan, Jing; Wang, Mingming; Yang, Ruijin
• Is Part Of: Food hydrocolloids. Volume 113(2021)
• Publication Date: 2021-04
• Subjects: High methoxylated pectin -- Hydrolysis -- Molecular weight -- Surface activity -- Critical micellization concentration -- Grease-removing power; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2020.106495
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: Ultrahigh methoxylated pectin (UHMP), which is of moderate molecular weight (MW, ~150 kDa) and high methoxylation degree (DM, >90%), is a novel surface-active material. To investigate the effect of MW on the surface activity of UHMP, four small UHMPs (MW = 85.90, 67.01, 41.24 and 27.24 kDa) of low MW and DM values above 90% were prepared via enzymatic hydrolysis using commercial polygalacturonase. Low MW UMHPs can reduce the water surface tension to ~45 mN/m, which corresponds to a larger reduction than that of UHMP (~55 mN/m). Moreover, their critical micellization concentration was increased to 1–3 g/L. Surface excess and molecular area data suggested that a suitable reduction in MW enhanced the absorption of UHMP at the O/W interface. However, the analysis of interfacial rheology showed that an interfacial film could not be formed when the MW of UHMP was reduced to 20–40 kDa. In view of the improved surface activity, the grease-removing power (GRP) of each of the UHMPs was measured and compared with that of citrus pectin (CP). The GRP of CP was 79% at 1.0 g/L, and this value was decreased to ~20% when the CP concentration exceeded 4.0 g/L due to pectin aggregation. With reduced MWs, the UHMPs presented substantially higher GRP values (80–90%) than CP, especially at concentrations of 4.0–10.0 g/L. Increasing the temperature (45 °C) can effectively increase the GRP of each pectin. However, small UHMPs still reached larger GRPs (85–95%) than UHMP (75–90%) and CP (90% at <2.0 g/L, ~40% at >2.0 g/L). The experimental results suggested that MW can significantly affect the surface activity of UHMP. UHMPs of various sizes have diverse potential applications, for example, as edible films and surface-active materials in daily chemicals. Graphical abstract: Image 1 Highlights: Ultrahigh methoxylated pectin of high DM>90% and various sizes (27, 41, 67, 86 kDa). Low surface tension (45 mN/m) and high critical micellization concentration (1~3 g/L). Improved pectin absorption at interface due to proper reduction in molecular weight. Fail to form interfacial film with overreduced pectin molecular weight of 20–40 kDa. Good grease-removing power (80–90%) at 4.0–10.0 g/L due to proper molecular weight.