Effect of metal ions and pH on the emulsifying properties of polysaccharide conjugates prepared from low-grade green tea. (May 2020)

• Record Type: Journal Article
• Authors: Han, Yu; Cheng, Zhe; Zhang, Yuntian; Zhang, Ni; Zhu, Xiangwei; Chen, Xiaoqiang; Shao, Yundong; Cheng, Yong; Wang, Chunpeng; Luo, Yayuan; Zhu, Lin; Xie, Jianchun; Wang, Chengtao; Huang, Youyi
• Is Part Of: Food hydrocolloids. Volume 102(2020)
• Publication Date: 2020-05
• Subjects: Tea polysaccharide conjugates -- Emulsion -- Stability; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2019.105624
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: Polysaccharide conjugates were water-extracted from low-grade green tea; this extract was designated as TPC-W. Various concentrations of TPC-W (0.5, 1.0, 1.5, 2.0, and 3.0 wt%) were then used as an emulsifier stabilize to oil-in-water emulsions prepared using medium chain triglycerides. The emulsion stabilized using 2.0 wt% TPC-W remained relatively constant during 10 days of storage at 25 °C, with the mean particle diameter (MPD) ( d 32 ) and zeta potential increasing from 1.8 to 2.4 μm and from −19.8 to −18.9 mV, respectively. The effect of metal ions (Na +, Ca 2+, and Al 3+ ) and the pH value on the stability of the 2.0 wt% TPC-W emulsions was also studied at 25 °C for 10 days. The system remained stable at Na + concentrations between 0.10 and 0.50 mol/L and Ca 2+ concentrations below 0.030 mol/L, with little change in the MPD ( d 32 ) of the emulsion droplets. When Al 3+ was added to the emulsion system, the MPD ( d 32 ) of the emulsion changed significantly; the addition of 0.001 mol/L Al 3+ increased the MPD ( d 32 ) from 2.2 to 5.8 μm. The MPD ( d 32 ) of 2.0 wt% TPC-W emulsions with pH values of 2.0–4.0 increased significantly during the storage period, but remained stable for emulsions in the pH range 5.0–8.0. The results revealed new applications of TPC-W extracted from low-grade green tea as an emulsifier. Graphical abstract: Image 1 Highlights: TPC-W prepared from low-grade green tea has emulsification ability. TPC-W emulsions kept stable at concentrations of 0.10–0.50 mol/L Na +, Ca 2+ below 0.030 mol/L, and pH values of 5.0–8.0. TPC-W strongly stabilized the emulsions, which supports their new application as natural emulsifiers.