Primary structure of gum arabic and its dynamics at oil/water interface

Noriyuki Isobe; Naoya Sagawa; Yuko Ono; Shuji Fujisawa; Satoshi Kimura; Keigo Kinoshita; Takeshi Miuchi; Tadahisa Iwata; Akira Isogai; Masayuki Nishino; Shigeru Deguchi

doi:10.1016/j.carbpol.2020.116843

Primary structure of gum arabic and its dynamics at oil/water interface

Carbohydr Polym. 2020 Dec 1:249:116843. doi: 10.1016/j.carbpol.2020.116843. Epub 2020 Aug 6.

Authors

Affiliations

¹ Research Institute for Marine Resources Utilization, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, 237-0061, Kanagawa, Japan. Electronic address: isoben@jamstec.go.jp.
² Research Institute for Marine Resources Utilization, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, 237-0061, Kanagawa, Japan.
³ Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
⁴ Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan; Department of Plant & Environmental New Resources, College of Life Sciences, Kyung Hee University, 1732 Deogyeong-daero, Giheung-ku, Yongin-si, Gyeonggi-do 446-701, Republic of Korea.
⁵ San-Ei Gen F.F.I., Inc., 1-1-11, Sanwa-cho, Toyonaka, Osaka, 561-8588, Japan.

PMID: 32933685
DOI: 10.1016/j.carbpol.2020.116843

Abstract

Gum arabic (GA), an arabinogalactan-based gum, is a well-known powerful emulsifier. However, the poor stability of emulsion has often been pointed out. In order to clarify the origin, the structure-property relationship of GA, especially the interfacial property at oil/water interface, needs to be investigated. Here, we tried to correlate the primary structure with interfacial property at oil/water interface. A series of structural analyses by SEC-MALLS, SAXS, etc. showed that the primary structure of GA was a disk-like star shaped nanoparticle. The dynamic interfacial tension measurement showed that GA molecules adsorb onto oil surface in 2 steps: Firstly, the micron-aggregates of GA approach onto the oil surface, and then the aggregates are dissociated into nano-particles so that they cover the oil surface. Therefore, the emulsification and emulsion stability are controlled not by the property of the primary structure of GA but by the higher-order molecular network structure made of GA molecules.

Keywords: (13)C CP/MAS NMR; Colza oil; Dodecane; Dynamic interfacial tension; Emulsion; Gum arabic; SAXS; SEC-MALLS.