Relationship Between Structure and Solubility of (1?3),(1?4)-β-d-Glucan from Barley. Masayuki Izawa, Yukinobu Kano, and Shohei Koshino, Brewing Research Laboratories, Sapporo Breweries Ltd., 10 Okatohme, Yaizu-shi, Shizuoka 425 Japan. J. Am. Soc. Brew. Chem. 51:0123, 1993.

The relationship between structure and solubility of barley β-glucan was clarified using a pyridylamination (PA) method. After fractionation of barley β-glucans by gel permeation chromatography, we investigated the difference in structure of several barley β-glucans, which had the same molecular weight distribution but different solubilities. Oligosaccharides released from barley β-glucan by lichenase were labeled by the PA method, followed by high-performance liquid chromatography (HPLC) fluorometric analysis. The PA method enabled us to analyze small amounts of insoluble hydrolysates of more than 9 degrees of polymerization using HPLC. The presence of blocks of up to 14 adjacent β-(1?4)-linkages in barley β-glucan were recognized. Results suggested that longer blocks of contiguous cellotriosyl residues separated by single β-(1?3)-linkages in barley β-glucan were more responsible for the insolubilization than were the longer blocks of adjacent β-(1?4)-linkages. Moreover, we examined the solubility of several barley β-glucans that had different structures. The results supported the above-mentioned consideration.

Keywords: Barley β-glucan, HPLC, Precipitate, Pyridylamination, Solubility, Structure