Non-starch polysaccharides in commercial beers on China market: Mannose polymers content and its correlation with beer physicochemical indices

Abstract Mannose polymers are important non-starch polysaccharides in beers. In this study, thirty-six beer samples representing three categories based on materials, including all barley malt beer, barley malt with adjuncts beer and wheat beer, were selected to investigate the content as well as its correlation with beer physicochemical indices, degree of polymerization, molecular weight and existent form of mannose polymers. The results suggested that mannose polymers level was significantly high in the wheat beer (156.76 mg/L and 456.50 mg/L calculated as mannan and glucomannan, respectively). Degree of polymerization was 23–47 and 46–162 calculated as mannan and glucomannan, and the molecular weight was 3,744 - 7,632 Da and 7,470 - 26,262 Da, respectively. Average ratio of glucose to mannose in glucomannan was between 1.79 and 1.93 without significant difference among three groups. Mannose polymers possibly exist in mannan, glucomannan or both. The content had significantly positive correlation with the original extract and viscosity of beers. Their correlation coefficients indicated more important influence on beer viscosity than β-glucan. This preliminary study would be helpful for revealing the structure of mannose polymers and its effect on beer brewing as well as human health.