Optimization for detection conditions of β-1,3-glucan and β-1,3-1,6-glucan by Congo red method

In order to quickly and efficiently detect the contents of β-1,3-glucan and β-1,3-1,6-glucan produced by microorganisms, the reaction conditions of Congo red method were optimized by single factor tests and response surface tests, and the methodology was investigated. The results showed that the optimal reaction conditions were Congo red mass concentration 0.2 g/L, reaction temperature 20 ℃, time 35 min, and pH 7. Under the optimized reaction conditions, the absorbance values of β-1,3-glucan and β-1,3-1,6-glucan were 0.645 and 0.734 respectively. The detection limits and quantification limits of the two glucans were 0.1 g/L, 2.0 g/L and 0.1 g/L, 0.8 g/L, respectively. The relative standard deviations (RSDs) of precision test results of the two β-glucans were 1.09% and 1.15%, the average recovery rates were 99.6% and 100.74%, and the RSD of recovery rates test results were 2.27% and 2.94%, respectively. The results showed that the Congo red method had good precision and accuracy, and was suitable for quantitative analysis of two β-glucans produced by microorganisms.