Optimised methodology for carboxymethylation of (1→3)‐β‐d‐glucan from Yeast (Saccharomyces cerevisiae) and promotion of mechanical activation

Summary With a view to utilise yeast (1→3)‐β‐ d ‐glucan as biological response modifiers with better water solubility, carboxymethylation was carried out by a two‐step alkalisation and etherification with monochloroacetic acid. Four technological parameters of carboxymethylation were investigated by orthogonal experiments for obtaining the maximum degree of substitution ( DS ), apparent viscosity (η) and solubility of carboxymethyl derivatives. In view of the orthogonal analysis, the optimal technological parameters were reaction temperature 50 °C, total reaction time 5 h, 3 mL of 50% sodium hydroxide as the second alkali dosage and 15 mL of 4 m chloroacetic acid. In addition, it was found that ball milling pretreatment for original (1→3)‐β‐ d ‐glucan can be an advantage for carboxymethylation. By contrast, DS , η and solubility of carboxymethyl product increased 24%, 6% and 22%, respectively, suggesting the effect of ball milling pretreatment could not be neglected on improvement of DS , η and solubility for carboxymethyl products.