Development of a High-Yield Process for Scalable Extraction of Beta-Glucan from Baker’s Yeast

There are various methods for extraction of beta-glucan from the yeast with their advantages and limitations. The aim of this study was the development of an easily scalable strategy for the extraction of beta-glucan from baker’s yeast. In this study, alkaline extraction and acid precipitation were used for the extraction of glucan from dried and wet yeasts. Effects of process variables, including NaOH concentrations (0.4, 0.6, and 0.8 M), temperatures (50, 60, and 70 °C), times of cell lysis (3, 5, and 7 h), and stirring speeds (200, 150, and 100 rpm) on beta-glucan extraction were investigated using 3-L stirred tank and Taguchi design. Proteinase K, NaOH, and lysis time were used to decrease protein impurity of the produced beta-glucan. Purities of the beta-glucan extracted from dry and wet yeasts included 39 and 43% (p ≤ 0.05). Results showed that by increasing cell lysis time from 2 to 4 h, the purity of beta-glucan increased from 43 to 51%. The concentration of NaOH of 82.42 % w/v (82.42 g in 100 mL of distilled water) caused the highest effect on beta-glucan extraction. In optimum conditions (NaOH concentration, 0.6 M; lysis temperature, 70°C; stirring speed, 100 rpm; lysis time, 7 h), the highest purity of β-glucan was achieved at 85%. The strategy introduced in this report is a scalable low-cost filtration method for the separation of yeast cells by using a 0.5-μm membrane, and spray dryer. The purity of the dried product is 85%, which is suitable for different applications.