Combined Acid-enzymatic Hydrolysis of Plant Waste to Obtain Nutrient Media for theCultivation of Yeast Rhodosporidium diobovatum

This study aims to establish an efficient and eco-friendly approach to beet pulp processing through the integration of acid and enzymatic hydrolysis and to explore the potential for cultivating Rhodosporidium diobovatum yeast on the resulting hydrolysate.The combined acidenzymatic hydrolysis of beet pulp produces hydrolysates containing approximately 80% reducing substances, representing a 40% increase compared to hydrolysates obtained via acid hydrolysis using phosphoric acid alone.The optimal conditions for the initial phosphoric acid hydrolysis stage include a raw material particle size of 0.5cm, a temperature of 170C, a reaction time of 10min, an acid concentration of 3% (wt.), a liquid-to-solid ratio (hydromodule) of 5.8, a stirring speed of 100rpm, and a pH range of 5.1 to 5.5.The optimal conditions for enzymatic hydrolysis (the second stage) are a temperature of 48C, a stirring speed of 100min -1 , a pH ranging from 5.1 to 5.5 in the presence of buffer solution, a hydromodule of 8, and a duration of 12h.Fermentolysate is a more favorable nutritional source for the yeast Rhodosporidium diobovatum compared to acid hydrolysate, resulting in a yeast biomass yield of approximately 75% and a residual raw material content of no more than 25-30%.Thus, integrated processing of sugar beet production waste can yield long-term economic and environmental benefits, facilitating the management of large quantities of waste, mitigating the risk of disruption to natural systems, and producing essential biotechnological products.