ИСТИНА

Sugar molasse is among the amplest waste generated during processing of sugar beet and cane. Molasse is characterized by a high concentration of organics (carbohydrates, up to 30–50 %) and the presence of melanoidins, recalcitrant dark colored substances. Although different avenues for treatment of the molasse waste were considered, the comprehensive approach to its valorization is still missing. We tested the combination approach to the conversion of beet sugar molasse into protein-rich biomass by means of its sequential inoculation with yeast (Saccharomyces cereviseae) and microalgae (Tetradesmus obliquus, Chlorophyta) cells. The efficiency of the molasse biotreatment was monitored in terms of biomass accumulation, carbohydrate consumption, and discoloration of the molasse as function of dilution and incubation time. Both sequential inoculation and incubation with yeast (7d) and/or microalgae (14 d) facilitated the removal of carbohydrates (30–50% over 7 days) but the removal of melanoidins (discoloration of the molasse) was observed only in the presence of microalgae. A moderate dilution of the molasse (8-16 times, ensuring the 30% transparency of the molasse in the orange-to-red range of the visible part of the spectrum) was sufficient for its efficient biotreatment of the molasse with the microalgae in combination with yeast. The presence of photosynthetic microorganisms (microalgae) turned to be essential for discoloration of the molasse. Efficient removal of carbohydrates has been achieved with sequential treatment of the molasse with yeast and microalgae provided that the molasse is sufficiently diluted to allow penetration of light to the microalgal cells.