Phytosterols from pressmud residue obtained after methanogenic fermentation

Summary Pressmud, a sugar factory waste, was fermented with methanogenic bacteria in an anaerobic fermenter for 40 days at 31±2°C. The pressmud residue obtained after fermentation was used as a source for the extraction of phytosterols. The anaerobic digestion degraded the organic matter and resulted in enrichment of phytosterols from 0.33% in the pressmud to 3.05% in the residue. Refluxing of 100 g of residue with benzene, petroleum ether, and ethanolic KOH (1051) yielded 8 g of soft cake, which on further fractionation with methylcyanide and isopropanol gave three fractions: 1) a crude mixture of phytosterols, 2) resin, and 3) undigested organic matter. The crude mixture of phytosterols after purification on neutral alumina followed by GLC analysis resulted in the separation of 68.7% of -sitosterol, 18.4% of stigmasterol and 12.9% of campesterol and brassicasterol together. Phytosterols were extracted more easily from fermented than from unfermented samples, because of biodegration of lipophilic compounds by the methanogenic bacteria.Acknowledgments. S.K.S. and J.C.S. are thankful to the authorities of the U.G.C., New Delhi, for the award of Teacher-fellowships. R.C.S., R.A.K.S. and D.K.M. are thankful to the authorities of the C.S.I.R., New Delhi, for providing R.A., S.R.F., and J.R.F., respectively. Reprint request to S.N.M.