production of citric acid from date pulp by solid state fermentation

a solid state fermentation method was developed for the production of citric acid from date pulp (obtained of date syrup production from the process) by aspergillus niger ptcc 5010. poor yield was obtained when potassium ferrocyanide treated date pulp were used as substrate, but methanol at a 3-4% concentration markedly increased the forma-tion of citric acid from the waste. the optimum range of ph and moisture for citric acid production were 3.5-4.5, and 70-80% respectively. this method produced about 168g cit-ric acid per kg of date pulp under optimum conditions. on the basis of reducing sugar consumed, the yield was 87% within eight days.