Optimizing endopectinase production from date pomace by Aspergillus niger PC5 using response surface methodology

In the first stage of experiments, a two-level fractional factorial design was used for screening of the most important factors among concentration of ammonium sulfate, potassium dihydrogen phosphate and date pomace, pH, total spore amount, aeration rate and fermentation time for the production of endopectinase from date pomace by Aspergillus niger PC5. Based on the results of first stage, ammonium sulfate (0.25–0.45%), pH (4.82–6.12) and fermentation time (50–90 h) were selected to be studied further. In the second stage, response surface methodology was used to determine the optimum fermentation conditions for production of the enzyme. Second stage results showed that, fermentation time was the most significant factor on endopectinase activity. After modeling of the fermentation process, maximum amounts of endopectinase (10.88 U ml−1) predicted to be in the following fermentation conditions: pH of medium 5, ammonium sulfate concentration of 0.3% and fermentation time of 76.05 h.