Optimization of pH and Initial Sugar Concentration for Citric Acid Production using Hydrolyzed Cassava Starch as Substrate

Author : De Guzman, Jocelyn Talavera
Major Adviser : Chay, Pham Binh
Committee Members :
Year : 1991
Month : October
Type : Thesis
Degree: BS
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Using batch process, the effects of pH and initial sugar concentration on citric acid fermentation by Aspergillus niger 3104 were evaluated. Among pH 3.0, 4.0, and 5.0 and initial sugar concentrations of 50 g/l, 100 g/l and 150 g/l, the combination of pH 4.0 and 50 g/l initial sugar concentration gave the highest citric acid production and maximum sugar consumption. The acid produced was 38.23 g/l which is 79.00 % yield sugar consumed and 76.46 % to the total sugar supplied. This optimum condition was applied to hydrolyzed cassava starch fermentation to citric acid. The cassava starch was liquefied using α-amylase and with glucoamylase which hydrolyzed the liquefied starch into simple sugars. The run without pure oxygen supplied gave 47.14 % yield and that with pure oxygen, 65.13 %, both with respect to the sugar utilized. Higher sugar consumption was also observed in the run with pure oxygen supplied. The efficiencies of the fermentations were calculated and served as indices of the performance. The run with pH 4.0 and 50 g/l dextrose concentration gave the highest efficiencies which are 98.75 % and 55.64 % using 0.8 and 1.42 Yp/s, respectively.

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