RDE Abstract of Completed Research
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Sugar and Co-Products Utilization / Alcohol
Acetic acid from alcohol
Rosemarie S. Gumera and Rosita P. Ebron
Batch fermentation of alcohol tailings into acetic acid was studied using both submerged and surface fermentation processes. Surface fermentation in glass bottles gave an optimum yield of 86% at peak acidity of 8.7% acetic acid from an initial acidity of 3.6% for a fermentation period of forty-nine (49) days or seven (7) weeks. Its initial alcohol content is 5% with theoretical equivalent of 6.5% acetic acid.
Submerged fermentation was conducted in two (2) different types of apparatus; an Erlenmeyer flask with bubbler and a fermentor with stirrer. Submerged fermentation in an Erlenmeyer flask gave an optimum yield of 53% at a peak acidity of 4.6% acetic acid from an initial acidity of 3.4% for a fermentation period of three (3) days an initial alcohol content of % equivalent to 5.2% acetic acid.
Submerged fermentation in a stirred tank fermentor gave a maximum yield of 65% at a peak acidity of 6.2% from an initial acidity of 3.0% for a fermentation period of six (6) days. Initial alcohol content of 5% equivalent to 6.5% acetic acid.
Only dilute, edible acetic acid can be produced from the biological fermentation of alcohol. Surface fermentation of alcohol into acetic acid was found to be economically feasible and is recommended for a small scale production, either home business venture or village type of production whereas submerged fermentation in a stirred tank fermentor showed a low return on investment and is not comparable to the Frings acetator commonly used by vinegar manufacturers that produces a high strength acetic acid for a shorter fermentation period. Improvement in the design of the stirred tank fermentor available in our laboratory such as that of the Frings acetator might increase the yield and return of investment. The nutrients that were formulated can be adjusted to get optimum results based on the new design of the fermentor or acetator.
Dilute acetic acid can be concentrated by freezing and the percent increase in acidity ranges from 85-97%.
