2.3. Ethanol and acetic fermentation
Alcoholic seed broth was prepared through the fermentation of S. cerevisiae in
coconut water, coconut sap and pineapple juice with the inoculum size of 1%
(v/v). The inoculated substrate was incubated for 7-10 days at room temperature
under static condition prior using it as a seed medium for acetic acid fermentation.
After that, 10% of A. aceti stock culture was inoculated into the seed broth and
incubated at the room temperature under static condition for 2 months. Samples
were withdrawn at 1 month interval to quantify acetic acid concentration through
titration assay. Proximate analysis was performed on all produced vinegars to
obtain its profile.