Previous study by the authors showed that an alternative process to an airlift fermenter in the
green vinegar production process could use a loofa sponge (a natural agricultural fibrous material) as
the supporting material for Acetobacter aceti WK. Subsequently, aim of this study was production of
green vinegar in a stirred tank reactor (STR). The filtered corn wine was supplied to the STR using
fixation of A. aceti WK cells on the surface of a loofa sponge cut to a thickness of 2.5 cm. The loofa
sponge was left in the STR until 60% of fermenting volume had been used. The charging rate of fresh,
filtered corn wine for a semi-continuous production process was investigated. The highest acidification
rate (ETA) was achieved at a charging rate of 30%. After 14 d of the adaptation period, the average
acidity of 4.1±0.1% was produced during six cycles of fermentation at 30°C and 1vvm aeration supply
within 40 d, while the ETA was in the range 0.0028%/h to 0.0067%/h. Scanning electron microscopy
(SEM) showed that the surface of the loofa sponge acted as a good fibrous structure for cell fixation of
A. aceti WK in the STR.