Abstract: A control arrangement for a two-stage submerged vinegar fermentation process for producing vinegar with a high acetic acid concentration of more than 15% is disclosed. The fermentation system includes a main fermentation tank and a secondary fermentation tank, a connecting line with a shut-off valve and a feed pump incorporated therein extending between the two tanks, separate mash and alcohol feed lines with incorporated feed pumps connected to the main fermentation tank, and a vinegar discharge feed line with an incorporated feed pump connected to the secondary fermentation tank. The control arrangement includes an alcohol analyzer and a liquid level sensing device on each of the tanks, a volume flowmeter incorporated in the alcohol feed line, and a controller for each of the tanks.

Abstract: A novel two-stage submerged fermentation process for producing vinegar with an acetic acid concentration of more than 15% is disclosed. In the first fermentation stage, the total concentration (i.e. the sum of the alcohol and acetic acid concentrations) increases from a starting level between 12 and 15% to a level above 15%, generally between 15 and 17%, but the acetic acid concentration is not permitted to exceed 15% while the alcohol concentration is maintained between about 1 to 5%, whereby both bacteria multiplication and acidification take place in the fermenting liquid. In the second fermentation stage, the total concentration is maintained constant but the acetic acid concentration is permitted to rise above 15% while the alcohol concentration drops almost to zero, whereby mainly acidification will occur while bacteria multiplication decreases and stops. The second stage is terminated when the desired acetic acid concentration above 15% is reached.

Abstract: Liquids containing microorganisms, macromolecules or finely-divided solid matter in a liquid are filtration-concentrated by movement of the liquid containing such particles through an elongated tubular channel having membrane filters, as walls thereof, with flat surfaces and pore diameters between 10.sup..sup.-2 mm and 10.sup..sup.-4 mm, preferably 2.times.10.sup..sup.-4 to 3.times.10.sup..sup.-4 mm. Laminar flow is maintained at the filter surface and forced transverse movement of contained particles into the filter is provided through a moderate static pressure head. The particle movement is in some embodiments supplemented by heavier particles used to transfer momentum to particles to be filtered thereby. Clogging of the filters is thereby reduced with resultant longer service life and longer intervals between filter maintenance or replacement.