Acetic Acid Fermentation of Soybean Molasses and Characterisation of the Produced Vinegar
1Department of Food Science and Technology, Londrina State University, Celso Garcia Cid (PR 445) Road, 86057-970, Londrina, PR, Brazil
2Embrapa Soybean, Carlos João Strass Road, 86001-970, Londrina, PR, Brazil
Received: 17 March 2019
Accepted: 3 February 2020
vinegar, acetic acid fermentation, soybean molasses, by-product of soybean processing
Soybean molasses is a by-product from the production of protein concentrate fromsoybean meal that predominantly contains sugars, with sucrose as the major component.In Brazil, soybean molasses is used for animal feed or it is discarded, although some industriesuse it to produce ethanol. This study aims to evaluate the parameters required forthe acetic acid fermentation of soybean molasses, and characterise the resultant vinegar.To study the most suitable parameters for the acetic acid fermentation, vinegar was producedfrom the alcoholic fermentation of soybean molasses through eight fermentationcycles: five for adaptation and three for production. The average acidity of the acetic acidfermentation product was 50.60 g/L, with an acetic acid fermentation yield, total yield ofacetic acid in broth and productivity 65.01 %, 92.76 % and 0.033 g/(L·h), respectively. Thevinegar produced from soybean molasses had an acidity of 5.07 % (m/V), residual ethanolcontent 0.17 % (m/V), sugars 7.86 % (m/V), dry extract 14.67 % (m/V), ash 2.27 % (m/V)and a density of 1.023 g/cm3. The contents of total phenolics and isoflavone decreasedafter the alcohol and acetic acid fermentations. Moreover, the isoflavone profile of thefermented product comprised only three forms: daidzein, glycitin and genistin. Accordingto our results, 3460 L of vinegar can be produced for every tonne of soy molasses, with anacetic acid concentration of 40 g/L, the minimum required by the legislation on vinegarproduction. Thus, these findings demonstrate that soy molasses represents a useful rawmaterial for the production of vinegar.