Vinegar is the product of a two-step fermentation process involving the alcoholic fermentation of sugars into ethanol by yeasts, and, subsequently, the oxidation of ethanol into acetic acid by acetic acid bacteria (AAB). Vinegar has been renowned as a food preservative since ancient times and is still used today in the food industry as a highly sought-after
condiment and a multi-functional product utilized for pickling, preserving and flavor-balancing purposes (Sengun and Karapinar, 2004; Steinkraus, 2002). All raw materials containing sugar or fruits can be employed as starting substances for producing vinegar.Several different types of vinegars are produced around the world by using diverse
manufacturing techniques and raw materials native to specific areas.In general, two well-defined methods, namely, slow surface culture fermentation and fast submerged fermentation, are used in vinegar
manufacturing(Tesfaye et al.,2002). The slow method is also called traditional vinegar production and the AAB grow on the surface of the liquid during the fermentation process, which may take from several
weeks up to a few months (Nanda et al., 2001). A non-toxic film composed of AAB and cellulose accumulates on the surface of the vinegar throughout the oxidation process. This film, called “mother of vinegar”,is used in the back-slopping practice as an indigenous starter culture to trigger acetification in the production of traditional vinegar