Ultrasonics in Vinegar Manufacturing and Aging

Vinegar, such as balsamic is an important condiment in cuisine. Hielscher ultrasonic devices are used for many processes in the manufacturing and maturation of vinegar.

Background on Vinegar Production

The production of vinegar, especially of high quality products, such as balsamic vinegar, is a time-consuming manufacturing process. Vinegar is an acidic liquid that is produced by oxidation or rather fermentation of ethanol. The mother of vinegar, a substance of cellulose and acetic acid bacteria, generates the vinegar turning alcohol into acetic acid by means of oxygen. This oxidation process produces the acid that gives vinegar its typical sour flavor and lightly pungent smell. The overall chemical reaction by the acetic acid bacteria (acetobacteraceae) is:

C₂H₅OH + O₂CH₃COOH + H₂O

The acetic acid concentration varies between 4 and 8% for table vinegar and increases up to 18% for pickling vinegar.

Ultrasonic Effects in Vinegar

Ultrasonics can be used in the manufacture of vinegar for various purposes. All effects can be easily demonstrated by sonicating a sample of vinegar for few seconds.

Smoother and Less Acidic Taste

In vinegar that has been sonicated, the acidic, sour taste became significantly smoother and tastier. This is an interesting application as there is a high demand for smooth vinegar that can be used in the cuisine to make fine delicious meals. Vinegar is a favored condiment to season salad dressings, meat and fish dishes, sauces, as well as desserts. Specially high grade balsamic vinegar is also savored as aperitif or digestif.

Flavoring of Vinegar

To diversify the common vinegar taste, the vinegar is often flavored after the oxidative fermentation by adding different flavoring substances, such as herbs (e.g. sage, thyme, oregano, tarragon, rosemary, basil), ginger, chili, or fruits (e.g. raspberry, blackberry, orange, mango, lime). Ultrasonically assisted extraction promotes the release of flavors from the cell matrix into the vinegar. Click here to read more about ultrasonic extraction.

Maturation and Oaking of Vinegar

As the maturation and aging of vinegar in wood barrels (such as cherry, chestnut, oak, mulberry, ash or juniper barrels) is very cost-intensive and sumptuous, vinegar is often manufactures in plastic tanks. To imitate the famous wooden flavor of barrel maturation, which is typical for top quality vinegar, vinegar producers add oak powder or oak chips (so-called 'alternative oaking') or wood flavor distillates. To achieve a satisfying result of oak flavoring, normally the oak chips have to remain for at least 4 - 6 weeks in the vinegar so that the liquid can be absorbed by the wood fibers. The use of ultrasound can speed up this process of alternative oaking significantly. Sonicating vinegar with the additive oak powder or oak chips, the highly intensive power of ultrasound and the generated ultrasonic cavitation assist the extraction of the oak flavor. Ultrasound creates alternating high pressure and low pressure cycles which leads to a higher mass transfer between the plant cells and the vinegar. Further, the fine particles of oak powder are very well dispersed in the liquid medium because ultrasound is a very effective means of dispersing.

Ultrasound is in food industry already a well-known method for extraction of flavors. By its highly energetic cavitational forces, sonication breaks cell walls and makes the intra-cellular material available. Since the plant material (wood fibers) becomes broken into smaller particles, more flavoring essences become available to the gustative nerves of the tongue. A second advantage of ultrasound is effective dispersing of solid particles into liquids.

Coloring of Vinegar

Ultrasonics for emulsifying, dispersing and dissolving of colorants in vinegar The ultrasound technology is an efficient method for emulsifying, dispersing and dissolving. This is helpful in vinegar manufacture when e.g. caramel color is added to the vinegar. Caramel color (food additive E150) is one of the oldest and most widley used food colorings. The highly viscous coloring liquid helps to give the vinegar the desired dark brown color.

Application of Ultrasonics

The application of ultrasonics to vinegar manufacturing and aging processes is very simple. In small batch scale - for up to 2L - you can use ultrasonic laboratory devices, such as the UP400S.

For production processing, Hielscher offers industrial ultrasonic devices with flow cell reactors, such as the UIP1500hd. These system work inline, e.g. when you pump from one batch to another.