The ultrasonic mixing technology is used in manifold ways in food and beverage industry. Hielscher Ultrasonics found a new application in the field of food processing: The sonication of vinegar, which is an important condiment in cuisine.
The production of vinegar (e.g. balsamic), especially of high quality products as balsamic vinegar, is a time-consuming manufacturing process. Vinegar, an acidic liquid, 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 + O2 → CH3COOH + H2O
The acetic acid concentration varies between 4 – 8% for table vinegar and increases up to 18% for pickling vinegar. Hielscher Ultrasonics tested the effects of ultrasound on vinegar. When vinegar 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 which can be used in the cuisine to make fine delicious meals. Vinegar is a favoured 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 flavored after the oxidative fermentation 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).
Aging 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 manufactured 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’). To achieve a satisfying result of oak flavoring, normally the oak chips have to remain minimally 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.
In the food industry, ultrasound is 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: The ultrasound technology is also an efficient method of emulsifying. This application is helpful in vinegar manufacture if e.g. caramel color should be 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.
Since Hielscher’s ultrasonic devices have a very high energy efficiency in converting electricity into cavitation within the liquid, the costs of ultrasonic treatment for vinegar are low. For vinegar, an energy input of 10-20 watts per milliliter is sufficient to achieve the desired effects. Hielscher Ultrasonics offers safe, reliable and efficient ultrasonic devices for non-thermal food processing.