The science of vinegar. Part 1. About tastes and vinegar as a process.

A variety of vinegars is not limited to balsamic, Apple and wine.
Find out what you need to create your own (e.g. celery) and how to insist it.
Review.
Vinegar production is the study of methods and ways of interaction of ingredients and microorganisms, as a result of which interesting, pleasant and complex tastes are born. In the article, we describe the fermentation processes and the ways that acetic bacteria manipulate their environment and thereby preserve, transform and complicate tastes. Necessary components of acetic fermentation: acidic liquid containing ethyl alcohol (from 5 to 18 percent by volume), acetic bacteria and oxygen. The mixture can be saturated with oxygen actively or passively. The passive method is more traditional-all other things being equal, the ratio of the surface area to the volume determines the fermentation rate. The active method involves saturating the mixture with oxygen using a device such as an aquarium pump, which allows you to complete the fermentation for 4-5 days. There are also industrial vinegar tanks capable of producing finished vinegar in a matter of hours.
This short series of posts focuses on vinegar. Immediately there is a reasonable question: "why the hell, in fact, to experiment with vinegar?"
One of the stated goals of our laboratory is “to study the components of Nordic cuisine, examining old and new ingredients and techniques, developing knowledge and ideas for the Nordic region and the world.”
Here are the main areas of our interests:
The study of the ingredients: the study of new and old Scandinavian ingredients (Scandinavian like the place of origin and belonging to the traditional cuisine) and their diverse applications – both raw and processed.
Study process: the study of the history of fermentation, especially the traditional ethnomycology, and figuring out ways to adapt these processes to modern realities and products.
Studying tastes: expanding both the vocabulary and grammar of the tastes we have to work with in the kitchen. In other words, the study is not only the variety of flavors at our disposal, but also our understanding of the possible flavor combinations. If you borrow terminology from artists, you can also talk about the palette and aesthetics.
Vinegar production combines all these directions: how the process is applied to a wide range of ingredients and transforms their taste, preserving the essence. It also creates acidity, which we, being in a climate deprived of citrus, can only welcome.
The basis of making vinegar is simple:
Acetic bacteria + alcohol + air - > vinegar
In the past, the Nordic food Laboratory conducted several experiments with rapid prototyping of unconventional vinegars. We took this iterative process to a new level by developing vinegars and immediately exposing them to sensory and chemical analysis techniques. Through this method, we hope to learn what happens in the process of making vinegar, how best to apply our method to the ingredients that we have, and how to incorporate the knowledge of taste chemistry into a subconscious, intuitive understanding of taste. In a broad sense, our goal is to strengthen the dialogue between culinary and scientific approaches to the study and development of products and techniques.

Microbiology and Engineering
At the Nordic food Laboratory, we are inspired by processes from around the world that use microorganisms, especially fungi and bacteria, to transform, preserve and deepen tastes. Each type of microorganism consumes and uses for life a particular source of nutrients (also called a substrate), which it metabolizes into substances such as alcohol, sugar, lactic acid and aromatic compounds and requires specific conditions such as the presence or absence of oxygen for survival.
The microorganisms of greatest interest for vinegar production-acetic bacteria-consume ethyl alcohol and oxygen and produce acidic, caustic, volatile acetic acid, which gives vinegar its unique taste. These naturally occurring bacteria sometimes ferment alcoholic liquids into vinegar spontaneously, without any human intervention, as sometimes happens in wineries when the barrels “deteriorate”. We can use this to our advantage, creating acidic, alcoholic, well-ventilated conditions in which they will thrive. Basically adding a portion of raw or unpasteurized vinegar as a starter to alcohol and providing access to plenty of oxygen. That's how we make vinegar.
Often, the creation of new foods, especially those requiring fermentation, begins with a study of the Microbiology of older products (in this case – the classic grape vinegars) and figuring out what conditions and parts of the process (salinity, acidity, oxygen enrichment and the ratio of surface area to volume) are most important, followed by the use of these methods in new ways that may not be obvious immediately.
Speaking practically and empirically, the main components of vinegar fermentation are a slightly acidic liquid containing 5 to 18 percent ethyl by volume, acetic bacteria and oxygen.
Unlike dairy fermentation, which is ideal for low-oxygen conditions like "under the marinade" or in a container with (hydro), acetic bacteria need oxygen to work. We can aerate vinegar passively, just leaving the container outdoors, covering it with a cloth or something similar to protect against insects, and get ready-made vinegar for 1-4 months.
Vinegar you can get faster if it is actively aerated. Some industrial producers achieve this by running proto-vinegar through chips, which thanks to its large surface area contribute to the complete fermentation of vinegar in a matter of days. Other approaches use turbine-like devices to run air through huge containers and can turn alcohol into vinegar in less than 20 hours.