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Nanomaterials have made it into wine-making. The "NAVINO" project advances the possibilities of wine fermentation.

Lukáš Dvořák and his team from the Department of Environmental Technology CXI TUL have been hard at work investigating collection, conservation and use of yeasts for wine fermentation directly in the vineyards. Their unique solution combines the latest know-how from nanomaterial engineering with traditional winemaking techniques in order to pour "pure wine" and fully enjoy its authentic terroir character.

Chief and Expert. Lukáš Dvořák (on the right) and Karel Havlíček (on the left) are teammates.

When did you first experience wine? How did the idea for such project come about?

Naturally, I first experienced wine, let us say tasted it, the day after my 18th birthday :-) The idea for our project with the working title "Na vino" arose in close cooperation with EPS biotechnology Ltd., which we have long-term cooperation with on other scientific research (R&D) projects. Since EPS biotechnology Ltd. has strongly focused on research into advanced biotechnologies including viticulture and brewing in recent years, "Na vino" is the first project that combines the latest know-how from nanomaterial engineering with traditional winemaking methods. We are trying to advance both fields and innovate in a hitherto unknown direction. In order to do that we want to develop two technological solutions for modern wine production. Specifically, carriers suited for the collection of yeasts directly in the vineyards, their conservation and subsequent use in the fermentation of grape must and wine.

What is the basis for handling of wine yeasts?

Our work is primarily focused on yeasts that occur naturally in vineyards. These are often somewhat more sensitive than their "industrially" cultivated relatives, so we try to "indulge" them through nanofiber carriers in the most suitable environment, i.e. in addition to the nanofibers, specific substances preferred by yeast are incorporated into the structure of the developed carrier, thus strengthening the colonization effect. We do not interfere with the properties of yeast itself, on the contrary, we try to preserve it as much as possible. Due to the fact that we "collect" them directly from vineyards and from specific varieties it is possible to obtain specific and unique wines that reflect the influence of the vineyard, variety and "terroir" in comparison to "industrially“ cultivated yeast.

How are the biomass carriers formed?

First of all, it is necessary to specify which microorganisms forming the biofilm we want to support in their growth, which type of environment and for what purpose we want to have them on our carriers. Then we proceed to the selection of a suitable material (the structure of the surface is especially important), its shape and the overall architecture of the carrier. Different types of microorganisms are characterized by a close connection to a certain type of environment, which we take into account in the development of biomass carriers especially in the testing phase. It is the testing of carriers in a defined environment and monitoring of the growth of biofilm using modern methods such as molecular genetics and respirometry that tells us whether we have chosen correct parameters of the carrier. If the microorganism does not "like" the carrier for some reason, we must either modify its 3D structure, add suitable additives, or choose other materials and such.

Which two solutions are you developing for winemakers?

We are developing 2 types of nanofiber yeast carriers for viticulture, which will serve to streamline two different processes. The first (so-called prospecting carrier) will be used to capture or collect wine yeasts located directly in the environment of the vineyard. This seems to be very promising and with high application potential, because a lot of emphasis has been placed on "terroir" wines lately. Additives and high affinity of the material and yeast guarantee a very efficient and optimal collection of only the required microorganisms directly in the real environment of the vineyards, which can then be transferred to the cellar, or used for fermentation of wine must and subsequent wine production.

The second type of carrier (so-called preservation / inoculation) will serve winemakers for the gentle preservation of wine yeasts and their subsequent use for inoculation processes, i.e. again for the preparation of preferment and fermentation of grape must itself. It is necessary that the selected carrier material and its modifications provide a very friendly environment for wine yeasts, i.e. maintain their good physiological condition throughout the preservation period, while meeting the requirements for easy handling. Of course, the used materials must in no case affect the character of the wine, in particular its organoleptic characteristics, i.e. bouquet, aroma and color.

 How will these solutions be different from current technologies? What kind of "novelties" will it enable“? 

The type of nanofiber biomass carriers developed by us for wine-making purposes is not used anywhere in the world, it is a completely new and unique solution. Thanks to their specific properties, nanofiber carriers will serve to streamline work with wine yeasts. This could have a positive impact not just on the efficiency of winemaking processes, but also on the quality of wine itself, underlining its character and the specific bouquet that is characteristic of the variety, the area and the winemaking process. However, this will only become clear after a series of tests that will better explain the results of our efforts ... As the saying goes: "In wine, there is truth!"

Who do you develop the carrier with?

We cooperate very intensively on the development with a partner company EPS biotechnology Ltd., which is in charge of the "wine" part, including testing the organoleptic properties of the wine. This is also very important, as the (nano) materials used must in no way affect the character of the wine. Guided tastings are also an essential part of the project. The task of professional evaluators is to find out whether the character of the wine has not been influenced by the use of the developed (nano) materials. The company Nanopharma is also involved in the development of nanofiber carriers in the form of a subcontract. They are helping us with the incorporation of selected additives into the nanofiber structure in order to support the suitable carrier surface properties for wine yeasts which they directly require. It is a very comprehensive cooperation of experts from several fields.

How challenging is this development? Could such research get you drunk? ;)

The development of nanofiber carriers is very interesting to us and sometimes also intricate. Only now it is fully apparent the challenge we are actually facing. New contexts which we did not even think about when planning and preparing the project have been emerging, but it is absolutely normal when dealing with the solution of quality projects. It is also one of the reasons we are deeply interested in the investigation, and, above all, the cooperation with all partners is absolutely professional. Maybe it's also due to the fact that we are starting to have the solution within reach, moreover, clearly imaginable and graspable and in this particular case also tastable, which undoubtedly significantly increases motivation :-) Could such research get us drunk? Of course, it could ... as the development moves in the right direction, it will intoxicate us with the knowledge and joy of a job well done, and hopefully it will soon reward us with the final product :-)

Electron microscope image illustrating the surface structure of a nanofibrous carrier made of polyvinyl butyral by AC electrospinning (alternating current electric field spinning).

Measurement of the contact angle of the nanofiber carrier surface. It is one of the basic parameters that shows the potential affinity of yeast for the developed nanofibrous carrier. Said surface is hydrophobic.

Surface structure of a nanofibrous carrier taken with a confocal microscope.

The fluorescence microscope captured a time sequence in the range of 0 - 3 - 20 hours in which the yeast colonized the surface of nanofibrous support. The picture shows how the individual adherent cells first grow into clusters, and only then form a continuous layer.

Optimization of the nutrient component composition used as additives in nanomaterials for the production of carriers. The area shows the growth response of yeast to different concentrations of individual additives. The red dot highlights the maximum growth that corresponds to the optimal composition of the nutrient component.

29. 6. 2021