20 Oct The quality of wine. Chapter XVII
The seasonal climate trend fluctuated a lot during the 2015-2016 vintage at Case Basse: we had a very warm and wet winter, a very wet spring right up to the start of July, then fortunately some hot weather with very little rain in July and August and the first two weeks of September. This climatic situation, especially the warm winter, has very negative consequences on vineyard health, in fact I saw a return of Esca and also cases of downy and powdery mildew, which I solved with a lot of manual work and great attention to treatments. The bad season can only be dealt with by greater care by the farmer:
- Drastically reducing the bunches, maintaining only the best ones in terms of health and degree of ripening.
- Eliminating the leaves and shoots that block the light and heat from the few remaining bunches.
- Eliminating every bunch affected by mould, dryness or other problems.
- Waiting for the best moment of ripening to harvest the grapes.
- Carrying out a further manual selection, bunch by bunch, in the cellar before destemming the grapes (my experience of 33 harvests, done personally in Montalcino, convinces me more and more that grapes should never be pressed, but only destemmed).
- Subsequent selection, berry by berry, always whole ones.
- In difficult periods, it is useful to carry out constant experiments and studies with universities, which have also followed me this year, teaching me and enabling me to understand and know more than I did in the 2015 vintage: in particular, I have gained new knowledge about fertilising, yeasts, vinification temperatures, leaf management, vines with Esca. Anyone interested in these themes should study “Viticoltura di qualità” (Quality viticulture) by professor Fregoni, “Microbiologia del vino” (Microbiology of wine) by the professors Vincenzini, Farris and Romano, which are, in my opinion, indispensable for anyone who works in or is interested in vinegrowing and wine producing.
The harvest was done before the heavy rains in September and the selection of each whole berry of the desired diameter led to our discarding considerable amounts of grapes, which did not enter the vinification vats.
The vinification in the three vats was the easiest and briefest in my forty-two years of producing wine: very strong-coloured musts with a remarkable abundance of polyphenols, characteristics that I have also maintained in the racked wines. The fermentation was marked by an enormous quantity of Saccharomyces yeasts (over 93 million every millilitre, i.e. 93 billion cells in a litre of must), which worked very well. The Saccharomyces yeasts are responsible for the so-called turbulent stage of fermentation and are able to bring the fermentation process to a close. There are several possible variants to this extremely simplified outline, especially in terms of quantity, because the development and activity of each species depend on numerous factors. In any case, the type of species present, the extent of its development and the persistence of each population in the fermentation process, thanks to the metabolic peculiarities that could be considered species-specific, are all elements that can strongly influence the sensory characteristics of the final product, for better or for worse, it needs to be said. The wines produced via spontaneous fermentation have a more complex aroma and taste than wines made with induced fermentation and are sometimes judged as “great”, with character and personality, and unique. At this stage, it is easy to attribute the origin of the higher complexity to the action of different species of yeasts, combined and/or in succession, and different strains within the same species. In this regard, a study carried out for me by Professor Massimo Vincenzini of the University of Florence on the intraspecific genetic variability of Saccharomyces cerevisiae (145 have been studied, isolated from the spontaneous fermentation of grape musts from a single vineyard during six consecutive harvests, from 1994 to 1999) has brought to light a striking biodiversity, both relatively to each individual vintage and between different vintages: from the total isolates examined, 50 different profiles of restriction of the mitochondrial DNA were obtained, 50 strains out of 145 isolated! Of course, as well as the chance to achieve a product of particular “greatness”, spontaneous fermentation, due to its intrinsic unpredictability of results, may also lead to products of modest quality. From my own personal experience, however, these cases are very often ascribable to poor grape health and/or poor care of the operations in the cellar. In any case, the analytical methods available today would enable us to monitor, almost in real time, the microbiological progress of the spontaneous alcoholic fermentation, making any necessary intervention possible. The importance of yeasts, especially Saccharomyces, has been highlighted in this period by the awarding of the Nobel Prize for medicine to the Japanese biologist Ohsumi, who has been a professor at the Tokyo Institute of Technology since 2009: the awarded research is on “autophagy”, i.e. how every cell of living organisms recycles the waste it produces every day, inside itself, and manages to survive. The scientist studied the cells of the Saccharomyces yeast of bread and discovered that, if the genes are modified, the waste accumulates and may lead to various diseases, such as diabetes, Parkinson’s disease, Huntington’s disease and cancer and also encourages ageing in humans. I would like to thank my microbiologist friend Professor Massimo Vincenzini who introduced me to the world of yeasts and bacteria over 23 years ago (and continues to reveal this universe to me), which through their transformation give us a better understanding of the working of human cells: the professor also carries out important research and studies on Saccharomyces of bread and relative baked products, as well as research on Saccharomyces of wine. The scientist Ohsumi has certainly opened up a whole new world on the possible health effects of sourdough starter and perhaps of wine made just from grapes, with no other additions.
What do you think?