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We all know wine contains alcohol, which has been a part of human socialization for millennia. However, the nitty-gritty of the microbiology behind the alcohol fermentation process is interesting.
Yeast Is Essential To Fermentation In Winemaking
Yeast (Saccharomyces Cerevisiae is the commercial version) is the fermentation promoter for wine – as Koji is the promoter for sake, soy sauce, and miso. “Yeast” is not just one thing – as in “apple” is not just one fruit, but a name for a whole range of rather different fungal microorganisms. Some strains of yeast are best used for bread, others for beer brewing, and wine making. Also, there are numerous types of yeast in each category – especially for wine making. In fact the flavor of your wine depends in large part on the strain of yeast used.
Not only is yeast fabulous in your kitchen, it’s a wonderful tool for scientific research. In fact, yeast was the first eukaryote to have its genome sequenced (Goffeau et al, 1996), and was the subject of the first systematic collection of barcoded gene deletion mutants (Schena et al, 1995)– all of which is very useful in science. (Chambers & Pretorius, 2010 https://pubmed.ncbi.nlm.nih.gov/21072064)
Wine is made by using yeast to convert sugars and starches – through fermentation – to alcohol and carbon dioxide (ie: bubbles). The same process occurs in baking, but in that context, the bubbles are what causes your bread to rise, and creates the tasty texturally delicious pockets in your loaf. Baking soda & vinegar is another way to make your baked goods light and airy – because mixing baking soda and acid creates a bubbly reaction.
You Can Make Wine With Wild Yeast Found On Grapes Without Adding Commercial Yeast
Modern wine making is a sterile and precise practice using single-strain inoculations, and pure cultures of pre-selected yeasts to assure control over the end product (better for mass production). However, at your house, or for us – in our Tiki Food Lab, our goal is to capture the Taste of Place – or Terroir. So, we want to capture and amplify the natural yeast found on the fruits, wine grapes, and grains we grow on our farm - without using artificial chemicals or preservatives.
The presence of sulfites is often discussed in wine. Sulfites are preservatives – that first became widely used in the food industry in the 1970’s and 1980’s when America discovered and fell in love with salad bars and buffets. (https://www.webmd.com/diet/what-to-know-sulfites-in-wine) Sulfites were used to keep the items sitting out on the buffet and salad bar looking fresh. Toss a little sulfite on your shrimp, to inhibit oxidation, and the shrimp looks nice and fresh after sitting out for 7 hours (obviously we are not a fan of buffets!). After people began having adverse reactions to sulfites, the FDA banned the use of sulfites on fruits and vegetables in 1986. However, sulfites are still added to wines as preservatives. Sulfites are naturally produced during wine making – but in low doses. In commercial wine making, additional sulfites are used to preserve the wine and to inhibit oxidation, so the wine stays clear and does not turn into vinegar.
Traditional wine making – also called wild fermentation or country wine- embraces resveratrol, which is a healthy compound naturally found in grape skins and other fruits. Resveratrol has strong antioxidant properties and protects against unwanted bacteria and fungal growth. In other words, your organic grapes come loaded with their own chemical defense program – including natural yeasts that can be used to make your own wine! You access resveratrol when you ferment wine with the skins – which is done in commercial red wine making, but not usually for white wine. This is why red wine has been shown to be good for your heart & cholesterol levels. In traditional wine making, you get even more resveratrol because no preservatives are used.
The term “terroir” is often used in reference to wine. The International Organization of vine and Wine (www.oiv.int) defines terroir as a concept referring to an area in which collective knowledge of the interactions between the identifiable physical and biological environment and applied vitivinicultrual practices develops, providing distinctive characteristics for the products originating from that area. We love the definition provided by I.S. Pretorius, in the learned article ‘Tasting the Terroir of Wine Yeast Innovation:” Terroir gives wine a specific address – whines from somewhere rather than anywhere. So, with that as our goal – to produce a cooking wine that references the flavors and feeling of our environment, The SG Tiki Farm. Here is the process for achieving that end:
Natural Wine Without Additives - Recipe For Making Tiki Terroir Wine At Home:
This wine recipe makes a gallon of Tiki Terrior Wine – which is our term for all natural home-made wine by capturing native yeasts and without using preservatives or chemicals.
1 Gallon of the best water you can find. We always emphasize that in cooking, fermentation, and your stereo equipment, the end result is a product of the weakest single element. So, if you use tap water, the chemicals that likely lurk therein will inhibit fermentation and yield less tasty results (if it even works at all).
700 Grams Sugar – also the better quality of sugar, the better the results. Raw sugar works well, as does palm sugar, turbinado sugar, coconut sugar, and feel free to experiment with different “sugars” like honey, maple syrup, and unsulfured organic molassas. After all, it’s all about creativity and experimentation!
900 Grams Fruit – Grapes are fabulous of course and we grow 5 types of muskadines at our farm! You can use an array of fruits such as berries, stone fruits, tropical fruits, herbs & spices. One consideration is the amount of yeast naturally found on fruits – grapes, apples, figs, peaches, pears, rose hips and you can even use spruce tips and unsulfured dried fruits.
First, sterilize all of your equipment by submerging in boiling water for 1-2 minutes or by soaking in One Step No Rinse Cleaner. Next, boil the gallon of water and add the sugar to dissolve. Cool until the temperature reaches 100 degrees, or less. In the meantime, mash your fruit in a sterilized bowl with a sterilized pestle or other mashing device. Once the sugar water is at temperature, then you can mix in the fruit.
Pour the fruit-sugar-water mixture (called wine must) into your fermentation vessel. We like to use wide open mouthed clear class containers that are about 1.5 gallons. That way, if you get a very vigorous ferment, it will not bubble over. Also, the wide mouth makes mixing easy.
Cover the top with fine cheesecloth, affix with a rubber band and store at room temperature out of direct sunlight. Thereafter, you need to stir the young wine rather vigorously 3 times per day! This is very important to mix the “lees” which is the sediment that forms at the bottom of the container (yeast needs air to grow and eat the sugars), to prevent solids on the surface from drying out and acquiring bad bacteria at the surface. Mixing the lees in France is called “battonage” which is used most often in making fancy full bodied white wines. However, it is also useful in making country wine.
After several days, you should see bubbling action. The key is to monitor your ferment, to determine when the bubbly fermentation slows down- which often occurs between 5 and 12 days after it starts. Ironically, the alcohol the yeast produces ultimately kills the yeast that was it’s very own mother! So, when your ferment starts to slow down is when the bubbles start to be reduced. That is when you want to filter out the solids by pouring it into a strainer (Shinwa) with a cheese cloth lining. Have a taste and decide if you like the flavor as is – or if you want to age it a bit more before placing in the refrigerator. You can also add some additional sugar by boiling water, mixing in sugar, cooling and adding to the wine. This will likely kick in a second round of fermentation. You can also add herbs, spices or other interesting flavors.
If you want to continue the aging process, after you strain out the fruit mash, you then pour the young wine into a small mouth bottle and affix an air lock. This allows the CO2 to escape through the water in the airlock, and keeps oxygen from entering the container – to prevent oxidization. The wine can now be aged at room temperature for a week, 30 days, or more – just make sure the water in the airlock does not dry out. Once you are satisfied with the flavor, then you can pour off into small top bottles with screw caps or corks and place in the fridge.
If you like it just as it is, then after you strain out the fruit mash, pour into bottles, cap and refrigerate. Keep in mind, the cooler temperature reduces ongoing fermentation, but you may want to “burp” it occasionally to prevent a refrigerator explosion, which is very unlikely, but good practice.
Zero Waste Consideration:
At our restaurant, Suis Generis in New Orleans, we strive to be the first zero waste restaurant in the Gulf South. Thus, we are always thinking about ways of using byproducts of our cooking and fermentation projects. So, save the fruit mash that you strain from the wine to use in sauces, soups and braising liquids. You will find that it adds unbelievable layers of flavor when used in cooking. This is one of our secret weapons in the quest for layers of complexity in cooking! Also, don’t worry about seeds in grapes, such as muscadines. Grape seeds are edible, and are squeezed to make grape seed oil. So, you can puree the whole concoction then strain out the solids to make an amazing sauce or gastrique.
In the batch we prepared here, we used the mash to make a sauce with a huge smoked python snake bean from the farm, safflowers, chili peppers & yuzu. The richness from the fermented grapes combined with the smoky bean, spice and acidic edge came out great! In fact, this is how we come up with items on our weekly changing menu – using what we have and applying interesting technique in search of umami and deliciousness! Finally, the Shinwa straining from making the sauce went into the fermentation bin to go out to the farm to build compost!
A note on safety. Be careful when performing any of your own fermentation, because things can go wrong. If you have immune deficiencies, they you probably do not want to play around with more risky ferments like capturing your own yeast to make wine. Some safety tips include: add packaged yeast to your fruit mixture (mash), or checking the PH to make sure it is 4.5 or less, which inhibits the formation of E. Coli and C. Botulinum. You can lower the PH by adding 6 grams of tartaric acid for every quart of water. Also, holding the wine for a month at room temperature is thought to be sufficient for E. Coli to die off.
Now That You Were Able To Make Wine Without Yeast - You Can Turn It Into Vinegar!
Once you have made the wine (ie: your fermentation is over), then you have a decision to make! You can bottle and store it in a wine fridge to age at the optimal temperature of 45-65 degrees (or regular fridge if you don’t have one). Alternatively, you can turn it into vinegar. At Suis Generis, we love acidity, because it is the best way to brighten any recipe. So, making vinegar is a great way to create your own acid to use in cooking and pickling.
Acetobacter bacteria is what creates vinegar. Commercial winemakers add sulfites to kill acetobacter bacteria, and to prevent acetic acid from forming in the wine (would make it sour). We don’t like to add chemicals to our ferments, so we do it the natural way. The bacteria that turns wine to vinegar is called acetobacter, and can be found everywhere including in the air, on fruit, flowers, vegetables etc.
To make vinegar like it has been done for millennia, you embrace your acetobacter bacteria. The easiest way to do that is to add a vinegar “mother” to the wine you already made. In a separate post, we will discuss how to capture your own mother from the flowers and fruits in your garden. After all, there is a beauty to harnessing the flavors of your environment – called terroir.
If you do not have a vinegar mother, you can also use the sediment at the bottom of a natural unfiltered vinegar – such as Braggs raw unfiltered apple cider vinegar. The goal is to present the proper environment for the wine to oxidize, which means the acetobacter bacteria found in your vinegar starter, uses oxygen and the alcohol present in the wine to create acetic acid, which is what we know as vinegar. When we say a wine is “corked” it’s because oxygen found its way past the cork and interacted with the wine to oxidize it – ie/bad for wine & good for vinegar. You should also know that most commercial wines just taste bad when oxidized because they have sulfites, which prevent the wine from turning into tasty vinegar.
Recipe To Make Vinegar From The Wine Made With Natural Wine Yeast:
Place your wine in a wide mouth container. Add your vinegar mother or about 2 tablespoons of the sediment from a raw unfiltered vinegar. Cover with cheesecloth and secure tightly with a rubber band. In fact, after you strain out your “musk” or grape/fruit matter after making your wine, you can use the same container. Put it in a place out of direct sunlight. Over the next few weeks, you will see a skin form on the surface of the liquid. Once the skin sinks to the bottom, 1-2 more weeks, then you will have vinegar and a mother to use on your next batch! For long term use, put into a closed bottle and store in the fridge.
Additional Resources and Reliance Materials:
Barnett J (1998) A history of research on yeasts: Work by chemists and biologists, 1789–1850. Yeast 14: 1439–1451 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164842/
I.S. Pretorius, Tasting the terroir of wine yeast innovation, FEMS Yeast Research, Volume
20, Issue 1, February 2020, foz084, https://doi.org/10.1093/femsyr/foz084
Winzeler E, Shoemaker D, Astromoff A, Liang H, Anderson K, Andre B et al. (1999) Functional characterization of the S. cerevisiae genome by gene deletion and parallel analysis. Science 285: 901–906
Swiegers JH, Bartowsky EJ, Henschke PA, Pretorius IS (2005) Yeast and bacterial modulation of wine aroma and flavour. Aust J Grape Wine Res 11: 139–173
Pretorius IS, Høj PB (2005) Grape and wine biotechnology: Challenges, opportunities and potential benefits. Aust J Grape Wine Res 11: 83–108
Lilly M, Bauer FF, Lambrechts MG, Swiegers JH, Cozzolino D, Pretorius IS (2006a) The effect of increased yeast alcohol acetyltransferase and esterase activity on the flavour profiles of wine and distillates. Yeast 23: 641–659
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