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Introduction
Yeast is the driving force behind our beverage industry, this microscopic fungus plays a key role in providing the aroma and flavour of many beverages we know and love. Used as the basis of alcoholic drinks for thousands of years, yeast uses the sugars from the products to convert into carbon dioxide and most importantly alcohol. Quite simply without yeast there is no alcohol, which is why it is especially important to find the correct yeast for the specific drink of choice.
What is Yeast?
So, what exactly is yeast? Yeast is a single-celled microorganism belonging to the fungi kingdom. Essentially it is a distant cousin of the common mushroom, however its uses are far more varied. Unlike plant cells, yeast does not require sunlight and can convert sugars from products such as apples, potatoes or grapes into a variety of ingredients. Such as carbon dioxide and alcohol. It is this process which we define as fermentation.
Types of Yeast Used in Beverage Production
When discussing yeast one thing that may surprise you to know is that there is not just one strain of yeast. There are in fact dozens of different yeast varieties, each contributing to a different flavour profile and aroma for your drinks. One of the most instrumental yeast species is known as Saccharomyces cerevisiae or more commonly known as “baker’s yeast”. This species of yeast is one of the oldest discovered and instrumental in producing beers, wines and even bread. The word “Saccharomyces” derives from the Latin “Sugar-Fungus”. Other yeasts include; Schizosaccharomyces, the only wine yeast that reproduces by fission whereas most wine yeast reproduce by budding, Kloeckera (Teleomorph Hanseniaspora), usually the most common "wild yeast" found in the vineyard, Candida (Teleomorphs for different species from several genera including Pichia, Metschnikowia, Issatchenkia, Torulaspora and Kluyveromyces), and Brettanomyces (Teleomorph Dekkera). Just to name even a few of these types of yeast.
Yeast in Beer Production
Simply, there are two main types of brewing yeast in beer production. Ale yeast, reportedly used since Ancient Egypt. This yeast does exactly what brewers want; it ferments quickly, consumes the correct amount of sugars to produce a moderate level of alcohol and can survive the anaerobic conditions of fermentation. Ale yeast can also produce much fruitier beers which can be less versatile but have a much more interesting flavour pallete.
Meanwhile Lager yeasts ferment at much lower temperatures than Ale yeasts (10-13°C). This yeast, first isolated in 1881, was created as a way of storing said yeast for much longer, allowing for transportation across the globe. The main benefit of Lager yeast is that it can be brewed at much lower temperatures, reducing the production of harmful bacteria. This results in a beverage that has a much longer shelf life.
Since the yeast is brewed at much lower temperatures there are some drawbacks. For example, they produce fewer esters and fusel alcohols, not to mention the increased sulfur content means the yeast absorbs fewer diacetyls. This can be reduced by using a procedure known as a diacetyl rest. A process of heating the brew to around 20°C and allowing it to cool for the next few days.
Yeast in Wine Production
Saccharomyces bayanus is the all-important yeast in the production of wine and cider beverages. For wine, there are good yeasts (vinification yeasts) and bad yeasts (spoilage yeasts). However, even a “good yeast” can become problematic in wine production if handled incorrectly. All yeasts, either good or bad, are present in the grapes themselves. Grapes are one of the first locations that we in fact discovered what yeast is.
In wine production, winemakers can choose to use commercially available yeast or leave the grape juice to allow the natural yeasts present to cause fermentation. This process is known as ‘wild ferment’.
Wild fermentation is easier said than done, there are many aspects to become aware of. For example, the grapes used must be perfectly ripe. They can’t be damaged or slightly stale/ rotten, this will ruin the process. Wild ferment is a much more time-consuming process as well and sometimes the fermentation process can become stuck/ incomplete if the yeast does not get enough nutrients to convert the sugars into alcohol.
To put it simply, wild fermentation provides a much closer representation of the grapes and will change year on year. However, the process of wild fermentation is a lot harder to get right, more time consuming and can easily go pear shaped. For many commercial wines, the wine is expected to taste the same year on year. So, when producing your wine take a moment to think about your customer base.
Yeast in Spirit Production
When producing alcohol for spirits and other alcoholic beverages there are two schools of thought. First named the “Simple Sugar Wash” method, in which the brewer mixes sugar, water, nutrients and yeast together to distill a spirit with a pH of around 5 – 5.5. Secondly there is “Mash Fermentation” in which yeast feeds on the sugars present in ingredients such as fruit, vegetable, grains and honey. The pH level critically must be around 5 and can be adjusted using acids such as lemon juice.
Yeast in Cider Production
There are many yeast strains to choose from when it comes to cider production. Some strains may produce a higher alcohol content but do not sit well within higher temperatures. Whereas others floccation ability will need to be taken into account, the ability for particles suspended in liquid to clump together which would result in less clarity in your cider. Luckily our supply of Fermentis yeast is perfect for all cider producers. We have stock of cider yeast, which is perfect for producing high or low gravity ciders. Allowing for aromatic and appealing flavours. Browse our collection here: Search Results - Vigo (vigoltd.com)
Challenges and Innovations in Yeast Use
When using yeast within brewing it is important not to create stressed yeast. As it can lead to a variety of problems which include imbalanced fermentation and creating off-flavours. Factors that can affect the yeast can include incorrect nutrient, sugar and yeast ratios. As well as chlorine's presence in the water and temperature inconsistencies.
Future Trends and Considerations
Scientists in Europe are working together to create new strains of yeast to improve the variety of flavour and drinks options for the rest of the world. ‘We want to introduce mutations naturally into yeast and we can do that by stressing and heating cells,’ said Prof. Bond. ‘Then we let them adapt to certain conditions to see which ones survive the best.’
By using a technique known as thermal stress adaptive evolution. The yeasts with promising taste profiles will be put under heat stress which can recreate the correct conditions for natural selection to occur. This results in a wider variety of flavours in a much shorter time frame. ‘The approach is to try do things naturally rather than going down the route of genetic modification which is not acceptable at the moment to the consumer,’ said Prof. Bond.
Vigo & Fermentis
Yeast and subsequent brewing of alcoholic beverages has been around for nearly as long as human civilisation itself. So, it’s safe to say that the production of alcoholic beverages is tried and tested. However, this does not mean that there isn’t room for development and innovation. Even now new strains of yeast are being discovered and new flavour profiles are being produced. Now is an extremely exciting time for alcohol production and with the advent of 0% alcoholic beverages becoming so popular now there are even more routes to go down.
Our yeast provider, Fermentis (Lesaffre), are key global players in yeasts and fermentation solutions. Together we can provide yeast for all alcohol types. From high total acidity favours a balanced fresh mouthfeel making SafOeno EF 85 ideally suited to the production of elegant white wines with respect for the grape variety. To SafCider AS-2 yeast, a fresh aromatic profile (apple, citrus) with nice, elaborated fruit notes (applesauce) bringing a good overall complexity, with a sweet and round mouthfeel. View our range of yeast related products here: https://www.vigoltd.com/Catalogue/Yeasts-nutrients
At Vigo we have been in the brewing business for 40 years now, learning all about the production of drinks. Whilst having extensive knowledge in the yeast used to create them. We are well equipped with our sales team and on-call engineers to help your business thrive.
Call us at 01404 892 109 or email techsupport@vigoltd.com for all your engineering needs in the vibrant and demanding drinks industry.
References
The Role of Yeast in Brewing | The Beer Connoisseur