The artful alteration of juice to cider

Fermentation was once considered to be a miracle of the gods. Without the scientific understanding of how fermentation works, it could be perceived as magic. One minute you have a raw product, then suddenly, out of nowhere, it becomes active and starts to bubble. Eventually the product you started with becomes something entirely different. If you leave a jug of apple juice out for long enough, this process will take place naturally without any human intervention. So, you can see how it was once perceived as some sort of divine intervention.

Nowadays those involved in the modern study of fermentation, aka zymology, look at these changes at the microscopic level in order to understand and control them. A lot of the wonder and mystery of fermentation has been removed, and we now have a pretty thorough understanding of how it works.

I like the romantic idea of fermentation, the one where you magically transform something raw into something new and delicious. On the other hand, it’s essential to use all the modern information we have available to make the best product possible.     

It wasn’t until the 1850s that the renowned French microbiologist, Louis Pasteur, completed a more thorough understanding of fermentation. He proved that living microorganisms — yeast and bacteria — were, in fact, responsible for fermentation and that it was not some spontaneous chemical change.

Fermentation, as defined by Penguin’s English Dictionary, is an “enzymatically controlled anaerobic breakdown of an energy-rich compound, e.g. a carbohydrate to carbon dioxide and alcohol, or an enzymatically controlled transformation of an organic compound.” This term may be a bit loaded, but what it’s saying is that fermentation is the process in which yeast consumes sugar and then produces both alcohol and carbon dioxide. Thus, to understand fermentation you really need to understand yeast.

In a nutshell, yeast are single-celled microorganisms that can be found all over the place: in the air, on a flower, in orchard soil, on pressing equipment, on your skin, in your belly, seriously everywhere. These little guys are living organisms that require food in the form of carbohydrates and nutrients. They also need a favourable habitat where the temperature is consistent, where there is no other yeast competing for the sugar and where there is no oxygen. It’s the cider maker’s job to make sure the yeast are happy and that they are doing their jobs, like a shepherd and their flock.

The thing is, there are so many different types of yeast out there. Some produce favourable outcomes and others do not. The cider maker chooses which yeasts they want to thrive, while also trying to inhibit the bad ones from interfering.

Traditional cider making relies on the wild yeast found naturally in the apple juice to start the fermentation. Depending on the quality of the juice, the level of sanitation and the ambient temperature, this method can produce an extremely complex cider that is truly unique. However, if the apples are rotten, the fermentation tanks aren’t totally clean or if the temperature is too warm, then there is a greater possibility of the wrong yeasts and bacteria taking over and creating off aromas and flavours. Your precious cider could end up smelling like feet and/or farts.

Those using more modern techniques employ cultured yeast strains that have been singled out for their favourable traits. Modern cider making relies heavily on this method of fermentation because it can lead to a predictably clean cider. Once the cider maker has sufficiently analyzed the juice, they then begin by killing the majority of the wild yeast by using sulphites. Basically, sulphites clear the playing field of competition and allow the desired yeast to establish themselves as the dominant yeast in town. After that, they go on their merry way, eating all the sugar until it’s all gone.

On average, a complete fermentation of cider (where the yeast has eaten all the available sugar) takes around two to four weeks. This all depends on the type juice, the type of yeast and the ability of the cider maker to control the ferment.

There is honestly so much more to say on the topic of fermentation and how vital it is to making cider. I still have so much to learn about the art of fermentation; it’s truly a lifelong pursuit for most. But a few things are for certain: making quality cider requires good juice, constant practice, continuous learning and a boatload of patience. Good luck, and love thy yeast.