Fermenting Apples for Cider

Fermenting apples is a key component of the cider making process. Along with all of the different strategies that go into fermenting apples, there are also traditional and modern methods that makers utilize based on preference and conditions or availability.

In Cider Planet, longtime cider maker and author Claude Jolicoeur talks about new and emergent regions that have contributed to this growing appreciation, and how they are building upon the old traditions while creating their own new ones. The excerpt below highlights how some of the world’s leading makers ferment apples for their cider. If you’ve considered making your own cider, knowing these fermentation methods is essential.

The following is an excerpt from Cider Planet by Claude Jolicoeur. It has been adapted for the web.

Unless otherwise noted, all photographs copyright © 2022 by Claude Jolicoeur.

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Fermentation

The must that undergoes fermentation may be of a single variety or a blend. In all cases, the acidity should be checked because it has an influence on the microbiological activities. When blending, the cider maker doses different varieties to attain a target acidity and the flavor sought. Single variety fermentations are done on varieties that natu- rally have adequate juice properties and acidity balance, and these generally are of the bittersharp or sharp classes. Varieties of the sweet and bittersweet classes that have a low content in acids are more rarely used for single variety fermentations as the cider maker needs to chemically raise the acidity to insure a healthy fermentation.

Yeast Inoculation and Nutrition Strategies

A most significant differentiation between traditional and modern fermentations is in the type of yeast used and how this yeast is fed. In a traditional fermentation, no yeast is added by the cider maker: The wild yeast strains that occurs naturally in the orchard and the cidery are what colonizes the must. There is then a succession of yeast and bacteria species and strains during the course of the fermentation that may yield richer and more complex flavors, and also some “funkiness,” which may be associated with off-flavors, or with authentic flavors, depending on one’s point of view. The cider maker has no real control over which strain is active, and this may induce more variability of flavor between batches. With time, house strains establish themselves in the cidery, and this may give a special character to the ciders of a given producer or even to the ciders of a region—and thus comes the notion of terroir. It may be interesting to note that some studies done in Spain have revealed that hundreds of identifiable strains of yeasts could be residing in an old cidery.

The other characteristic of traditional fermentations is that the nutrient level is low. This is because apples from traditional, unfertilized orchards contain much less nitrogen, and also, the cider maker doesn’t add yeast nutrients. This results in low yeast populations and slow fermentations. In traditional fermentation, the much lower yeast population is normally able to feed itself from naturally occurring nutrients, and thus the addition of nutrients is not necessary or beneficial.

The strategy is very different for a modern fermentation. First, the wild microorganisms are eliminated, usually by an appropriate dosage of sulfite or by pasteurization. Then a selected yeast strain is inoculated, putting it in position to take control of the fermentation without competition from wild microorganisms that could alter the flavor profile. This yeasting strategy ensures excellent consistency of flavor from batch to batch, and produces a “clean” cider dominated by the fruit, typical of modern style ciders. The yeast nutrition strategy is also quite different in modern fermentations. Since the juice used to make the cider is generally from high-density orchards that are fertilized, it is rich in nitrogen, which is used by the yeast as a nutrient. This produces high populations of yeasts, which in turn need to be fed during the course of the fermentation. Hence the cider maker needs to have a good nutrition regime to ensure the yeast will make a good, strong, and healthy fermentation.

Traditional Fermentation

In its purest traditional form, the fermentation itself is simply a matter of filling clean barrels (or wooden vats of sometimes huge volumes) with the freshly pressed and untreated must, and then letting nature do its thing until the cider is ready. A few different approaches are possible. The barrels may be filled to the top, right at the start, and then during the turbulent phase of the fermentation, the foam is allowed to escape through the bung (and make a mess on the floor). Or the barrels may be only partially filled so the foam stays contained in the barrel, and a racking to a smaller barrel is done after the turbulent phase is completed. These barrels are then filled to the top and an airlock is fitted. A third possibility is to have a spontaneous keeve, which is a method that utilizes a naturally occurring pectin gel (see the next section for more on this). In all these approaches, once the fermentation is going, one or two rackings may optionally be performed to slow things down and help in the clarification. The only other interventions done by the cider maker are to keep the barrels well filled and make sure no oxygen comes in contact with the cider. The fermentation proceeds slowly during winter, and the cider is ready in the spring or beginning of summer. It may then be bottled or served directly from the barrel.

I found one good account of this basic traditional cider making process in a book written by Thomas Andrew Knight, in 1811, titled Pomona Herefordiensis. It goes as follows:

The art of making fine cider and perry is exceedingly simple, when proper varieties of fruit, in a perfect state of maturity, can be obtained. Such fruit should remain in heaps of not more than twelve inches deep, in the open air till it has become perfectly mellow, and it should then be ground in a mill of stone till the pulp and rind are perfectly reduced, and have acquired a deep and uniform brown colour. The juice is then expressed, and placed in casks to ferment, where it is as soon as possible separated from its grosser lees; and excess of fermentation is prevented by placing the casks in a cool and airy situation, and by drawing off the liquor from one cask to another.

There are nowadays only a few cider makers who manage their fermentations in a truly traditional fashion as described here, and I have met or have heard of some in all the traditional cider making regions. They are usually very small producers who still make their cider the way their grandfather and great-grandfather used to make it. The vast majority of cider producers—and that includes those who are considered traditional cider makers—incorporate some of the modern technologies in their process.

Keeving

The practice of keeving is traditional in France and England. It is also done by a few producers of the traditional-style cider in other regions. The principle is that the pectins present in the apple are partly degraded by an enzyme and combined with calcium to form a calcium pectate gel. This gel rises by buoyancy to the top of the vessel and forms a thick layer with a gelatinous consistency. This gelatin has a light brown color and is called the chapeau brun (brown cap). The process yields a perfectly clarified must under the chapeau brun, and this must is racked to another vessel where the fermentation will proceed. The process additionally reduces the amount of natural nutrients of the must, and thus the yeast population remains small. As a result, the fermentation speed is very slow. A selected yeast is normally not added when doing a keeve; these fermentations rely on natural wild yeast. Another advantage with this process is that a keeved fermentation is very easy to stop by a simple racking at the moment chosen by the cider maker to yield a cider that retains some of the natural apple sugars, unfermented. Thus it is possible to produce a stable sweet or medium-sweet cider.

A century ago, the role of enzymes wasn’t well known, and keeving relied on the small quantities of enzymes that are naturally present in the apple. The success of the process was irregular and unpredictable. Cider makers had nevertheless understood that they could improve the chances of obtaining a successful keeve by a maceration of the pulp and an addition of some form of calcium, considered as a keeving aid (crushed chalk was often used). It wasn’t until the end of the 1980s that the industry was able to provide pectin methyl-esterase enzyme (PME) to cider makers, which, when combined with an addition of calcium chlodire, permits regular success of the keeve process. This is a good example of a traditional process that has been modernized, in this case with the help of recent developments in enzyme technology.

Chaptalization

The word chaptalization is derived from the name of Jean-Antoine Chaptal (1756–1832), a French chemist, doctor, and politician under Napoleon Bonaparte, who described the process in a book published in 1801, L’art de faire, gouverner et perfectionner les vins.

Chaptalization is the addition of sugar to the must in order to increase the alcoholic strength of the beverage after the fermentation is completed. The original intent is to chaptalize a must only in years when the conditions weren’t so good for ripening and the fruits have a lower than normal sugar content. Then, the addition of sugar increases the alcoholic potential to a level comparable to an average year, thus permitting better conservation. In wine making, and in particular for wines that are made under a label of origin certification, chaptalization is strictly controlled and can only be done within the limits described here. This is not the case, however, in cider making: In many production regions, unless there is a label of certification, chaptalization is usually left to the discretion of the cider maker. As a consequence we sometimes see producers who systematically overuse chaptalization to make ciders that have an alcohol level higher than could normally be obtained from a natural apple juice. Chaptalization is more common in modern cider making practices; however low levels of chaptalization may also be seen in more traditional ciders.

Modern Fermentation

Nowadays, in all cider making regions, modern fermentation is done in stainless steel, fiberglass resin, or plastic tanks (all materials that were developed during the twentieth century). Wood barrels are not used in modern fermentations, but we may still see some used for the maturation of cider. The modern fermentation practices normally ensure a good repeatability of the flavor profile from batch to batch, which is a desirable trait for modern-style ciders. The following operations and steps are usually seen:

• Pre-fermentation clarification, a process also called débourbage, by adding a pectic enzyme to the juice as it exits the press, and then letting it rest between 12 to 48 hours. Sometimes a fining agent is added to increase the sedimentation. The must might not be perfectly clarified, but there would be a good deposit in the bottom of the tank. The must is then transferred to another tank where the fermentation will take place.
• Elimination of the wild microorganisms and inoculation of a selected yeast strain as described previously.
• Control of yeast nutrients.
• Temperature regulation to ensure the yeast will perform at its optimum conditions.

When the right conditions are met, the fermentation then proceeds to dryness (until all the sugar is fermented) in a matter of a few weeks, compared to months in a more traditional way. Rackings are normally not done during the fermentation, but may be done once it is completed (or almost completed), before storing the cider for maturation.

Maturation

Once the alcoholic fermentation is completed, many producers (both of modern or traditional inclination) let the cider age for a period of time before further processing. During such maturation many bio-chemical transformations may occur even if there is no more fermentation per se. In particular, we note some smoothening of the cider, due in part to the action of some lactic acid bacteria. This maturation may be sur lies (“on the lees”), if the producer prefers to let the cider age in the presence of the lees that were produced by the alcoholic fermentation. This gives a special flavor from the decaying dead yeast cells. In other cases, the cider is transferred to a new vessel and thus separated from the lees before maturation.

We often see cideries that use wood casks for the maturation of their ciders. This may modify the flavor of the cider as it picks up some tannins from the wood. Also, if the cask was previously used to store some other beverage, the flavor of the cider may reflect it. For example, in the United States, ex-bourbon barrels are often used for this.

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