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Introduction to Alternative Fermentation of Cider

Though most commercial ciders available in the US are clean fermented, cider making has a long history of wild, spontaneous fermentation and in some areas of the world still does and others are seeing it make a comeback[1]. Cider is one of the easiest fermented beverages to make at home as it only requires picking up a container of fresh pressed, unpasteurized juice and letting it ferment.

Unlike beer, cider does not sour due to microbial activity, but instead undergoes Malolactic Fermentation, which convert malic acid to lactic acid. Cider can, however, get funky with the presence of alternative microbes in either primary or secondary fermentation.

Malolactic Fermentation

Malolactic fermentation (MLF) is a process through which malic acid is converted to lactic acid by lactic acid bacteria (LAB). The main impact of MLF on cider is likely to be seen in de-acidification, as malic acid is a stronger acid than lactic acid[2], and the conversion will increase pH and change the perception of acidity. The process can create other compounds and change the flavor or aroma of the cider; notably, MLF can produce diacetyl well above the taste threshold and other compounds that may not be above the taste or aroma threshold, but together may increase perceived complexity [3].

For natural MLF, which is caused by lactic acid bacteria present on the fruit, MLF begins after primary fermentation. Yeast cells undergo autolysis and release nitrogen-rich compounds, polysaccharides, and fatty acids, which can serve as food sources for LAB [4].


Beer and Cider/Wine Hybrids

For maximum MLF in beer that has fruit added to it, one recommendation is to ferment the fruit/cider/wine separately and then blend it into the beer. Add O. oeni to the must before yeast for 48 hours, then add a MLF yeast such as Lavlin 71B (estimated to reduce malic acid by 30%). Blend the resulting wine/cider with the beer after it has fermented [5].


Oenococcus oeni is considered the primary MLF bacteria in wine because it can withstand the harsh conditions of wine. Other lactic acid bacteria besides O. oeni also have some malolactic fermentation capabilities. Pediococcus, Leuconostoc and Lactobacillus species are often present at the beginning of MLF, but generally die off in wine towards the end of MLF. These genera are generally seen as spoilage species that create off-flavors in wine and cider making, specifically exopolysaccharide (ropy) production and biogenic amines. Despite this general rule, some strains of P. damnosus have been found to positively affect Albariño and Caiño white wines due to their ability to perform MLF, and dominated over inoculations of O. oeni. The strains used were ones that did not produce exopolysaccharides or biogenic amines, and were determined to have a positive influence on the white wine [6].

In the presence of citric acid, which is the case of wine and perry, O. oeni has been shown to produce diacetyl and acetic acid during MLF [7]. Tariq Ahmed from Revel Cider Co. attributes a "Flanders red-like" character to his perries made from Bartlett pear due to the acetic acid production from citric acid and sorbitol in the pears [8].

Resource/reference to add:

See also:


Basic Cider Making Resources

Mixed Culture Fermentation

Cider fermentation occurs in up to three phases: an oxidative phase, which occurs due to the presence of apiculate or non-Saccharomyces yeast and is usually only seen with wild fermented ciders, and it responsible for the production of aromatic and flavor compounds; an alcoholic phase, in which mainly Saccharomyces spp. out compete the oxidative phase yeast species and carryout out the bulk of the fermentation; and a malolactic fermentation phase.[9]

With inoculated fermentation, you are unlikely to experience the oxidative phase due to a lack of the required yeasts, though wild, especially spontaneous, fermentation is very likely to undergo this phase.

The question has been asked: can Brettanomyces spp. act as an oxidative phase yeast before Saccharomyces spp. takes over fermentation? The is currently unknown.

Inoculated Fermentation

Talk about using mixed cultures with Sacch, Brett, and lactic acid bacteria added from commercial sources.

Using Saccharomyces and Brettanomyces Cofermentation

(To do)

Talk about using Sacch and Brett co-pitched, and Sacch pitched in primary and Brett pitched in secondary.

100% Brettanomyces

(To do)

Spontaneous Fermentation

Spontaneous fermentation of apple juice to cider is very easy and can be done without any more effort than buying fresh pressed, unpasteurized, and untreated (raw) apple juice and then forgetting about it for a few weeks or even months. While not available everywhere, if you live in a region with apple orchards it is very easy to find in the fall. Usually sold directly by the orchards, or available at a cider mill, the fresh pressed juice will already contain all the microorganisms needed to ferment out the sugars.

In the US your fresh pressed juice will most likely come in a plastic milk jug style container. You have two options to ferment this juice:

  1. In the fridge - this will typically take longer than room temperature fermentation, and often results in a sweeter end product with a more pronounced apple flavor.
  2. At room temperature - this would proceed much like any normal fermentation, and due to the unknown nature of the microbes contained within, is likely to really dry out.

The cold fermentation option has some pitfalls, however, so your results may vary. Much like a lager, it is possible that you might need a diacetyl rest, requiring you to warm the cider up for a short period of time. This can kick off fermentation by microorganisms that were previously dormant, which is likely desired to reduce the diacetyl content anyway. The other major issue faced by cold fermented ciders is sulfur (H2S) production. Due to the colder temperatures, the sulfur will off gas less, again requiring warming of the cider to encourage off gassing. If the cider tastes good otherwise, further fermentation can be halted with the use of sulfites. Adding sulfites (SO2) will also reduce the (H2S) sulfur (see "Controlling Reductive Wine Aromas" by Dr. Karl J. Kaiser).

Harvesting Organisms from Spontaneous Cider

As apple juice is relatively low in pH, it is an environment that will limit the growth of unwanted spoilage microorganisms naturally. Yeast can be harvested from fresh pressed apple juice or even apple pomace (the left over material after pressing)[10]. Follow the steps on Wild Yeast Isolation to harvest your cider culture.


"Keeving" is the traditional process of Western England and France for naturally carbonating a sweet cider.

Major Regions of Commercial Cider

(To do)

All regions produce cider both made spontaneously and with brewer's yeast only (as per Gareth Young). We are mainly interested in spontaneous fermentation producers and their procedures.

Southern England





See Also

Additional Articles on MTF Wiki

External Resources