Beyond the basics of creating the various cider styles, there are additional process controls that cider makers might employ. This section explores these advanced (and generally optional) topics, including malolactic fermentation, keeving, oaking, stabilization, clarifying, aging, and blending. To develop a good understanding of the various techniques, processes, products and methods, we discuss how they are used, the pros and cons of using alternatives, and how they affect the final product.
What is MLF?
Malolactic Fermentation (MLF) is the conversion of one molecule of malic acid (C4H6O5) into one molecule of lactic acid (C3H6O3) plus one molecule of carbon dioxide (CO2). In addition to a slight increase in carbonation, MLF alters the balance of the cider by reducing acidity, removes nutrients, and may present significant flavor and aroma changes. The exact changes occurring during MLF will depend on the organism performing the MLF, and what conditions the cider is experiencing. Intentional malolactic fermentation is encountered quite rarely in North American homebrewing competitions, but as styles exhibiting MLF and the apples used to create them grow in popularity and availability, judges will start seeing more entries featuring spicy and smoky characters.
What performs MLF?
MLF is not performed by the beer or wine yeasts pitched to make cider or by wild yeasts already present in the fruit, but rather by Lactic Acid Bacteria (LAB). The three main classes of LAB that perform MLF are Pediococcus, Oenococcus, and Lactobacillus. At the moment BJCP has no sour cider styles thus all species of Pediococcus would be considered spoilage LAB until shown otherwise, and unwelcome outside of C2F – Specialty Cider/Perry. You may have seen vials of have Oenococcus oeni available in a home winemaking shop – most red wines and some white wines undergo MLF. There is only one Oenococcus species but several strains available. The third class of LAB, Lactobacillus, has several species common in cider and is what creates the phenolics associated with the BJCP English Cider style and to a lesser extent French Cider.
Despite their reputation on the internet, wine yeasts such as Lalvin 71B (and a few others) do not perform a partial MLF. A few of these yeasts simply metabolize a portion of malic acid. It is not performing malolactic fermentation, it is not creating lactic acid, and it is not creating the spicy/smoky phenolics, but rather simply reducing acidity. Use of these malic reducing yeasts will not turn a New World Cider into English. These strains may still be useful for reducing acidity and increasing drinkability in very high acid cider blends. In low acid blends such yeasts may reduce acidity to levels judges do not find refreshing or may even invite bacterial contamination.
When/under what conditions does MLF happen?
Lactic acid bacteria are inhibited by high alcohol, low pH, low temperature, lack of nutrients, high relevant acid concentrations, and presence of bound and especially free sulfites.
Alcohol high enough to inhibit MLF really doesn’t happen in cider without a lot of added sugar. Varying by strain but generally in the range of 13% ABV, inhibition of MLF by alcohol is really more of a grape wine issue.
Temperature of 60 °F (15 °C) is low enough to keep most strains from starting, though it will often continue at this temperature if it has already begun. Lactic Acid Bacteria like the 60 – 75 °F (15 – 24 °C) temperature range, with some variation between individual strains. MLF in low temperature cider can take months to complete.
Generally pH below 3.2 will keep MLF from beginning, and many strains are at least somewhat inhibited below 3.5. Oenococcus generally works at lower pH than Lactobacillus and Pediococcus, making it ideal for wine and cidermakers looking to reduce acidity without added phenolic characters.
Malolactic fermentation can be performed at any time and some winemakers use this tool during primary, however in cider MLF is usually performed after primary fermentation is finished – LAB can also metabolize sugars as yeast do, creating things like acetic acid that cidermakers want to avoid in the finished product. This is one area where a sour cider would likely differ from those BJCP has current guidelines for.
Leaving the cider on a small amount of the lees can help encourage MLF as nutrients necessary for LAB to perform are liberated as the lees are broken down. Extremely high levels of malic acid can create an environment that inhibits LAB, while high levels of lactic acid may kill LAB – as always sensitivity can vary significantly by strain.
Some sulfite will be Bound to the phenolics, acetaldehyde, and sugars in the cider, while the rest of the sulfite will be Free. The relative concentration of the different forms of sulfite will depend on the cider pH, with Free + Bound representing Total sulfite. Details about sulfite may be found in the Troubleshooting section. Generally LAB will be inhibited by more than 10 ppm Free and 30 ppm Total sulfite.
What effects does MLF have?
All classes of LAB will perform the same basic transformation of malic into lactic acid, but will differ in their other effects. As just mentioned, effects will also differ based on the conditions of the beverage.
Acidity Reduction – Complete reduction of malic acid will reduce the acidity by half if no other acids are present, i.e., malic % is in the high 90’s. If other fruit are used, i.e., acids other than malic are present in significant amounts, the reduction will be less.
pH Increase – Note that in a highly malic cider the pH increase can be significant. Cidermakers strive to keep pH low enough (<3.8) to help protect the cider from microbial contamination and may monitor the increase.
Acid Flavor – Recall that malic is considered to have a harsher flavor than lactic, thus cider with lactic acid often seems smoother, less metallic, and more approachable, not just simply less acidic.
Reduction of the base fruit character – Expect cider that has experienced MLF to have lower amounts of overt apple and perhaps a more nuanced fruit character. Some find the overall aroma more complex after MLF; however, if the initial fruit did not have much complexity others may find cider dominated by smoky MLF to be fairly simplistic.
Phenolic Flavors and Aromas – Spicy, smoky, restrained barnyard. These aromas/flavors are the result of the LAB breaking down phenolic acids in the apple juice. These phenolics are not associated with the Oenococcus oeni strains that winemakers are pitching to finish their red wines and a few whites like Chardonnay, so do not make the mistake of grabbing such a vial and expecting it to suddenly “turn your cider English”. MLF happens with existing lactobacillus bacteria once conditions for their growth sufficient. Also, don’t confuse the phenolic substances being acted upon with the true apple tannins. Dessert apples can have high levels of phenolic acids and very low tannin levels, i.e., one does not need a tannic cider to be able to perform MLF. Pronounced barnyard funk aroma without the spicy and smoky phenolics generally indicates a Brett infection and is a flaw.
Diacetyl Production – Diacetyl is acceptable in cider as long as it complements the finished product. Judges need to be able to appreciate subtlety to judge cider, especially New World Cider. Many Beer Judges have trained themselves to be sensitive to the buttery flavor and aroma, and slick mouthfeel of diacetyl. Those who have taken a liking to (or hatred for) Chardonnay are also likely familiar to the common profile from MLF. Few cider enthusiasts seem to feel as negatively about it as the average Beer Judge. Presence of diacetyl is not a reason to not perform a full sensory analysis of the cider. Please take that to heart with your judging if you are particularly sensitive to diacetyl. Remember these can be very dry, delicate beverages. A small amount of butter isn’t a reason to disqualify a cider from medal contention, but diacetyl should never be a dominant character. Judges blind or extremely sensitive to diacetyl may wish to discuss this with their fellow judge before the flight.
Promotes Stability – Despite seeming counter-intuitive because the increase in pH during MLF may leave the cider prone to bacterial contamination, the process can indeed promote a stable cider. Consider what processes are going on and what substances are present. Malic Acid is the target of multiple microbes, thus its presence makes the cider somewhat more susceptible than a cider without malic. Also, in performing malolactic fermentation LAB are removing other nutrients from the cider or wine. Thus, those nutrients are not available for other spoilage microbes to consume. If they cannot survive, they cannot do much to spoil a cider. High pH cider is not really desirable, and all other things equal one should try to keep pH at or below 3.8, but if a cider is dry and LAB have used up the last micronutrients available, there isn’t much left for spoilage microbes to chew on even if pH is a bit higher than ideal. With appreciable residual sugar, fairly low acid, and low alcohol content, French Cider can be among the least stable cider you will encounter. Just a small amount of nutrient becoming available can sometimes reactivate such ciders in the bottle.
Mousiness – At low levels often associated mouse with an initial bready flavor that lingers in the aftertaste, building in strength on the palate, very often becoming Cheerio- or (unbuttered) popcorn-like, with a bit of an unpleasant film-like feel on the tongue. The name “mousiness” is because while low levels of it can be minimally unpleasant, higher levels, especially with a higher-pH palate, may be reminiscent of a mouse cage or wet rodent fur. Obviously at this level, mouse is a serious fault. Mouse itself has no aroma, though some associate a certain bread-like aroma with other processes LAB are performing on cider at the same time they are creating mouse.
Though mousiness is never a positive in cider and wine and should be avoided, some find it quite pleasant in beer. Ability to detect mouse varies significantly, but an alkaline mouth rinse can often help make the flavor more noticeable. Some judges cannot detect mouse at all, while others do not even need the mouth rinse for the level to be extremely objectionable. Everyone’s palate is different, and you should expect your own ability to detect it to vary with pH of your palate at a given moment.
If you’ve been making or judging sour beer or experienced wine that has gone mousy, you may be familiar with THP, aka the various Tetrahydropyridines. Various sour beer brewers have experienced THP aging out over time, some believing it has been transformed into something with a higher detection threshold. That seems plausible but mouse is incompletely understood and evidence of it disappearing in cider or wine is lacking. If the infection is moderate to severe and the judge’s sensitivity fairly high, it can become undrinkable. Though incompletely understood, we do know mousiness in cider is a fault. New cidermakers are encouraged to avoid it with sulfite and sanitation, and to not start experimenting until they know their process, have a history of creating “clean” cider, and are prepared to dump what doesn’t turn out. Judges should point out the presence, intensity, and effect on drinkability of mousiness, but should not try to diagnose without complete information.
Where will judges encounter it?
English and French are by far the most common BJCP styles featuring MLF you can taste. New World Cider as BJCP defines it should be free of smoky/spicy/old horse MLF character.
What about in Specialty Cider and Perry? Herb/Spiced Cider or Cider with Other Fruit may include MLF, as can Specialty Ciders. New England Cider, Applewine, and Ice Cider should be free of spicy/smoky phenolics from LAB. Phenolics can and usually do seem out of place if not expected thus entrants should tell the judges what to expect. A judge reading that the base of a Cider With Other Fruit is English is going to expect tannin, and will not be surprised by moderately high MLF; with French, they will expect less MLF and bitterness.
Keeved cider is currently rare in North American competitions dominated by New World entries; however, the practice is more common in other styles, most specifically French Cider. As entrants occasionally identify a cider as keeved in the Specialty Information section, a basic understanding of the keeving process is considered useful for cider judges.
Goal of Keeving
At its core keeving is about removal of nutrients from apple or pear juice. The goal of the removal is to starve the yeast of nutrients before fermentation would normally end in dryness, so the finished beverage may be bottled retaining some residual sweetness without added sugar.
Process of Keeving
Fruit to be keeved is washed and milled identically to non-keeved cider. Fruit should be very ripe. After milling the fruit is usually macerated by holding at a cold temperature for a period of hours, up to a full day, before pressing. The process is done at a low temperature as wild yeast fermentation is not desired yet. Maceration can be done on almost any cider, but is more common with this method. Keeved cider differs from other methods primarily due to two processes: enzymatic reduction of nutrients, and repeated timely racking.
Nutrient Reduction: Removal of nutrients from apple/pear juice is done enzymatically with Pectin Methylesterase (PME). This enzyme occurs naturally in small amounts in apples and pears; however, modern keeving more often involves the cidermaker using additional PME. Note that PME is not the same as the Pectic Enzyme (pectinase) often added to cider to promote clarity. Pectinase added to juice that will be keeved will actually interfere with the keeving process. Pectin Methyl Esterase in the juice will convert some of the pectin to pectic acid. As fruit ripens, nitrogen content is reduced and pectic acid increased, thus use of very ripe, late-maturing fruit is typical in keeved cider. Use of dessert fruit naturally high in nutrients is unlikely to result in a successful keeve. PME also works better at higher pH, may struggle to successfully keeve an extremely high acid, low pH must, and thus is perfectly suited for the bittersweet apples heavily used in French-style ciders.
In addition to PME, a successful keeving requires the presence of Calcium. Apples and pears contain small amounts of calcium that sometimes is insufficient to form a good keeve. The efficiency of the process may be assisted with the addition of calcium chloride to the juice. Calcium combines with pectic acid to form an insoluble gel-like substance called calcium pectate. During this time initial fermentation has begun; however, the cold temperatures involved keep initial yeast activity very low. By trapping the initial bubbles of carbon dioxide from a slow fermentation (or in the case of some commercial cidermakers by capturing nitrogen bubbled up through the juice), the gel is forced to the surface. The gel also traps other substances in the juice. At the same time pectin may combine with tannins or proteins in the juice, fall to the bottom, and further clarify the juice. This process will commonly take several days at minimum, and up to a few weeks. Vigorous fermentation will break apart the gel and the keeve will have failed.
Timely racking: Between the gel at the top and the pectin and proteins at the bottom is the goal – the clear, low nutrient juice in the middle. This juice is racked away from the top and bottom portions and fermented slowly at cool temperatures with yeast already present in the fruit. Keeving requires control over the fermentation process, as it is not just about nutrient removal, but also about racking away from yeast that are working too fast, to reduce population, slow fermentation, and ensure fermentation can be stopped at the correct time. Commercially available yeast will work too fast and too vigorously to control this process. Inattentive cidermakers may find that an initially successful keeve still proceeded to full dryness if they did not adequately control the fermentation. It may take multiple rackings to adequately slow fermentation, which often takes months to complete at low temperature.
Bottling: Fermentation must be extremely slow at time of bottling, with only a few points of sugar able to be fermented before the yeast quit. As residual sugar levels of keeved cider are usually significantly higher than this small amount, the use of champagne bottles that can handle high pressure is typical – theoretical levels of carbonation possible can cause bottle explosions, and the stronger champagne type give a more reasonable margin of error. Expect carbonation in the bottle to take at least a few additional months before the few remaining yeast quit. Commercial cidermakers may pasteurize bottled keeved cider once the desirable carbonation level is achieved. For amateurs, pasteurization is done rarely and choosing the correct time to bottle can require significant practice. Cool storage is safest for keeved cider as it may take only a small amount of nutrient becoming available to restart fermentation, resulting in over-carbonated bottles or worse.
Effects of Keeving
General effects on the cider: Juice tends to darken during maceration and the keeve. Calcium pectate gel traps vitamins like thiamin as well as lowering the nitrogen content of the must. The gel also traps some of the native yeast, lowering the population in the remaining juice and helping to slow fermentation. Properly keeved juice racked away from the cap will be much clearer than unkeeved juice. Fermentation will proceed much slower than traditional methods, which is further encouraged by low temperatures. Successive rackings to reduce yeast population can stop fermentation with significant residual sugar remaining despite the yeast being well under their normal alcohol tolerance. Finally, the process will result in loss of a noticeable percentage of the original juice. As fermentation is very slow and excess headspace undesirable, fermentation vessels should be kept topped off with each subsequent racking.
Effects noticeable during judging: Alcohol content tends to be low to very low, occasionally even below 3% ABV. A proper keeved cider will have noticeable residual sweetness. Judges may consider a final gravity in the range of 1.005 as an approximate minimum for a successfully keeved cider, with significantly higher sweetness possible. Also remember that tannins, acidity, serving temperature and palate variability will affect perceived sweetness. An entry indicating keeving was performed but that shows zero residual sweetness would indicate the entrant did not rack properly or otherwise control fermentation. This would indicate the entrant has missed their goal, however as keeved cider is not a defined style the cider should still receive a full evaluation on its own merits. It is also possible for a keeve to be too successful, stopping fermentation too early, resulting in cloyingly sweet, flat cider. Very skilled cidermakers may be able to successfully re-start and control a stalled fermentation of keeved cider. Regardless of whether a keeved cider finished too dry or too sweet, judges without significant cidermaking experience should focus on a fact-based evaluation, indicating that the balance is too sweet or dry, without focusing on unknown techniques. Cider may also be encountered that has significantly greater carbonation than entered or is desired if fermentation did not stop as soon as expected. In some cases this may result in gushers or worse. Finally, the long slow fermentation may leave the cider prone to oxidation if headspace in the fermenter is not kept to a minimum.
Some aspects of this topic are well beyond what the average judge will care about. Indeed, few amateur cider makers currently even calculate or test for Free Sulfite. However, the effects of sulfiting or a lack thereof are often very evident in amateur cider evaluation, and it may help a judge to understand how those characters came to be, and how they could have possibly been avoided. Judges interested in more specifics are directed to Andrew Lea’s work on the subject (http://www.cider.org.uk/sulphite.html)
What is Sulfite?
Sulfiting refers to the addition of sulfur dioxide (SO2), generally in the form of potassium metabisulfite or sodium metabisulfite. These forms are most well known as Campden tablets, which are both calibrated to give a little over 50 parts per million (ppm) of sulfur dioxide per tablet per (US) gallon. The two basic functions of sulfur dioxide in cider (or other beverages) are anti-microbial, and anti-oxidant. Homebrewers have likely used one or both of them to bind chlorine or chloramines in brewing water.
Use of sulfur dioxide in alcohol likely dates well over 1000 years, particularly in grape wine, and is also produced naturally by many yeasts during fermentation. Sulfites have a long history of uses as food preservatives, some of which are now outlawed. A small portion of people, particularly asthmatics, may have a severe reaction to presence of Free Sulfites in alcohol. Dried fruit may be especially high in sulfites if not labeled as unsulfured. Use of sulfites in cider is not required but will greatly decrease chances of microbial contamination if used correctly.
Sulfur dioxide is popular for sanitation partly because the commercial yeast we commonly pitch and to some extent wild yeast used in spontaneous fermentation are more resistant to it than other micro-organisms. The ability to inhibit or outright kill film yeast, mold, bacteria, and prevent MLF, while allowing commercially-pitched Saccharomyces yeasts to function relatively unimpeded is a valuable trait.
Between sodium and potassium metabisulfite the latter tends to be more popular, as many desire to limit added sodium and potassium is a commonly needed yeast nutrient anyway. Both forms are suitable for use, however. Sulfite may be added before fermentation at a low concentration to inhibit some of the worst spoilage organisms while still allowing some complexity from native yeasts to develop.
Effects of Sulfite (Good and Bad):
- Kills or inhibits wild yeast.
- Kills or inhibits other spoilage micro-organisms.
- Helps prevent malolactic fermentation (MLF).
- Binds to oxidation products.
- Promotes color stability (However, in the case of red-fleshed apples, will make it difficult to keep that red color).
- May be noticed as struck match aroma and flavor in the finished cider.
- Overuse may make cider seem metallic or bitter.
- Often used along with sorbate in stabilization of cider.
- Small percentage of people may have severe reactions to sulfite.
Timing and Dosage of Sulfite
Sulfite might be added at different times during the cider making process; however, the goal of each addition may not be the same. Prior to fermentation the primary concern is contamination. In post-fermentation cider, alcohol is helping protect against spoilage and oxidation becomes a major concern.
A molecular sulfur dioxide concentration of 1 ppm will kill most spoilage micro-organisms. Lower levels will work on some, while higher levels will eventually impede commercial yeast. There are legal limits for sulfite use in commercial alcohol in many countries, with actual limits varying by country and by beverage, however amateur cider makers should strive to keep Total Sulfite under 200 ppm. Unfortunately one cannot simply pitch a few Campden tablets into a carboy and assume the bad stuff is dead. While it’s possible this approach will work, it’s also possible that such a practice will do nothing for a cider.
Prior to Fermentation – When added to fruit juice all of the sulfite is initially Free, i.e. unattached and available to react with substances in the juice. However, within the first several hours, a large portion of becomes Bound sulfite, which is not capable of killing micro-organisms. Total sulfite is the sum of Bound and Free sulfite. What is it bound to? – It depends on the juice and conditions. Binding with acetaldehyde is a large portion of what is removed from Free sulfite. Use of pectic enzyme may result in sulfite bound to a by-product. Presence of rotten fruit among the juice will also result in increased sulfite binding. Some is bound to sugar, some becomes oxidized, and some will blow off when racking. The point of all of this is that a large portion of sulfite added will be quickly incapable of performing as an anti-microbial. In fact, bound sulfite will not perform as an anti-oxidant either.
With the previous paragraph in mind, it may seem like a cider maker could simply assume approximately 2/3 of added sulfite becomes bound and multiply the amount added by 3. However even a large portion of the free sulfite will not function as an anti-microbial. To show why, consider sulfur dioxide (SO2), a gas that readily dissolves in water. In solution, it reacts with that water, forming bisulfite ions and sulfites. Of the three, only molecular SO2 will kill microbes; the other two will not. The relative concentration of these three substances in solution depends on the pH.
Cider fermentation and storage generally takes place between pH of 3 and 4. At pH of 3, less than 10% of sulfite is molecular SO2. At pH of 4, it is well under 1% of total. Therefore a cider maker cannot add a safe level of sulfur dioxide to a cider with pH of 4 and expect to kill spoilage organisms. At a pH in the mid 3’s a realistic number would be 2% of sulfur dioxide is present as molecular SO2, which means to get a concentration of 1ppm molecular SO2 one needs to add 50 times as much SO2 – 50 parts per million.
At high pH closer to 4, the cider maker must first acidify the juice before sulfiting can be effective. If pH is near 3, very little may be necessary and indeed some people use none. In the case of perry, extra acetaldehyde in pear juice means even higher rates of Bound Sulfite, thus perry makers may need to add higher rates of sulfur dioxide, or at least be sure to use no rotten fruit. Free Sulfite can be measured by hobbyists with reasonable accuracy, however test equipment and calculation tend to be somewhat expensive and time-consuming.
After Fermentation – Sulfite may be added at multiple occasions, especially if it will be racked several times. Fermentation will create additional substances that can bind sulfite. For anti-microbial uses the Free vs Bound concern is the same and significantly more than 1 ppm sulfur dioxide will be needed to get effective amounts of molecular SO2. Total sulfite will still decrease as some is oxidized, and some blown off in racking or subsequent CO2 blow off. If trying to prevent malolactic fermentation, 10 ppm Free and 30 ppm Total Sulfite will often suffice. As some yeasts may produce as much as 30 ppm sulfite during fermentation, depending on conditions no additional sulfur dioxide may need to be added to inhibit MLF.
For anti-oxidant purposes, pH does not affect the amount of sulfur dioxide needed. Recall that a portion of sulfite becomes bound to acetaldehyde. Acetaldehyde is a common precursor to oxidative reactions and thus sulfite binding will help limit oxidized, sherry-like aromas. The 50 ppm rate previously mentioned for anti-microbial purposes is commonly used for anti-oxidative purposes as well. Some free sulfite will be blown out in splashing while racking, thus a cider maker might sulfite with every other racking, measuring free sulfite and treating to make sure it remains high enough to protect the cider.
For those allergic to sulfites, free sulfite is the portion that matters. By the time of bottling any sulfite added prior to fermentation should have been bound, removed, or oxidized, thus only late additions may cause sulfite allergies.
Sulfite and Judging
The presence of sulfur dioxide may be noted in cider flavor and aroma; however, its absence seems to show up almost as often in the form of oxidation or contamination. Excessive SO2 may be noted as an acrid, smoky, struck-matchstick aroma and flavor that may slightly irritate the nose and throat, especially if such sulfiting was recent. A very slight sulfur dioxide aroma is quite common and would generally not be a significant flaw. There is a tradeoff made – cider makers may cope with a slight SO2 aroma while young in order to give a cider more longevity. Note “sulfite” character is in contrast with the similarly-sounding “sulfide”, often identified as rotten eggs and usually indicative of unhappy yeast / a struggling fermentation.
If sulfur dioxide use was insufficient for the pH of the cider, micro-organisms may have been able to act upon the cider in the form of MLF or any number of infection characters. Insufficient stabilization including sulfite may end up re-starting fermentation in the bottle, leaving a cider lower in sweetness and higher in carbonation than entered, and even result in exploding bottles.
Cider insufficiently protected from oxygen will often darken quickly, leaving cider lacking brightness and brown in color. Fruit ciders may lighten with oxidation, and in red-fleshed apple cider moderate levels of sulfite may bind to the substances that cause red color, leaving the cider pinkish brown in hue. Insufficiently sulfited cider will more quickly develop “cooked” characters or sherry notes. Oxidation is a part of proper maturation of an alcoholic beverage but should proceed slowly and has its limits.
The common presence of greater amounts of binding acetaldehyde in Perry may require higher levels of sulfite to protect, however with the common delicate character of many pears, struck match aroma will quickly detract.
A brief review of oak in cider is presented below. Judges wishing to learn more specifics about the effect of various oak forms and varieties on cider are directed towards Petar Bakulic’s excellent work on the BJCP Mead Education page and Mead Study Guide. Much of the information is directly applicable to cider, with the caveat that few ciders are as big as the average mead, and thus few styles can support high oak levels.
Encountering oak in judging
Oak can be welcome in most cider, but should usually be subtle. Cider does not generally have the huge body of some red wines, and cannot be oaked similarly without the base cider being buried. Most ciders are closer to a low alcohol white wine, featuring subtle fruit and/or fermentation character, especially when dry, semi-dry, or medium in sweetness. Fuller-bodied ciders do exist; however, attempts to oak something as heavily as, say, many imperial stouts will usually result in an overdone oak character and possibly even a ruined beverage. Ciders with immediately-noticeable, moderate-to-high levels of oak should be entered in Specialty Cider/Perry with oak identified in Specialty Information. Oak is also fairly common in New England Cider, where it should be identified by the entrant in Specialty Information if noticeable.
Very subtle oak may be nearly indistinguishable from naturally occurring fruit tannins or aging processes. Many judges will look for any specialty character listed, and lower the score if they do not detect each. Judges sometimes need to be reminded that the mere presence of something on the pull sheet does not indicate it will be obvious, nor that everything listed will be equal in intensity. If an entrant declares oak as part of a specialty cider or perry’s description, then the judge should treat it as a secondary characteristic. It should be noticeable as something that could be that character, but does not have to be obvious and should never be dominant. Judging is improving; however, unfair judging does still sometimes happen, thus entrants should probably not identify extremely subtle oak (or other additives). Always keep in mind that most cider is a relatively delicately-flavored beverage and that oak character is easily overdone.
Exposing cider to oak imparts structure, complexity, and additional flavor and aroma. Specific flavor and aroma characters depend on the variety and toast level. Oak adds a huge number of characters at various intensities but common flavors and aromas added include oaky, woody, toasty, and vanilla.
Once added, oak cannot be removed. It may mellow over time, but may not happen while the cider is still in peak condition. It’s always better to add a little oak and then repeat the process, then to make a strong addition and hope an excessive oak level eventually balances.
Oak can add color to cider. The higher the toast level and the longer the contact time, the more color will be added – usually with amber tones. The color addition might be less noticeable in more deeply-colored ciders or if dark fruits or adjuncts were used.
Oak can add tannins, which contribute a fuller mouthfeel and drier finish, but should not by itself exhibit high levels of astringency. Tannins can make a cider seem drier than it is, and can balance sweetness just as acidity can. Thus a small amount of oak may help a cider that is otherwise slightly too sweet in balance. At higher levels, oak tannins are noticeably astringent. tannins add structure to the cider, and can help a cider store longer. Red wines with higher tannin levels often age gracefully, yet may take several years before they peak. A similar impact may be seen with cider, though as generally a lower alcohol beverage than grape wine the average period of enjoyability is somewhat more limited. Tannins tend to soften over time.
Most cider is oaked after fermentation, but occasionally cider may be fermented in or on oak. Oak comes in French, Hungarian, and American varieties, and at several different levels of toast ranging from untoasted to heavy toast. The highest toast levels are of limited use in cider due to their intense flavors and high char levels, and must be used with caution to avoid clashing or overwhelming the base beverage.
Oak comes in a variety of shapes and sizes for many different fermentation, aging and storage vessels, but chips and cubes are the easiest to find. Small or full-size oak barrels can also be used. Other oak forms include strips, spirals, stave segments, powder and oak essence. Powder is often included in wine kits, and is essentially sawdust. Essence is a liquid extract and can be very harsh. Neither are recommended.
Contact time and surface area of the oak in contact with cider will determine the amount of oak character imparted. Smaller products with a great deal of surface area such as chips and powder work very quickly, however the resulting character is generally lacking in complexity, and the speed of the process can leave a cider quickly over-oaked. Larger oak products such as Cubes, staves, spirals and strips can add a deeper, more complex character, at the expense of working slower. Large barrels may take significantly longer to impart oak character, but leaves the cidermaker with greater margin of error on when to remove the cider.
Stabilization means attempting to keep the character and composition of a cider stable over time. Cider can primarily change through continued fermentation (whether through the primary yeast strain or through other microorganisms). Age-related changes are normal and are covered in a separate discussion under Aging. Obviously keeping oxygen out of contact with the cider will enhance stability. Haze-causing particles may contribute to a lack of stability and shelf-life, thus clarification of cider will be considered here as a part of stabilization.
Clarifying agents work to remove haze from cider. Haze can be the result of suspended yeast, particles of protein, pectin haze, starch haze, polyphenols (tannins) in the cider, added spices or hops, or perhaps a bacterial contamination. Pectin is the compound in fruits that will gel when heated. Different varieties of fruit have more pectin than others. Pectic Enzyme (Pectinase) breaks down the long polysaccharide chains that form the pectin. It is generally added at the start of fermentation, but may be added after fermentation if a pectin haze is noted. Pectinase is more effective above 59 °F (15 °C), and should not be added to juice undergoing a keeve. Formulations and usage rates vary, so be sure to check manufacturer’s recommendations.
Proteins are positively-charged, while yeast are negatively-charged. Clarifiers bind electrostatically to the proteins and other compounds and precipitate them out. Because they each work differently, no one fining agent can remove every possible cause of haze. In most cases, one agent on its own will provide satisfactory results. For difficult juices, the most effective approach is to use positively charged and a negatively charged clarifying agent successively. Pear juice is notoriously difficult to clarify and some lack of clarity is acceptable in all Perry styles.
Most ciders that have finished fermenting will naturally clarify on their own given enough time and appropriate racking. However, many cider makers do not want to lose the volume of cider that multiple rackings would entail. Before attempting clarification, make sure that the fermentation is complete; a stuck fermentation will not clear. Assuming the cider has finished fermenting, cooling the cider may be attempted first; a 10-20 °F (6-12 °C) drop is generally sufficient. If fruit was added, some pectic enzyme can help clear up any pectin haze. If these steps don’t produce results, fining agents can be used (they are generally more effective at cooler temperatures). As a last result, mechanical filtration can be used. However, filtration can also remove color and flavor compounds, and may unintentionally oxidize the cider if not done properly.
It is important to note that microflora may be present and capable of activity beyond the point at which the yeast cease fermentation. In ciders that may finish with considerable residual sugar, without high alcohol (below 10 percent), with high pH (above 3.8), or with any combination of the three, it is critically important that the amounts of nutrients used do not exceed that which will be consumed by the yeast during growth and fermentation. Excess nutrient at that point will simply serve to nourish organisms that may harm your cider.
Reliable methods of stabilization all start with ensuring fermentation has completed. As was discussed in the Fermentation section of Process Options, the best way to stop fermentation is to let it finish naturally. Removing yeast or inhibiting yeast from restarting fermentation will then stabilize the cider. Once stabilized, the cider can be sweetened to the desired level without restarting fermentation.
Some choose to let time and multiple rackings, possibly assisted by clarifying agents (particularly those positively-charged ones that will precipitate yeast). This can work, although it takes quite some time, causes volume loss with each racking, and isn’t guaranteed to work every time (some yeast can always remain and restart fermentation if sugar is added).
Filtration will remove yeast, but can also remove color and flavor components. Most yeast can be removed with a 3 μm (micron) filter, with total yeast removal at 0.8 to 1.2 microns. Spoilage bacteria can be removed with a .45 micron filter. All bacteria can be removed with a .2 micron filter, and is considered true sterile filtration. However, the tighter the filtration, the more color and flavor may be removed from the cider.
Flash pasteurization is a “high temperature, short time” method of heat pasteurization for perishable beverages. These methods are more generally used by commercial cidermakers, who may desire a carbonated beverage well below normal yeast alcohol tolerance to have minor to significant amounts of residual sugar. The liquid is moved in a controlled, continuous flow where it is subjected to 160-165 °F (71-74 °C) temperatures for 15-30 seconds, then rapidly cooled. Most home cider makers do not possess the carefully controlled heat exchangers necessary to perform this process. Attempting to pasteurize finished cider can result in loss of color, flavor, aroma, and possibly alcohol. Cooked flavors can also result. With current technology, this process is best left to commercial operations.
The most common method of stabilization for cider makers (other than the “do nothing” option) is to use a combination of potassium metabisulfite and potassium sorbate. These preservatives stun any remaining yeast and prevent them from reproducing. They will still be present, but will be unable to restart fermentation. Drawbacks from this approach is that some people are allergic to sulfites, and if sorbates are added an objectionable odor of geranium leaves can be created if a malolactic fermentation subsequently occurs.
The do nothing alternative relies on taking steps to cause yeast to precipitate (time, finings, racking), followed by cold storage and (possibly) rapid consumption. High-gravity ciders that are closer to the alcohol tolerance of the primary yeast strain are less likely to restart fermentation, as are ciders with a lower pH level. Obviously, ciders that are fermented dry are unlikely to continue to ferment, but many prefer the taste of sweeter ciders.
Cider is one beverage where North American home enthusiasts are largely making a different sort of beverage than artisan commercial cidermakers. Note this is changing as apples and pears become more widely available to hobbyists, and no statement about superiority of one method over another is being made. Homemade cider tends to have a lower alcohol content than grape wine or mead, and thus has never had the stereotype of mead or wine of needing to be aged for a significant length of time in order to be drinkable. Modern homemade cider seems to have more in common with the Staggered Nutrient Addition mead movement, and hobbyist cidermakers often finish their beverages in weeks or even days. However, nearly all cider can still be matured to reach its peak flavor.
Aging normally reduces esters, bitterness, alcohol sharpness, color, and intensity of flavors. Proteins, tannins, yeast, and other particulates tend to precipitate from solution, enhancing clarity. The most noticeable positive change from aging is typically a smoothing and melding of flavors. Those who prefer big, bold flavors will often enjoy younger ciders, but well-aged cider can develop a layered quality and complex character that is rarely seen in young cider. The presence of tannins does help stabilize cider and increases the ability of cider to age for a longer period of time, just as with wine.
Note that aging does not imply oxidation, although some oxidation is inevitable unless all but the best handling and packaging procedures are followed. Some dip their bottles of cider in wax for long-term storage as an oxygen barrier. This is a good solution, provided that oxygen wasn’t introduced into the cider during handling prior to bottling. Natural corks will allow some oxidation, but synthetic corks can be an effective barrier. Traditional crown-type bottle caps are probably the least effective for long-term storage. Having clean cider that is free of faults is important for long-term storage, but keeping oxygen away from it is the most important factor for successful storage.
Aside from oxidation, other factors that can degrade a cider during storage are heat, light, and mechanical agitation. If oxygen is present, all of these factors will increase the rate of oxidation. However, they can also degrade an oxygen-free cider. They speed up the rate of chemical reactions, and can cause flavor and color to become more muted.
Oxidation generally causes colors to become duller and darker, causes the clarity to lose its brilliance, and causes fruit flavors to move from tasting like fresh fruit to tasting like dried fruit; in essence, it tastes stale. Oxidation may create aldehydes, which can increase the bitterness level. Oxygen can allow aerobic bacteria, such as acetobacter, to flourish. Finally, oxidation is responsible for aromas like paper and wet cardboard, almond/nutty.
Not all oxidation is bad, since oxidation can produce interesting complexity in cider. The organic chemistry is fairly complicated and involves multiple reactions, but oxygen, alcohols and acids can react slowly to produce esters. Oxidation can also produce nutty, sherry-like aromatics.
The main choice in aging is whether to bulk age or to bottle age. Bulk aging is simply aging in anything other than the final bottle, typically a carboy or keg. Anything inert and gas impermeable will work. Bottle aging is transferring the finished cider to a bottle after fermentation is complete, the cider is stabilized, and any final adjustments are made.
Bottle aging is the traditional method for most home cider makers. It provides the best protection against oxidation since it is not kept in an intermediate container, and is likely to involve less racking. The disadvantages are that the cider may change while aging, and adjustment becomes much more difficult. Differences may exist from bottle to bottle.
Bulk aging is a more relaxed approach, since it allows the cider to mature and change as a full batch. It may sit on lees, or it may not. If it does, this can add additional nutty, toasty, bready yeast flavors, as well as providing minor stabilizing effects. The advantages of bulk aging are that the cider can be adjusted and blended over time, that fermentation is more likely to be completely finished, that clarification is enhanced, and that the final product will likely have more consistency from bottle to bottle. The disadvantage is that multiple rackings might be required, and that introduces a higher chance of oxidation and spoilage. If bulk-aged in a carboy, care must be taken to prevent the airlock from going dry. Any transfers should be done after purging containers with CO2 to minimize oxidation.
Blending can be thought of as another form of cider adjustment, although it can be used to create a totally new beverage. Blending is the mixing of cider with another beverage (usually another cider, but it could be something else). It can be used to create consistency between batches, to correct flaws in a batch, or to create a new concept. Sometimes it is easier to blend than to attempt to correct a problem by using direct adjustment with additives.
Some common scenarios for blending include:
- Blending a sweet cider with a cider that is dry, highly acidic, tannic, or high in alcohol to create a more balanced cider. Sweetness balances acidity, or takes the edge off dryness. Note that it is possible to add sweetness to a very dry cider and have it still seem dry. Yet the palate can seem softer, which makes the cider much easier to drink.
- Blending a traditional cider without strong flavors (except perhaps a compatible varietal juice character) with a cider that has an overdone character (such as too much fruit, spice, alcohol, oak, etc.). If blending cider has strong flavors as well, they shouldn’t exacerbate problems in the base cider. A blending cider with a strong varietal character can sometimes add a pleasant complexity to the base cider, allowing the juice to match strength-with-strength with the other strong flavors.
- Blending an overly sweet cider with other ciders needing to be back-sweetened. While the overly sweet cider might be unpalatable on its own, it is a very useful cider to have on hand. If the sweet cider is clean, it will always be useful as an alternative to adding raw juice as a sweetener.
- Blending different types of cider (say, a fruit cider with a spiced cider) can be done to create another type of cider. This doesn’t have to be done with the entire batch; it can be done to yield three different ciders from two fermentations. This can be a fun way to test concepts without making a full batch.
- Blending cider with other beverages (such as beer, wine, mead, fruit wine, or something else) to create fruit or specialty ciders. Ciders are often better if all the fermentables are fermented together, but this can be a technique used to quickly create another style of cider if needed. Sometimes you might want to test different combinations of ingredients, such as testing ideas for different fruit ciders by blending different wines with different ciders. Making separate batches of cider and wine and then blending them creates more combinations without having to manage as many fermentations. If one combination is particularly pleasing, you then know to repeat that in future full-scale batches.
- Finally, blending can be done to get rid of a defective batch of cider. This is not really recommended, but some people cannot bear to part with an expensive batch of cider even if it has issues. Blending small amounts of it can extend other batches and hopefully keep defective flavors below the sensory threshold. Dumping it is probably the better option.
- To successfully blend cider, you first need to understand the profile of the ciders (or other beverages) that you will be blending. Taste them and record their characteristics. Think about the relative intensities of the different flavor components. Then develop a concept of what blending experiment you’d like to try. Start on a small scale, using samples from each source in a separate container. If you find something you like, you can scale it up. But if you make an abomination, then at least you can dump it without having ruined your full batches.Tasting is critical at every stage in the blending process. You won’t necessarily know what ratios to use, so blending is best done in small increments. Make changes, and then taste again. Keep iterating until you’re satisfied. Keep track of the amounts you are blending so you can scale up. But remember that if you taste as you go, the quantities being blended are changing. When scaling up, you should still use less than you’d expect and keep tasting. Your palate is your best guide. Endless tweaking is rarely successful, so be prepared to stop when you are satisfied with the result.