‘perry making is more of an art than cider making’
This page is designed to be read in conjunction with the cider making guide. The basic processes of cider and perry making are very similar, however the differances are important. References and comparisons will be made to the cider making process throughout this description of perry making.
This page is organised into several sections. The principle stages of the fermentation are described, followed by an overview of the cider making process, a discussion of the characteristics of the pair juice, the microbiology of the process, the changes in the composition of the perry during fermentation, and finally a description of how to make your own perry.
Unlike cider making, you do need to know some of the technical detail to make the best possible perry. Research into perry making is less well advanced than into cider making so the depth of detail is not so pronounced. For this reason perry making is more of an art than cider making. There’s a further reading section at the end if you want to know more.
While the current editorial team will be more than glad to have your feedback; please be aware that this was written by Gillian Grafton not by the current editors! This document is as accurate as Gillian made it, but you’re on your own – we don’t accept any liability for the contents!
Principles of Fermentation
Perry is made from pear juice which has undergone two different kinds of fermentation. The first fermentation is carried out by yeasts which have either been added deliberately or which are naturally present on the pear skins. This fermentation converts sugars to ethanol and the higher alcohols (fusel alcohols). The second fermentation, the malo-lactic fermentation converts L(-)-malic acid to L(+)-lactic acid and carbon dioxide. This fermentation is carried out by lactic acid bacteria which are present in the pear juice. The malo-lactic fermentation can occur concurrently with the yeast fermentation but more often is delayed until the fully fermented perry reaches 15 C, normally in the late spring or early summer of the year following that in which the perry was made.
The Perry Making Process
The process starts with the picking of the pears. These are left to mature for a period of between 2 days and 1 week depending on the variety of pear used. This period is much more critical than the equivalent period for apples in the cider making process. If not left long enough then very little pear flavour is imparted to the perry, if left for too long then the fruit begins to rot from the centre outwards (and thus may go unnoticed) and will ruin the finished perry. The matured pears are crushed in a “scratcher” or in more modern plants they are pulped in a grater mill. As with the cider making process, the crushed pulp is known as the pomace or pommy. Unlike the cider making process, in perry making it is essential that the milled pomace is allowed to stand for a period before pressing. This allows the pomace to lose tannins and thus aids clearing of the perry. The usual period for standing is overnight up to 24 hours. Next the pulp must be crushed to extract the juice. This is done in a cider press, descriptions of which can be found in the cider making guide.
The pressed juice is then fermented in one of two different ways. Traditionally the juice is run into wooden pipes (barrels which can contain 120 gallons) or smaller wooden barrels, and the bung is removed. No yeast is added, the fermentation relies on wild yeasts. The fermentation will start within 1-2 days and will continue for several weeks during which time the barrel is topped up with perry. When fermentation is over, the bung is replaced and the perry is matured for 5-6 months.
Alternatively the pear juice is treated with sulphur dioxide to inhibit natural wild yeasts, and is then fermented with added pure yeast cultures. The amount of sulphur dioxide which is required is substantially more than is needed for cider making. This is because pear juice contains more acetaldehyde than apple juice. The acetaldehyde neutralises the effect of sulphur dioxide. At least 100 to 150 ppm sulphur dioxide is required to be effective. In the UK the legal limit for sulphur dioxide is 200 ppm and may well be reduced by subsequent legislation. Always check your local regulations first! The problems associated with the need to add high levels of sulphur dioxide have led some commercial producers to flash-pasteurise the juice. The advantages of this are that it completely controls the wild yeast levels. The disadvantages are that it destroys the bacteria responsible for the subsequent malo-lactic fermentation. The acidity must be reduced after the main yeast fermentation by a controlled fermentation with a suitable strain of lactic acid bacteria.
As with commercial cider making, commercial perry makers often blend new and old perries to ensure consistency of the product. Because of the difficulties associated with high tannin pears, commercial perry makers use low to medium tannin pears which will often be a mixture of different varieties. The resulting perry, although requiring less skill to make, is of a lower quality than that made with high tannin pears.
The perry is matured in large storage tanks to allow for any further precipitation of tannins. Blending is carried out at this stage. Mutual reactions between the blended perries can occur and hazes and deposits often form. These are removed by filtration or centrifugation. The finished perry is checked for stability by cooling it to 4 C for 24 hours and observing whether any deposits or hazes form. If the perry is clear then it is either sulphited or flash-pasteurised. The perry may then be sweetened and is artificially carbonated in the bottle by counter-pressure bottle fillers. The resulting product may be considered analagous to keg beer. A common example of this type of perry is the sparkling wine substitute Pomagne (often sold as Babycham). This bears little resemblance to real perry so please don’t be put off trying the real thing by this inferior cousin!
Traditional perry is served completely flat and may well be cloudy. It may rarely be found as a naturally-conditioned cask perry in a similar way to real ale. Naturally sparkling perry may be made by the traditional champagne method in a bottle but this is very difficult to do since tannin deposition interferes with the process of disgorging the yeast deposit. For this reason it is almost never seen.
Characteristics of Pear Juice
Perry pears tend to have a high sugar content than cider apples and may give specific gravities of up to 1090 or even more. Unlike cider apples there is a proportion of unfermentable sugars present, the main contributer being sorbitol. This can lead to final gravities of between 1010 and 1020. The sorbitol does not contribute towards the alcohol content of the perry but will leave a residual sweetness and fuller flavour.
The acid composition of perry pears differs substantially from that of cider apples. Many perry pears contain appreciable levels of citric acid which may be the predominant acid in some varieties. Malic acid is also present, and the levels vary with pear variety, in some pears it is the dominant acid whilst in others the levels are less than those of citric acid. Citric acid will give a sharper taste than malic acid for the equivalent amount of acid present. It can also lead to microbiological problems (see below). Pear juice also contains minor acids such as quinic and shikimic acids.
The tannin content of apple juices gives the resulting cider an overall flavour of bitterness with some astringency. The tannin content of pear juices is quite different. Astringent leucoanthocyanins predominate and may be up to 1% of the total juice. The juice also contains complex leucoanthocyanins which are colloidal in nature and which are responsible for the heavy hazes and precipitates characteristic of perries. The particular component responsible is probably a polymer of 5,7,3,4-tetrahydroxyflavan- 3,4 diol.
Pear juices are lower in soluble pectin than apple juices. The soluble nitrogen content of pear juices is even lower than that of apple juices. The levels of asparagine and aspartic acid are lower. Some perry pears may also contain the unusual amino acid amino-cyclopropane-carboxylic acid. The final result of all this is that pear juice does not support yeast growth as well as does apple juice and fermentation is therefore often sluggish. Commerical operations routinely add ammonium sulphate to the juice to ensure rapid fermentations.
The compounds contributing to flavour, namely the higher alcohols and esters, are similar in perries compared with ciders. However, the range and amount of compounds seems to be smaller in perries, consequently the aroma of perry is less intense than that of cider and faults in the making show up more readily. Some perries may contain excessive levels of acetaldehyde and ethyl acetate. This problem can only be overcome by blending.
The Microbiology of Pear Juice
Compared with apple juice this is less well characterised. The main wild yeasts present are likely to be the same as those present on apples, namely, Aureobasidium pullulans, Rhodotorula spp., Torulopsis, Candida, Metschnikowia, and Kloeckera apiculata. Fermentation is not only affected by the species of wild yeast but also the tannin levels of the pear juice. If the pear is a high tannin variety and has not been allowed to stand sufficiently long before pressing, then heavy precipitates of tannin may separate from the juice taking the natural yeasts with it. This will result in a long lag period before fermentation can occur and will greatly increase the chances of infection of the perry.
The low nitrogen content of the juice also affects the microbiological makeup, favouring undesirable bacteria over wanted yeasts. This can be overcome by the addition of yeast nutrients. The recommended amounts being 1 g thiamine hydrochloride and 8 oz ammonium sulphate per 1,000 gallons for each 10 degrees drop in specific gravity required.
In a perry which is well sulphited before the main yeast fermentation, lactic acid bacteria are kept in check until the end of the fermentation. The acitivity of the bacteria then comes into its own, breaking down malic acid into lactic acid in the malo-lactic fermentation. The species responsible have not been identified, but may be presumed to be the same or similar to those responsible for the malo-lactic fermentation in cider. A problem arises with perry however. In those pears with a high citric acid content, the lactic acid bacteria can convert the citric acid into acetic acid (vinegar) producing a vinegar taint. Since the lactic acid bacteria are anaerobic (grow in the absence of oxygen), excluding air from the perry cannot prevent this occurance. Production of even small amounts of citric acid will effectively ruin the perry. Fortunately this is not an invariant occurance. The bacteria which only attack malic acid and not citric acid outnumber those which will attack both. The problem can be completely avoided by flash pasteurisation of the perry after the main fermentation is complete, followed by controlled fermentation with a specific, known strain of lactic acid bacteria.
Changes in Pear Juice Composition During Fermentation and Maturation
The majority of the changes which occur during fermentation are those which also occur in cider fermentation. The initial yeast fermentation converts sugars to ethanol or higher (fusel) alcohol plus carbon dioxide. There is also an increase in acidity due to the production of L(-)-malic acid by the yeast. Once the yeast fermentation is over, the yeast release nitrogenous compounds, pantothenic acid, and riboflavin into the perry. These compounds are used by the lactic acid bacteria for the subsequent malo- lactic fermentation.
The maturation phase of the perry includes the malo-lactic fermentation in which lactic acid bacteria convert malic acid to lactic acid plus carbon dioxide. An important differance between cider and perry occurs at this point. As previously mentioned, perry pears may have substantial levels of citric acid. This can be converted, by some strains of lactic acid bacteria, into acetic acid. This taints the perry with a vinegar taste, effectively ruining the perry. Fortunately, the predominant bacteria present in pear juice are those which will not convert citric acid to acetic acid, but this is always a possibility to be born in mind.
The major differance between perry and cider maturation is the changes in tannin levels which occur during the process of perry making. Tannin behaviour is unpredictable, the juice may clear before fermentation (when the tannin is thrown out as a gelatinous mass) or it may clear during fermentation. Tannin may also persist in the finished perry which may then throw hazes or deposits at a later stage. Extended milling periods and allowing the pomace to stand before pressing can substantially reduce these problems. Oxidation and adsorption of tannin by the pomace are the main mechanisms which contribute to the reduction of tannin levels. The oxidation is partly carried out by pear tissue enzymes and is also partly non-enzymic. Proteins in the pomace contribute to tannin reduction by causing a preciptation of the tannins. In the juice itself, tannin precipitation is favoured by high tannin levels, by the presence of oxygen, high acidity and low temperatures. The increase in alcohol levels as fermentation procedes retards the precipitation. Addition of sulphur dioxide reduces tannin precipitation by the formation of sulphonic acid derivatives of the tannins which increases their solubility. The final contributing factor is the ripeness of the pear used to make the perry. Best results are found in pears which are ripe but not over-mellow. This is the reason why the milling period of pears is so critical.
Home Perry Making
First pick your pears. They should be fully ripe (see the discussion above on the importance of this point) without being over-ripe. The pears should be left for a period of 2 days to 1 week depending on variety. This period is critical for the production of good perry. Please consult the pear variety guide for the milling periods of common perry pear varieties. Do not wash or sterilise the pears if you want the perry to be fermented with wild yeasts.
Having matured the pears for the critical period, you must pulp them. This is best achieved by hiring a fruit mill from a homebrew store. For an alternative approach to milling fruit, see the short description by Ifor Williams in his Sacks’N’Socks Cider recipe. Do not seperate the juice and the pulp. Allow them to stand, covered, for several hours (preferably overnight) in a cool place. The cooler the better, since this aids precipitation of tannins and development of flavour. Once the pulp has stood for the required period you now need to press it to extract the juice. This is best achieved in either a purpose-built cider press, or by hiring a wine-makers fruit press. These are available for hire from most large homebrew stores.
Once the juice is separated from the pulp you should check the pH. The pH will depend on the variety of pear used, if too many sharp pears are used then the pH will be too acid. Aim for a pH in the range 3.9 to 4.0. To lower the pH add malic acid – do not add citric acid, this will greatly increase the chances of spoilage of the perry by inappropriate fermentation of the citric acid to acetic acid. To raise the pH add precipitated chalk. 1 tsp of pectolase per gallon of juice may be added at this stage to aid in clearing of the perry. This step is optional and probably not necessary since pears are low in pectin, and in any case the major problems with lack of clarity in perries are due to tannins not pectin.
Now check the original gravity. Pears are generally high in sugar content and it is unlikely that you will need to add extra sugar. Nevertheless it is wise to check. Aim for a starting gravity of over 1055. Bear in mind that many pear juices, especially after a long hot summer will contain appreciable amounts of non-fermentable material. The final gravity of the perry may well be above 1000 even when fully fermented.
Place the juice in a suitable fermenting vessel. Traditionally this is a wooden barrel, but a wine fermenter is probably a better idea since it is easier to sanitise. Put the juice under an airlock and leave to ferment naturally. The perry is traditionally fermented at whatever is the outside temperature at the time. If you wish to ferment with a specific yeast strain then add 1 crushed campden tablet per gallon of juice and leave to stand, covered, for 48 hours. Note that pear juices require the addition of more campden tablets than do apple juices. However there are statutary limits to the amount of sulphur dioxide which can be added to food stuffs – consult your local regulations on this point. After standing for 48 hours, pitch with a yeast of your choice. For a traditional style English perry you should use an ale yeast. For a pear wine, use a wine yeast such as a champagne yeast.
Check the gravity regularly. There is not the same tendancy with perries to go on fermenting past the desired finishing gravity as there is with ciders. However, if you wish to produce a sweet perry then you should add 1 crushed campden tablet per gallon of juice when your target final gravity is reached.
Once the final gravity is attained the perry must be matured. Rack the perry into glass carboys or other similar container and place under airlock. Cleanliness is of the utmost importance at this stage to avoid the introduction of those strains of lactic acid bacteria which will produce acetic acid from the natural citric acid of the perry. Perry is traditionally left to mature in outbuildings throughout the winter. The fluctuations in temperature will not hurt it, and in fact exposure to the low temperatures of an English winter will encourage the deposition of excess tannins. Don’t, however allow the perry to freeze! Beware of blending perries, this can lead to the formation of hazes. If you do blend perries they will need an extended maturation period to clear these hazes. As the temperature rises to 15 C in the spring or summer following the year in which the perry was made, the malo-lactic fermentation will occur. Once this is over, the perry may be racked and bottled. Traditional perry is flat, however you may serve it slightly carbonated in the style of real ale. Beware of trying for too high a carbonation level, lactic acid bactera grow readily under high carbon dioxide pressures so you run the risk of accidental acetification of the perry. Perry carbonated in the champagne style is very difficult to make, not only because of the risk of acetification, but also because tannin deposition interferes with the process of disgorging the yeast deposit.
Although the process of perry making requires a little skill and attention to detail, it is perfectly possible to produce a perry at home which is the equal of many if not all of the excellent varieties available at specialist producers throughout the country.
Good luck and enjoy your perry!
- Perry Pears edited by L.C. Luckwill and A. Pollard. Published by the University of Bristol, 1st edition 1963. ISBN unknown. This is a production of The National Fruit and Cider Institute. The book covers all aspects of perry making from selecting the varieties to making the finished product. Highly readable and enjoyable and strongly recommended to anyone wishing to produce good perries.