THE SCIENCE OF CIDERMAKING
Part 1 - Introduction
Anyone wanting to make cider on a small scale is often presented with misleading dogma and half-truth which is confusing and misleading to the novice, and seems to result from an almost wilful ignorance of the scientific principles of cidermaking. In part, this stems from a general lack of accessible information about the subject. Since the Long Ashton Research Station closed its Cider Section in 1986 there has been no 'official' source of advice for cidermakers, and there have been few reliable books on the topic. This series of articles tries to fill the gap and to put the science of cidermaking into its proper perspective, so that potential small-scale cidermakers can make their own choices from the options available. There are, after all, as many different ways of making cider as there are people who make it.
Definition and History
First of all, what is cider? In the UK it is understood (and legally defined) to be a beverage made "wholly or partly from the fermented juice of apples". Similar words (cidre, sidra) are also used in France and Spain. In Germany and Switzerland, although cider is made there, there is no specific word and the term 'Apfelwein' is used instead. In the USA and Canada, 'cider' commonly refers to a cloudy but unfermented 'farmgate' apple juice, unless qualified by the term 'hard cider' to denote that it has been fermented. The word 'cider' itself is supposed to be derived from Greek or even Hebrew sources and simply means 'strong drink', although a millenium of usage now ties it in with apples. Presently, most commercial cider is made in the UK (ca 100 million gallons annually) followed by France, Ireland, Spain, Germany and Switzerland. Production in other countries is vanishingly small. Although it seems to have been made in the Mediterranean basin around the time of Pliny (1st century AD), it became well-established in Normandy and Brittany in early medieval times (from 800 AD onwards). Shortly afterwards it seems to have taken hold in Britain, and the first mention of established production in this country is from 1205.Although cider was once made all over the Uk even as far north as Yorkshire, the centre of UK cider production is now in a band stretching northwards from Devon, through Somerset, Gloucestershire, Worcestershire and Herefordshire, with sporadic local operations in Suffolk, Kent, Sussex, Berkshire and the Midlands. In the 17th and 18th centuries it seemed to have reached something of a zenith, with cider being compared to the best French wines and exported from the West Country to London. A number of manuals on the subject were published at this time, including Worlidge's famous 'Vinum Britannicum - a treatise on Cider and Perry'. John Evelyn, the diarist, politician and arboriculturalist, published his 'Pomona' in 1670, which discusses fruit growing in general and cider making in particular, and includes contributions from authors throughout the country. This book (part of his epic 'Sylva') went through several editions and is still available in facsimile today.
Cider did not seem to last as a serious competitor to wine (possibly due to punitive taxation), and by the end of the 19th century it seems to have been made without much care on most West Country farms. It was often considered as part of the labourers' wages, particularly at harvest time when last season's cider would be consumed. The growth of rail transport and bottling technology, however, enabled a new market to be established in towns and cities throughout the 20th century, dominated by a few large manufacturers. From the 1990's there has been a new divergence, between the mass-market producers on the one hand and the smaller specialist producers on the other.
The Fruit
It has to be said that cider of a sort can be made from almost any type of apple. In Suffolk, Kent and Sussex, surplus dessert or cooking apples are used with great success. In Germany and Switzerland, little distinction is made between dessert, cider and juice apples and the ciders are very acceptable locally although somewhat thin and acidic to an English palate. In the USA (upstate New York) 'Golden Russetts' have been used to make high quality commercial ciders. Despite this, much of the present mystique of cider making lies with the selection of 'true' cider apples - that is, those cultivars grown for no other purpose. In the West Country and in Northwest France, where arguably the finest ciders are made, these are centred on the high-tannin 'bittersweet' and 'bittersharp' varieties (if low in tannin, these are correspondingly described as 'sweets' or 'sharps'). Since these are generally unavailable on the open market except in glut years , anyone planting a new cider orchard would be well-advised to go for these 'true' cider apples. Not only do they have the extra 'body' and 'bite' due to high tannin, but they also press much more easily than dessert apples due to their fibrous structure. Some of these varieties, at least, also possess the elusive character of 'vintage quality' which sets apart the best cider from the run of the mill. But if you do not have these apples, do not despair - just make sure you select full flavoured dessert varieties like 'Cox' and 'Russett' rather than 'Bramley' and 'Golden Delicious', with a modicum of crab apples (to supply the tannin) if you can get any.A word about 'tannin' is probably in order here, since it is so frequently mentioned in connection with cider and yet is so frequently confused with acidity. This is perhaps because in most 'crab' apples (which are not a true species, merely domestic apples which have gone wild from seed) both acidity and tannin are high. Acidity is easy to understand - a lemon provides a good example of this. Tannin is exemplified by the mouth-puckering taste of strong tea, or by the taste of a sloe - it can be both bitter and/or astringent ('hard' or 'soft'), depending on its chemical structure and molecular size. In cider making, we need both tannin and acidity in moderate amounts, as will appear later. The other major component we need is sugar to ferment into alcohol. This can of course come in a bag from Tate and Lyle but is better for our purpose if it comes from a bittersweet cider apple!
Milling and Pressing
Whatever kind of apples are used, they must first be milled to a pulp before the juice can be pressed out. This is rather different from winemaking where the grapes need only a light crushing to break the skins before expressing the juice. Traditionally, apple milling was done in a circular stone trough by a rotating stone wheel drawn round by a horse. From the 18th century onwards, roller mills based on two closely spaced but contra-rotating shafts were used, either hand or steam powered. Resourceful people have managed to adapt domestic mangles for this purpose, fitting the rollers with stainless steel screws to break up the fruit! Scratcher or grater mills, in which a wheel bearing coarse knives or graters rotates against a fixed surface, are also popular and form the basis of the high speed mills used in most modern cider factories. Domestic versions of this mill are also available. At worst, a food processor or a thick lump of timber may be used to smash the fruit to a pulp, or a rotating blade ('Pulpmaster') may be harnessed to the end of an electric drill. To extract the juice from the pulp, wooden screw 'pack' presses were used from medieval times onwards. The apple pulp had first to be built into a 'cheese' using alternate thin layers of pulp and straw. Pressure was then applied to the cheese, the straw providing drainage channels so that juice could flow to a receiving tray and thence to a barrel as the compressed pulp diminished in volume. This principle is still used in many modern cider presses, large and small. The straw has long been replaced by wooden slats and terylene cloths, and the pressure is provided by an hydraulic pump, but the principle of making the cheese still remains. Small-scale versions of this press are readily available from specialist suppliers.In the horizontal piston press (Bucher-Guyer) which is now used in large cider factories, flexible nylon drainage channels are provided throughout an enclosed steel cylinder which is filled with pulp and gradually compressed. New types of belt press, where a thin layer of pulp is squeezed continuously between two endless woven steel and nylon belts, were originally developed for sewage sludge dewatering, but have recently become popular in commercial juice and cider factories!
Small-scale basket presses are relatively cheap and widely available for domestic use, being commonly used for grapes, but they do not always give good juice yields on apples because no allowance is made for drainage channels in the pulp and not all the juice can find a pathway out. Problems with 'slimy pulp' will be discussed in a later section.
The interval between milling and pressing is nowadays kept very short by most cidermakers and is usually only a matter of minutes, the pulp being fed straight to the press. However, this was not always the case in traditional cidermaking, particularly in France, and various interesting and useful enzymic changes take place if this period lasts for several hours ('cuvage'). Similarly, the way in which the juice is treated before fermentation ('keeving') can also have important implications for cider quality. These aspects are considered in a later article.
Fermentation and storage
Once the juice is expressed, the 'new traditionalist' and the large cider maker tend to part company. The 'new traditionalist' adds nothing, doesn't interfere with the natural course of fermentation at all, and is quite at the mercy of the wild yeast and bacteria that get to his juice first! The factory cider maker manipulates the process completely, adds cultured yeast and sugar syrups, and has total technical control! The 'new traditionalist' may by good luck produce a superb cider but all too often it is acetic, murky, full of strange odours and really quite unpleasant to drink, except to the committed fanatic or to the unsuspecting tourist who expects no better of his 'scrumpy'. The factory maker always produces a consistent product, but it is bland and undistinguished, competing with the lager market in suburban pubs and clubs. Somewhere between these two extremes lies the middle ground of highest quality where the small-scale 'craft' cider maker is aiming to operate and which these articles are intended to help.Whether traditional or otherwise, certain features should remain the same. The right sort of yeast must be present, and must dominate other less desirable organisms. There must be sufficient nutrient in addition to sugar for the yeast to grow, it must convert much of the sugar to alcohol, and it must generate desirable flavour characteristics as it does so. After fermentation, most or all of the yeast should be removed and the cider should be stored in the absence of air, protected from spoilage yeasts and bacteria. Otherwise it acquires peculiar off-flavours and eventually turns to vinegar.
Exactly how we achieve these objectives is the subject of the following articles. To conclude this introduction, we list an outline flow chart for cider making, with options which any individual cider maker may choose to exercise as he wishes. These options are discussed in detail as the series proceeds.
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| APPLES | Varietal selection Nutrient levels |
| HARVEST | . |
| STORAGE | Fruit blending |
| WASHING | . |
| MILLING | 'Cuvage' of pulp Pectinase addition |
| PRESSING | Keeving Pectinase addition pH (acidity) adjustment SO2 addition Yeast addition Nutrient addition |
| FERMENTATION | Use of concentrate Addition of sugar |
| RACKING | Malo-lactic fermentation SO2 addition Natural (arrested) sweetening. |
| STORAGE IN BOTTLE OR CASK | Fining Filtration Added sweetener and preservative SO2 addition Pasteurisation |
© Andrew Lea 1997. Lightly revised 2009
http://www.cider.org.uk/frameset.htm