Cider apples are a group of apple cultivars grown for their use in the production of cider (referred to as "hard cider" in the United States). Cider apples are distinguished from "cookers" and "eaters", or dessert apples, by their bitterness or dryness of flavour, qualities which make the fruit unpalatable but can be useful in cidermaking. Some apples are considered to occupy more than one category.
In the United Kingdom, the Long Ashton Research Station categorised cider apples in 1903 into four main types according to the proportion of tannins and malic acid in the fruit. For cider production, it is important that the fruit contains high sugar levels which encourage fermentation and raise the final alcohol levels. Cider apples therefore often have higher sugar levels than dessert and cooking apples. It is also considered important for cider apples to contribute tannins, which add depth to the finished cider's flavour.
Classification of cider apples Long Ashton Research Station classification system In 1903, Professor B.T.P. Barker, the first director of the Long Ashton Research Station (LARS) in Bristol, England,Miles, C., King, J., & Peck, G. (2015). Commonly Grown Cider Apple Cultivars in the U.S. Mount Vernon, WA: WSU Mount Vernon NWREC. Retrieved 27 April 2018. established an analytical classification system for cider apples based on tannin and malic acid percentages in pressed juice. This system is divided into four categories,Lea, A. (2015, April 21). Cider Apple Compositional Data. Retrieved 27 April 2018. which are as follows:
+ Long Ashton four class system Classification Malic Acid (% w/v) Tannin (% w/v) Examples Comments Sweet (SW) <0.45 (low) <0.2 (low) Slack-ma-Girdle, Sweet Alford, Sweet Coppin,Merwin, I., Valois, S., & Padilla-Zakour, O. (2008). Cider Apples and Cider-Making Techniques in Europe and North America. Horticultural reviews. 34. 365-415. 10.1002/9780470380147.ch6. Northwood Sweets are defined by low acid and tannin levels. Most dessert apples are also sweets,Michigan State University. (2017, Fall). Apple Cultivars for Production of Hard Cider in Michigan. Extension Bulletin E3364. Retrieved 27 April 2018. though there is a group of cider cultivars with these characteristics. Sharp (SH) >0.45 (high) <0.2 (low) Crimson King, Tom Putt, Brown's Apple, Backwell Red The high acidity of sharps, like that from bittersharps, can add "bite" to the cider. While there is a group of sharp cider apples, most cooking apples are also sharps,Thompson-Witrick, K.A., K.M. Goodrich, A.P. Neilson, E.K. Hurley, G.M. Peck, and A.S. Stewart*. 2014. Characterization of the polyphenol composition of 20 cultivars of cider, processing, and dessert apples (Malus X domestica Borkh.) grown in Virginia. Journal of Agricultural and Food Chemistry 62:10181-10191. and traditional cooking varieties were often used in cidermaking in eastern England.Quinion, M. (1982) Cidermaking, Shire, p.5 Bittersweet (BSW) <0.45 (low) >0.2 (high) Brown Snout, Dabinett, Yarlington Mill, Chisel Jersey, Hangdown Bittersweet cultivars are often of European origin;Bradshaw, T. (2015, March 30). Cider Apple Research at UVM (and other U.S. Land Grant Institutions). University of Vermont. Retrieved 27 April 2018. they were often widely supposed to have originated in northwestern France, and bittersweet cultivars were often referred to by the terms "French" and "Norman" in the cider-producing counties of Gloucestershire and Herefordshire respectively.Martell, C. Native Apples of Gloucestershire, Gloucester Orchard Group, p.38 The raised levels of tannin add bitterness or astringency to the cider, a desirable quality. Bittersharp (BSH) >0.45 (high) >0.2 (high) Foxwhelp, Hewe's Crab, Kingston Black, Cap of Liberty Having high levels of tannin and acid, bittersharps are particularly suitable for single-varietal ciders.Valois, S., Merwin, I. A., & Padilla-Zakour, O. (2006). Characterization of fermented cider apple cultivars grown in upstate new york. Journal of the American Pomological Society, 60(3), 113-128. Retrieved 29 April 2018. Along with bittersweets, these have historically been known as “spitters” because they are naturally unpalatable.
Long Ashton's classification system also included a three-level classification of tannin: "full" for an apple with pronounced tannins (e.g. a "full bittersweet" such as Chisel Jersey, "mild" for light tannins such as Cummy Norman, and "medium" such as Dabinett.Jolicoeur, C. (2013). The New Cider Maker's Handbook: A Comprehensive Guide for Craft Producers, p. 47Annual Report - Long Ashton Research Station, 1936
+ Long Ashton seven class system Classification Malic acid % Tannin % Examples Sweet <0.45 <0.20 Sweet Alford, Woodbine Bittersharp >0.45 >0.20 Mild Bittersweet 0.45 0.20-0.25 Cummy Norman, Hangdown, Perthyre, Royal Wilding. Medium Bittersweet <0.45 0.25-0.30 Dabinett, Dove, Yarlington Mill. Full Bittersweet <0.45 >0.30 Knotted Kernel, Strawberry Norman. Medium Sharp 0.45-0.75 <0.20 Lambrook Pippin, Langworthy, Crimson King. Full Sharp >0.75 0.20 Cap of Liberty, Fair Maid of Devon, Frederick.
Tannins are further sometimes categorised as "hard" or "soft", for bitter and astringent tannins respectively.
British cidermakers normally blend juice from apples of multiple categories to ensure a finished cider with a balanced flavour and for the best and most consistent quality. While traditional ciders were made from whatever apples were available locally, the blend of sugar, acid and tannin required for a successful cider is difficult to achieve from any single cultivar with the possible exception of some bittersharps.Lea in Bamforth and Ward (eds.) (2014) The Oxford Handbook of Food Fermentations, Oxford: Oxford University Press, p. 156 As bittersharps are rare, a common modern approach is to use a range of bittersweet varieties with some sharps, or a cooking apple such as the readily available Bramley, to balance the acidity.Lea, The Science of Cidermaking: Fruit and Cultivation, accessed 18-05-18 Sharps, with their high acid content, also keep the cider's pH below 3.8 to prevent spoilage; sweets help provide adequate sugar for fermentation to the proper alcohol content.
French and Spanish classification systems In addition to the Long Ashton Research Station classification, Charles Neal has written about a French classification system."Cider Apple Varieties - Cider School". Cider School. Retrieved 2018-05-11. In France and Spain, the system has an intermediate category called acidulée or acidulada respectively, which is sometimes used to classify cider apples that are semi-tart and have low tannin content. Similar to the English system, acidity and tannins are considered. Apples are classified as follows:Pommiers á cidre - Variétés de France, J.M. Bore et. J. Fleckinger
+ French classification system Classification Malic Acid (% w/v) Tannin (% w/v) Examples Douce 0 - 0.40 <0.2 (low) Doux Normandie, Rouge Duret Amere 0 - 0.40 >0.3 (high) Cidor, Domaines Douce Amere 0 - 0.40 0.20 - 0.30 (medium) Bedan, Saint Martin Acidule 0.40 - 0.60 <0.20 (low) Judeline, Blanchet Aigre Amere >0.60 > 0.3 (high) Cazo Jaune Aigre >0.60 <0.2 (low) Avrolles, Judaine + Spanish classification system Classification Malic acid % Tannin % Examples Acido > 0.65 < 0.145 Blanquina, Teórica Amargo < 0.45 > 0.2 Clara Dulce < 0.45 < 0.145 Pepa, No Prieta Antigua, Coloradona Dulce-Amargo < 0.45 0.145 - 0.2 Obdulina Acido-Amarga > 0.65 0.145 - 0.2 Meana Acidulado o Semiacido 0.45 - 0.65 < 0.145 Dolores, Campillo In the US, there are four regions where cider apples are grown in orchards: the Northeast, Mid-Atlantic, Midwest, and Northwest. Out of the twenty most commonly grown cider apple varieties, half originate from England, two come from France, and the rest originate in America. Most special cider cultivars for European ciders are bittersweets and bittersharps, which have high tannin content. There are not a lot of cultivars with high tannins readily available in the U.S.Peck, G., C. Miles, J. King, T. Bradshaw, N. Rothwell, and Merwin, I. (2014). An Introduction to Hard Cider in the U.S. eXtension. Retrieved 27 April 2018. Most ciders in the United States are made from culled dessert apples that are generally sweets and sharps. There is no systematic classification of North American apple cultivars for cider-making purposes. However, there is a database for apple varieties called the U.S. National Plant Germplasm System (NPGS).
Other classification considerations Beyond the Long Ashton or English system and French system for classifying cider apples, there are other considerations for characterisation. Other measurements taken of apple varieties towards use in cider classification include pH, polyphenol composition, yeast assimilable nitrogen (YAN), and soluble solid concentration (ºBrix).Michigan Apple Committee. How to make cider. Retrieved 27 April 2018. The sharpness of an apple is affected by pH and titratable acidity. Most cultivars must reach pH levels of around 3.3 to 3.8 to aid in the fermentation process, and additions of malic acid may be necessary if the cider apple is over this desired threshold. Soluble solids as measured in units of degrees Brix can be used to quantify the potential alcohol that a yeast can ferment from the initial juice of the cider apple. This is carefully considered in cultivars from areas where there are tax regulations on the percentage of alcohol by volume that is contained in these products. In the United States, "hard cider" legally falls between the 0.5% to 8.5% alcohol by volume tax bracket.Protecting Americans from Tax Hikes Act of 2015, Pub. L. No. 114-113, 129 Stat. 2244 (2015) Cideries that exceed a soluble solids level of 17 °Brix will be subject to higher tax levels that are classified under cider wine. In the United Kingdom, cider falls in two duty brackets, with a flat rate for up to 7.4% ABV, and a higher duty rate for ciders between 7.4% to 8.5% ABV.More about cider and perry. Campaign for Real Ale. (2014). Foaming is an intricate, yet essential component that can be used to assess the overall quality of a cider and distinguish between natural and sparkling ciders. Chemically, hydrophobic polypeptides contribute to the initial foam, bubble size, the extent to which it persists, number of nucleation sites, and the froth of the foam (foam collar). These chemical compositions and parameters are quantitatively measured through metrics such as foam height, foam stability height, and stability time.Blanco-Gomis, D., Mangas-Alonso, J. J., Expósito-Cimadevilla, Y., & Gutiérrez-Álvarez, M. D. (2010). Characterization of cider by its hydrophobic protein profile and foam parameters. Food Chemistry, 121, 220-226. The olfactory sensory profile is used to determine the specific aroma of the cider. Research is still ongoing in this field, but the aromas that contribute to the sensory perceptions of cider mainly come from the phenols 4-ethyl guaiacol and 4-ethyl phenol.Antón, M. J., Valles, B. S., Hevia, A. G., & Lobo, A. P. (2013). Aromatic profile of ciders by chemical quantitative, gas chromatography-olfactometry, and sensory analysis. Journal of Food Science, 79, S92-S99.
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