Regional Variation in Juice Quality Characteristics of Four Cider Apple
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HORTSCIENCE 51(12):1498–1502. 2016. doi: 10.21273/HORTSCI11209-16 and accounted for 6% of the total U.S. cider production in 2015 (TTB, 2016). The number of cideries in Washington increased more than 5- Regional Variation in Juice Quality fold in the last 9 years, from less than 10 cideries in2007to56reportedcideriesin2015(North- Characteristics of Four Cider Apple west Cider Association, 2015; The Cyder Mar- ket, 2015). (Malus 3domestica Borkh.) Cultivars in Quality cider is traditionally made from bittersweet (acid <0.45%, tannin >0.20%) and bittersharp (acid >0.45%, tannin >0.20%) Northwest and Central Washington cider apples (Barker and Burroughs, 1953). Travis Robert Alexander1, Jacqueline King, Andrew Zimmerman, Growers have historically selected cider apple and Carol A. Miles cultivars for their fruit acid and tannin content levels (Alwood, 1903; Barker, 1911; Buell, Department of Horticulture, Washington State University Northwestern 1869; Trowbridge, 1917). As the supply of Washington Research and Extension Center, 16650 State Route 536, cider apples is heavily outweighed by demand, Mount Vernon, WA 98273 dessert apple juice often forms the base of both craft and industrial ciders as it tends to be more Additional index words. bittersharp, bittersweet, ‘Brown Snout’, Dabinett’, ‘Kingston Black’, readily available and relatively inexpensive ‘Yarlington Mill’, acid, tannin (Merwin et al., 2008; Moulton et al., 2010). Abstract. In this study, four cider apple (Malus 3domestica) cultivars, Brown Snout, Dabinett, Craft cider makers usually achieve their de- Kingston Black, and Yarlington Mill, were collected from four orchards, two in northwest sired levels of bitterness and sharpness by Washington and two in central Washington, to compare juice quality characteristics. blending in bittersweet, bittersharp, and crab Northwest Washington has a cool, humid summer climate (16.0 8C on average during this apple cultivars, whereas industrial cider ma- study) and is the origin of the state’s cider apple industry, while central Washington has a hot, kers add exogenous malic acid and tannin dry summer climate (22.1 8C on average during this study) and is the center of the state’s (Khanizadeh et al., 2000; Lea, 2008; Merwin dessert apple industry. Each year from 2012 to 2015, fruit of the four cultivars were harvested et al., 2008; Pollard, 1953). For product consis- and stored at each orchard until they were collected. Fruit were pressed and the juice analyzed tency, cider makers should chemically analyze for five quality characteristics important to cider making: soluble solids concentration [SSC their juice throughout production (M. Roberts, (%)], specific gravity (SG), pH, titratable acidity [TA, malic acid equivalent (g·LL1)], and personal communication). The ability to create tannin [tannic acid equivalent (%)]. Harvest dates and climate data were recorded annually a consistent product is critical in an industry for each orchard location. There were no significant differences in any of the juice quality where juice supply varies from year to year both characteristics due to region and no significant interaction of region, cultivar, and/or year. in quantity and characteristics. Results did show, as expected, a significant difference in all five juice characteristics due to Chemical analysis of cider juice gener- cultivar. ‘Brown Snout’, ‘Dabinett’, and ‘Kingston Black’ were higher in SSC and SG than ally includes an assessment of SSC (%), SG, · –1 ‘Yarlington Mill’; ‘Dabinett’ had the highest pH and lowest TA while ‘Kingston Black’ had pH, TA [malic acid equivalent (g L )], and the lowest pH and highest TA; and tannin was highest in ‘Yarlington Mill’ and lowest in tannin [tannic acid equivalent (%)]. SSC and ‘Kingston Black’. There was also a difference in SG and tannin due to year; SG was lowest in SG can be measured with a refractometer, 2013 while tannin was highest in 2012. The difference in SG from year to year may be a result which measures the refractive index of a so- of variable year-to-year storage time at each orchard before collection of fruit. The difference lution, or a hydrometer, which measures the in tannin from year to year was likely due to climatic variation over the four years of this relative density of a solution to a reference study. On average, growing degree days (GDD) increased 10% and chilling hours (CH) (usually pure water), assuming proper cali- decreased 10% from 2012 to 2015 in both regions. Classification of the four cultivars included bration of each instrument. A refractometer in this study differed from historical records at the Long Ashton Research Station (LARS) in is generally used prefermentation as ethanol England; in the current study, the four cultivars exhibited tannin levels below 0.20% and significantly alters the refractive index, would not be classified as bitter, unlike their historical classification at LARS. Results from whereas a hydrometer is used throughout this study indicate that variations in juice quality characteristics occur between cultivars as fermentation with decreasing accuracy to- expected and occur within a cultivar from year-to-year, but for the four cultivars included in ward the end of fermentation as increasing this study variations did not occur due to production region in Washington. ethanol alters the density of the solution (often providing for a negative sugar con- centration). Prefermentation measures of Cider is fermented apple (Malus ·domestica less than 1.2% alcohol by volume (ABV) as both SSC and SG are used to predict alcohol Borkh.) juice, and is often referred to as found in French cidre doux, to 8.5% ABV in content postfermentation and accordingly hard cider in the United States in contrast to traditional English ciders (Lea, 2008). In the aide the cider maker in deciding if exoge- the nonfermented, unfiltered apple juice United States, current federal law defines nous sugar should be added or if juices with that is referred to as fresh cider or sweet cider by an ABV of less than 8.5%; anything higher sugar content should be blended cider (Khanizadeh et al., 2000; Trowbridge, above this ABV may still be considered a cider (Moulton et al., 2010). pH can be measured with a pH meter or pH indicator paper, the 1917).Cidermayvaryinalcoholcontentfrom but is taxed at a higher wine or champagne rate choice depending on the cider maker’s depending on percent ABV and carbonation preference for accuracy. TA can be mea- levels [Alcohol and Tobacco Tax and Trade sured by titration with a base using pH Received for publication 21 July 2016. Accepted Bureau (TTB), 2015]. Although cider only indicator paper or a pH meter to reach the for publication 8 Sept. 2016. accounts for 1% of the alcoholic beverage targeted endpoint, again the choice regard- We gratefully acknowledge the financial support market in the United States, it is the fastest ing the method for monitoring pH is based provided by the Washington State Department of growing segment with a 22-fold increase in on preference for accuracy. Cider makers Agriculture, Washington State University Center production from 2007 to 2015 (TTB, 2016). In target a pH range of 3.3–3.7 and a TA range for Sustaining Agriculture and Natural Resources, 2007, 2.9 million liters of cider were produced of 1.0–15.0 g·L–1 malic acid (Mitchell, Northwest Agricultural Research Foundation, in the United States, increasing to 65 million Northwest Cider Association, and State project 2015). For pH, the targeted range is based WN00427–Acc. no.1000194. liters in 2015 (TTB, 2016). The volume of cider on optimal yeast fermentation conditions, 1Corresponding author. E-mail: travis.alexander@ produced in Washington grew 25-fold from and for TA, the targeted range is based on wsu.edu. 2007 to 2015, from 168,000 to 4 million liters, desired final product flavor, specifically 1498 HORTSCIENCE VOL. 51(12) DECEMBER 2016 sharpness. Tannin is traditionally measured Washington State to make appropriate purchas- were black and fruit felt firm and/or had by titration with potassium permanganate and ing and planting decisions for their region. reached the desired threshold range of 11–14 indigo carmine indicator (Lowenthal, 1877). °Brix depending on cultivar and weather. For Tannin also contributes to final product flavor, Materials and methods WSU NWREC, apples were harvested when specifically the astringency and mouthfeel of seeds were black, flesh was in the 8–9 range on the cider. Cider apple orchards. This study included the 9-point BC/Ontario starch ripeness scale, Planting site has a significant impact on four orchards, with two orchards located in and/or fruit had reached the desired threshold apple fruit quality; for example Miller et al. northwest Washington, Alpenfire Cider and range of 11–14 °Brix depending on cultivar (2005) found an inconsistent interaction Washington State University Northwestern and weather (Chu and Wilson, 2000; Lau, between site and cultivar for more than one Washington Research and Extension Center 1988). For Snowdrift Cider Co., apples were juice quality characteristic. Specifically, the (WSU NWREC), and two orchards located in harvested when flesh surface area was greater authors found that SSC and TA were signif- central Washington, Snowdrift Cider Co. and than 60% free of starch (8–9 range on the icantly higher for apple cultivars Golden Tieton Cider Works. Alpenfire Cider is located BC/Ontario scale) and/or there was significant Delicious and Gala Supreme than for culti- in Port Townsend (48°4#57$, 122°52#34$) ground fall. For Tieton Cider Works, apples vars Fuji and Enterprise across 14 planting with a Tukey gravelly loam soil (isotic, mesic were harvested when seeds were black, fruit sites in North America. However, fruit Vitrandic Haploxerepts; U.S. Department of tasted sweet (subjective metric specific to the weight and TA were found to be signifi- Agriculture, 2013). The trees from which cider maker), and/or there was significant cantly higher for all four cultivars at the apples were harvested were grafted on dwarfing ground fall.