Editing Perry (section)

===Perry-making technique===
[[File:Cider-quern.jpg|thumb|right|Quern for making perry and cider at [[Hellens]], Herefordshire, where a large orchard was planted to commemorate the coronation of [[Anne, Queen of Great Britain|Queen Anne]] - avenues of perry pears from it still survive. The varieties 'Hellens Early' and 'Hellens Green' were named after the house.]]
Traditional perry making is broadly similar to traditional cider making, in that the fruit is picked, crushed, and pressed to extract the juice, which is then fermented using the wild yeasts found on the fruit's skin. Traditional perry making employed [[Quern-stone|querns]] and a rack and cloth [[Fruit press|press]], in which the pulp is wrapped in cloth before being squeezed with a press.<ref name=":8">{{Cite book|title=Handbook of Alcoholic Beverages: Technical, Analytical and Nutritional Aspects|last=Buglass|first=Alan J.|publisher=John Wiley & Sons, Ltd.|year=2011|isbn=978-0-470-51202-9|pages=240–241}}</ref> Modern perry production can use a [[belt filter|belt press]], which is much more efficient for pressing fruit.<ref name=":8" /> It works by sending the fruit down a conveyor belt, on which it is then pressed by rollers.<ref name=":8" /> The principal differences between perry and cider production are that pears must be left for a period to mature after picking, and the [[pomace]] must be left to stand after initial crushing to lose [[tannin]]s, a process analogous to wine [[Maceration (wine)|maceration]]. <ref>Grafton, G. [http://homepage.ntlworld.com/scrumpy/cider/perry.htm Perry Making] {{webarchive|url=https://web.archive.org/web/20070207121437/http://homepage.ntlworld.com/scrumpy/cider/perry.htm |date=7 February 2007 }}, accessed 8 December 2009 {{verify source |date=September 2023 |reason=This ref was deleted Special:Diff/841647144 by a bug in VisualEditor and later restored by a bot from the original cite located at Special:Permalink/841634534 cite #6 - verify the cite is accurate and delete this template. [[User:GreenC_bot/Job_18]]}}</ref> Additionally, because of the variation in hardness of the fruit, determining if a pear is ready for pressing than an apple can be more difficult.<ref name=":7">{{Cite web|url=http://www.ciderworkshop.com/perry.html|title=The Cider Workshop {{!}} Production {{!}} What's different about perry?|website=www.ciderworkshop.com|access-date=2018-05-14}}</ref> Also, key chemical compositional differences occur between apples and pears; these factors play a crucial role in prefermentation and fermentation decisions for perry production.
[[File:BeltPress.svg|thumb|A diagram of a belt press]]

Compared to most apples, pears tend to have more sugar and total phenolic compounds. The main sugars in perry pears are [[glucose]] (192 –284&nbsp;mg/L), [[xylose]] (140–176&nbsp;mg/g), and [[galacturonic acid]] (108–118&nbsp;mg/g). Types of sugar that are present in the juice play an important role in yeast activity and determine the success of fermentation. Unlike the juice of apples, pear juice contains significant quantities of unfermentable sugar alcohols, particularly sorbitol.<ref>{{cite book|last1=Buglass|first1=A. J.|title=Cider and Perry|date=2011|publisher=John Wiley & Sons, Ltd.|location=CH11|pages=231–265}}</ref> The presence of sorbitol can give perry a residual sweetness, in addition to a mild laxative effect.<ref>{{cite book|last1=Jolicoeur|first1=C|title=The New Cider Maker's Handbook|date=2013|pages=155}}</ref>
Pear juices contain rather low levels of amino acids, sources of nitrogen such as aspargine, aspartic acid and glutamic acid.<ref>{{cite book|last1=Buglass|first1=A. J.|title=Cider and Perry|date=2011|publisher=John Wiley & Sons, Ltd.|location=CH11|page=237}}</ref>

After initial fermentation, many perries go through [[malolactic fermentation]]. On average, compared to apples, pears have higher levels of titrable acidity, most of it being citric acid. In environments with high levels of malic acid, such as grape must in winemaking, malolactic fermentation bacteria convert malic acid to lactic acid, reducing the perception of acidity and increasing complexity of flavour. However, if high levels of citric acid are present, as in pear pomace, malolactic fermentation bacteria catabolise citric acid to acetic acid and oxaloacetic acid, instead of lactic acid.<ref>{{cite journal|last1=Yoshimi|first1=Shimazu|last2=Uehara|first2=Mikio|last3=Watanabe|first3=Masazumi|title=Transformation of Citric Acid to Acetic Acid, Acetoin and Diacetyl by Wine Making Lactic Acid Bacteria|journal=Agricultural and Biological Chemistry|volume=49|issue=7|pages=2147–2157|doi=10.1080/00021369.1985.10867041|year=1985}}</ref> This results in a floral, citrus-like aroma in the final product, lacking the diacethyl odour typical for most products that have undergone a malolactic fermentation.