Editing Pasteurization (section)

==Effects on nutritional and sensory characteristics of foods==

Because of its mild heat treatment, pasteurization increases the shelf-life by a few days or weeks.<ref name="Fellows-2017"/> However, this mild heat also means there are only minor changes to heat-labile vitamins in the foods.<ref name="Rahman-1999">{{Cite book|url=https://books.google.com/books?id=vus1aZ1-sCkC&pg=PA102|title=Handbook of Food Preservation|last=Rahman|first=M. Shafiur|date=1999-01-21|publisher=CRC Press|isbn=978-0-8247-0209-0|language=en|access-date=30 March 2021|archive-date=19 July 2022|archive-url=https://web.archive.org/web/20220719140715/https://books.google.com/books?id=vus1aZ1-sCkC&pg=PA102|url-status=live}}</ref>

===Milk===
According to a systematic review and meta-analysis,<ref name="Macdonald-2011">{{Cite journal|last1=Macdonald|first1=Lauren E.|last2=Brett|first2=James|last3=Kelton|first3=David|last4=Majowicz|first4=Shannon E.|last5=Snedeker|first5=Kate|last6=Sargeant|first6=Jan M.|date=2011-11-01|title=A systematic review and meta-analysis of the effects of pasteurization on milk vitamins, and evidence for raw milk consumption and other health-related outcomes|journal=Journal of Food Protection|volume=74|issue=11|pages=1814–32|doi=10.4315/0362-028X.JFP-10-269|issn=1944-9097|pmid=22054181|doi-access=free}}</ref> it was found that pasteurization appeared to reduce concentrations of vitamins [[vitamin B12|B12]] and [[vitamin E|E]], but it also increased concentrations of [[vitamin A]]. However, in the review, there was only limited research regarding how much pasteurization affects A, B12, and E levels.<ref name="Macdonald-2011"/> Milk is not considered an important source of vitamins B12 or E in the North American diet, so the effects of pasteurization on the adult daily intake of these vitamins is negligible.<ref name="USDA-2001">U.S. Department of Agriculture. 2001. Dietary reference intakes-recommended intakes for individuals. National Academy of Sciences. Institute of Medicine, Food and Nutrition Board. Available at: [http://fnic.nal.usda.gov/nal_display/index.phpinfo_center~4&tax_level~3&tax_subject~256&topic_id~1342&level3_id~5140]{{dead link|date=August 2017|bot=InternetArchiveBot|fix-attempted=yes}}.</ref><ref name="USDA-2009">U.S. Department of Agriculture. 2009. "What's in the foods you eat" search tool. Available at: "https://www.ars.usda.gov/northeast-area/beltsville-md/beltsville-human-nutrition-research-center/food-surveys-research-group/docs/whats-in-the-foods-you-eat-emsearch-toolem/ {{Webarchive|url=https://web.archive.org/web/20170425133424/https://www.ars.usda.gov/northeast-area/beltsville-md/beltsville-human-nutrition-research-center/food-surveys-research-group/docs/whats-in-the-foods-you-eat-emsearch-toolem/ |date=25 April 2017 }}</ref> However, milk is considered an important source of vitamin A,<ref name="Haug-2007">{{Cite journal|last1=Haug|first1=Anna|last2=Høstmark|first2=Arne T|last3=Harstad|first3=Odd M|date=2007-09-25|title=Bovine milk in human nutrition – a review|journal=Lipids in Health and Disease|volume=6|pages=25|doi=10.1186/1476-511X-6-25|issn=1476-511X|pmc=2039733|pmid=17894873 |doi-access=free }}</ref> and because pasteurization appears to increase vitamin A concentrations in milk, the effect of milk heat treatment on this vitamin is a not a major public health concern.<ref name="Macdonald-2011"/> Results of meta-analyses reveal that pasteurization of milk leads to a significant decrease in [[vitamin C]] and [[folate]], but milk is also not an important source of these vitamins.<ref name="Haug-2007"/><ref name="USDA-2009"/> A significant decrease in [[vitamin B2]] concentrations was found after pasteurization. Vitamin B2 is typically found in bovine milk at concentrations of 1.83&nbsp;mg/liter. Because the recommended daily intake for adults is 1.1&nbsp;mg/day,<ref name="USDA-2001"/> milk consumption greatly contributes to the recommended daily intake of this vitamin. Except for B2, pasteurization does not appear to be a concern in diminishing the [[nutritional value|nutritive value]] of milk because milk is often not a primary source of these studied vitamins in the North American diet.

===Sensory effects===

Pasteurization also has a small but measurable effect on the sensory attributes of the foods that are processed.<ref name="Fellows-2017" /> In fruit juices, pasteurization may result in loss of volatile aroma compounds.<ref name="Rahman-1999" /> Fruit juice products undergo a [[Deaerator|deaeration]] process before pasteurization that may be responsible for this loss. Deaeration also minimizes the loss of nutrients like vitamin C and [[carotene]].<ref name="Fellows-2017" /> To prevent the decrease in quality resulting from the loss in volatile compounds, volatile recovery, though costly, can be utilized to produce higher-quality juice products.<ref name="Rahman-1999" />

Regarding color, the pasteurization process does not have much effect on pigments such as [[chlorophyll]]s, anthocyanins, and [[carotenoid]]s in plants and animal tissues. In fruit juices, [[polyphenol oxidase]] (PPO) is the main enzyme responsible for causing browning and color changes. However, this enzyme is deactivated in the deaeration step before pasteurization with the removal of oxygen.<ref name="Rahman-1999" />

In milk, the color difference between pasteurized and raw milk is related to the [[homogenization (chemistry)|homogenization]] step that takes place before pasteurization. Before pasteurization milk is homogenized to emulsify its fat and water-soluble components, which results in the pasteurized milk having a whiter appearance compared to raw milk.<ref name="Fellows-2017"/> For vegetable products, color degradation is dependent on the temperature conditions and the duration of heating.<ref name="Peng-2017">{{Cite journal|last1=Peng|first1=Jing|last2=Tang|first2=Juming|last3=Barrett|first3=Diane M.|last4=Sablani|first4=Shyam S.|last5=Anderson|first5=Nathan|last6=Powers|first6=Joseph R.|date=2017-09-22|title=Thermal pasteurization of ready-to-eat foods and vegetables: Critical factors for process design and effects on quality|journal=Critical Reviews in Food Science and Nutrition|volume=57|issue=14|pages=2970–95|doi=10.1080/10408398.2015.1082126|issn=1549-7852|pmid=26529500|s2cid=22614039}}</ref>

Pasteurization may result in some textural loss as a result of enzymatic and non-enzymatic transformations in the structure of [[pectin]] if the processing temperatures are too high as a result. However, with mild heat treatment pasteurization, tissue softening in the vegetables that causes textural loss is not of concern as long as the temperature does not get above {{convert|80|C|F}}.<ref name="Peng-2017" />