Editing Rennet (section)

=== Modern method ===
Deep-frozen stomachs are milled and put into an enzyme-extracting solution. The crude rennet extract is then activated by adding acid; the enzymes in the stomach are produced in an [[Zymogen|inactive form]] and are activated by the [[stomach acid]]. The acid is then [[Neutralization (chemistry)|neutralized]] and the rennet extract is filtered in several stages and concentrated until reaching a typical potency of about 1:15,000; meaning 1&nbsp;g of extract can coagulate 15&nbsp;kg of milk.{{Citation needed|date=July 2019}}

One kilogram of rennet extract has about 0.7&nbsp;g of active enzymes – the rest is water and salt and sometimes [[sodium benzoate]] ([[E211]]),
0.5%–1.0% for preservation. Typically, 1&nbsp;kg of cheese contains about 0.0003 g of rennet enzymes.<ref>{{Cite web|title=Cheese Technology: Lesson 14. CALF RENNET: PREPARATION AND PROPERTIES|url=http://ecoursesonline.iasri.res.in/mod/page/view.php?id=147314|access-date=2021-02-04|website=ecoursesonline.iasri.res.in}}</ref><ref>{{Cite web|date=2017-08-31|title=Hooked on Cheese: Cheese for Vegetarians|url=https://www.thedailymeal.com/eat/hooked-cheese-cheese-vegetarians|access-date=2021-02-04|website=The Daily Meal|language=en}}</ref>