Editing Gelatin (section)

=== Composition ===
When dry, gelatin consists of 98–99% protein, but it is not a nutritionally complete protein since it is missing [[tryptophan]] and is deficient in [[isoleucine]], [[threonine]], and [[methionine]].<ref>Potter, N.N. and J.H. Hotchkiss. (1998). ''Food Science (5th ed.)'' Gaithersburg, MD: Aspen.{{page needed|date=November 2024}}</ref>{{page needed|date=November 2024}} The [[amino acid]] content of hydrolyzed collagen is the same as collagen. Hydrolyzed collagen contains 19 amino acids, predominantly [[glycine]] (Gly) 26–34%, [[proline]] (Pro) 10–18%, and [[hydroxyproline]] (Hyp) 7–15%, which together represent around 50% of the total amino acid content.<ref name=":12">Poppe, J. (1997). Gelatin, in A. Imeson (ed.) ''Thickening and Gelling Agents for Food (2nd ed.)'': 144–68. London: Blackie Academic and Professional.</ref> Glycine is responsible for close packing of the chains. Presence of proline restricts the conformation. This is important for gelation properties of gelatin.<ref>{{cite web|title=Gelatin Handbook|url=http://www.gelatin-gmia.com/images/GMIA_Gelatin_Manual_2012.pdf|archive-url=https://web.archive.org/web/20170516200308/http://www.gelatin-gmia.com/images/GMIA_Gelatin_Manual_2012.pdf|archive-date=16 May 2017|access-date=27 September 2017|df=dmy-all}}</ref> Other amino acids that contribute highly include: [[alanine]] (Ala) 8–11%; [[arginine]] (Arg) 8–9%; [[aspartic acid]] (Asp) 6–7%; and [[glutamic acid]] (Glu) 10–12%.<ref name=":12" />