Huile de jojoba

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NOT A TRIGLYCERIDE. Jojoba 'oil' is a liquid WAX: about 97 % of it is long-chain wax esters (C36-C46) in which one monounsaturated fatty acid (mainly C20:1 and C22:1) is esterified to one monounsaturated fatty alcohol (mainly C20:1-OH and C22:1-OH), with only about 1 % free acids and 1 % free alcohols (CIR 2008, citing McKeown 1983). Consequences for soapmaking: (a) its saponification value is only about 93 mg KOH/g, roughly half that of a normal soap-making oil, because each ester carries one very heavy acid plus one heavy alcohol; (b) wax esters saponify far more slowly than triglycerides, so under cold- or hot-process conditions most of the jojoba stays unreacted and acts as a superfat / conditioning additive rather than forming soap; (c) even complete saponification would liberate about half its mass as fatty alcohols (the CIR table reports 51 % unsaponifiable matter and 52 % total acids), which do not form soap. Treat jojoba as a non-soap-forming additive; if a calculator must assign it a lye demand, use the SAP given here and expect the real lye consumption to be lower. The fatty-acid percentages refer to the ACID moieties of the wax esters, not to triglyceride fatty acids. Fatty-acid ranges are from the PRIMARY open-access paper (Molecules 2022, 15 elite Egyptian jojoba lines, Table 3): gadoleic/eicosenoic C20:1 67.85-75.50, erucic C22:1 12.60-14.81, oleic 7.86-10.99, palmitic 0.20-3.18, stearic 0-0.66, linoleic 0-1.17, linolenic 0-0.36, palmitoleic 0.26 in one line; iodine value 82.28-94.75 g I2/100 g across lines (the paper quotes the International Jojoba Export Council standard as 82-87), peroxide 0.25-1.19 meq/kg, oil content 41.97-48.31 %. ADDITIONAL: Molecules 2021 (commercial jojoba wax, sample JD1, Table 1): acids C16:0 0.03, C18:1 12.54, C20:1 71.9, C22:1 13.85, C24:1 nervonic 0.98 %; alcohols C20:1-OH 45.3, C22:1-OH 48.7, C24:1-OH 5.77 % (nervonic acid and the alcohols are outside the key list). The oleic upper bound (12.54) and palmitic lower bound (0.03) come from that sample. ADDITIONAL: Cosmetic Ingredient Review Expert Panel final report (2008; the CIR safety assessments are published in the International Journal of Toxicology), Table 1 'Physical properties of jojoba liquid wax (Habashy et al. 2005)': freezing point 9 C, boiling point 398 C, smoke point 195 C, flash point 295 C, refractive index 1.46 (25 C), specific gravity 0.87 (15 C), viscosity 50 cP, iodine value 81, saponification value 93, acid value 2, acetyl value 2, unsaponifiable matter 51 %, total acids 52 %. The SAP 'typical' (93), the IV lower bound (81) and the unsaponifiable value are transcribed from that table; the CIR report is a compilation rather than a primary measurement, so flag if a stricter provenance standard is required. Hydrogenated jojoba (the solid 'jojoba wax') is a different material (CIR: saponification number 90-95, iodine value 1, melting point 69 C). Melting point of the liquid wax not given as such (freezing point 9 C above). INCI not verified on CosIng in this session, left null.

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