Canola oil vs high-erucic rapeseed oil in soap
Canola is low-erucic rapeseed oil, at most 2 % erucic acid by the Codex standard, and it is the kind sold as food. High-erucic rapeseed oil carries far more, 31 % in the calculator’s figures, and those long chains mean it takes 6.9 % less lye. Enter the wrong one and the bar below comes out at 3.5 % or 6.5 % superfat, so check which rapeseed oil a recipe means.
Rapeseed Oil - Low Erucic Acid (Canola Oil) Rapeseed Oil (high erucic acid) Compare them with other oils
The published figures
| Canola oil | High-erucic rapeseed oil | |
|---|---|---|
| Saponification value, mg KOH/g | 182–193 | 168–181 |
| Used by the calculator, mg KOH/g | 187.5 (midpoint) | 174.5 (midpoint) |
| SAP for NaOH, g/g | 0.1337 | 0.1244 |
| Iodine value, g I₂/100 g | 105–126 | 94–120 |
| INS (SAP − IV) | 72 | 68 |
| Melting point, °C | — | — |
| Unsaponifiable matter, % | ≤ 2 | ≤ 2 |
| Name on a soap label | Sodium Canolate | — |
Each oil alone
| Canola oil | High-erucic rapeseed oil | Usual range | |
|---|---|---|---|
| Hardness | 7 | 6 | 29–54 |
| Cleansing | 0 | 0 | 12–22 |
| Conditioning | 93 | 60 | 44–69 |
| Bubbly lather | 0 | 0 | 14–46 |
| Creamy lather | 7 | 6 | 16–48 |
A single oil’s hardness, cleansing and the rest are the same sums the calculator shows for a recipe, applied to that one oil. They explain what the oil brings to a blend; they do not predict how a soap of only that oil would feel.
Swapping one for the other
Gram for gram, high-erucic rapeseed oil takes 6.9 % less lye than canola oil. For a kilogram of oil at a 5 % superfat, that is 127.0 g of sodium hydroxide for canola oil and 118.2 g for high-erucic rapeseed oil.
In the bar below, where it is 25 % of the oils, weigh the lye for one and put in the other without recalculating, and the superfat moves:
| Lye weighed for | Oil used | Superfat |
|---|---|---|
| Canola oil | High-erucic rapeseed oil | 3.5 %recalculate |
| High-erucic rapeseed oil | Canola oil | 6.5 %recalculate |
The superfat is the share of the oils the lye leaves unsaponified, planned here at 5 %; below zero, there is more lye than the oils can take. Put the oil you actually have in the lye calculator and it works out the lye for that oil.
The same bar with either
The bar: 25 % of the one or the other, at a 5 % superfat, for 1,000 g of oils. The rest: 30 % olive oil, 25 % coconut oil, and 20 % shea butter.
| With canola oil | With high-erucic rapeseed oil | Usual range | |
|---|---|---|---|
| Sodium hydroxide, g | 138.6 | 136.4 | |
| Hardness | 36 | 35 | 29–54 |
| Cleansing | 17 | 17 | 12–22 |
| Conditioning | 61 | 53 | 44–69 |
| Bubbly lather | 17 | 17 | 14–46 |
| Creamy lather | 19 | 18 | 16–48 |
| Iodine value | 67 | 65 | 41–70 |
| INS | 138 | 137 | 136–165 |
| Linoleic and linolenic acid, % | 13.5 | 12.0 |
Open the bar with canola oil Open the bar with high-erucic rapeseed oil
Fatty-acid profile
| Fatty acid | Canola oil | High-erucic rapeseed oil | |
|---|---|---|---|
| Palmitic acid | C16:0 | 4.8 (2.5–7) | 3.8 (1.5–6) |
| Palmitoleic acid | C16:1 | 0.3 (0–0.6) | 1.5 (0–3) |
| Stearic acid | C18:0 | 1.9 (0.8–3) | 1.8 (0.5–3.1) |
| Oleic acid | C18:1 | 60.5 (51–70) | 34.0 (8–60) |
| Linoleic acid | C18:2 | 22.5 (15–30) | 17.0 (11–23) |
| α-Linolenic acid | C18:3 n-3 | 9.5 (5–14) | 9.0 (5–13) |
| Arachidic acid | C20:0 | 0.7 (0.2–1.2) | 1.5 (0–3) |
| Gadoleic acid | C20:1 | 2.2 (0.1–4.3) | 9.0 (3–15) |
| Behenic acid | C22:0 | 0.3 (0–0.6) | 1.0 (0–2) |
| Erucic acid | C22:1 | 1.0 (0–2) | 31.0 (2–60) |
| Lignoceric acid | C24:0 | 0.2 (0–0.3) | 1.0 (0–2) |
The figure the calculator uses for each oil, as a percentage of its fatty acids, with the published range in brackets.
Recipes with canola oil
- Budget lard and canola bar 25 % of the oils
- Indigo and annatto funnel pour bar 25 % of the oils
- Tomato and charcoal swirl bar 25 % of the oils
- White tea faux funnel pour bar 20 % of the oils
- Egg yolk feather swirl bar 17 % of the oils
- Supermarket oils bar 15 % of the oils
Guides
- The 25er-Rezept: Germany's four-oil beginner soap, with or without palm
- SAP values: what they measure and why tables disagree
Other comparisons
Where these numbers come from
Rapeseed Oil - Low Erucic Acid (Canola Oil)
Verbatim mirror of the FAO file CXS_210e.pdf; the official FAO link (https://www.fao.org/fao-who-codexalimentarius/sh-proxy/en/?lnk=1&url=https%3A%2F%2Fworkspace.fao.org%2Fsites%2Fcodex%2FStandards%2FCXS%2B210-1999%2FCXS_210e.pdf) was Cloudflare-gated at retrieval. Table 1 (Section 3.1) = mandatory GLC fatty-acid ranges, % of total fatty acids, ND = not detectable (<=0.05%). Table 2 (Appendix 'Other quality and composition factors') gives saponification value, iodine value (Wijs) and unsaponifiable matter of CRUDE oils; the Appendix is explicitly ADVISORY (a product not meeting it may still conform). This print predates the 2021-2025 amendments; the 2024 additions (avocado, camellia seed, sacha inchi, high-oleic soya bean) are not included.
Rapeseed Oil (high erucic acid)
Verbatim mirror of the FAO file CXS_210e.pdf; the official FAO link (https://www.fao.org/fao-who-codexalimentarius/sh-proxy/en/?lnk=1&url=https%3A%2F%2Fworkspace.fao.org%2Fsites%2Fcodex%2FStandards%2FCXS%2B210-1999%2FCXS_210e.pdf) was Cloudflare-gated at retrieval. Table 1 (Section 3.1) = mandatory GLC fatty-acid ranges, % of total fatty acids, ND = not detectable (<=0.05%). Table 2 (Appendix 'Other quality and composition factors') gives saponification value, iodine value (Wijs) and unsaponifiable matter of CRUDE oils; the Appendix is explicitly ADVISORY (a product not meeting it may still conform). This print predates the 2021-2025 amendments; the 2024 additions (avocado, camellia seed, sacha inchi, high-oleic soya bean) are not included.