Milk thistle seed oil: SAP value and fatty acids
Milk thistle seed oil has a saponification value of 187.84 mg KOH/g. One gram needs 0.134 g of sodium hydroxide (NaOH) for bar soap or 0.188 g of potassium hydroxide (KOH) for liquid soap to turn fully into soap, before any superfat.
Key numbers
- SAP, NaOH
- 0.133908 g per g oil
- SAP, KOH
- 0.18784 g per g oil
- Saponification value
- 187.84 mg KOH/g
- Iodine value
- 103.9
- INS
- 84
- INCI name
- Silybum Marianum Seed Oil
Example: 100 g of Milk thistle seed oil with no superfat needs 13.4 g of 100% NaOH, or 18.8 g of 100% KOH. A 5% superfat uses 5% less.
In soap
Its main fatty acids in our cited profile are linoleic (63.2%) and oleic (17.1%). The eight fatty acids used in soap-quality scores make up 94% of the profile.
On its own it scores 13 for hardness, 0 for cleansing and 81 for conditioning, with a saturated : unsaturated split of 13 : 81.
Linoleic-rich oil. The two lab studies differ by ~8%; use the supplier COA. Published sources for this oil differ by more than 3%, so checking your supplier's certificate of analysis matters more than usual.
Fatty-acid profile
| Fatty acid | % of fatty acids | Counts toward |
|---|---|---|
| lauric | 0% | hardness, cleansing, bubbly lather |
| myristic | 0.1% | hardness, cleansing, bubbly lather |
| palmitic | 8.9% | hardness, creamy lather |
| stearic | 4.3% | hardness, creamy lather |
| ricinoleic | 0% | conditioning, bubbly and creamy lather |
| oleic | 17.1% | conditioning |
| linoleic | 63.2% | conditioning |
| linolenic | 0.4% | conditioning |
Basis: Molecules 2023 Table 3, n-hexane-extracted oil, mean of 3 (sums to 100%). The paper's cold-pressed column was not used: it sums to only 93.7% and has large SDs..
Soap-quality scores (this oil alone)
| Hardness | 13 |
|---|---|
| Cleansing | 0 |
| Conditioning | 81 |
| Bubbly lather | 0 |
| Creamy lather | 13 |
| Iodine | 104 |
| INS | 84 |
Each score adds up certain fatty acids, the way Soap Ledger scores a whole recipe. They are for comparing recipes; they don't predict how a bar will feel, and they say nothing about safety or skin.
Sources
SAP value: 187.84 mg KOH/g (Median of sources' mgKoh_mid), from Characteristics of Silybum marianum as a Potential Source of Dietary Oil and Protein (Ahmad et al., Pakistan Journal of Scientific and Industrial Research 50(1):36–40, 2007), PCSIR (peer-reviewed). Printed value: 194.78 ± 0.23 mg KOH/g.
Published values we checked:
- 194.78 ± 0.23 mg KOH/g — PCSIR (peer-reviewed)
- 180.9 mg KOH/g — Tarbiat Modares University (peer-reviewed)
Fatty acids and iodine: Milk Thistle Oil Extracted by Enzyme-Mediated Assisted Solvent Extraction Compared with n-Hexane and Cold-Pressed Extraction (Molecules 2023; DOI 10.3390/molecules28062591), MDPI (peer-reviewed, open access). Also checked: PCSIR (peer-reviewed) (Table 2 (iodine value); abstract and Table 5 (fatty acids)).
NaOH and KOH values are converted from mg KOH/g with the molar masses 39.997 and 56.106 and rounded to 6 decimals, exactly as in the Soap Ledger app. Real oils vary by origin, grade and lot: check your supplier's certificate of analysis. Verify every weight before you make this, and follow lye safety. Not a safety or compliance certification.
Last updated .