Grapefruit seed extract
Sold to hold off rancidity and orange spots.
Opens the calculator’s starter recipe with this additive in it. No source gives a dose to fill in, so enter your own.
What it is
Grapefruit seed extract is sold as a liquid heavier than water, Citricidal among the brands.
BioChem Research primary source
How much
- 0.5–5 % of the batch Cavitch, The Natural Soap Book primary source
- 0.1 % of the oils in a controlled test Dunn, “The Dreaded Orange Spot” primary source
- up to 0.12 % of the batch in rinse-off products, the highest reported use: not a recommendation CIR primary source
No dose to fill in: enter your own.
When and how
- Usually: into the oils.
- Stir it in as it is.
Cavitch, The Natural Soap Book primary source
What it does to the recipe
- It changes neither the lye nor the water: it is only weight in the bar.
Cavitch, The Natural Soap Book primary source
Worth knowing
- Caution: In Dunn’s test, at 0.1 % of the oils, it did nothing against rancidity. Dunn, “The Dreaded Orange Spot” primary source
- Caution: Tests of commercial extracts found their antimicrobial effect came from added synthetic preservatives, such as benzethonium chloride. von Woedtke 1999; Takeoka 2001; Ganzera 2006; Brandin 2007 primary source
Spoons and drops
- 1 tsp ≈ 5.81 g (5.46–6.16 g)
- 1 tbsp ≈ 17.4 g (16.4–18.5 g)
- 1 cup ≈ 279 g (262–296 g)
BioChem Research primary source
INCI name
Citrus Grandis Seed Extract
- CAS number
- 90045-43-5, 8016-20-4
- EC number
- 289-904-6
Guides that discuss it
Sources
Susan Miller Cavitch, The Natural Soap Book (Storey Publishing, 1995): honey, "no more than 4 tablespoons (59 ml) of warm honey for a 12-pound (5.45 kg) batch of soap" (pp. 66–67); vitamin E at about 0.06 % and grapefruit seed extract at 0.5–5 % of the ingredients, in the oils before the lye; the Goat Milk Soap (pp. 110–114) takes "½ pound (227 g) cold goat milk" beside "2½ pounds (1.13 kg) cold, distilled water", the lye solution drizzled into the milk at 80 °F, because too much goat milk "makes the soap more vulnerable to premature rancidity"; fresh aloe gel "can sting and itch".
Kevin M. Dunn, "The Dreaded Orange Spot", The Handcrafted Soapmaker (Winter 2005/06): additives at 0.1 % of the oil weight in olive-oil soap held at 60 °C. Rosemary extract and EDTA "lengthened the induction period beyond 300 hours", BHT to 150; grapefruit seed extract, vitamin C, vitamin E and sodium citrate were "virtually identical" to plain olive-oil soap; BHT with sodium citrate did best, and "ROE + Sodium Citrate actually performed worse than ROE alone".
Cosmetic Ingredient Review, citrus-derived seed ingredients: Citrus grandis seed extract up to 0.12 % in rinse-off products.
The highest concentration reported to CIR in industry surveys: what has been used, not a recommendation.
Four independent analyses of commercial grapefruit seed extracts (von Woedtke et al., Pharmazie 1999; Takeoka et al., J. Agric. Food Chem. 2001; Ganzera et al., Phytomedicine 2006; Brandin et al., 2007) found their antimicrobial effect came from synthetic preservatives such as benzethonium chloride.
Citricidal grapefruit seed extract (BioChem Research, 2002): specific gravity 1.107–1.138; current extract data sheets 1.15–1.25.