Tomato paste (canned)
Orange to red. Label appeal: a soap made with a favourite fruit or vegetable. Faiola, Pure Soapmaking primary source, Faiola, Pure Soapmaking primary source
Opens the calculator’s starter recipe, 1000 g of oils, with this additive at the dose it fills in, ready to change.
What it is
Canned tomato paste without added salt: about three quarters water and 12 % sugar in USDA’s figures. It is acidic too, 1–2.4 % acid as citric acid in an analysis of processors’ paste.
USDA FoodData Central primary source, Aykas et al. (2020) primary source
How much
- 4.56 % of the oils filled in (from a published recipe) Faiola, Pure Soapmaking primary source
- up to 6 % of the batch Fisher, The Complete Photo Guide to Soap Making primary source
The calculator fills in 4.56 % of the oils: 45.6 g for the 1000 g of oils in its starter recipe.
When and how
- Usually: at light trace.
- Stir it in as it is.
Faiola, Pure Soapmaking primary source, Faiola, Pure Soapmaking primary source
What it does to the recipe
- Every 100 g takes 1 g of sodium hydroxide, which the calculator adds to the lye.
- 73.5 % is water, taken off the recipe’s water.
- 0.47 % is fat, which stays in the bar as extra superfat.
- 12.18 % is sugar, which heats the batch.
USDA FoodData Central primary source, Aykas et al. (2020) primary source, Stoichiometry primary source
Worth knowing
- Titrated, it holds 0.99–2.4 % acid, counted as citric acid; the calculator adds the lye for the average, 1.6 %. Aykas et al. (2020) primary source, Stoichiometry primary source
- Caution: It heats the batch: work cool and do not insulate it, or it can crack or overflow the mould. USDA FoodData Central primary source, Soap Queen supplier or guide
- Its colour fades with light and time. Faiola, Pure Soapmaking primary source
Spoons and drops
- 1 tsp ≈ 5.33 g
- 1 tbsp ≈ 16 g
- 1 cup ≈ 262 g
USDA FoodData Central primary source
INCI name
CosIng has no single INCI name for it: label it by what it contains.
Recipes that use it
Guides that discuss it
Sources
Anne-Marie Faiola, Pure Soapmaking (Storey Publishing, 2016), chapter 9, Layered Tomato Swirl Bars: "1.5 ounces tomato paste" for 32.9 oz of oils, stick-blended into one of three containers of batter at very light trace, their "beautiful, rich color"; chapter 5: "Shades of orange and red, such as the tomato color in Layered Tomato Swirl Bars will fade, but not as drastically or as quickly as the greens."
Anne-Marie Faiola, Pure Soapmaking (Storey Publishing, 2016), chapter 5, "Juices and Purees": "If you’re selling your soap, adding purees adds flair to your label and sets your product apart from the competition"; "Add a liquid puree at thin trace or as a portion of the water phase"; "Purees must be finely ground; never use chunks of fruit or vegetable in soap. Larger pieces of fruit or vegetables will eventually mold or cause a discoloring “halo” effect"; "The shelf life of soap made with fresh veggie or fruit juices and purees is about one year, even if the color fades before that time."
USDA FoodData Central, food 170459: Tomato products, canned, paste, without salt added (water 73.5 g, fat 0.47 g, sugars 12.18 g per 100 g; 1 tbsp = 16 g; 1 cup = 262 g).
D. P. Aykas, K. Rodrigues Borba and L. E. Rodriguez-Saona, "Non-destructive quality assessment of tomato paste by using portable mid-infrared spectroscopy and multivariate analysis", Foods 9 (2020) 1300: 1,843 tomato paste samples from four major California processors, 2015–2019; titratable acidity 0.99–2.40 %, mean 1.6 ± 0.2 %, as citric acid, found by titrating 10 g of paste in 100 mL of water with 0.1 N NaOH; 24.1–38.1 °Brix, mean 29.4; pH 4.14–4.49. Titratable acidity is the lye the acid takes, so at 1.6 % as citric acid a gram of paste takes 0.016 × 0.6246 = 0.00999 g NaOH.
Processors’ paste at 24.1–38.1 °Brix; a thinner paste holds less acid and a thicker one more.
Neutralisation stoichiometry with IUPAC 2013 molar masses: grams of NaOH per gram = protons × 39.997 ÷ molar mass. Disodium EDTA dihydrate (372.24 g/mol) takes 2; sodium bicarbonate (84.007 g/mol) 1; magnesium sulfate heptahydrate (246.47 g/mol) 2; borax decahydrate (381.37 g/mol) 2, to sodium metaborate; malic acid (134.087 g/mol) 2; citric acid (192.124 g/mol) 3. An acidity given in milliequivalents per litre takes that many millimoles of NaOH per litre.
David Fisher, The Complete Photo Guide to Soap Making (Creative Publishing International, 2018), p. 113: "keep the additives to no more than 5 or 6 percent of the soap’s total weight—or 1 ounce (28 g) per 1 pound (454 g) of soap"; "If you leave chunks of fruit or other additives in the soap, they are likely to turn rancid or moldy, or both". P. 114, cucumber purée soap: "Though it contains more than 95 percent water"; it "adds a lovely natural pastel yellow-green color"; the purée replaces "half the lye-water" and is added to the batter at light trace.
Soap Queen, insulating soap: sugars and milks run hot, and insulating them "can cause the soap to volcano, crack".