Calcium Lactate Spherification: How Much to Use (Basic and Reverse)
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Short answer: for basic spherification, use a 1% calcium lactate bath (10 g per litre of water) and 0.5% sodium alginate (5 g per litre) in the flavoured liquid. For reverse spherification, the calcium goes into the liquid instead, at about 1% calcium lactate, and the drops set in a 0.5% sodium alginate bath.
Both methods rely on the same reaction: calcium ions meet dissolved sodium alginate and form a thin gel skin around a liquid centre. What changes is which side holds the calcium. This guide gives the doses, explains why calcium lactate needs twice the dose of calcium chloride, and walks through both methods step by step.
How much calcium lactate and alginate per litre?
| Method | Flavoured liquid | Setting bath | Time in bath |
|---|---|---|---|
| Basic (direct) | 0.5% sodium alginate (5 g per 1 kg of liquid), pH above 3.6 | 1% calcium lactate (10 g per 1 L of water) | About 1 min for caviar, about 2 min for large spheres |
| Reverse | About 1% calcium lactate (10 g per 1 kg of liquid)* | 0.5% sodium alginate (5 g per 1 L of distilled water) | Up to 2 min |
*The Pennsylvania College of Technology reverse spherification recipe uses 4 g of calcium lactate gluconate in 200 g of yogurt (2%). Calcium lactate carries about twice as much calcium per gram, so the same calcium comes from roughly 1% calcium lactate (2 × 9.3 ÷ 18.4 ≈ 1). Treat it as a starting point and test one sphere first.
Why 1% calcium lactate but only 0.5% calcium chloride?
The bath needs about 0.18% calcium, and each calcium salt contains a different share of calcium. The spherification handout used in Harvard's Science and Cooking course lists:
| Calcium salt | Calcium content | Dose for a 0.18% calcium bath |
|---|---|---|
| Calcium chloride | 36.1% | 0.5% (5 g/L) |
| Calcium lactate | 18.4% | 1% (10 g/L) |
| Calcium lactate gluconate | 9.3% | 2% (20 g/L) |
The trade-off is flavour. The same handout notes that calcium chloride has an unpleasant salty taste that must be rinsed off, while calcium lactate has a better flavour and is mostly used for reverse spherification, where the calcium stays inside the sphere. That is why most cooks searching "calcium lactate vs calcium chloride" end up with lactate for anything that will be eaten as is.
How do you make basic spherification (caviar)?
- Check the pH of the flavoured liquid. It must be above 3.6, or the alginate will not hydrate. If it is too acidic, add small amounts of sodium citrate before the alginate and re-measure with pH paper or a meter.
- Blend 0.5% sodium alginate into a third of the cold liquid with an immersion blender, then add the rest. Pre-mixing the alginate with a little sugar helps it disperse.
- Rest the mixture in the fridge for about an hour (up to 24 hours for thick liquids) so air bubbles escape. Bubbles make spheres float and create weak spots.
- Dissolve 10 g of calcium lactate per litre of water for the bath. You can add sugar, up to 20%, to make the bath denser so spheres keep their round shape.
- Drop the liquid into the bath with a syringe, held a few centimetres above the surface, or with a measuring spoon for large spheres.
- Wait about 1 minute for caviar or 2 minutes for large spheres, stirring the bath gently.
- Lift out and rinse in clean water with a slotted spoon. Serve right away: basic spheres keep gelling inward until they become solid balls.
How do you make reverse spherification?
Reverse spherification suits liquids that already contain calcium (dairy) or that are too acidic or alcoholic for the basic method. The gel skin forms on the outside only and does not keep thickening, so spheres hold longer and can be larger.
- Make the alginate bath: blend 5 g of sodium alginate per litre of distilled water (the PCT recipe uses 7.5 g in 1,500 g). Use distilled water if your tap water is hard, since its calcium would gel the bath. Let it rest, ideally overnight, to remove bubbles.
- Add calcium to the liquid: about 10 g of calcium lactate per kilogram of flavoured liquid. Stir until dissolved.
- Spoon the liquid gently into the bath, turning the spoon so the drop slides in. Keep spheres from touching, or they will stick together.
- Leave up to 2 minutes for the membrane to form.
- Rinse each sphere in clean water and store it in a little juice or the base liquid until serving.
What goes wrong, and how do you fix it?
- Liquid thickens before it reaches the bath: it contains free calcium. Switch to reverse spherification or bind the calcium with sodium citrate (pH above 4.5). Our guide to sodium citrate vs citric acid explains how this buffer works.
- Spheres flatten at the bottom: the bath is too light or the drop fell from too high. Add sugar to the bath and lower the syringe.
- Spheres burst when lifted: the skin is too thin. Leave them a little longer in the bath.
- Spheres float and stay open on top: trapped air. Rest the alginate mixture longer or strain it through a fine sieve.
Why weigh to the 0.1 g?
At 0.5% and 1%, a 250 mL batch needs only 1.25 g of alginate and 2.5 g of calcium lactate. Measuring spoons are not accurate at that scale, so use a scale that reads to 0.1 g, or 0.01 g for very small batches.
Sources
- HarvardX Science and Cooking — Spherification how-to (course handout): 0.5% alginate, 0.18% calcium bath, calcium content of each salt, pH limit, bath times and density tip.
- Pennsylvania College of Technology — Spherification and reverse spherification: tested basic and reverse recipes with gram quantities.
- PubChem — Calcium lactate: compound identity and molecular weight.
LiquidShop supplies food-grade calcium lactate and sodium citrate from Canadian stock, in formats from 1 kg. Formats and specifications are on the calcium lactate product page.
