Gelatin & Agar Setting Calculator

Gelatin and Agar Guide

What's the key thing to understand about Gelatin Strength Levels?

Gelatin is graded by 'bloom strength' — bronze (125-155 bloom), silver (160-170), gold (190-220), platinum (235-265). Higher bloom = stronger set per gram. Most UK supermarket leaf gelatin: platinum (~2g per leaf). Most powdered gelatin: ~250 bloom. Conversions: 1 leaf platinum gelatin (2g) ≈ 1 teaspoon powdered (~3g — accounting for lower bloom of typical supermarket powder). Standard ratio: 1.5-2% gelatin by liquid weight for standard table jelly. 0.5-1% for soft mousses. 3-5% for firm gummy sweets that need to hold a distinct shape and bite.

What's the key thing to understand about Working with Gelatin?

Leaf gelatin: bloom in cold water 5 minutes until soft and floppy. Squeeze out excess. Dissolve into warm (not boiling) liquid — over 80°C destroys some gelling power. Powdered gelatin: 'bloom' first — sprinkle over 4-5× volume of cold water. Wait 5 minutes. Then warm gently to dissolve, then add to main liquid. Important: gelatin does NOT set if added to boiling liquid OR not properly hydrated first. Maximum set develops over 4-12 hours in fridge. Use ASAP after setting — gelatin can 'weep' — a process called syneresis, where liquid slowly separates out of the set gel over time, particularly if stored too long or at an inconsistent temperature.

What should I know about Agar Agar?

Agar is a vegan/vegetarian alternative to gelatin, extracted from seaweed. Different properties: sets MUCH firmer per gram (use ~1/3 the amount of gelatin). Sets at higher temperature (~40°C vs ~15°C for gelatin). Stable at room temperature once set. Less melt-in-mouth — has more brittle texture. Standard agar ratio: 0.5-1% by liquid weight for standard set. Method: agar must be boiled to activate — bring to rolling boil for 2-3 minutes. Then pour into mould. Agar flakes: need roughly 3× more than powdered agar by weight to achieve the same set, since flakes are less concentrated.

What Prevents Setting?

Fresh pineapple, papaya, kiwi, fig, ginger, paw paw: contain bromelain or papain enzymes that destroy gelatin protein. Always use cooked or canned versions. Excess acid: lemon juice, vinegar weaken gelatin set. Use more gelatin OR balance with sugar (sugar strengthens gelatin set, paradoxically). High alcohol content: weakens set. Use ~50% more gelatin for spiked jellies (jelly shots). Too much fat: prevents proper dispersion — emulsify carefully. Solution to gelatin failure: re-melt gently to around 40°C, correct the ratio or remove the interfering ingredient, then re-set — gelatin can usually be rescued this way unless it's been overheated repeatedly.