What can I use instead of egg yolk (as thickener)?
The yolk used for its thickening rather than its enriching role. Its proteins coagulate between roughly 150°F and 158°F, and its lecithin emulsifies at the same time.
What it does in a recipe: Thickening plus emulsification and richness, giving a custard's smooth, coating body. Pick the swap that covers that job — the ratios below are written so you can act on them without doing any arithmetic.
Starch gelatinisation reaches a comparable viscosity, and it is far more forgiving — a starch-thickened custard can boil without curdling, where a yolk-thickened one cannot.
MethodWhisk the slurry into the simmering liquid and cook for a minute or two until it thickens and loses any starchy taste.
Trade-offThickness without richness. You lose the yolk's fat, its colour and its emulsifying power, so a hollandaise or a mayonnaise cannot be made this way at all.
Allergen checkThis is the standard route when egg is being avoided, and it introduces no allergen of its own. In a custard, plant milk plus cornstarch gives a workable egg-free result.
The starch supplies the viscosity and the fat supplies the richness and mouthfeel, which between them account for most of what a yolk was doing in a sauce.
MethodThicken with the starch first, then whisk in the fat off the heat so it emulsifies smoothly.
Trade-offStill no lecithin, so it will not hold a demanding emulsion, and the colour stays pale rather than turning golden.
Allergen checkAdds dairy where the yolk had none. Use a plant-based cream or a neutral oil if milk is also being avoided, and check the carton for nut or soy bases.
Whole egg
Reliable
1 egg yolk = 1/2 whole beaten egg (about 2 tbsp)
The yolk within the whole egg does the same work; the white simply comes along, adding water and a protein that sets firmer and at a slightly higher temperature.
MethodTemper it carefully — whisk a ladle of the hot liquid into the beaten egg before returning it to the pan, or it will scramble.
Trade-offSlightly firmer and less silky, and more prone to setting into visible threads if the heat gets away from you.
Silken tofu is a set protein gel that blends into a smooth, thick emulsion, so it can give body and a creamy mouthfeel to a cold or gently warmed sauce.
MethodBlend until absolutely smooth and keep the heat gentle — pushed too hot it separates and turns grainy.
Trade-offFaintly beany, noticeably paler, and it will not thicken further with heat the way a yolk does.
Allergen checkSilken tofu is soy. It is a common egg-free choice, but it trades one top allergen for another, so it is no use where both are a concern. Check the packet and treat a diagnosed allergy as a medical matter.
Worth knowing
Yolks thicken in a narrow window — around 150°F to 158°F — and scramble above it. Temper them by whisking hot liquid into the yolks rather than the reverse, keep the heat low, and pull the pan the moment the sauce coats the back of a spoon. A pinch of cornstarch in the yolks buys you a real safety margin against curdling.
Cooking around an allergy? Diet tags here describe the ingredient itself, not any particular brand. Processed products change formulation without notice and shared production lines are common, so read the label on everything you use. A severe allergy is a medical matter — confirm with the manufacturer or your clinician rather than relying on a substitution chart.