Custards, creams & meringues
crème fraîche
crème fraîche · A cultured dairy cream with a velvety texture, gentle tang, and remarkable stability at high heat — the workhorse thick cream of classical French cooking. True crème fraîche achieves its body and flavor through lactofermentation by mesophilic bacteria, not through the addition of thickeners or stabilizers.
The formula
1000 ml heavy cream (≥35% fat) : 30–45 ml cultured buttermilk (2–3 tbsp)
The fat content of the cream determines final body: European‑style 35–40% fat cream yields a crème fraîche that holds its shape when whipped; lower‑fat cream will be thinner. The culture is non‑negotiable — without it you have sweetened whipping cream.
Identity
- Cultured via mesophilic lactobacilli, not thickened with starch or gelatin
- Minimum 30% fat — genuine crème fraîche cannot be made from half‑and‑half
- Sour‑tangy but not aggressively acidic; complexity develops over 24–48 h
- Heat‑stable: does not break or curdle at simmer or in reductions
- Spoonable and spreadable when cold; liquid enough to pour when brought to room temperature
- White with no color — yellowing indicates oxidation or poor‑quality cream
Ingredients
| Base | Heavy cream | Minimum 35% fat for proper body; European‑style 40% fat cream produces the best result. UHT cream works but develops less complex flavor. |
| Culture | Cultured buttermilk or mesophilic dairy culture (Lactococcus lactis, Leuconostoc cremoris) | The culture ferments lactose to lactic acid, dropping pH and denaturing milk proteins to create the signature silky body. Store‑bought buttermilk contains suitable strains. |
| Culture | Existing crème fraîche (inoculant) | If available, 2 tbsp of previous‑batch true crème fraîche can substitute for the culture — a classic back‑slopping method. |
Method
- 1Combine cream and cultured buttermilk (or culture) in a clean glass or ceramic vessel. Stir gently to incorporate.Distributes the culture evenly through the fat phase so fermentation is uniform throughout the batch.
- 2Cover loosely with cheesecloth or a loose lid. Place in a spot with stable temperature between 18–22 °C (65–72 °F).Mesophilic cultures are active in this range; too cold and fermentation stalls; too warm and unwanted pathogens may proliferate. Loose covering allows CO₂ from fermentation to escape while preventing dust entry.
- 3Let rest undisturbed for 12–24 hours. Check at 12 hours for initial thickening; the culture will work faster in warmer conditions.Lactic acid bacteria need time to produce enough acid (typically pH ≤ 4.6) to set the proteins and create the characteristic thick, spoonable texture. Rushing produces weak body.
- 4Once noticeably thickened and tasting tangy, refrigerate immediately. The cream will continue to firm as it cools.Cold arrests fermentation; without refrigeration, acidity will overdevelop and produce a harsh, almost cheese‑like result within another 12 hours.
- 5Whisk briefly before use if a slightly looser consistency is desired for drizzling.Crème fraîche is thixotropic: gentle agitation breaks the protein network temporarily, making it pourable while it re‑sets at rest.
Techniques that matter
Lacto‑fermentation
Controlled bacterial fermentation of lactose to lactic acid is the structural and flavor‑defining mechanism. This is what distinguishes true crème fraîche from all imitations.
Acid‑set protein coagulation
As pH drops below the isoelectric point of casein proteins (~pH 4.6), they unfold and tangle, forming the gel‑like network that gives crème fraîche its body without any added thickener.
Thixotropy / shear thinning
The protein‑fat network in cultured cream breaks under stirring or whisking, temporarily thinning the product. This property allows crème fraîche to be poured while still being spoonable at rest.
Variations & derivatives
Crème fraîche à la NormandyNormandy, France
Made from raw cream from Normandy cows; traditionally set overnight in a cool cellar using whatever wild mesophilic cultures are present in the air — the original terroir‑driven crème fraîche.
Crème épaisseFrance
A thicker, more set cultured cream with less fat (typically 25–30%); used as a spread and for certain sauces where extra body is needed. More acidic than crème fraîche.
Schmand / Saure SahneGermany / Austria
German sour‑cream analogues; Schmand is 20–24% fat and slightly more acidic. Not cultured in the same mesophilic tradition but functionally similar for cooking.
SmåñaScandinavia
Nordic cultured cream with slightly different bacterial strains producing a more buttery, less tangy flavor profile.
Used in these dishes
Substitutions
- American commercial 'crème fraîche' (pasteurized, no live culture) → Sour cream + 1 tbsp heavy cream per cup — Commercial versions are often just cream with bacterial flavoring — not truly cultured. Adding a splash of real cream improves richness.changes result
- Full‑fat sour cream → Stir in 1–2 tbsp heavy cream per 240 ml to loosen and enrich; whisk well — Acceptable in cooked applications (sauces, soups) where the tang is welcome and heat stability is needed. The result lacks the silky mouthfeel of true crème fraîche.
- Greek yogurt → Whisk with 2 tbsp heavy cream per 240 ml to approximate richness and thin slightly — Greek yogurt is more acidic and more heavily protein‑coagulated. Works in cold applications; breaks more readily under heat than true crème fraîche.
Troubleshooting
Cream fails to thicken after 24 hours
Insufficient culture — the cream may be ultra‑pasteurized (UHT), which damages the fat globule membrane and can inhibit culture activity; or the temperature was too cold. → Move to a warmer spot (22–24 °C); add another tablespoon of cultured buttermilk; allow another 12–24 hours. For future batches, use pasteurized (not ultra‑pasteurized) cream.
Separation or curdling when heated in a sauce
The crème fraîche may be old and over‑acidified (pH < ~3.5), or it was added to a boiling liquid rather than incorporated off‑heat. → Always add crème fraîche off the heat or after removing from direct heat. If the sauce begins to break, transfer to a bowl over an ice bath and whisk vigorously to cool quickly, halting coagulation. Use fresh crème fraîche for cooking.
Off‑flavors: bitter, yeasty, or fermented beyond tang
Left to culture at room temperature too long (beyond 36–48 hours total), or stored too warm after refrigeration — spoilage organisms have outcompeted the desired culture. → Discard. This batch is not salvageable. Refrigerate promptly in future; taste at 12‑hour intervals once thickening begins; use immediately or keep refrigerated once the desired tang and body are reached.