Buttermilk

Traditional buttermilk forms when fresh milk meets a culture of lactic acid bacteria. The microbes ferment lactose, lowering pH and causing the milk proteins to coagulate. The resulting thick liquid separates from whey, creating a mildly sour, buttery fluid. In perfumery, the scent is captured by fermenting milk under controlled temperature, then extracting the volatile lactones with a food‑grade solvent. After filtration, the extract is distilled at low pressure to preserve the delicate gamma‑nonalactone. Many houses now synthesize the lactone from readily available fatty acids, achieving identical aroma without dairy handling. Both routes yield a clear, slightly sweet, milky oil that blends easily with other ingredients.