Fat

Fat is the phase that does not mix with water until you force it. In milk it is droplets. In butter it is the continuous food. In a bottle of olive oil it is the whole product. Taste it as richness, as oiliness, and as the carrier of aroma. Emulsion is how it stays mixed.

Butter has a legal floor #

U.S. statute: Butter is made exclusively from milk or cream, or both, with or without common salt and coloring, and contains not less than 80 percent milk fat by weight ¹. That 80 percent is identity, not a sauté tip. Below it, you are not calling the product butter in that legal sense.

Milk and cheese #

FAO: milk fat is present as an emulsion and will rise if left to stand; cheesemakers also standardize fat in the vat so the cheese matches a target ². Most of that fat should go into the curd. Greasy whey is lost yield. Fat in the paste tastes round; too little tastes lean and often drier.

Olive oil is graded as oil, not as butter #

USDA AMS extra virgin is a voluntary U.S. grade: virgin oil with excellent flavor and odor (median of defects equal to zero, median of fruitiness greater than zero) and free fatty acid, as oleic acid, not more than 0.8 grams per 100 grams, plus further chemical requirements in the standard ³. It is not an FDA standard of identity. How to taste it: Olive oil tasting. The ingredient page is Olive oil. How it goes off: Oxidation.

Observe: cream line, butter that weeps water, cheese that oils off in a warm room, oil that smells of crayons or stale nuts. Salt in Butter is optional in the statute and a flavor choice in the kitchen. Smoke point varies with the fat and its condition; cooking cues matter more than a universal table.