Milk-based espresso drinks require that the milk be heated and produce a thick microfoam vaguely like shaving cream. I have tried every variation and brand of milk available in my area and concluded that pasteurization seriously effects the taste and texture of the foam.
- The very best is “raw” milk straight from the cow, un-pasteurized and un-homogenized. The foam is beautifully thick and the milk imparts a caramel sweetness to the espresso. Unfortunately, this is illegal in most states and a potential health hazard if handled incorrectly.
- We usually heat raw milk at home, a process called vat pasteurization (150F for 30 minutes). Somehow this reduces the sweetness yet preserves most of the thick foam.
- In Europe most milk is processed with ultra-high temperature (UHT) pasteurization. In the US some half-gallon cardboard containers are labeled as such. We buy organic brands. Somehow this preserves the thick foam but has none of the natural sweetness from raw milk.
- No other milk produces the thick foam you need for espresso drinks. Instead, it’s like a lousy latte from Starbucks: hot milk with a bit of soapy foam bubbling on the surface. Most milk in the US is processed with high-temperature/short-time (HTST) pasteurization. A food science book I read says this changes the flavor substantially but American consumers now expect that “cooked” flavor. It says 10% of the whey protein is denatured, which may explain why it doesn’t produce the proper foam.
Raw milk is illegal, expensive and easily contaminated with killer bacteria. I don’t want to use it. However, we’ve tried head-to-head tests comparing raw milk against the best commercial milk we can find for a variety of recipes, including Indian desserts. In blind tests it is easy to notice the vastly better flavor from raw milk compared to regular milk. It’s in a completely different league. (FYI: French chefs agree that young raw-milk Camembert in France is better than that made from pasteurized milk.) I’m forced to continue smuggling in raw milk, but I’ve purchased better health insurance just in case things go wrong.