Does anyone know why milk tastes so much different out of the carton than from a glass? 
Why does milk taste better in a glass than a plastic carton?
It doesn’t. That’s what milk's spokespeople say, anyway. “The great taste of milk is the same regardless of the package it comes in,” they insist. Rather, they say, “the particular way that people choose to enjoy their milk can affect their perception of taste.” Sure, most people would agree that the milk is indeed delicious and refreshing, and pouring it into a glass could influence the sensation of its flavor. But is it possible that the subtle variation in taste that some notice among plastic cartons and glass bottles is more than just a psychological effect of their milk-consumption rituals?
Given that the formula is always the same, yes, according to Sara Risch, a food chemist and member of the Institute of Food Technologists. “While packaging and food companies work to prevent any interactions, they can occur,” she says. For example, the polymer that lines plastic cartons might absorb small amounts of soluble flavor from the milk. Conversely, acetaldehyde in plastic cartons might migrate into the milk. The FDA regulates this kind of potential chemical contact, but even minute, allowable amounts could alter flavor.
Your best bet for getting milk’s pure, unaltered taste is to drink it from a glass bottle, the most inert material it’s served in. Even that’s not a sure bet, though. Milk maintains strict uniformity in processes in all of its worldwide bottling facilities, but it concedes that exposure to light and how long the product sits on store shelves may affect the taste. So yeah, the packaging might mess with milk’s flavor, but we’ll still take it any day over soy milk.
