Some Like it Warm: The Lowdown on Mexican Milk
Tara A. Spears
It’s udder-ly amazing how many first timers to Mexico are shocked to see milk being sold unrefrigerated. But, once you learn the explanation, you’ll be impressed with Mexican ingenuity. Unlike the commercially produced milk in the United States and Canada, some Mexican milk is kept at room temperature in airtight and light-sealed paper cartons. Due to the surge of foreign visitors in recent years, most food markets also sell refrigerated milk in plastic cartons. How milk is stored comes down to how the milk is processed.
A popular misconception is that the room temperature milk is not real cow’s milk; yes, the un-refrigerated milk in Mexico is cow’s milk. Often foreigners think that this is powdered milk mixed with water to enable it to be shelved instead of having to be refrigerated but that’s not true.
Some milk in Mexico is not pasteurized in the same way as NOTB. Pasteurization is heating a food product to remove any bacteria so that it lasts longer. Milk can be pasteurized at four different temperatures and time duration using four different techniques:
LOW-TEMPERATURE-LONG-TIME TREATMENT (LTLT.) This pasteurization process takes the longest time and the food product is boiled at very low heat to eradicate pathogenic bacteria. Milk is pasteurized at 145F (63C). This process takes 30 minutes.
HIGH-TEMPERATURE-SHORT-TIME TREATMENT (HTST.) This form of pasteurization uses a higher temperature to kill bacteria, and because of this, it takes less time to pasteurize. Under this method, milk is pasteurized at 161F (72C). At this temperature, it only takes 15 seconds to pasteurize.
ULTRAPASTEURIZATION. Ultrapasteurization involves superheating the milk to 280F (138C) for about 2 seconds. Due to the type of packaging, this milk must still be refrigerated. However, it lasts in the refrigerator for 2 to 3 months. After the package is opened though, bacteria in the air will cause milk to spoil, so you can expect it to last the typical week or two in the refrigerator.
ULTRA-HIGH TEMPERATURE PASTEURIZATION (UHT). This milk is superheated between 280F and 302F (138C to 150C) for only a second or two. The packaging for this milk is airtight and light-sealed which allows it to be stored at room temperature for up to 6 months. However, when the package is opened, bacteria in the air causes the milk to spoil in the typical week or two.
In the US and Canada, the milk is heated for 15-20 seconds at 161 – 167 degrees Fahrenheit (71.6C – 75C) by way of the HTST treatment. The boxed milk in Mexico is heated by way of the Ultra-High Temperature Pasteurization (UHT) method. This is why the milk is safe to keep at room temperature when it is in an airtight and light-sealed container.
Pasteurization can affect the flavor of foods. Some foreigners find that the milk tastes richer or creamier in Mexico than it does NOTB. This could be merely subjective, but it could also be because Ultra-High Temperature Pasteurization (UHT) has been shown to change the flavor less than Low-Temperature-Long-Time Treatment (LTLT). UHT also damages the nutrient content less than LTLT. That said, any changes in flavor are likely negligible.
In the early 1990s, one company attempted to sell UHT milk on American shelves, but it never caught on. Why? For starters, the high temperatures make UHT milk taste a bit more “cooked” than HTST milk. But most likely, Americans’ obsession with refrigeration is to blame.
While pasteurization has helped provide safe, nutrient-rich milk for over 150 years, some people continue to believe that pasteurization negatively affects the nutritional profile of milk. That could not be further from the truth. In fact, there are no meaningful changes to the nutrient package of milk as a result of pasteurization. When it comes to milk’s nutrients, all of milk’s minerals remain after pasteurization; there is, however, one small change when it comes to vitamins. Raw milk contains a miniscule amount of vitamin C (3.7 milligrams per serving), which does not survive the pasteurization process.
After learning why some Mexican milk is sold in the aisle, I tried it. I’ve come to prefer the taste of the UHT products over the refrigerated versions. Rest assured that the cardboard carton milk in the aisle is just as healthy and flavorful.