Often, when we buy milk in the store, we only pay attention to the expiration date. In fact, there are several other things to consider to make sure that milk does not go to waste.
The way the milk is processed
All dairy products of this type that you meet on supermarket shelves are divided into three types:
- Pasteurized milk – that which is heated once to 60 ° C. During this, the microorganisms are killed, but their spores remain, so the bacteria can multiply again under favorable conditions.
- That is why pasteurized milk can be stored at low temperatures and for a short time.
- Ultra-pasteurized – the producer quickly heats the milk to 150 °C and immediately cools it down. At this point, the bacteria that could cause the product to sour die, but the flavor and aroma of the milk are preserved.
- Sterilized – Milk is heated to 100 °C or more for a long time. Simply put, it is boiled milk, which no longer has beneficial bacteria. It is not possible to make cottage cheese from such a product, but the shelf life of the product increases many times over.
This classification helps people divide all types of milk into two types: short and long. The short-pasteurized product has been heated at low temperatures. Long – ultra-pasteurized and sterilized, as well as products made from it.
Types of milk packaging
In addition to the above factors, the shelf life of milk is also affected by the packaging in which the milk is found. It comes in:
- soft – high-strength polyethylene;
- semi-rigid (thermoplastic) – plastic packaging, usually cups with foil instead of a lid;
- semi-rigid from combined materials – cardboard boxes with several layers of coating.
Most often, manufacturers choose cheap packaging, and this is reflected in the cost of milk. If you see milk in a polyethylene or paper bag, it is most likely a pasteurized product with a shelf life of 3-5 days.
Thermoplastics can be found in packaging for yogurt or sour cream, and the most important thing is the tightness of the package. Provided that the manufacturer did not economize on materials, such a sour milk product will be stored for 5-7 days.
Ultra-pasteurized and sterilized milk requires good hermetic and quality packaging, buying such products in bags is categorically not recommended.
How long does store milk in the refrigerator
You must remember that the shelf life of pasteurized milk is always a maximum of 5 days, and after opening – 48 hours. Ultra-pasteurized and sterilized milk can remain drinkable for 10 days. That said, if you open the milk, ultra-pasteurized milk is stored for as long as the manufacturer specifies, while sterilized milk is stored for 96 hours.
Short dairy products are stored at 2-4°C. Long milk can be kept in the refrigerator door or on the top shelves, where the temperature is higher. Sterilized milk in a tetrapak, for example, can tolerate temperatures up to 25°C.
How to tell if milk is spoiled
Sometimes, even with proper storage, dairy products appear to be spoiled. You can determine whether this is true or not, according to external signs:
- fatty milk (4.7% or more) – a film forms, which disappears when stirred;
- Skimmed milk – a bluish tint appears;
- Sterilized milk – a creamy tint.
If the milk is gone, you will feel the sourness and see clots, and when boiled, the product will curdle. Many housewives do not throw away sour milk but turn it into sour milk by adding a special sourdough starter to the heated product. In addition, you can always make pancakes from spoiled milk.