Milk is rich in minerals, vitamins, proteins, good fats and carbohydrates. However, should it go bad, the only result you would get from drinking it would be to find yourself with a severe stomach ache. Even if the expiration date indicates that it should still be good, you have to consider several factors that can make it go bad ahead of time. By analyzing its smell, texture, color, testing it with heat or observing if it reacts in contact with baking soda, you will be able to understand if the milk is spoiled.
Steps
Method 1 of 4: Examine the Milk
Step 1. Make sure the expiration date hasn't passed by more than 7 days
If the milk has been stored correctly, it will last for 7 days past the expiration date indicated on the package. However, if the date has passed and the milk has been completely left out of the refrigerator, it is highly likely that it has gone bad.
- The duration of the milk depends on the amount of fat and lactose it contains. Whole milk has a maximum shelf life of 5 days beyond the expiration date. On the other hand, lactose-free or skimmed milk can last up to 10 days beyond the recommended expiration date.
- If the milk has been out of date for more than a week, it is preferable to throw it away, even if it appears normal to the sight and smell.
Step 2. Smell the milk to see if it smells bad
Smelling the milk to see if it is bad is the first thing to do, and probably the most obvious. Fresh milk is practically odorless, while spoiled milk has an unpleasant odor. If you immediately jump back when you smell it, there is no doubt that it has gone bad.
- If the milk looks good but smells so bad it makes you jump, it's best to avoid drinking it.
- When you have a hard time figuring out if it gives off an unpleasant odor, have someone else sniff it or test it using another method.
Step 3. Check the consistency of the milk to see if there are any lumps
Fresh milk has a slightly denser consistency than water, depending on the percentage of fat, and when you pour it it flows slowly. Cream and whole milk are thicker than skim milk, but when you move or pour them they should appear fluid.
- If you notice that there are lumps in the milk, it means that it has gone bad. The lumps may have settled on the bottom, so swirl the package before pouring the milk.
- Examine the inside of the milk package. If there is any solid residue, it means it is spoiled and you need to throw it away.
Step 4. Examine the color of the milk to see if it is yellowed or stained
Pour it into a clear glass cup and observe it in the light. If the milk is still good, it will be a pure white color. Conversely, spoiled milk is usually yellowish or dirty.
If you have trouble assessing the color of the milk, place a blank sheet behind or next to the glass for comparison. If it is yellowish, it is most likely spoiled
Step 5. Determine if milk is left out of the refrigerator
The milk must be kept cold; if it remains at room temperature for an extended period of time, it may spoil, regardless of the expiration date. If you know that the milk has been left out of the refrigerator for more than an hour, it is likely that it has spoiled.
In case you don't live alone, ask the other family members if the milk is left out of the refrigerator
Method 2 of 4: Heat the Milk in the Microwave to Determine if It's Bad
Step 1. Pour the milk into a glass suitable for microwave use
When it's not enough to examine the milk to see if it's gone bad, you can give it another test. Pour some into a clear glass cup until it reaches a height of 3 cm.
Test only a small amount of milk, so if you know it's still good, you can use the rest
Step 2. Heat the milk in the microwave for 30-60 seconds
Put the glass in the microwave and heat the milk for 30-60 seconds, depending on the power used (if you use the maximum power, heat it for 30 seconds).
If in doubt, it is best to start heating the milk for 30 seconds. If it's still not hot enough at that point, you can warm it up for another 30 seconds
Step 3. Throw away the milk if it has an abnormal consistency
When the milk is hot, swirl it in the glass to see if it stays liquid or tends to thicken. If it lumps or becomes thicker after heating it, it means it is rotten.
- When the milk turns sour, the proteins bind due to the high acidity and lumps form. This is why milk curds.
- A thin film may form on the surface of the milk when you heat it. Don't worry - it doesn't necessarily mean it's spoiled. Remove the patina, swirl the glass and see if it thickens or lumps. If it stays liquid, it means it's still good.
Method 3 of 4: Analyzing Milk Acidity
Step 1. Pour a teaspoon (10g) of baking soda into a saucer
There is no need to use a large amount of baking soda to perform this test - it takes less than a teaspoon to see if it reacts to milk. Simply make sure that the baking soda is not too old and therefore no longer active, otherwise the test result would be unreliable.
If you find that the baking soda in the pantry has expired, use another method to tell if the milk is bad
Step 2. Pour a few drops of milk over the baking soda
The milk must not have been heated previously, so take it straight out of the package. A couple of drops are enough to see if a reaction is created when the two elements come into contact.
Step 3. If the baking soda reacts and froths, the milk has turned sour
When the milk is fresh, the bicarbonate does not react in any way, but if it is spoiled, the high acidity will cause the bicarbonate to react and small bubbles of carbon dioxide will form. The quantity of foam corresponds to the degree of acidity of the milk; the greater the number of bubbles, the more acidic the milk is. Throw away the milk even if the bubbles are almost imperceptible.
If foam forms, throw the milk away without hesitation, although it still looks good to the eye and smell
Method 4 of 4: Extend the Shelf Life of the Milk
Step 1. Store it below 4 ° C
Fresh milk should always be kept in the refrigerator. If it stays at room temperature for a long time, it will go bad more quickly.
Put the milk carton at the bottom of the refrigerator to make sure it stays cold. If you keep it in the refrigerator door, the temperature will vary each time you open it. Such temperature changes can shorten the shelf life of the milk
Step 2. Protect the milk from light
If you store it in a glass cup or clear plastic container, it will not last as long as milk stored in its original packaging or in a colored plastic container. Milk deteriorates when exposed to light and even the few seconds that elapse between opening and closing the refrigerator door can shorten its shelf life.
If the milk comes in a clear bottle, store it near the back wall of the refrigerator, hidden behind other foods to keep it out of the light
Step 3. Seal the milk container
If fresh milk is left exposed to air it can go bad quickly, even if you store it in the refrigerator, so make sure the cap is screwed onto the container properly. It is usually best to keep milk in its original packaging which is designed for just that purpose.
- If the original container is damaged, pour the milk into a jug with an airtight lid (or a food container). Do not leave it exposed to air, for example in a glass, even if you keep it in the refrigerator. Write the expiration date on the container.
- If the lid of the container does not guarantee an airtight seal, cover it with cling film to prevent the milk from being exposed to the air.
Step 4. Freeze the milk if you want it to last a long time
You can keep it in the freezer for up to 3 months. If you live alone or have a habit of using it only infrequently, it is a useful option to save money and avoid waste.
- When it's time to use the milk, transfer the container to the refrigerator or hold it under cold running water.
- The texture and color of the milk changes slightly when you freeze it. Once thawed, pouring it you may notice that it has the texture and color of sour milk, although technically it is still good. The taste may also be less desirable.
- Almost all varieties of milk can be frozen, even vegetable milk and buttermilk.
Advice
- Depending on the brand, buttermilk may contain small particles of butter that should not be confused with lumps of spoiled milk.
- Sour milk can be cooked or used for cooking. Several recipes require it as an ingredient.
- In the long run, the milk of vegetable origin, for example that of almonds, could separate. It is a natural phenomenon and generally it is enough to shake the container to restore its true consistency. If not, it's best to throw it away.
