How to know if milk is spoiled (5 common ways)

In this brief guide, we are going to answer the question “how to know if milk is spoiled”, discuss the different methods of identifying spoiled milk and the potential health effects of drinking spoiled milk.

How to know if milk is spoiled?

We know if milk is spoiled by checking the expiry date on the package. If it has passed, then the milk would be not suitable to consume. Spoiled milk gives off a strong sour odour and also exhibits yellowish colour. The texture of milk also gets a little thick and lumpy.

Milk is an essential dairy product that we consume in our daily lives. It has a lot of nutrients like carbohydrates, fats, vitamins, etc. Therefore, milk is considered to be a complete food. But we should also know if milk is spoiled or not; otherwise, it can produce several harmful effects on our health. 

We can identify spoiled milk by observing any signs which are discussed below:

  • Expiry date:

The best way to know that the milk is spoiled or not is by checking the expiry date of the milk on the package. Therefore, it is always advised to consume milk before the expiry date. In addition, packaged milk should be stored in a dry and cool place. If milk is improperly stored, then it spoils a lot quicker. 

  • Texture: 

Fresh milk should be thin and have a smooth texture. If you see any lumps in the milk or the milk is exhibiting any yellowish colour, it means that the milk is spoiled and has become unhealthy to consume. The best way to check the texture is by pouring milk into a glass and seeing if there are any lumps in it or if it is starting to curdle or not. If you see any such sign, it is better to treat it, make any other product, or consume it.

  • Colour:

The colour of fresh milk is pure white. So if you see any pale yellow shade, it is a vital sign that the milk is spoiled. The best way to figure this out is by pouring milk in transparent glass and watching it in the sunlight. If it is exhibiting any yellowish shade, then it is because it has gone wrong.

  • Smell:

Fresh milk has a very light smell or may have no scent at all. However, if your milk is spoiled, then it starts to give off some foul smell. This bad smell indicates that the milk should be thrown away and not to be consumed.

  • Taste:

Fresh milk has a very light milky taste. If the milk is starting to spoil, then the taste of it starts to get sour. This is also one of the best ways to figure out whether the milk has spoiled or not.

Other FAQs about Milk which you may be interested in.

How long can fresh milk be left out?

How long can I keep formula milk in the fridge?

Methods to check the quality of milk:

  • Check if milk was out in the open for too long:

Suppose you have followed all of the instructions mentioned above and wonder why your milk has spoiled three days before the expiry date. It is because your milk would have stayed out in the open for too long. Make sure to keep your milk in the refrigerator in a cool and dry place. If milk is kept out in the open in warm temperatures, there are strong chances to get spoiled long before the expiry date.

  • Microwaving:

The easy method is to microwave a sample of your milk. First, pour a little bit of milk into your glass and microwave it. After microwaving, take it out and observe if there are any lumps or any yellowish shade. If the milk is exhibiting any of such characteristics, then it means that the milk is spoiled.

  • Checking with baking soda:

This is also an easy method to confirm whether your milk has gone bad or not. In this method, you will take one tablespoon of baking soda on a plate or saucer. Add your milk to it. If you experience that they have not reacted and not made any bubbles, then it is because your milk is fresh.

If you add milk to the baking soda and give off bubbles, it means that the milk is spoiled. Spoiled milk has a higher content of acids; that’s why they react with baking soda and produce bubbles.

Health effects:

Spoiled milk gets sour, which may become very difficult to consume. If you drink a little bit of spoiled milk, then it’s possible you may not feel sick.

Consuming spoiled milk can sometimes produce foodborne illnesses. You may feel nausea, vomiting, stomach cramps, and diarrhoea. You won’t have to worry because it will go away with time, considering taking proper care and proper diet for yourself.


So we discussed five signs of spoiled milk. Those were a sour taste, lumpy texture, yellowish colour, foul smell, and expired milk. We also discussed three easy methods through which we can confirm that the milk is spoiled or not.

After that, we discussed the harmful effects on our health after consuming spoiled milk.

I hope you found this blog helpful if you have any queries feel free to comment.