The dangers of reheating milk

It both surprises and saddens me to be writing this blog; it is unbelievable that in 2018 there are still cafes that are reheating milk for their coffee.

Quite simply, it is bad practise to reheat your milk, and this blog will be focusing on two of the reasons why. The first reason is regarding Occupational Health and Safety.

Health and Safety Concerns

“Safe temperatures are 5 degrees or colder, or 60 degrees or hotter. Potentially hazardous food needs to be kept at these temperatures to prevent food-poisoning bacteria, which may be present in the food from multiplying to dangerous levels. These bacteria can grow at temperatures between 5 degrees and 60 degrees, which is known as the temperature danger zone. The fastest rate of growth is at around 37 degrees, the temperature of the human body.”

The above information is taken from Food Standards Australia. If you work with food and/or in the hospitality industry you are probably well aware of the temperature ‘danger zone’.

All dairy foods, including milk, are considered to be potentially hazardous foods. As baristas, we have a responsibility to treat milk with the care it requires, in order to deliver a safe and delicious product to our customers. When steaming milk, it is common practise to heat it to a temperature somewhere between 60 and 70 degrees; a safe and drinkable temperature for coffee consumers.

When the heated milk is left sitting in the temperature danger zone, bacteria and other harmful pathogens multiply quickly. Now, you might think that reheating this same milk again above the 60 degrees will kill off any bacteria that may have grown during this time, but this is simply not true. For pasteurisation to occur, the bacteria-infested milk would need to be kept at a higher temperature for an extended period of time before pasteurisation occurs and it becomes safe to consume. This is not achievable behind a bar in a busy cafe.

Reheating milk is quite simply putting customers health at risk. As food and beverage attendants, it is our duty of care to ensure we are doing everything possible to provide consumers with safe and hygienically prepared products.

The dangers of re-steaming milk

Taste and Texture

Dairy milk is composed of fat, sugar (lactose) and protein.

When we heat a jug of milk, the protein is essentially cooked, which hardens and helps trap the air to create foam. So, as you can imagine, if you proceed to heat the milk a second time, the proteins that initially facilitated the formation of the foam have already become denatured. Think of it like steak, you wouldn’t put a steak back into the pan after it has already been cooked to perfection, would you? The same goes with milk. Constant reheating leads to milk that has a rough, grainy texture and is unpleasant to drink.

The sugars in the milk break down once heated into small simpler sugars which have a sweeter taste, complimenting the coffee and helping to create a balanced drink. The optimal temperature for sweet, silky milk is between 60-65 degrees, but the sweetness deteriorates each time the milk is reheated. The sugars break down further until the milk ends up have a distinctive, burnt oatmeal flavour.

There are a few key practises to ensure sweet, silky milk every time:

  • Always keep your milk refrigerated. Milk that has been left out for an extended period of time will become difficult to foam as the fat content breaks down in higher temperatures.
  • Ensure your milk jug is rinsed thoroughly after each use.
  • Do not reheat milk


We understand that wastage is a concern for most businesses, particularly in the hospitality industry. Wastage as a whole is something we should all be concerned about, but reheating milk is not the answer!

The solution is to use less milk to begin with. Start with a smaller jug of milk and, with a bit of practice, you will learn how much milk you need for the number of coffees you have to make. Start with a 400mL jug for the times during service when the orders are small and sporadic. Once you know which size jug is required for however many number of coffees, you will end up with little to no milk left over at all. The customer has a safe and delicious beverage; the barista can take pride in their beautifully steamed milk that is fresh, sweet, and glossy; the business owner can rest easy knowing that wastage is being kept to a minimum; and the cows and farmers can all walk off in to the sunset knowing their hard work is being put to good use.

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Summah Grant

Barista Trainer