Cheesemaking troubleshooting with the guru of cheese

Estimated reading time: 7 minutes

• The article was based on a webinar presented by cheese guru, Hans Keller, on behalf of the Dairy Standard Agency (DSA). Following his initial webinar, the DSA was inundated with requests for assistance with challenges experienced during the cheesemaking process.
• Keller emphasised the necessity of paying close attention to the entire cheesemaking process. There are no timesaving methods or any kind of shortcuts, as it can jeopardise the process.
• When milk is pasteurised, it kills unwanted bacteria and pathogens which may accidentally be present. Care must be taken not to overheat the milk because it may lead to the milk proteins separating from the whey, leading to weak or soft curd, or no curd at all.
• The next step is renneting, a required milk-clotting process, which is done by adding a complex formulation of enzymes to the milk.
• The next vital step is separating the milk into solid curds and liquid whey, which is an important process when making cheese and tofu, but must be avoided when making sauces, custard, and the like.

In August we published an article on cheese fermentation and its effects on different types of cheese. The article was based on a webinar presented by cheese guru, Hans Keller, on behalf of the Dairy Standard Agency (DSA). Following his initial webinar, the DSA was inundated with requests for assistance with challenges experienced during the cheesemaking process. A second webinar was therefore presented and Keller once again shared his expertise with attendees.

Keller was a researcher with the Agricultural Research Council (ARC) for many years and knows everything there is to know about the processes involved in cheese-making. Off the bat, he emphasised the necessity of paying close attention to the entire cheesemaking process. There are no timesaving methods or any kind of shortcuts, as it can jeopardise the process. Keeping tabs on temperature regulation and proper sanitation are also vital.

With this in mind, he discussed the steps involved in cheesemaking and the problems that can arise.

Pasteurisation

When milk is pasteurised, it kills unwanted bacteria and pathogens which may accidentally be present. Care must be taken not to overheat the milk because it may lead to the milk proteins separating from the whey, leading to weak or soft curd, or no curd at all. It may also result in a loss of milk fat, or streaks or layers of mould in the cheese, instead of adding complexity in flavour or a certain appearance such as that of blue cheese.

“If you think you have over-pasteurised, adding some extra multi-fluoride will help up to a certain point,” says Keller. “It is therefore important to pasteurise milk at the correct temperature, not too high or low, and according to the right timing. Milk cannot be de-pasteurised.”

Watch Plaas TV’s insert on chemical usage in the dairy industry here.

Renneting

The next step is renneting, a required milk-clotting process, which is done by adding a complex formulation of enzymes to the milk. Heat can have a major negative impact on the rennet-coagulation properties of milk, and Keller advises cheesemakers to keep the heat of the milk lower rather than higher.

Another crucial point is to always use the prescribed amount of rennet, as too little or too much of it may have a negative effect on the rennet-clotting properties. Once it has been stirred in, immediately stop the milk from moving to avoid streaking.

Curdling and salting

The next vital step is separating the milk into solid curds and liquid whey, which is an important process when making cheese and tofu, but must be avoided when making sauces, custard, and the like.

“If you are hasty and heat the milk too fast, the emulsion will form a skin on the surface. This will prevent the whey from appearing and lead to the acidity being too high,” says Hans. “Try to keep the temperature close to 34°C, which will cause some of the bacteria cultures required during curdling to create lactic acid.”

Once the correct acidity and texture are acquired, the curd is cut, followed by the salting process. Salt is added to prevent further growth of some of the cheesemaking cultures, as well as to make cheeses with a longer shelf life and with different flavours. However, some bacteria grow faster than others which can lead to colour differences if the salt is not equally distributed throughout. This is followed by clotting and if the salt is not properly distributed, the clots will have a white appearance. It is therefore vital to salt thoroughly from the outside inwards.

Keller says there are two ways of salting, namely dry and wet. “We don’t often make use of dry salting in South Africa but if you do, make sure that the salt is of good quality. Some people sterilise their salt in a bid to kill any unwanted bacteria.”

The ripening process

The ripening of cheese is another key step in the cheesemaking process. Cheese is often left to mature for a prolonged period and when it is moved from one room to the next, holes may appear in the cheese due to carbon dioxide bubbles which are released because of the change in temperature. 

Take note of the following:

• Early ripening requires the pre-checking of all equipment, including the moulds, and making sure everything is clean and sanitised.
• Late blowing: This occurs much later in the cheese-ripening process when the spores of certain bacteria germinate and butyric acid fermentation starts. A tell-tale sign is usually a crack or pocket and irregular or large gas bubbles within the cheese when it is cut open. Some of the organisms that cause blowing are safe to consume, while others are not.
• Some bacteria and enzymes produce off-flavours. This is mostly attributed to milk that has not been properly pasteurised and a lack of salt, among other things.
• Adding too little salt may lead to bitter tasting cheese.

For more information on their webinar series, contact The Dairy Standard Agency on 012 665 4250, email jacqueline@dairystandard.co.za or visit www.dairystandard.co.za. – Carin Venter, Stockfarm