Acidity in cheese provides a pleasant flavour, but the cheesemaker should control acid development during the cheesemaking process. Different cheeses require different acid levels, e.g. some require quite a lot of acid, such as cream cheese, quark, strong crumbly Feta, sharp and bity Cheddar and even yoghurt and sour cream. Some cheeses only require a lower level of acidity including Gruyere, Comte, Parmesan and most wash rinds, then cheeses that require a mid-range of acidity include Camembert and Brie, Cheddar, Edam, Mozzarella etc

Starter cultures (starter/s) are added to the milk at the beginning of the cheesemaking process. It may be a single strain starter culture or multiple strains of starters. The starter then ‘starts’ to ferment the milk sugar or lactose to make lactic acid. The acid level of the cheese is very important for food safety and preservation, as well as contributing to the flavour and maturation of the cheese. The starter/s continue to grow in number in the milk and later in the curds and whey, and even grow when the curd is added to the hoop and over the next several days after the cheese is removed from the hoop.

When you eat dinner, you may use a knife and fork to break down the fats, carbohydrates and proteins into smaller components that fit into your mouth. The starter/s produces enzymes so they can ‘fit’ the fats, carbohydrates and protein components through their cell walls. This enables the starters/s to grow and multiply in numbers and to continue to break down the fats, proteins and sugars in the milk into a food source they can ingest and allow them to grow and multiply. Eventually, the starter/s will die out. However, the enzymes they produce will remain in the cheese for the life of the cheese, still breaking down fats, carbohydrates and proteins into smaller components. Your cheese is now maturing. These enzymes are not alive as such, they are not biological, not chemical, but produce biochemical reactions.

This means that the amount of acid in your cheese correlates to the amount of starter culture in your cheese, then this also correlates to the number of enzymes in your cheese. So, it is important to aim for the right level of acidity in your cheese. There are several ways that the cheesemaker can do this:

• Add the correct amount of starter at the beginning of the cheesemaking process;
• Use the correct holding time between adding the starter and adding the rennet and then the time between adding the rennet to cutting. There is not much for the cheesemaker to do apart from aiming for the correct milk temperature;
• Have the milk at the correct temperature so the starter can grow optimally. If the milk is too cold or too warm, the speed at which starters grow and multiply will change; Remember mesophiles and thermophiles or mixtures of both,
• The correct size of the cut. The cut size determines the volume of water + fats + carbohydrates + proteins inside the curd particle. If the curd particle is too small, you may be limiting the food source of the starter/s and if the curd size is too big you may have too much food for the starter/s,
• The speed of stirring and volume/amount of stirring undertaken. Stirring can cause the curd particles to lose moisture at different rates. It also means the cheesemaker can increase or decrease stirring speed to help rectify the previous cutting step if the cut size was not correct;
• Keeping the cheese at the correct temperature straight after hooping and keeping it at the correct temperature as it ages. The activity of the starter culture and the enzymes will increase or decrease with changes in temperature
• Have the correct final moisture in the cheese at hooping. Moisture and temperature can speed up and slow down the rate of maturation.

There are many aspects of the cheesemaking and the cheese maturation process, none of them hard, but the cheesemaker needs to control these aspects. The aim is to make the best cheese possible. Keeping good records of each stage of the cheesemaking process may be a big help.

Whenever you are adjusting or changing the cheesemaking process, to achieve the best cheese, make minimal changes each time and asses those changes before making further changes.