It's the night before my last major exam this year. I already have plans for after the exam... Make cheese, but this time enlisting the help of my girlfriend for a laugh. But every good cheese needs a population of bacteria to taste divine, so here is an easy way to whip up both commonly used bacterial cultures for your cheese!

Step 1: What You Need

These few ingredients are simple and found in most supermarkets: A tub of natural(unflavoured) yoghurt A tub of Cultured buttermilk- the keyword being cultured Ice cube tray- I used a Lego one since I had measured it out and each ice cube would contain half an ounce of frozen culture. When preparing your culture you should measure out the volume of your ice cube tray so that you know how much each cube will contain

Step 2: A Waiting Game

Now for the long bit. The bacteria in the buttermilk are mesophilic, meaning they thrive in room temperature conditions. So take the lid off the buttermilk, place a tissue over the lid, to keep dust out, and set it aside overnight. This lets the bacteria reproduce at optimal conditions so that the buttermilk will have the maximum population, key to making cheese.

The yoghurt is different. It's bacteria are thermophillic, they thrive in slightly warmer conditions than that of the mesophilic bacteria. I'm not sure if you leave it out overnight, I bought naturally set yoghurt. This means that the bacteria have reproduced and converted the lactose sugar into lactic acid, decreasing the pH of the milk and thickening it. Just like why we are leaving the buttermilk out.

Step 3: Freeze It

If you bought naturally set yoghurt then you can freeze it straight away. Mix it with a spoon so that it becomes slightly more workable and pour it into an ice cube tray. Place it in the freezer for a few hours until frozen. Because of the thickness and bacterial population of the yoghurt I started to freeze it whilst waiting for the buttermilk to thicken overnight

Step 4: Bag It and Tag It

Now that the culture is frozen, pop out the cubes into a freezer bags, marked with the date of freeze and the temperature preference of the bacteria. This is important so they can be used in the right cheese, at the correct optimal temperature and so that you know when to renew the culture. Once frozen, the culture should be used within one month, or renew after that month by thawing in some milk, allowing the bacteria to multiply again then freeze the new thick soured milk.