THE LAST WORD

Knobbly cheese Why do Grana Padano, cheddar and feta cheeses, to use three random examples, all break in different ways and have inside surfaces with very different appearances? After all, they are all cheese.

n Don’t forget Brie, which starts out as a delicious cream cheese and ends up as a delicious, creamy cheese. Cheese is mainly protein and fat, with combinations of water, salts and organic products but, as with every food, the recipe and proportions of ingredients make the difference between a feast for a king and indigestion for a beggar. Also, the character of a cheese changes as it matures.

Fats, proteins and water determine cheese texture. The protein molecules start out as chains and, if they pack neatly with little water and fat between them, they make a strong plastic – hitting someone with a block of Grana Padano could kill them. In contrast, bacterial and fungal enzymes break up proteins in soft cheeses like Brie until they cannot form strong structures, and fresh cottage cheeses have not yet had a chance to form such structures at all.

Soft, matured cheeses also contain a great deal of fat, which forms a creamy emulsion with the water and proteins. There are enough such combinations of ingredients and recipes to make thousands of cheese types.Jon RichfieldSomerset West, South Africa

n In the 1970s and 1980s, I was at the UK’s National Institute for Research in Dairying, and I did a lot of research into the science of cheesemaking.

Grana Padano is a hard cheese, cheddar is semi-hard and feta is a soft cheese. Their differences in texture and flavour reflect differences in their production, which change fat and moisture content and determine how much curd structure is left in the final product. Grana Padano starts with partly skimmed cow’s milk, cheddar uses full fat cow’s milk and feta uses full fat sheep or goat’s milk.

In cheddar cheese, it is possible to see the boundaries between curd pieces where they have been cut up in the cheese vat. If you break a piece of mature cheddar gently, it will break along these edges. Moisture in the cheese acts as a plasticiser, making it pliable and elastic.

Fat plays a vital role in softening the cheese, acting as a lubricant

between the grains as well as giving a smooth mouth feel. The making of Grana Padano causes more fusion of its curd pieces, giving a closer texture. The lower moisture and fat contents make it harder than cheddar.

Nearly all cheesemaking starts the same way: a coagulating enzyme is added to the milk,

along with an acidulant. Usually, the acid is generated

by lactic acid bacteria and the enzyme is rennet. This is often extracted from calves’ stomachs, though microbial rennets are also available. At the near-neutral pH of milk (about 6.7), rennet acts on casein, the main group of proteins in milk, causing it to coagulate. As the bacteria multiply, the acidity increases and the curds shrink.

To release the whey, the curds are cut into pieces – about 2 cubic centimetres for cheddar and around 0.5 cm3 for Grana Padano. For feta cheese, the curds are cut up and placed in a mould, where they are allowed to drain.

In cheddar cheesemaking, the curds and whey are warmed to 36 ̊ C for an hour or so. This warming – called scalding – shrinks the curds and squeezes out more whey. The bacteria continue to produce acid and the pH falls to around 5.5. At this point, the curds form a semi-solid mass that is cut into blocks.

Next, these are compacted by stacking, or “cheddaring”. The weight of the blocks on top compresses those underneath, and the curds fuse together. By regularly turning the pile, they are all treated equally.

This continues until sufficient acid has been produced and the blocks have a structure that resembles chicken breast meat. They are milled into much smaller pieces and salt is added.

Finally, the curds are placed into moulds and pressed. The

cheeses then ripen over several months, which is when the flavour develops.

In Grana Padano cheesemaking, the curds and whey are heated to 55 ̊ C. The curds are then placed in a cheesecloth to drain, cut into two pieces and put in separate

moulds, where they stay for about 8 hours. Then, in new moulds, they spend the next three weeks in brine. The maturing process takes another nine months at least.

In feta making, the curds drain for several hours. They are cut up, salted and left for several days while the salt infuses. They are then placed in brine for several weeks at 20 ̊ C, before being transferred to a cold store for final maturation. The result is a smooth-grained, high-moisture, salty cheese.Richard MarshallSenior Lecturer, Food EnterpriseSchool of Society, Enterprise & EnvironmentBath Spa University, UK

This week’s questionMy noiseWhy does your own snoring usually not wake you up? Mine, I am told by those who hear it, can be especially loud.Francis CurranJohannesburg, South Africa

“The proteins make a strong plastic – hitting someone with a block of Grana Padano could kill them”

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“Cheddaring continues until the blocks have a structure that resembles chicken breast meat”