🔄 Ripening

Ripening is the maturation of cheese after it is made, during which it develops its flavour. It is described as the most important factor affecting cheese flavour. Fresh cheeses such as cottage and cream cheese need no ripening.

Ripening time depends on the type: semi-hard cheeses take 2–3 months, hard cheeses such as cheddar 3–12 months, and extra-hard cheeses such as Parmesan and Romano 1–2 years. In one study of a Camembert-type cheese, ripening lasted 40 days: the first 24 hours at 14 °C and 70 % humidity, then 14 days at 14 °C and 90 % humidity, and from day 16 the cheese was wrapped and kept at 4 °C.

Inside the cheese, enzymes are at work. Proteinases and peptidases cleave the casein chains and produce free amino acids; in hard and semi-hard cheeses, casein breakdown is the most important flavour pathway. Lipase breaks the ester bonds between triglycerides and fatty acids, and the released medium- and short-chain fatty acids form characteristic flavours and indicate maturity. Lipolysis has a positive effect in Parmesan, Emmental, blue cheeses and Romano.

Ripening is not just leaving cheese on a shelf: it is enzymes, moulds and bacteria at work after the cheese is made. Fresh cheeses such as cottage and cream cheese skip it, semi-hard cheeses take 2–3 months, hard ones 3–12 months and extra-hard ones such as Parmesan 1–2 years. In Camembert a white mould does the work, in blue cheeses Penicillium roqueforti, in Emmental propionic acid bacteria make the holes, and in smear cheeses brine and Brevibacterium linens form the crust. So an aged cheese differs from a young one in what is working inside.

On a cheese label, look for the type and the ripening time: “fresh”, “semi-hard”, “hard” or “extra-hard”, plus words about a bloomy rind or blue veins. Fresh cheeses sit in the chiller cabinet in sealed tubs, while ripened ones are cut from the block at the cheese counter of supermarkets, delis, specialist cheese shops and farmers' markets. The rind of Camembert or Brie is edible, but the pack and the producer's description tell you how the cheese was ripened.

Moulds and bacteria also take part. Penicillium camemberti is involved in ripening Camembert and Brie; in the study, mould grew rapidly during the first 16 days and produced a large amount of proteases. Blue cheeses such as Roquefort and Stilton ripen through growth on the surface and inside; the cheese is pierced for aeration to promote Penicillium roqueforti, which forms the blue veins. The holes in Emmental and Swiss cheese are formed by carbon dioxide from propionic acid bacteria, which convert lactate into propionate, acetate and carbon dioxide. Brevibacterium linens is involved in ripening smear cheeses such as Limburger, which is brined several times to form a light brown crust. Salt helps control acidity, texture, flavour, holes and moisture, and inhibits contaminating microbes.