Sunday Food: Cheese Ripening, a.k.a. Aging
(Picture courtesy of chlot‘s run at flickr.com.)
While most of us like some or many cheese varieties, more and more are making their own, and the aging process which we see advertized is one we’re becoming more aware of. Several kinds of additives are applied to the basic curd component to accomplish this taste formative process, and some are only allowed to give a particular name to the cheese in particular areas where the composition of the ground water through local chemical elements is right for the cheese, such as Roquefort.
Cheese ripening or alternatively cheese maturation is a process in cheesemaking. It is responsible for the distinct flavour of cheese, and through the modification of “ripening agents“, determines the features that define many different varieties of cheeses, such as taste, texture, and body.The process is “characterized by a series of complex physical, chemical and microbiological changes” that incorporates the agents of: “bacteriaand enzymes of the milk, lactic culture, rennet, lipases, added moulds or yeasts, and environmental contaminants.” The majority of cheese is ripened, save for fresh cheese.
Ripening is influenced by a variety of factors, ranging from the microflora to the curd, and others. The enzymatic process is the most crucial process for all cheeses, although bacteria plays a role in many varieties. The most important agents in this process include the four following elements: “Rennet, or a substitute for rennet, starter bacteria and associated enzymes, milk enzymes, second starter bacteria and associated enzymes, and non-starter bacteria”. Each of these factors affects the cheese-ripening process differently, and has been the subject of much research. It is important for manufacturers to understand how each of these elements work, so that they are able to maintain the quality of the cheese while producing the cheese at an acceptable investment of time and cost. These agents contribute to the three primary reactions that define cheese ripening: glycolysis, proteolysis, and lipolysis.
By taking the cheese through a series of maturation stages where temperature and relative humidity are carefully controlled, the cheese maker allows the surface mould to grow and the mould ripening of the cheese by fungi to occur. Mould-ripened cheeses ripen faster than hard cheeses, in weeks as opposed to the typical months or even years. This is because the fungi used are more biochemically active than the starter bacteria. Where the ripening occurs is largely dependent on the type of cheese: some cheeses are surface-ripened by moulds, such as Camembert andBrie; and some are ripened internally, such as Stilton. Surface ripening of some cheeses, such as Saint-Nectaire cheese, may also be influenced by yeasts which contribute flavour and coat texture. Others are allowed by the cheesemaker to develop bacterial surface growths which give characteristic colours and appearances. The growth of Brevibacterium linens, for example, creates an orange coat to cheeses.
In contrast to cheddaring, making cheeses like Camembert requires a more gentle treatment of the curd. It is carefully transferred to cheese hoops and the whey is allowed to drain from the curd by gravity, generally overnight. The cheese curds are then removed from the hoops to be brined by immersion in a saturated salt solution. This is because the amount of salt has a large effect on the rate of proteolysis in the cheese, stopping the bacteria from growing. If white-mould spores have not been added to the cheese milk, the cheese maker applies them to the cheese either by spraying the cheese with a suspension of mould spores in water, or by immersing the cheese in a bath containing spores of, e.g., Penicillium candida.
If you have ever wondered about the differences in price among cheeses, this is your explanation. The more that has to be controlled, and performed, to produce the taste you look for, the more you will be reimbursing the cheese maker for doing, and knowing when and how to do it.
(Picture courtesy of Stephane Kllgast at flickr.com.)