Diet contributes to the quality of cows’ milk cheeses.
LE TERROIR—THE LAND. For several years food producers have been talking of nothing else, often out of a desire to protect or expand their markets. If they are to be believed, there is a special relationship between a region and its products; no version of a product made elsewhere is as good as the original, which for this reason is the only one to merit a protected designation of origin.
Agronomic analysis has demonstrated the effects of climate, soil, and exposure in the case of wine, but cheese proved to be a trickier proposition. Working with producers in the northern French Alps and the Massif Central, Jean-Baptiste Coulon and his colleagues at the Institut National de la Recherche Agronomique station at Clermont-Ferrand recently succeeded not only in illuminating the relationship between the land and the quality of its cheeses but also in proposing objective criteria for according them certain legal protections.
Taste and Region
What makes a cheese good? The distinctive characteristics of a cheese may result from the physical features of the region in which it is produced, the types of animals that provide the milk from which it is made, and the people who make it. Producers who talk about terroir emphasize the importance of the cows’ environment and, in particular, of their diet: green grass, hay, and silage (wet grass stored in silos, where it ferments). Does this diet really determine the quality of a cheese?
The first attempts to answer this question, beginning in 1990, involved twenty makers of Gruyère in the Franche-Comté region of France and revealed a significant correlation between the taste of their products and the geographic site of their operations. In other words, one can give a rigorous definition of what “raw milk” means in Franche-Comté. Subsequent analysis of the volatile components of Gruyère made in Switzerland showed that mountain pasture cheeses are distinct from those of the plains: Fragrant molecules belonging to the class of terpenes (limonene, pinene, nerol), for example, are present in much higher quantities in mountain pasture cheeses. What accounts for these variations? Agronomists initially supposed that they resulted from differences in vegetation.
However, in these early studies methods of production and the characteristics of the animals had not been taken into account. Would the observed differences not have been found if the type of cow or the type of fabrication had been modified? In other words, can cheeses typical of mountain pastures be obtained by treating milk from alpine cows with production methods used at lower elevations?
TheTerroirs of Reblochon
Coulon and his colleagues decided to use Reblochon as a case study. Examining samples taken from several producers who used comparable fabrication techniques, they demonstrated that dietary characteristics determined the sensory characteristics of the cheese. They showed that cows grazing in two different parts of the same mountain pasture—one a southerly slope covered mainly by Dactylis glomerata and Festuca rubra and the other a northerly slope sparsely planted with Agrostys vulgaris and Nardus stricta along with unproductive patches of moss and Carex davalliana—gave cheeses that differed notably with regard to taste and color. The cheeses from the south-facing precincts were shinier and less yellow, and their taste was more intense, fruitier, and spicier.
The sensory differences between cheeses may be a direct result of the molecular content of the cows’ forage. Carotene, which is present in vegetables, gives cheese their color. It is also known that ingestion of certain subtoxic plants (such as Ranonculus and Caltha palustris, which seem to be more common in north-facing mountain pastures) changes the cellular permeability of mammary tissue and facilitates passage into the milk of enzymes that alter the quality of cheese made from it. Moreover, it is possible that microorganisms typically found in the soil of grazing lands may have a significant influence on the characteristics of cheeses, but this remains to be demonstrated.
The Effects of Silage
Finally, more recent studies have examined the effects of silage, which in certain regions is a matter of controversy (some say it produces mediocre cheese). The new studies involved more than twenty farms producing raw milk Saint-Nectaire of recognized quality. More than sixty cheeses were analyzed by means of sensory studies, with judges instructed to evaluate taste, odor, and texture.
It was discovered that the principal differences between these cheeses resulted from methods of fabrication and the diet of the cows rather than the manner in which their forage was stored. In particular, cows feeding on hay did not always produce cheeses that differed notably from ones made from the milk of cows that were fed on silage. The stocking of forage under controlled conditions therefore has only a limited effect on characteristics other than color.