Concealed within the cardoon\u2019s flower are enzymes, cyprosin and cardosin, that are capable of curdling milk. This makes artichoke thistle a vegetarian alternative to animal rennet (which is extracted from a baby ruminant\u2019s stomach). Cheesemakers who use cardoon report that it differs from animal rennet in that it\u2019s a gentler coagulant, creating a curd that\u2019s more easily broken apart. It imparts vegetal flavors and\u2014sometimes\u2014a slight bitterness to the finished cheese.<\/p>\n
Most thistle-rennet cheeses<\/a> hail from Spain, Portugal, or Italy. This geographical spread could be ascribed to the cardoon\u2019s natural proliferation, but some have suggested\u2014at least on the Iberian Peninsula\u2014that the dispersion matches the flight of persecuted medieval Jews, for whom cheeses made with animal rennet contravened dietary laws.<\/p>\n Regardless of how cardoons got their start in cheesemaking, the method stuck. In Portugal, thistle rennet use can be traced back to the Romans; it\u2019s described as \u201cthe curdling herb\u201d in the first-century manuscript De Re Rustica<\/em>. A 16th century treatise on Spanish agriculture lauds the cardoon in cheesemaking: \u201cFor perfection of taste, the best is curdled with the thistle flower, which is sweet and not bitter like that made with animal coagulants.\u201d<\/p>\n That \u201cperfection of taste\u201d is still widely celebrated by the Spanish and Portuguese today\u2014rounds of Torta del Casar or Serra da Estrela often act as party centerpieces, much like fondue in Switzerland. Makers of thistle-rennet wheels are concentrated around Extremadura in western Spain and across the border into Portugal. These cheeses, like those made with animal rennet, are not all alike. Some, such as Torta del Casar, are earthy and intense on the palate, eaten with the top sliced off and the gooey interior scooped out, while others, including Portugal\u2019s Serpa, are firmer and sharp.<\/p>\n Milk, however, matters. The curdling herb traditionally favors sheep\u2019s and goat\u2019s milk; cow\u2019s milk coagulated with cardoons often yields intensely bitter wheels, a result of its different peptide sequences. There are a few exceptions, however, such as the elusive Armada, a Spanish cow\u2019s milk cheese made near L\u00e9on.<\/p>\n Curds in these areas are frequently more than just foodstuff. The semi-hard \u00c9vora\u2014a raw sheep\u2019s milk cheese traditionally produced using the milk of the indigenous Merino sheep breed\u2014is a classic example. Fresh milk is filtered through a cloth and warmed over low heat before salt and thistle rennet is added. Collected from the countryside, the petals and stamens of the flower are mashed with salt and water and left to ferment for several hours before being added to the cheese. Aged either 30 or 90 days, \u00c9vora is piquant and salty in flavor. More than just a tasty morsel, these small, yellow cylinders were historically used as payment for the poorest workers in this once-depressed area; the robust earthenware jars in which they were stored are often used as a decorative element in local homes today, a reminder of that hard history.<\/p>\n \u00c9vora PDO<\/p><\/div>\n Though the cheese earned PDO status in 1996, \u00c9vora producers are not immune to the allure of commercial conveniences. According to Victor Lamberto, a self-described \u201cgastronaut\u201d and Slow Food leader of the Alentejo region in southern Portugal, the government has been actively persuading producers to switch from using the traditional stamen-and-petal mixture to a standardized, more reliable industrial version of cardoon rennet. This might explain why some cardoon cheeses, traditionally semi-hard in texture, are appearing in supermarkets when younger (and oozier). In Lamberto\u2019s opinion, many Portuguese makers are switching from quality to quantity; cheaper Spanish milk is changing the terroir while new hygiene laws are moving producers off farms and onto industrial estates. Together these elements are eroding the tradition of \u00c9vora, and many other thistle-rennet Portuguese wheels face the same fate. Though Percival is typically an evangelist for animal rennet, thistle rennet supersedes that. \u201cUsing the cardoon flower is a more interesting choice than a laboratory-derived rennet,\u201d she says. \u201cIt\u2019s a traditional technique, more interesting from a flavor perspective.\u201d Holbrook can attest to the rennet\u2019s dimension. \u201cThe flavor was interesting, different,\u201d she says of her first taste of thistle cheese in 1994. She was so intrigued that she took some cardoons home with her to experiment. The result was the now-famous Cardo, a raw Saanen goat\u2019s milk cheese with a pinkish rind and a complex flavor. \u201cCardo is exactly the Portuguese recipe,\u201d Holbrook says, \u201cbut the end result is totally different as our milk and climate are different. The rind, for example, would be dry and quite leathery in Portugal, whereas here it\u2019s pink and damp.\u201d<\/p>\nBitter Sweet<\/h2>\n
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<\/a>Eau de Thistle<\/h2>\n
\n\u00c9tablissements Coquard, a French cheesemaking supply company, began selling an industrial cardoon extract five years ago. According to Coquard director, Francis Perret, the product is still little known in the marketplace, but \u201cinteresting\u201d as it can shorten the ripening time for soft cheeses. \u201cIn general, this coagulant is not recommended for hard or cooked cheeses,\u201d he adds.<\/p>\n
\nTake heart, however: not all traditional cardoon cheeses are disappearing. Cacio Fiore, a square-shaped ancestor of Pecorino Romano, was almost lost post-WWII when the macro-minded push for economic recovery left no place for farmhouse cheese. Today, following support from the local government and Slow Food, Cacio Fiore is being revived, and its processes enshrined in a Slow Food presidium.<\/p>\nCardoon in Cold Climes<\/h2>\n
\nWhile researching at Harvard\u2019s Dutton Lab in 2014, Percival sourced cardoon stamen from pioneering English cheesemaker Mary Holbrook, who produces a Portuguese-inspired thistle rennet cheese on her Somerset farm. \u201cThey were full of microbes,\u201d Percival says of the stamens. \u201cAs with animal rennet, there\u2019s something more complex involved than just the single enzyme that does the work.\u201d<\/p>\n
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