Oysters are probably the only creature on this earth that can be eaten raw and alive, in natura, in the most varied of settings – in the wild on some isolated coastline, in the warmth of our home or in some fancy or makeshift restaurant. Perhaps this is one of the very palpable reasons for both the delight and disgust they conjure up in their friend and foe respectively or for the simultaneous feelings of fear and excitement that the oyster can arouse, especially in beginners. An animal that has managed to outlive the dinosaurs and their contemporaries has not only adapted itself remarkably well but also its longevity merits our respect in that it has acquired its own idiosyncratic form of existence over these thousands of millennia. And this primeval quality is coupled with the specific marine terroir (sometimes even in these contexts called meroir), which the oyster indelibly carries inside its shells. Nonetheless, there are a plethora of ways to prepare oysters: they can be canned, pickled, dried, smoked, baked, stewed, steamed, fried, grilled, roasted, boiled, barbecued, as a starter or main or side dish, as stuffing or sauce or even taken as a shot. Oysters have been quite aptly compared to mushrooms, in that both seem so innocuous but can be oh so deadly, although one obvious difference is that any slightly off-putting smell other than that of fresh, sea air, betrays it as a bad’un. On the plus side, oysters are today one of the most rigorously controlled foods and strict hygiene standards have to be followed.

Let it be said from the beginning, oysters have never been considered a meal in themselves, although some addicts will beg to differ. On the contrary, they are appetisers and be as it may that they are highly nutritious, they “nourisheth little” (as our redoubtable Henry Buttes wrote [see my first post about the months with an ‘R’]),  i.e. they will never fill you up. And that is why there are untold stories of people eating huge amounts of them only still to be able to devour the main course of the meal.

As we venture then to start eating our platter of oysters, we need to observe some precautions (as with many pleasurable experiences). One safe step to take when eating raw oysters is to turn it over in its shell and inhale its odour. There should be an easily identifiable smell of fresh sea air. If in doubt, don’t eat it; any self-respecting restaurant will always bring in another, even were the waiter to disagree. Certainly, some fines de claires and, for instance Swedish natives, will respectively have a slightly sweeter or earthy smell, as they originate from more brackish water. However, the colour of the raw, moist flesh can range from creamy, pale yellow, grey, beige, green or even reddish, and the rim of the mantle may be coloured in much darker hues, but usually black; for example, some oysters from Arcachon have been known to develop a brownier shade, whilst in certain areas of Brittany oysters can assume a reddish-orange colour, probably due to the reaction between a metal, like iron, and an acid, that can also be present in the some clays along the shore. The liquid inside the shell should be clear, or not excessively cloudy, but often when the flesh is disturbed, some discolouring may occur and it is then that the odour is decisive. Some connoisseurs advise that the “first water” in the shell should be poured out as it may contain impurities from the final stages of cultivation or be only sea water, and if this happens then the living oyster will automatically secrete its own liquid during a couple of minutes, which is milder and richer than the original. Some restaurants will severe the oyster’s adductor muscle holding it in place to the left and lower shell, but some don’t and scraping it off the shell adds to the suspension of elation before the oyster is scooped into the mouth – in the phrase of the Parisian poet and chroniqueur, the Symbolist Léon-Paul Fargue, it feels like “kissing the sea on her lips” (on a l’impression d’embrasser la mer sur la bouche).

Now comes the exciting part, when the solemn enactment of chewing can be relished. Where on earth the idea of just swallowing the oyster whole came from is beyond imagination; no doubt, from someone who didn’t dare to try or even want to experience the real taste of an oyster. Poor old William Thackeray, that novelist of the burlesque, on the first of his lecture tours to America in the 1852 was offered some enormous oysters (some say Saddlerocks) at a dinner in the luxurious Tremont House Hotel in Boston. In horror, he inquired of his host what he should do with this “animal”, and was told “we Americans swallow them whole”. That he proceeded to do, though the experience left him quite shocked after which he blurted out, “I feel as if I’d swallowed a live baby”. Again the Americans are fond of slurping their oysters too in great numbers, which conjures up a more orally aggressive approach to the ritual, as exemplified in the stories about a notorious and brash New York character in the late 19th century, called Diamond Jim Brady, who used to down 300 oysters or so at any one meal. An almost even greater piece of sacrilege is advising the eater to chew just two or three times before swallowing. On the contrary, it is the leisurely act of chewing, the caresses of the tongue on the soft, chilled, juicy flesh, sucking in some air to allow the flavours to moisten the palate and pausing for stillness to reflect that is the joy and essence of any savouring pleasure: “my tongue was a filling estuary, my palate hung with starlight” was Seamus Heaney’s description of eating his oysters “alive and violated” down in Clarinbridge, near Galway in his poem Oysters (1979). On the other hand, Woody Allen would feel far more a greater affinity with the sentiments of Thackeray, as he with characteristic contempt coiled at the idea of eating oysters: “I want my food dead – not sick, not wounded – dead.” Even though the physiology and biochemistry of taste need to be brought into any explanation or understanding of the various taste sensations that are stimulated by the juicy flavours of the flesh, for the enjoyment and appreciation of our food, we are rather guided by our subjective impressions, past experiences and proficiencies which we translate into judgements and comments on what we are eating.

The tongue consists of around 1 million taste cells, which are divided into about 10,000 taste buds on its surface and other parts of the mouth. Taste sensitivity can vary among humans, which may also be affected by the ability of the brain to process complex taste sensations. But generally, there are now considered to be five types of recognisable tastes – bitterness, saltiness, sourness, sweetness and umami (although some would like to include sub-modalities for fats and spiciness as well):

Bitterness has a much lower threshold, as it helps to pick out traces of alkaloids like toxins that can be harmful, but also substances often contained in dark green vegetables;

Saltiness and sweetness, our most easily identifiable and common tastes, have high thresholds: the former can also be receptive to certain metals and minerals too, whilst the latter is associated with carbohydrates and high-energy nutrients such as fruit and cereal foods;

Sourness detects the acidity in food that is also prevalent in fermented products;

Umami is a Japanese word meaning, confusingly enough, “savouriness” but is due mainly to glutamate or glutamic acid, one of the naturally occurring amino acids (building blocks of protein), and three kinds of ribonucleotides, inosinate, adenylate and guanylate, that are present in cured meat, aged cheese and high-protein food generally, and the taste is often translated as “brothy” (in the sense of stock from bones). It is also found in abundance in algae, fish, soy and oyster sauce, green tea and ripe tomatoes.

One of the most splendid descriptions and attempts to “nail” the essence of the rich, multifarious array of tastes in oysters has been given by Rowan Jacobsen in his A Geography of Oysters (2007), who runs an admirable crusade on identifying and preserving the indigenous terroir of American food, though his first love is the enjoyment of oysters. He compares the ritual of eating oysters to some Zen spirit, more like the Japanese tea ceremony, as it is as much art as consumption, though not satiation.

Like wine, the flavour of oysters comes in stages.

The salinity of the sea provokes the first, immediate sensation, filling the nose and preparing the mouth for its morsel. Here there are suggestions often of a sea-breeze, floral traces of, say, samphire, or an aroma of seaweed, rock pools and the shoreline. Too much salt can be neutralised by the addition of acid, hence the lemon or mignonette sauce.

Then comes literally the body of the oyster, drowning the mouth with flavour. All this disintegrates into nothing if the oyster is swallowed. No, chewing and masticating the soft flesh brings out the body of the oyster, however small or slight, and releases the multitude of flavours that we can discern and associate to other food experiences. So we don’t start swooning about amino acids or alkaloids, rather we search for comparable flavours that we have experienced with meats, fruits or vegetables. Just in this moment of culinary magic, the plethora of tastes and flavours that can flood into the mouth can range from oils and metals to greens and fruit, from milk and mushroom to smoke and stone. Generally, the rock oysters tend to have softer, smoother textures, whilst the meat of natives provides more resistance, with an almost al dente quality. However, the range of tastes can be quite extraordinary: the obvious salinity can be expressed as salty, briny or sometimes tangy (the French often mention an iodé taste which is usually translated as briny); tastes of metals such iron, brass, copper or zinc; traces of vegetables as in spinach, broccoli, celery, asparagus, artichoke and cucumber, or of fungi like mushrooms, morels and algae, or of herbs like parsley and black or green tea; the fruitiness can be associated to melon, peach, apricot, even avocado or citruses or translated into various kinds of nuts like almonds, hazelnuts and walnuts; often one can find descriptions of stone, slate, chalk or flint, probably connected to the calcium content of the shell; another taste that can be experienced is that of cream or butter, and even slicks of fish oil. In other more general terms, other adjectives that have been used in characterising oysters are smoky, dry, tannic, rich, smooth, round, crispy or thin, similar to those encountered in wine tasting.

Finally comes the finish – the aftertaste that lingers on in the mouth, sometimes for hours, and more likely to be sensed as one of minerals,metals or oils, but also on occasions slight fruity or floral tones. Before listening in on a few connoisseurs of oysters, it is worth to bear in mind the essence of the French concept of terroir, as oysters change their taste from season to season and of course since they filter the water around them are influenced by the nutrients in their vicinity. For instance, after their summer ordeal of spawning when they can lose 75% of their weight, and as the water cools down and becomes less salty, they build up their body mass again and metabolise food into glycogen, a carbohydrate, and lipids to keep them through the cold months. Then the oyster’s flesh is full, firm, plump and has an almost ivory texture. In itself, glycogen is tasteless, but when broken down glucose is produced, whilst lipids contain fats and fatty acids, essential for energy storage. This can explain the taste sensations of butter, oil, cream and juicy fruits, for example, when the oyster is chewed carefully.

A few quotations from Jacobsen’s book will suffice. He selects his favourite Pacific oysters, many of which “have a hint of melon gone murky, as if you stored cantaloupe slices and sardines in the same refrigerator container…and some a delicious finish that people call watermelon..” (p.49): from the west coast of Vancouver Island, “art-deco-patterned, lavender-flecked Nootkas, in fact, taste strong, with hints of muskmelon and a flavor of cold, slightly sweet raw milk – animal, but good”. Penn Coves from Washington state “are a prime example of the “clean finish” style of Pacific oyster – light, salty, fresh, like a cucumber sandwich wrapped in parsley”. From the other side of the country in the Chesapeake Bay, Rappahannocks are “extremely mild oysters, exhibiting a simple sweet-butter flavor…and…with the most evanescent of wines can be delicacy itself – a lesson in the pleasure of minimalism” (p13-14). North American oysters have long since been marketed with alluring brand names, to distinguish them from their out-of-town neighbours.

The Shellfish Association of Great Britain has produced a well-defined and useful guide to oysters, dividing the various tastes into flavour, saltiness, sweetness and umami and isolating the nose, body, finish and texture of the oysters. Flavour is scored in terms of its lightness or fullness, saltiness in terms of either being neutral or briny, whilst sweetness and umami are assessed as being mild or strong; first of all, the nose often inhales the sea breeze and shore-line aromas of salt, seaweed and floral notes, whilst the body captures the flavours, often of nuts, greens, fruits and butter, from which sweetness can be guessed. In the finish are sensed the metallic, sugary and earthy aftertastes, which range from short and sharp to slow and lingering. The meat’s texture is often described as being firm, plump, smooth, creamy or meaty. However, if one compares the cupped and flat oyster from the same water, then the differences can be quite striking; for instance, from Maldon in Essex, the two are described in the guide as follows:

  Maldon Pacific cupped Maldon European flat
nose light aroma of the sea brackish
body rich flavour of walnut and avocado very subtle taste of driftwood
finish tart tang of steel followed by a sweet aftertaste slow-burning strong metallic finish which builds up to a crescendo
texture smooth and meaty chewy and firm

Mary Fisher’s eulogy to oysters, Consider the Oyster (1941) rarely misses a chance to point out all the goodness they contain, and cites various historical sources emphasising their benefits for body and mind in equal portions. She writes of the 15th century French king, the great Louis XI, who made it obligatory for his advisers to feast on oysters each day so as to aid their intellectual faculties. Of course, whatever the real basis for all these claims from Cicero to Casanova, from doctors to writers and cooks and from ordinary people to lay scientists, there is hardly any reason not to doubt the accumulated popular belief, be it wisdom or superstition that they were brain food, an aphrodisiac or considered a vital appetizer or starter for any serious banquet, worthy its name. Even today, as she concluded an oyster diet for any man “is still good as long as the oysters are fresh and clean, whether it goes to nourish his brain, his belly, or his most private parts” (p29). Nowadays there is more or less scientific proof of the oyster’s nutritional values.

Again its nutritional value does change during the year and even across the different species so that the figures presented here are average estimates: although like most organisms it consists mostly of water, around 85%, they are also one of the most nutritionally well balanced of foods, containing about 9-10% protein, 3-4% carbohydrates and 1-2% lipids, especially its healthy component, polyunsaturated fatty acids. Oysters contain twice as much of the healthier unsaturated fats, of which polyunsaturated fat forms the greater part, than saturated fat, but the overall fat content is still five times lower than for crab or chicken breast. The majority of the polyunsaturated fats comes from the omega-3 fatty acids which the body cannot synthesise itself so that it needs them through its diet. 100g of oysters are considered to be a rich source of them, providing more than two days of the recommended daily allowance (RDA).

As regards trace minerals, it is well known that oysters per 100g provide an overload of copper and zinc, sometimes well over 5 times the RDA: also they are, like most shellfish, a generous source of iron, iodine, manganese, phosphorus, selenium, sodium, calcium, magnesium and potassium in that order. Because of its high sodium content, the oyster is not recommended for those on a low-salt diet. In keeping with its low-fat concentrations, the oyster provides fewer calories, about 70-80 kcal (300-330 kJ) per 100g and therefore is a source of low-energy food and can be reliably included in any low-calorie diet; (a recommended daily calorie intake for adults is between 2000 and 2500 kcal).

But it must be stressed that there are some wide variations between species and this is even more noticeable, regarding the concentrations of different vitamins. Oysters are an excellent source of fat-soluble vitamins like A, D and E – 100g supplying about 10% of an adult’s RDA; and even of water-soluble vitamins such as B1 (thiamin), B2 (riboflavin), B3 (niacin) and B6 (pyridoxine) 100g provide a sixth of RDA, but only traces of vitamin C (ascorbic acid), although French sources regard the oyster as one of the largest providers of this vitamin in the animal kingdom. However, when it comes to the important vitamin B12 (cobalamin), 100g of oyster supplies up to more than 9 times the RDA.

There has been controversy about whether oysters can be recommended as a low-cholesterol diet, as many would like to, although all shellfish do contain cholesterol, especially lobsters, crabs and shrimps. The USDA claims that oysters per 100g provide as much as a sixth of the recommended daily value, which per se is a high amount. But on the other hand, it seems as if the presence of omega-3 fatty acids, that indirectly counteract the body’s own cholesterol levels, helps to reduce the effects of the relatively high cholesterol in oysters, and also aided by the presence of large amounts of non-cholesterol sterols which inhibit its absorption. In any case, cholesterol from food has only a marginal effect on the level of cholesterol in the blood; in this sense, the amount of the harmful saturated fat in food is of greater significance.