by Tom Stobart
[Port – French: porto German: Portowein Italian: vino di Oporto Spanish: vino de Oporto]
PORTULACA. See purslane.
POTASSIUM PERMANGANATE. See disinfectants.
POTATO. The potato crop of the world exceeds even the wheat crop in volume and value. Some 90% of potatoes are grown in Europe, but there is hardly anywhere except the lowland tropics and the polar ice regions (excluding part of Greenland) where they are not grown. They are the world’s best-known vegetable.
The potato (Solanum tuberosum) belongs to the nightshade family and is a native of the Andes, particularly of the region around Lake Titicaca. It was an important staple for the Incas. First mentioned in Pedro de Leon’s Chronica del Peru in 1553, potatoes were brought back to Spain by the conquistadores without arousing much interest there. Since potato, from the native word batata, originally referred to the *Sweet potato (a hot-country plant of quite a different family), early references were confused. Even today, in Spanish, patatas are potatoes and batatas are Sweet potatoes.
Tubers brought to Britain by Sir John Hawkins in 1563 were probably Sweet potatoes, which do not thrive in the British climate. It is possible that the forerunner of today’s potato was brought back from Chile by Thomas Heriot, a botanist, when he returned on one of Sir Francis Drake’s ships in 1586. Either they were given to Sir Walter Raleigh or he brought them back himself What is certain is that he got tubers from somewhere and had them planted on his Irish estate at Youghal, County Cork. They were not a very choice kind, long and knobbly, with deep eyes (these were not bred out until the late 18th century). However, by 1633, when the first illustration appears of a potato in the second edition of Gerald’s Herbal, we find it listed there as the ‘potato of Virginia:’ ‘The Indians do call this plant pappus, meaning roots: by which name also the common potato [did he mean Sweet potato?] are called in most Indian countries. The temperature and virtues be referred unto the common potatoes, being likewise food, as also a meat for pleasure, equal in goodness and wholesomeness unto the same, being either roasted in embers or boiled and eaten with oil, vinegar and pepper, or dressed any other way by the hand of some cunning in cookery.’
But parsons and politicians showed less enthusiasm. ‘Baulion saith that he heard that the use of these roots was forbidden in Burgundy (where they call them Indian artichokes) for that they were persuaded the too frequent use of them caused the leprosy.’ Gaspar Baulion had encouraged farmers near Lyons to start growing potatoes in 1593, but they were stopped by the authorities in Besancon because of that superstition. Scottish preachers considered potatoes unfit food because they were not mentioned in the Bible.
Potatoes were accepted gradually in Ireland, and by 1739 they were being extensively grown in Scotland and were becoming known in Holland, Germany and Italy. In France, the potato was popularized in the eighteenth century by the enthusiasm of Antoine Auguste Parmentier, with the help of Louis XVI, who even used a potato flower as a buttonhole on one occasion. Hence, in culinary French, parmentier signifies that a dish contains potato.
Potatoes returned to America in 1719, with Irish immigrants to New England; in Ireland, the population had begun to depend on them. Potatoes were a crop that gave a heavy yield and suited the climate of Ireland. But first a leaf-curl virus spoiled the breeder’s efforts; then, in 1845, came the potato blight after a warm, damp summer. Blight is caused by a fungus; potatoes go black and turn to a mass of rotten slime. The result of the potato blight was famine, with far-reaching political and human consequences. Today, with seed potatoes grown in cold, blight-free areas, such as Scotland, blight is less of a problem. Scientific breeding has produced disease-resistant varieties, but the dangers which would go with dependence on one crop are still sometimes demonstrated.
Potatoes have excellent nutritive value when fresh, being rich in vitamin C and potassium (0.6%), when these are not allowed to leach out into cooking water. Frying, steaming or pressure cooking are good from this point of view, but when potatoes are peeled, left to soak in cold water and boiled, most of the soluble nutrients are removed. Although potatoes contain 18% carbohydrate, mainly as starch, they also have 2% of good protein, and since the rest is almost all water, they are not very high in calories – unless, of course, they are fried or eaten with tons of butter, but that is hardly the fault of the potato.
It is often said that the best part of the potato is in the skin. If you hold a thin slice of potato up to the light, you will see that just inside the skin there are several denser layers, and that the middle part of the potato is more transparent. This middle part contains less starch and nutrients, and more water than the outer layers. Since peeling removes a good part of the outer layers, peeling is a wasteful practice. Cooking potatoes in their skins gives them a special taste which is not universally liked. It also restricts the use of potatoes as a ‘neutral’ vegetable. lf potatoes are young and freshly dug (depending to some extent on variety), the skins can be scraped off easily or rubbed off with a coarse pan cleaner. The skins are not loosened by dunking them in boiling water. While some potatoes can be scraped after being in boiling water for 2 minutes, there is no certainty that one variety will behave like another. It is important at least to use a peeler that removes only the finest sliver of skin, and to cook potatoes immediately after they have been peeled.
Only a few of the many potato varieties are grown commercially. Recognizing even these few is difficult; most cooks do little more than distinguish between the white and the red ones (though varieties sold in Britain should now be named). Greengrocers are rarely much help; they often do not know whether a potato is waxy or floury, which to the cook is fundamental. Floury ones have more starch in their surface layers; this swells when they are heated and bursts the skin. Waxy potatoes are best for potato salad, but make a gummy mess when mashed. Other differences are less fundamental. For instance, some potatoes have white flesh (which is preferred in the US) and others have the yellower flesh opted for in parts of Europe. Sizes and shapes also vary greatly. There are kidney-shaped ones, such as the very special Jersey Royal Kidney, and enormous ones, like the Idahos, which are best for baking.
Varieties are chosen by farmers to be disease free and give heavy crops in the potato-growing localities. Some may be grown because they are good keepers, and market preferences are also considered. The British particularly like the floury, red-skinned potatoes, such as King Edward (Redskin or Kerr’s Pink in Scotland). But what is valued in one place is not in another, and although reds tend to be more in demand and therefore more expensive in Britain, this is not the case elsewhere.
It is rare for potato varieties to be chosen and grown for their outstanding flavour, but early varieties are grown for use as new potatoes. Main crop potatoes lifted too soon and sold as new potatoes are inclined to be soapy and to blacken after they are cooked. New potatoes of quality come only from earlies grown for the purpose. In spite of the ‘new potatoes’ that are now imported, it is still common in Britain for people with small vegetable gardens to grow a few earlies for the incomparable pleasure of eating them freshly dug in early summer. This passion is not pursued to the same extent elsewhere. In the US, many seedsmen’s catalogues do not even give potatoes a mention or do not offer more than a couple of well-known varieties, like Red Russet or Idaho.
Potatoes are usually bought in larger quantities than other vegetables, and it is worth knowing a little about storage and the blemishes from which they are likely to suffer. Potatoes with rotten patches, holes or cuts made during lifting should clearly be rejected. Scabs, caused by limey soil, are not of great consequence, but dark patches may indicate blight or may result from the improper use of chemical fertilizers, a condition whose causes are not yet fully understood. Green potatoes have been exposed to the light; they taste bitter and contain mildly poisonous alkaloids called solanines, which can cause an upset stomach. Withered potatoes are old and have lost their vitamins. Potatoes that have been allowed to get too cold taste sweet (wh
ich is why potatoes should never be stored in the refrigerator). Sometimes but by no means always, the sweetness goes off if the potatoes are kept for a week in a very warm kitchen.
Potatoes that are very irregular in shape or have big eyes are wasteful. Good-sized, regular and smooth-skinned potatoes are easier to peel. (Buying cheap potatoes may not be economical.) The washed potatoes, which are sold in bags in many supermarkets, go green quickly and will not keep well because the skins have been damaged by the high-pressure hoses used to clean them. When potatoes are mature and have been lifted at the right moment, they keep well in cool, dry, dark conditions. Eventually, they will start to sprout, though, and anti-sprouting agents are often used to inhibit sprouting. In sprouted potatoes, the starch has been partly converted to dextrin and the food value is reduced. In some countries, ready-peeled and chipped potatoes are sold in bags. As they have to be treated chemically with antioxidants and preservatives to keep them white, they are not allowed everywhere. Hollow potatoes can usually be blamed on a drought followed by a very wet spell.
Potato flour, potato starch and instant potato. Potatoes are steamed, dried and ground, or the starch is extracted by pulverizing and washing, to make various products for use in the kitchen. Potato starch or flour is of special importance to people on a gluten-free diet. It can be used for thickening, but tends to have a taste of its own. Also, it is called for in various cakes and biscuits where a tender starch is needed. Instant potato or powdered potato is typical of the cooked and dried product. Some brands are a good substitute if you are in a hurry; others are nasty.
[Potato – French: pomme de terre German: Kartoffel Italian: patata Spanish: patata]
POTTING. ‘By potting is generally meant the operation of preserving edible substances in a state for immediate use in small pots or jars’, says Cassell’s New Dictionary of Cookery, published at the turn of the century. ‘Potted meats, fish etc., are commonly sold in shops. They are all intended for relishes, and are spread on bread like butter.’
The method of preserving perishable foods in pots is far, far older than preservation in sealed, sterile glass jars. As a means of preserving meat, fish and shell fish, it depends essentially on sealing with fat. The contents of a pot, unlike the contents of a terrine, for instance, offers a small surface to the air in relation to its bulk (unless the pot is very shallow). When things are cooked with plenty of fat and little water, the temperatures are high enough to kill most organisms, and what few might be left are sealed in, unable to spread or infect their surroundings because they are isolated by solidified fat. The hard fatty surface prevents contamination from the air, especially if it is covered with a bladder as used to be the practice in the past. When refrigeration came along, such methods of preservation became unnecessary, but the tradition of tasty potted meats remained. Potted food – as opposed to food in a pot – implies some degree of preservation combined with readiness for immediate use. In this category come the French confits of goose, duck, turkey, rabbit and pork, as well as rillettes, rillons, rillots and rillauds, because spreading like butter is not a necessary part of the scenario, although potted products in England were nearly always pounded to a paste. I would also include the Arab *qawwrama, as this is a confit of fat-tailed sheep preserved in fat and designed to keep all through the winter.
The extent to which potting was done in the past is not realized today, and as the deep freeze makes the long-term conservation of potted foods easy, we might pay them more attention and revive old recipes. In the Cassell’s, which is typical of its period, there are dozens of recipes for potting, which mention among fish – herring, char, trout, salmon, eel, lamprey and sprats; among shell fish – lobster, crab, crayfish, shrimps and prawns; among game – hare, rabbit, pheasant, partridge, larks; among meats – beef, mutton, veal, fowl, ham, tongue, and mixtures such as ham and fowl, veal and tongue. In general, all were made the same way, by cooking the meat or fish, pounding it with salt, cayenne, mace or nutmeg, and butter, baking in a moderate oven, and pouring an extra layer of clarified butter on top.
From a safety point of view, there are objections to some of the old recipes for pounding or repotting the pastes when they are cold, then sealing them without re-sterilizing by heat. Some of these recipes could have caused botulism. However, there will be no problem if potted meats are eaten within a few days or kept in the freezer.
Potted cheese is in a different category because the cheese was not cooked, merely pounded to a paste with butter and flavourings before being put into pots. It was then covered with a layer of clarified butter to prevent it drying out (though it would have continued to mature like any other cheese). No doubt potting cheese was often regarded as a way of using up the bits and keeping them for a day or so, but there are some distinguished recipes, such as Boulestin’s for Roquefort pounded with butter and a dash of armagnac, which Elizabeth David recommends in her Spices, Salt and Aromatics in the English Kitchen (Grub Street).As she remarks ‘the old recipes are coming back into use as methods of giving flavour, character and improved texture to factory cheeses which have so little personality of their own.’ Recently, a number of commercially-made potted cheeses have also come on the market. In them, cheese is mixed with wine, beer, garlic, and herbs in various ways. Many are nice, but their claim to be potted would rest only on their being sold in pots (and many of them are sold by weight in cut pieces) as they are not sealed with clarified butter or sterilized and are not meant to be kept.
POURGOURI. See burghul.
POUTARG. See botargo.
PRALINE. A mixture of caramelized sugar and roasted nuts used in confectionery and on ice cream. The simplest way to make it is to put nuts and sugar (in equal quantities or more nuts than sugar) in a copper pan and to stir the mixture over heat until the sugar starts to caramelize, by which time, if the heating is done slowly, the nuts should also be sufficiently roasted. Turn the praline out (correctly, on a marble slab) and let it cool. Grind it in a mill or crush it in a mortar, and store it in an airtight tin. Some recipes involve roasting the nuts and caramelizing the sugar separately.
[Praline – French: praline German: gebrannte Mandel Italian: mandorla tosta Spanish: almendra garapiñada]
PRAWN. See shrimp.
PRÉ SALÉ. See mutton.
PRESERVATION. All foods deteriorate when kept beyond their natural life, which may be anything from a few hours to a year or more. Storing food is not a human innovation -various mammals store the food which is necessary for their survival over the winter, using things which have dried naturally, or nuts, grains and pulses, which are dormant but alive. Insects also store food – bees were making a good job of refining and sealing up honey long before the appearance of man.
Foods are open to attack by *micro-organisms and even by their own enzymes. Storage methods are all designed to minimize spoilage, if not to remove it entirely. Until the middle of the 19th century, the methods in use had all been discovered by chance, and the reason that they worked was not understood; it was not until Pasteur showed the causal role played by micro-organisms in fermentation and decomposition that progress could become systematic and rapid. Today, many of the old methods, like smoking, are now retained only for the flavour they impart to the food, and a revolution has taken place in our eating habits.
Not all methods of preservation actually kill the micro-organisms- the low temperatures of *freezing immobilize them, as does the absence of water produced by *drying. Other methods, though, do involve killing all the micro-organisms in the food – *sterilization – and preventing other organisms getting in. The most important method of sterilization is heating, but there are others, mainly involving chemical *preservatives. Micro-organisms are also killed by ultra-violet light (even that in sunlight) but much more effective are other rays and radiation, which kill all living tissue. It is even possible to sterilize food in the can by radiation which will go through the metal. However, this treatment, promising though it may be at first sight, appears
to cause changes in the food which lead to bad flavour, and work on the irradiation of food is still largely experimental.
Unless the sterilized food can be sealed (or unless preservatives are added), it is open to immediate reinfection. Early methods depended on a capping of fat or clarified butter. *Potting is not suitable for very long-term preserving as fats eventually go rancid. So do oils, which are used similarly: *mushrooms, *basil, *sardines and *anchovies are commonly preserved under olive oil in Mediterranean countries, and mustard oil preserves pickles in India. The main methods of scaling, though, are *bottling and *canning.
The other traditional method of preserving was salting, which involved applying common salt, often mixed with saltpetre, either as a *brine or by *drysalting. Salt works mainly by osmosis – preventing the organisms from getting water, it is toxic to some organisms but tolerated by others. In sufficient strength, it will stop virtually all organisms as well as inhibiting the action of enzymes. Sugar in sufficient concentrations also stops micro-organisms from getting water, it is a preservative, for example, in jams.
*Smoking is usually an adjunct to salting and drying. It covers the surface of meat or fish with a layer of chemicals that have antiseptic properties. Today, its importance as a method of preservation is minimal.