Stir frying

Stir frying(Chinese:炒;pinyin:chǎo;Wade–Giles:ch'ao;Cantonese Yale:cháau) is acooking techniquein which ingredients are fried in a small amount of very hot oil while being stirred or tossed in awok. The technique originated inChinaand in recent centuries has spread into other parts of Asia and the West. It is similar tosautéingin Western cooking technique.
Wok frying may have been used as early as theHan dynasty(206 BC – 220 AD) for drying grain, not for cooking. It was not until theMing dynasty(1368–1644) that the wok reached its modern shape and allowed quick cooking in hot oil.However, there is research indicating that metal woks and stir-frying of dishes were already popular in theSong dynasty(960–1279),and stir-frying as a cooking technique is mentioned in the 6th-century ADQimin Yaoshu.Stir frying has been recommended as a healthy and appealing method of preparing vegetables, meats, and fish, provided calories are kept at a reasonable level.
The English-language term "stir-fry" was coined and introduced inBuwei Yang Chao,How to Cook and Eat in Chinese(1945) to translate the Chinese termchǎo炒.Although using "stir-fry" as a noun is commonplace in English, in Chinese,chǎois used as a verb or adjective only.
TheChinese character炒 is attested ininscriptions on bronze vesselsfrom theEastern Zhouperiod (771–256 BC), but not in the sense of stir frying.Dry stirring was used in theHan dynasty(206 BC –  220 AD) to parch grain.Although there are no surviving records of Han dynasty stir frying, archaeological evidence ofwoksand the tendency to slice food thinly indicate that the technique was likely used for cooking.
The term initially appears in the sense of "stir frying" in theQimin Yaoshu(齊民要術), a sixth-century agricultural manual, including in arecipeforscrambled eggs.In sources from theTang dynasty(618–907),chaorefers not to a cooking technique, but to a method forroasting tea leaves. It reappears as a cooking method in a dozen recipes from theSong dynasty(960–1279). The Song period is when the Chinese started to usevegetable oilfor frying instead ofanimal fats. Until then, vegetable oil had been used chiefly in lamps.
Historically, stir frying was not as important a technique asboilingorsteaming, since the oil needed for stir frying was expensive. The technique became increasingly popular in the lateMing dynasty(1368–1644),in part because the wood and charcoal used to fire stoves were becoming increasingly expensive near urban centers, and stir-frying could cook food quickly without wasting fuel."The increasingly commercial nature of city life" in the late Ming andQing(1644–1912) periods also favored speedy methods.But even as stir frying became an important method in Chinese cuisine, it did not replace other cooking techniques. For instance, "only five or six of over 100 recipes recorded in the sixteenth-century novelJin Ping Meiare stir fry recipes and wok dishes accounted for only 16 percent of the recipes in the most famous eighteenth century recipe book, theSuiyuan shidan".
By the late Qing, most Chinese kitchens were equipped with awok range(chaozao炒灶 orpaotai zao炮臺灶) convenient for stir-frying because it had a large hole in the middle to insert the bottom of a wok into the flames.
Stir frying was brought to America by earlyChinese immigrants, and has been used in non-Asian cuisine.
The term "stir fry" as a translation for "chao" was coined in the 1945 bookHow To Cook and Eat in Chinese, by Buwei Yang Chao. The book told the reader:
Although using the term "stir-fry" as a noun is commonplace in English, in Chinese, the word 炒 (chǎo) is used as a verb or adjective only.In the West, stir frying spread from Chinese family and restaurant kitchens into general use. One popular cookbook noted that in the "health-conscious 1970s" suddenly it seemed that "everyone was buying a wok, and stir frying remained popular because it was quick." Many families had difficulty fitting a familydinnerinto their crowded schedules but found that stir-fried dishes could be prepared in as little as fifteen minutes.
Broadly speaking, there are two primary techniques:chaoandbao. Both techniques use high heat, butchaoadds a liquid and the ingredients are softer, whereasbaostir fries are morecrispybecause of theMaillard reaction.
Thechao(炒) technique is similar to the Western technique ofsautéing.There are regional variations in the amount and type of oil, the ratio of oil to other liquids, the combinations of ingredients, the use of hot peppers, and such, but the same basic procedure is followed in all parts of the country.
First thewokis heated to a high temperature, and just as or before it smokes, a small amount of cooking oil is added down the side of the wok (a traditional expression is 热锅冷油 "hot wok, cold oil") followed by dry seasonings such asginger,garlic,scallions, orshallots. The seasonings are tossed with a spatula until they arefragrant, then other ingredients are added, beginning with the ones taking the longest to cook, such as meat ortofu. When the meat and vegetables are nearly cooked, combinations ofsoy sauce, vinegar, wine, salt, or sugar may be added, along with thickeners such as cornstarch,water chestnutflour, orarrowroot.
A single ingredient, especially a vegetable, may be stir-fried without the step of adding another ingredient, or two or more ingredients may be stir-fried to make a single dish. Although large leaf vegetables, such as cabbage or spinach, do not need to be cut into small pieces, for dishes which combine ingredients, they should all be cut to roughly the same size and shape.
Wok hei(simplified Chinese:镬气; traditional Chinese:鑊氣; Jyutping:wokhei)romanizationis based on theCantonese Chinesepronunciation of the phrase; when literally translated into English, it can be translated as "wokthermal radiation"or, metaphorically, as the "breath of the wok". The phrase "breath of a wok" is a poetic translation Grace Young first coined in her cookbookThe Wisdom of the Chinese Kitchen.In her book,The Breath of a Wok, Young further explores the ideas and concepts ofwok hei.An essay called "Wok Hay: The Breath of a Wok" explains how the definition ofwok heivaries from cook to cook and how difficult it is to translate the term. Some define it as the "taste of the wok," a "harmony of taste," etc.: "I think of wok hay as the breath of a wok—when a wok breathes energy into a stir-fry, giving foods a unique concentrated flavor and aroma."
When read in Mandarin, the second character is transliterated asqi(ch'iaccording to itsWade-Gilesromanization, sowok heiis sometimes rendered aswok chiin Western cookbooks) is theflavour,tastes, and "essence" imparted by a hot wok on food during stir frying.Out of theEight Culinary Traditions of China, wok hei is encountered the most inCantonese cuisine, whereas it may not even be an accepted concept in some of the others.
To impartwok heithe traditional way, the food is cooked in a seasoned wok over a high flame while being stirred and tossed quickly.The distinct taste ofwok heiis partially imbued into the metal of the wok itself from previous cooking sessions and brought out again when cooking over high heat.In practical terms, the flavour imparted by chemical compounds results fromcaramelization,Maillard reactions, and the partial combustion of oil that come from charring and searing of the food at very high heat in excess of 200 °C (392 °F).Aside from flavour,wok heialso manifests itself in the texture and smell of the cooked items.
In the eighteenth and nineteenth centuries, thebaotechnique (Chinese:爆;pinyin:bào;lit.'pop', 'explosion') of stir-frying on a high flame was typical of cuisine from the northern Chinese province ofShandong.The wok is first heated to a dull red glow over a high fire. The oil, seasonings, and meats are then added in rapid succession. The food is continually tossed, stopping only to add other ingredients such as broths, vegetables, or more seasonings. The purpose ofbaois to highlight natural tastes, so minimal seasoning is added.Because of the high heat,baois ideal for small amounts of food that cook quickly, so the juices do not flow out of the items.Meat is coated with egg white or starch in order to contain the juices.When the food is cooked it is poured and ladled out of the wok. The wok must then be quickly rinsed to prevent food residues from charring and burning to the wok bottom because of residual heat.
A larger amount of cooking fat with a highsmoke point, such as refined plant oils, is often used inbao. The main ingredients are usually cut into smaller pieces to aid in cooking.
Writers extol the quick cooking at high heat for retaining color, texture, and nutritional value.One study compared the effects of boiling, steaming, and stir frying onbamboo shoots. Boiling and steaming decreased the amount ofprotein, soluble sugar, ash, and total freeamino acidsby more than one-third. Stir-frying bamboo shoots increased their fat content by 528.57% due to the addition of oil. With 78.9% retention, stir frying preserved significantly morevitamin Cthan boiling. Taking into consideration the total retention of nutrients, the study concluded that stir frying is the method best suited for bamboo shoots.Similar results were found for stir frying red peppers.
Another study examined the nutritional value of broccoli after five common cooking techniques: steaming, boiling, microwaving, stir-frying and stir-frying followed by deep frying. The study found that the two most common methods of home cooking in China, stir-frying and stir-frying combined with deep frying insoybean oil, resulted in a much greater loss ofchlorophyll, soluble protein, soluble sugar and vitamin C. The method which affected these values the least was steaming. Stir frying for five minutes and stir frying combined with boiling caused the highest loss ofglucosinolates, which according to this study are best preserved by steaming.A study performed by the Spanish National Research Counsel stir-fried the broccoli for only three minutes and thirty seconds and found that nutritional value of these broccoli samples varied depending on which cooking oil was used. Comparing these results to an uncooked sample, the study found that phenolics and vitamin C were reduced more than glucosinolates and minerals. Stir-frying with soybean, peanut, safflower or extra virgin olive oil did not reduceglucosinolates, and broccoli stir-fried withextra virgin olive oilorsunflower oilhadvitamin Clevels similar to uncookedbroccoli. These levels were significantly lower with other edibleoils.
Stir frying is not withouthealthrisks. Recent studies show thatheterocyclic aminesandpolycyclic aromatic hydrocarbonsare formed by stir fryingmeatat very hightemperatures. These chemicals may causeDNAchanges that may contribute to increased risk ofcancer.
The process of stir-frying is used in the preparation of someChinese herbal medicinesunder the term 'dry-frying'.  Stir frying a medical herb with honey is commonly used to increase its sweetness and therefore its spleen and stomachqitonic effects.  Stir frying invinegaris typically used whenever one wants to direct the properties of an herb more to the liver based on the principle that the sour taste belongs to the liver.There is no scientific evidence for any of these medicinal claims.