Baking, grilling or broiling food, especially starchy foods, until a toasted crust is formed generates significant concentrations of acrylamide, a known carcinogen from animal studies; its potential to cause cancer in humans at normal exposures is uncertain. Public health authorities recommend reducing the risk by avoiding overly browning starchy foods or meats when frying, baking, toasting or roasting them.
Human diet was estimated to cause perhaps around 35% of cancers in a human epidemiological analysis by Richard Doll and Richard Peto in 1981. These cancer may be caused by carcinogens that are present in food naturally or as contaminants. Food contaminated with fungal growth may contain mycotoxins such as aflatoxins which may be found in contaminated corn and peanuts. Other carcinogens identified in food include heterocyclic amines generated in meat when cooked at high temperature, polyaromatic hydrocarbons in charred meat and smoked fish, and nitrosamines generated from nitrites used as food preservatives in cured meat such as bacon.
Wine refrigerators offer a smaller alternative to wine cellars and are available in capacities ranging from small, 16-bottle units to furniture-quality pieces that can contain 400 bottles. Wine refrigerators are not ideal for aging, but rather serve to chill wine to the proper temperature for drinking. These refrigerators keep the humidity low (usually under 50%), below the optimal humidity of 50% to 70%. Lower humidity levels can dry out corks over time, allowing oxygen to enter the bottle, which reduces the wine's quality through oxidation. While some types of alcohol are sometimes stored in freezer, such as vodka, it is not possible to safely freeze wine in the bottle, as there is insufficient room for it to expand as it freezes and the bottle will usually crack. Certain shapes of bottle may allow the cork to be pushed out by the ice, but if the bottle is frozen on its side, the wine in the narrower neck will invariably freeze first, preventing this.
Cooking often involves water, frequently present in other liquids, which is both added in order to immerse the substances being cooked (typically water, stock or wine), and released from the foods themselves. A favorite method of adding flavor to dishes is to save the liquid for use in other recipes. Liquids are so important to cooking that the name of the cooking method used is often based on how the liquid is combined with the food, as in steaming, simmering, boiling, braising and blanching. Heating liquid in an open container results in rapidly increased evaporation, which concentrates the remaining flavor and ingredients – this is a critical component of both stewing and sauce making.
Fruits are the ripened ovaries of plants, including the seeds within. Many plants and animals have coevolved such that the fruits of the former are an attractive food source to the latter, because animals that eat the fruits may excrete the seeds some distance away. Fruits, therefore, make up a significant part of the diets of most cultures. Some botanical fruits, such as tomatoes, pumpkins, and eggplants, are eaten as vegetables. (For more information, see list of fruits.)