A kitchen utensil is a small hand held tool used for food preparation. Common kitchen tasks include cutting food items to size, heating food on an open fire or on a stove, baking, grinding, mixing, blending, and measuring; different utensils are made for each task. A general purpose utensil such as a chef's knife may be used for a variety of foods; other kitchen utensils are highly specialized and may be used only in connection with preparation of a particular type of food, such as an egg separator or an apple corer. Some specialized utensils are used when an operation is to be repeated many times, or when the cook has limited dexterity or mobility. The number of utensils in a household kitchen varies with time and the style of cooking.
Benjamin Thompson noted at the start of the 19th century that kitchen utensils were commonly made of copper, with various efforts made to prevent the copper from reacting with food (particularly its acidic contents) at the temperatures used for cooking, including tinning, enamelling, and varnishing. He observed that iron had been used as a substitute, and that some utensils were made of earthenware. By the turn of the 20th century, Maria Parloa noted that kitchen utensils were made of (tinned or enamelled) iron and steel, copper, nickel, silver, tin, clay, earthenware, and aluminium. The latter, aluminium, became a popular material for kitchen utensils in the 20th century.
Iron is more prone to rusting than (tinned) copper. Cast iron kitchen utensils, in particular, are however less prone to rust if, instead of being scoured to a shine after use, they are simply washed with detergent and water and wiped clean with a cloth, allowing the utensil to form a coat of (already corroded iron and other) material that then acts to prevent further corrosion (a process known as seasoning). Furthermore, if an iron utensil is solely used for frying or cooking with fat or oil, corrosion can be reduced by never heating water with it, never using it to cook with water, and when washing it with water to dry it immediately afterwards, removing all water. Since oil and water are immiscible, since oils and fats are more covalent compounds, and since it is ionic compounds such as water that promote corrosion, eliminating as much contact with water reduces corrosion. For some iron kitchen utensils, water is a particular problem, since it is very difficult to dry them fully. In particular, iron egg-beaters or ice cream freezers are tricky to dry, and the consequent rust if left wet will roughen them and possibly clog them completely. When storing iron utensils for long periods, van Rensselaer recommended coating them in non-salted (since salt is also an ionic compound) fat or paraffin.
Stainless steel finds many applications in the manufacture of kitchen utensils. Stainless steel is considerably less likely to rust in contact with water or food products, and so reduces the effort required to maintain utensils in clean useful condition. Cutting tools made with stainless steel maintain a usable edge while not presenting the risk of rust found with iron or other types of steel.
Aluminium's advantages over other materials for kitchen utensils is its good thermal conductivity (which is approximately an order of magnitude greater than that of steel), the fact that it is largely non-reactive with foodstuffs at low and high temperatures, its low toxicity, and the fact that its corrosion products are white and so (unlike the dark corrosion products of, say, iron) do not discolour food that they happen to be mixed into during cooking. However, its disadvantages are that it is easily discoloured, can be dissolved by acidic foods (to a comparatively small extent), and reacts to alkaline soaps if they are used for cleaning a utensil.
There are several types of ceramic utensils. Terracotta utensils, which are made of red clay and black ceramics. The clay utensils for preparing food can also be used in electric ovens, microwaves and stoves, we can also place them in fireplaces. It is not advised to put the clay utensil in the 220-250 temperature oven directly, because it will break. It also is not recommended to place the clay pot over an open fire. Clay utensils do not like sharp change in temperature. The dishes prepared in clay pots come to be particularly juicy and soft – this is due to the clay’s porous surface. Due to this porous nature of the surface the clay utensils inhale aroma and grease. The coffee made in clay coffee boilers is very aromatic, but such pots need special care. It is not advised to scrub the pots with metal scrubs, it is better to pour soda water in the pot and let it stay there and afterwards to wash the pot with warm water. The clay utensils must be kept in a dry place, so that they will not get damp.
Archaeologists and historians have studied the kitchen utensils used in centuries past. For example: In the Middle Eastern villages and towns of the middle first millennium AD, historical and archaeological sources record that Jewish households generally had stone measuring cups, a meyham (a wide-necked vessel for heating water), a kederah (an unlidded pot-bellied cooking pot), a ilpas (a lidded stewpot/casserole pot type of vessel used for stewing and steaming), yorah and kumkum (pots for heating water), two types of teganon (frying pan) for deep and shallow frying, an iskutla (a glass serving platter), a tamhui (ceramic serving bowl), a keara (a bowl for bread), a kiton (a canteen of cold water used to dilute wine), and a lagin (a wine decanter).