Blender

A stand mixer or simply blender is an electrically operated kitchen appliance for mixing liquid or semi-solid ingredients or for pureeing food. In contrast to blender sticks used for similar purposes, these are stand-alone devices. The American term is blender, in German gastronomic stand mixers for mixing cocktails or in juice bars are called so.

The stand mixer was developed by Stephen Poplawski in 1922. He used the device to make soda drinks. Fred Osius improved Poplawski's invention in 1935 when he developed the Waring Blendor from it.

A stand mixer consists of two main parts. The base contains an electric motor that can usually be switched or controlled for several operating speeds. A closed container made of stainless steel, glass or transparent plastic sits on top. At the bottom of the container, depending on the design, there may be a removable blade star for cleaning purposes, which is set into rapid rotation by the electric motor by means of a clutch, thus chopping and mixing, emulsifying or suspending the ingredients.

The rotating knives fling the mixed material against the wall of the container, creating an inefficient rotational funnel. A roughly triangular cross-section of the container and/or ribs on the wall help break the rotational funnel and direct the flow of liquid back to the blades in the center. Some blenders require a lid to keep the liquid from splashing out of the container. Some models have additional blades on the back edge of the blades on the blade star; a switch position for ice crushing then rotates the blade star in the opposite direction, counteracting premature wear of the actual blade edges.

The rotation speed of the blade star has a great influence on the achievable fineness of the solid particles or on the emulsion stability. A higher speed (e.g. 37,000 rpm in gastronomy mixers compared to 12,000 rpm in household mixers) not only results in a faster mixing result (mixing, smaller particle size and breakdown of plant fibres and cells). A shorter mixing process is also associated with less motor heating (overheating can lead to premature wear), which, in addition to the more stable construction of these devices, has a favourable effect on the service life of the device. However, noise emissions can increase significantly at higher speeds.

Mixing of longer duration or higher rotation can lead to a heating of the mixed material due to friction effects or cavitation and thus to a better emulsification by melting of contained fats or to a better dissolution of sugar. On the other hand, heating can also have undesirable effects on vitamins and minerals that are not temperature-resistant.

More powerful blenders can start from a standstill with the blender jar already filled with ice and hard fruits or vegetables, otherwise larger ingredients may only be added during operation. For this purpose, the lids of many blender jars have a central opening, as liquid can be ejected along the jar wall when the lid is completely removed.

For crushing hard objects (model cars, mobile phones, batteries, etc.), shown in US commercials made famous by viral marketing (Will It Blend), an extra-robust special appliance with a stronger motor, sturdier clutch and wear-resistant blades is needed. An imitation in the stand mixer at home would permanently damage the household appliance and could be dangerous to the user.

The frequently used blender containers made of polycarbonate run the risk of releasing water-soluble plastic components that are hazardous to health, such as bisphenol A, when preparing hot pureed soup or when cleaned with hot water in the dishwasher for long periods of time.

Finer emulsions, nanosuspensions or extracts can only be achieved with special homogenizers, such as a dispersing stir bar (see also dispersion), in which more efficient shear forces and cavitation effects are created in a narrow gap between a rotor and a stator.

See also

• List of kitchen appliances