The main difference between smoothies and milk shakes is that fruit is the principal ingredient of the former and ice cream is the primary ingredient of the latter. Smoothies can also include a wider variety of ingredients than shakes and usually have a lower fat and sugar content. The milk shake emerged from the steamy American diners of the 1950s, whereas the smoothie has its roots in the macrobiotic vegetarian restaurants of the 1960s.
Smoothies have a yogurt, milk or juice base and are sometimes made entirely from fruit. Ice cream and full-cream milk functions as a base for milk shakes. Ice cubes are another common base for smoothies, but milk shakes don’t need added ice because of their ice cream content.
Fruit is the primary ingredient of most smoothies, although vegetables, grains and oatmeal are also typical ingredients. Breakfast smoothies, for example, can contain honey, muesli and eggs. Milk shake recipes, on the other hand, are usually restricted to milk, ice cream and -- occasionally -- fruit, and tend come in coffee, chocolate or vanilla flavors.
Milk shakes tend to have higher fat and sugar levels than smoothies because of their ice cream content. Chocolate is also a more common ingredient in milk shakes than smoothies, and some recipes include sweet syrups. However, some milk shake recipes have a high fruit content, while those for smoothies can also contain rich ingredients like chocolate and double cream, as well as fruit.
The culinary evolution of the smoothie and the milk shake has followed a different trajectory. The milk shake first emerged in the U.S. in 1885, although at that time it was a type of tonic that contained eggs and whiskey. The modern milk shake made its debut as a culinary icon in American diners in the 1950s after the invention of automated milkshake machines, which became a popular fixture in fast food restaurants. Smoothies became popular in the U.S. in the mid 1960s when there was a resurgence of interest in macrobiotic vegetarianism. California, always a trend-setter, borrowed the fruit juice smoothie from its Latin American neighbors, whose traditional juice bars were a precursor to the contemporary Californian health restaurants.
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