Rhubarb is a perennial growing from short, thick rhizomes. It produces large poisonous leaves that are somewhat triangular, with long fleshy edible stalks and small flowers grouped in large clusters that are greenish-white to rose-red.
In culinary use, the fresh raw stalks are crisp (and resemble red celery) with a strong, tart taste. Rhubarb is not a true fruit, but, in the kitchen it is usually prepared as if it were.
Grown primarily for its fleshy stalks, technically known as petioles,the use of rhubarb stalks as food is a relatively recent innovation which was first recorded in 17th-century England after affordable sugar became available to common people, and reached a peak between 1920 – 1950.
Rhubarb is grown widely, and with greenhouse production it is available throughout much of the year. Rhubarb grown in hothouses (heated greenhouses) is called “hothouse rhubarb”, and is typically made available at consumer markets in early spring, before outdoor cultivated rhubarb is available. Hothouse rhubarb is usually brighter red, tenderer and sweeter-tasting than that grown outdoors. In temperate climates, rhubarb is one of the first food plants harvested, usually in mid- to late spring (April/May in the Northern Hemisphere. It is ready to consume as soon as harvested, and freshly cut stalks are firm and glossy.
Rhubarb damaged by severe cold should not be eaten, as it may be high in oxalic acid, which migrates from the leaves and can cause illness.
The color of stalks can vary from the traditional crimson red, through speckled light pink, to light green. The color doesn’t affect its suitability for cooking: The green-stalked rhubarb is more robust and has a higher yield, but the red-colored stalks are more popular with consumers
Rhubarb is packed with minerals, vitamins, organic compounds, and other important nutrients. Some of these components are dietary fiber, protein, vitamin C, vitamin K, B complex vitamins, calcium, potassium, manganese, and magnesium. Rhubarb is also a rich source of antioxidants such as beta-carotene, lutein, and zeaxanthin,
Commonly, the stalks are cooked with sugar and used in pies, crumbles and other desserts, but it can also be put into savory dishes or pickled. Rhubarb can be dehydrated and infused with fruit juice. In most cases, it is infused with strawberry juice to mimic the popular strawberry rhubarb pie.
For cooking, the stalks are often cut into small pieces and stewed (boiled in water) with added sugar, until soft. Little water is added, as rhubarb stalks already contain a great deal of water. Rhubarb should be processed and stored in containers which are unaffected by residual acid content, such as glass or stainless steel. Spices such as cinnamon, nutmeg, and ginger are sometimes added. Stewed rhubarb or rhubarb sauce, like applesauce, is usually eaten cold. Pectin, or sugar with pectin, can be added to the mixture to make jams.
Rhubarb is often paired with strawberries to make strawberry-rhubarb pie. Rhubarb can be used to make a fruit wine. Being a bit sour, it is very refreshing and can be drunk cold, especially during the summer.