Cooked rhubarb is higher in polyphenols


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Cooking rhubarb stems helps release some compounds called polyphenols. These antioxidant molecules are recognized for their anti-cancer properties. As rhubarb is high in soluble fiber, it helps to reduce cholesterol levels. It is one more reason to eat it! Cooked as a fruit, rhubarb is actually a vegetable, according to botanical textbooks. Only the stem is eaten, the leaves being toxic.

Cooking rhubarb…for more polyphenols!

Other cooking methods (except blanching), such as rapid cooking, slow cooking and baking, are said to increase the polyphenol content and therefore the antioxidant capacity of this vegetable. This is the finding of an article, Effect of different cooking regimes on rhubarb polyphenols, published in Food Chemistry. However, rapid cooking leads to degradation of some compounds. Slow cooking and baking better preserve rhubarb’s antioxidant capacity. Cooking for 20 minutes releases a maximum of polyphenols. Chemical analysis has identified over 40 phenolic compounds in raw rhubarb.

Composition of one rhubarb stalk (51 grams)

Rhubarb is low in calories (11 Kcal per stalk), carbohydrates and fat. It is an excellent source of vitamins and minerals, including potassium and calcium. Fiber accounts for 74% of dry weight, with 66% insoluble and 8% soluble. Insoluble fiber helps prevent constipation, while soluble fiber helps reduce cholesterol levels, especially LDL (Low Density Lipoprotein). HDL (High Density Lipoprotein) levels remain unchanged.

Main components of rhubarb:

Water47.74 g
Carbohydrates2.32 g
Dietary fiber0.9 g
Protein0.46 g
Total fat0.1 g
Potassium147 mg
Calcium44 mg
Beta-carotene31 µg
Vitamin K14.9 µg
Vitamin C4.1 µg
Lutein and zeaxanthin87 µg
N.B. This list is incomplete. Only the main constituents are listed. For more information on other rhubarb constituents, see the Health Canada website.

However, its high oxalic acid content makes it a food to be avoided by those suffering from kidney stones. Rhubarb leaves are extremely toxic, as their oxalic acid content is too high to be eaten.

Two varieties to enjoy!

Personally, I know 2 varieties of rhubarb. In Canada, there’s the one with green stems (Victoria) and the ones with red stems (Canada Red, McDonald and Valentine). The red variety is said to be more tender than the green. Stems are harvested from spring to early summer, as the quantity of oxalic acid increases with the season.

Many ways to cook it!

In compote, pie, sorbet and even to accompany white meat, it lends itself to a multitude of recipes. Being very acidic and bitter, it is mostly used with sugar. See our recipe for rhubarb squares suitable for gluten-free diets.


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