Rutabaga - Phytochemistry

Phytochemistry

Rutabagas and other cyanoglucoside-containing foods (including cassava, maize (corn), bamboo shoots, sweet potatoes, and lima beans) release cyanide, which is subsequently detoxified into thiocyanate. Thiocyanate inhibits thyroid iodide transport and, at high doses, competes with iodide in the organification process within thyroid tissue. Goitres may develop when there is a dietary imbalance of thiocyanate-containing food in excess of iodine consumption, and it is possible for these compounds to contribute to hypothyroidism. Yet, there have been no reports of ill effects in humans from the consumption of glucosinolates from normal amounts of Brassica vegetables. Glucosinolate content in Brassica vegetables is estimated to be around one percent of dry matter. These compounds are also responsible for the bitter taste of rutabagas.

Along with watercress, mustard greens, turnip, broccoli and horseradish, the perceived bitterness in rutabaga is governed by a gene affecting the TAS2R bitter receptor, which detects the glucosinolates in rutabaga. Sensitive individuals with the genotype PAV/PAV found rutabaga twice as bitter as insensitive subjects (AVI/AVI). For the mixed type (PAV/AVI), the difference was not significant for rutabaga. As a result, sensitive individuals may find rutabaga so bitter as to be inedible.

Other chemicals that contribute to flavor and odor include glucocheirolin, glucobrassicanapin, glucoberteroin, gluconapoleiferin, and glucoerysolin. Several phytoalexins that aid in defense against plant pathogens have also been isolated from rutabaga, including three novel phytoalexins that were reported in 2004.

Rutabaga contains significant amounts of vitamin C: 100 g contains 25 mg, which is 42% of the daily recommended dose.