Submitted to: Journal of Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2012
Publication Date: 11/9/2012
Citation: Takeoka, G.R., Dao, L.T., Harden, L.A., Pantoja, A., Kuhl, J.C. 2012. Antioxidant activity, phenolic and anthocyanin contents of various rhubarb (Rheum-spp.) varieties. Journal of Food Chemistry. DOI: 10.1111/j.1365-2621.2012.03174.x.
Interpretive Summary: Culinary rhubarb is consumed as a vegetable and is prized for its use in pies, tarts and sauces. Rhubarb stalks are also processed for jam, jelly, compote, juice and wine and used as ingredients in ice cream, yogurt, candies and other specialties. The roots and rhizomes of rhubarb have been extensively studied due to their importance as medicines to treat constipation, inflammation and cancer. However, much less is known about the composition and activity of the stalks. Therefore, we studied the antioxidant activity, phenolic and anthocyanin content of fifteen rhubarb varieties. Three of the varieties, Valentine, Cawood Delight and OR 23, had higher total phenolics than kale, a vegetable rich in phenolics. Anthocyanin concentration in rhubarb was moderate, ranging from 25.4 ± 3.8 to 197.6 ± 31.5 mg/100 g DW. Valentine and OR 23 had the highest antioxidant activity of the varieties investigated. Due to their high total phenolics content and antioxidant activity, Valentine and OR 23 appear to have potential nutritional advantages over other varieties. Additional studies are needed to determine the structure and concentration of individual phenolics in these varieties.
Technical Abstract: Antioxidant activity (ABTS assay), total phenolics, and total anthocyanins were determined in the petioles of fifteen rhubarb (Rheum spp.) varieties. Antioxidant activity ranged from 491 ± 60 (Victoria 574/27) to 1820 'mol Trolox/g DW (Valentine). The phenolic content varied from 673 ± 41 (Loher Blut) to 3540 ± 216 mg GAE/100 g DW (Valentine) and was highly correlated (r = 0.907) with antioxidant results. The concentration of anthocyanins ranged from 25.4 ± 3.8 (Rheum palmatum Rubra) to 197.6 ± 31.5 mg/100 g DW (Valentine). The percentages of two main anthocyanins in rhubarb, cyanidin 3-glucoside and cyanidin 3-rutinoside varied from 59.15:40.85, respectively, in Valentine to 22.12:77.88, respectively, in Goliath.