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Takeoka G.R.,Western Regional Research Service | Dao L.,Western Regional Research Service | Harden L.,Western Regional Research Service | Pantoja A.,U.S. Department of Agriculture | And 2 more authors.
International Journal of Food Science and Technology | Year: 2013

Summary: Antioxidant activity (ABTS assay), total phenolics and total anthocyanins were determined in the petioles of twenty-nine rhubarb (Rheum spp.) varieties. Antioxidant activity ranged from 463 ± 50 (Rheum officinale) to 1242 ± 2 μmol Trolox per g DW (Valentine). The phenolic content varied from 673 ± 41 (Loher Blut) to 4173 ± 23 mg GAE/100 g DW (Plum Hutt) and had a low correlation (r = 0.663) with antioxidant results. Seven of the varieties (Plum Hutt, Valentine, Minnesota No. 8, Cherry Red, Cawood Delight, Coulter McDonald and OR 23) had higher total phenolics than kale, a vegetable rich in phenolics. The concentration of anthocyanins ranged from 19.8 ± 1.5 (Crimson Red) to 341.1 ± 41.6 mg/100 g DW (Valentine). The percentages of two main anthocyanins in rhubarb, cyanidin 3-glucoside and cyanidin 3-rutinoside varied from 66.07:33.93, respectively, in Valentine to 9.36:90.64, respectively, in R. officinale. © 2012 The Authors. International Journal of Food Science and Technology © 2012 Institute of Food Science and Technology.


Takeoka G.R.,Western Regional Research Service | Buttery R.G.,Western Regional Research Service
Food Chemistry | Year: 2012

2-Acetyltetrahydropyridine is an important flavour constituent that imparts roasty, popcorn-like, and cracker-like odours to foods, such as bread, rice, popcorn, taco shells and tortilla chips. We postulated that the homologue with a formyl group in the C-2 position, 2-formyltetrahydropyridine, might have similar desirable odour qualities. Synthesis of this compound was performed by oxidation of 2-piperidinemethanol with silver carbonate supported on Celite®. This reaction produced a major volatile (46.9% of the total volatiles) with a retention index of 1023 on DB-1. GC-O revealed that the unknown had a strong cracker-like odour. The electron impact mass spectrum of the unknown had the following major ions: m/z 82, 111, 54, 68, 28, 43. The m/z 53-54 ratio and m/z 82-83 ratio were consistent with a 1,4,5,6- tetrahydropyridine ring structure. GC-FTIR of the unknown revealed an N-H stretching band at 3435 cm -1 and a Fermi doublet at 2827 and 2713 cm -1 that indicated the presence of an aldehyde. A strong carbonyl absorption band was present at 1703 cm -1. The unknown was tentatively identified as 2-formyl-1,4,5,6-tetrahydropyridine, based on its retention index, odour quality, mass spectrum, and vapour phase infrared spectrum. © 2011 Elsevier Ltd. All rights reserved.

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