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Title:Chemical characterization of proanthocyanidins in purple, blue, and red corn after different milling processes and their anti-inflammatory properties
Author(s):Chen, Cheng
Advisor(s):de Mejia, Elvira
Department / Program:Food Science & Human Nutrition
Discipline:Food Science & Human Nutrition
Degree Granting Institution:University of Illinois at Urbana-Champaign
Colored corn
Milling processes
Abstract:Proanthocyanidins (PA) are oligomers and polymers of flavan-3-ol units, also known as condensed tannins. The monomers include catechin, epicatechin, and gallic acid esters. They have beneficial effects on several chronic diseases because of anti-inflammatory and antioxidant effects. These effects depend on the degree of polymerization of PA. PA are natural bioactive compounds found in a variety of foods, including barley, cocoa, blueberry, and cinnamon. The objective of this study was to compare the PA profiles of purple, blue, and red corn kernels after dry milling, wet milling, and dry grind processing, and to determine the anti-inflammatory features of PAs extracted from colored corn. Among purple, blue, and red corn, purple had the highest PA concentrations. In purple corn, among three processing methods, the kernel pericarp contained the highest concentration of PA in dry milling (43.5 2.1 mg catechin equivalent/kg corn); steep water contained the highest concentration of PA in wet milling (170.3 4.4 mg catechin equivalent/kg corn); and DDGS had PAs of 35.05 2.5 mg catechin equivalent/kg corn; wet milling recovered all PAs from kernel sample . Red corn had lower concentrations of PAs, with 19.6 0.5 and 33.78 3.2 catechin equivalent/kg corn for pericarp and steep water, respectively. Blue corn had the lowest concentration and different distribution patterns, in which small grits contained the highest concentration in dry milling (2.82 0.31 catechin equivalent/kg corn), and gluten slurry contained the highest concentration in wet milling (13.67 0.50 catechin equivalent/kg corn). The extract was passed through a Sephadex LH-20 column to purify PA, analyzed using HPLC-ESI-MSMS and normal phase HPLC with fluorescence detector. UPLC-ESI-MSMS and normal phase HPLC indicated the most of PA from purple corn pericarp have degrees of polymerization below 10, which is considered favorable for their health benefits. Biomarkers of inflammation such as cyclooxygenase and nitric oxide were tested using purified extracts, indicated active inhibition effects on inflammation. Purple corn dry milling pericarp PA inhibited 66% of inducible nitric oxide synthase, and 89% of cyclooxygenase-2. In conclusion, for the first time, this study reports the composition of PA from colored corn kernel coproducts from dry milling, wet milling, and dry grind, and the anti-inflammatory effect from purple and red corn pericarp.
Issue Date:2017-04-28
Rights Information:Copyright 2017 Cheng Chen
Date Available in IDEALS:2017-08-10
Date Deposited:2017-05

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