Investigating the interaction of ascorbic acid with anthocyanins and pyranoanthocyanins
Advisor:Giusti, M. Monica
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Series/Report no.:2017 Edward F. Hayes Graduate Research Forum. 31st
Juices colored by anthocyanins are subject to color loss related to fortification with ascorbic acid (AA), likely through condensation at carbon-4 (C4) of anthocyanins (ACN). To investigate this mechanism, pyranoanthocyanins (PACN), having a fourth-ring covalently occupying C4, were synthesized to compare against ACN (chokeberry extract and cyanidin-3- galactoside). Pyranoanthocyanins were synthesized by combining chokeberry anthocyanins with pyruvic acid. AA was added to either chokeberry ACN, cyanidin-3-galactoside or 5- carboxypyranocyanidin-3-galactoside. Samples were stored in the dark for five days at 25oC. Spectral (380-700 nm), color (CIE-L*c*h*) and HPLC data were collected. Extensive bleaching was observed for ACN+AA, with half-life (t1/2) reduced from 35.7 to 0.3 days. An 8-13 fold increase in t1/2 was observed for PACN-AA compared to ACN-AA. A 10 nm hypsochromic shift was observed for PACN-AA, and three new chromophores were formed. The PACN having enhanced resistance to bleaching suggested AA accessibility to C4 played a critical role in ACN bleaching.
Food, Agricultural, and Environmental Sciences (FAES): 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)
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