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Research Project: Defining, Measuring, and Mitigating Attributes that Adversely Impact the Quality and Marketability of Foods

Location: Healthy Processed Foods Research

Title: Phenolic composition of pomegranate peel extracts using an LC-MS approach with silica hydride columns

Author
item Young, Joshua - Microsolv Technology Corporation
item Pan, Zhongli
item Teh, Hui Ean - University Of California
item Menon, Veena - San Jose State University
item Modereger, Brent - San Jose State University
item Pesek, Joseph - San Jose State University
item Matyska, Maria - San Jose State University
item Dao, Lan
item Takeoka, Gary

Submitted to: Journal of Separation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2017
Publication Date: 4/1/2017
Citation: Young, J.E., Pan, Z., Teh, H., Menon, V., Modereger, B., Pesek, J.H., Matyska, M.T., Dao, L.T., Takeoka, G.R. 2017. Phenolic composition of pomegranate peel extracts using an LC-MS approach with silica hydride columns. Journal of Separation Science. 40(7)1449-1456. doi:10.1002/jssc.201601310.

Interpretive Summary: Pomegranate (Punica granatum L.) is a shrub that produces an edible fruit, replete with a myriad of nutrients. Pomegranate are different from other antioxidant-laden foods in that a wider array of polyphenols are present, allowing for inactivation of a broad range of deleterious free radical species. Different parts of the plant contain various classes of phytochemicals. The peel is rich in polyphenols, flavonoids, ellagitannins, and proanthocyanidins. Although this component of the fruit is inedible itself, extraction of its nutritional constituents for consumption can be accomplished by preparing a tea or juice. In fact, much of the antioxidant activity of pomegranate is found in the peels. Recent research has reported that ellagitannins may slow the aging process. Our work has shown that only one of the five pomegranate cultivars studied contained the important ellagitannin, punicalagin. This research highlights the need to study the phenolic composition of pomegranate peels to select cultivars that contain nutritionally important phenolics.

Technical Abstract: The peels of different pomegranate cultivars (Molla Nepes, Parfianka, Purple Heart, Wonderful and Vkunsyi) were compared in terms of phenolic composition and total phenolics. Analyses were performed on two silica hydride-based stationary phases: phenyl and undecenoic acid columns. Quantitation was accomplished by developing an LC-MS method approach for separating different phenolic analytes, initially in the form of reference standards and then with pomegranate extracts. The HPLC columns used in the separations had the ability to retain of a wide polarity range of phenolic analytes, as well as offering beneficial secondary selectivity mechanisms for resolving the isobaric compounds, catechin and epicatechin. The Vkunsyi peel extract had the highest concentration of phenolics (as determined by LC-MS) and was the only cultivar to contain the important compoundds punicalagin. Comparison to the Folin-Ciocalteu assay demonstrated the greater specificity of the LC-MS approach in being able to distinguish individual compounds as opposed to merely total phenolic content.