Stilbene concentration was analyzed in juice and tissue of muscadine grape (Vitis rotundifolia Michx.) and bunch grape (Vitis labrusca L.) from fresh fruit, after processing and after postharvest treatments. Five filter types were evaluated for percent resveratrol recovery when filtering standard and spiked juice samples in preparation for HPLC analysis. Only two (polycarbonate and Anopore) of the five filter types had more than 90 percent recovery. Polycarbonate was chosen for sample preparation since it was more durable during handling. Eight muscadine grape cultivars and three bunch grape cultivars were evaluated. Skin tissue had approximately 100 times higher stilbene concentration than did the pulp for all cultivars studied. Carlos and Magnolia muscadine cultivars had the greatest skin stilbene concentration of all the muscadine cultivars evaluated. Except for Sweet Jenny, bronze cultivars had greater skin stilbene concentration than black skinned cultivars. Miss Blanc Vitis labrusca grape had greater skin stilbene concentration than all other cultivars. Stilbene concentration of fresh juice extracted from Noble and Carlos muscadine grapes was relatively low compared to processed juices. Juices obtained using hot press and freezing methods of juices extraction had significantly higher stilbene concentration than free run or cold pressed juice. Although Carlos skin tissue had significantly more stilbenes than Noble skins, there were no significant differences between free run, cold press or hot press juices obtained from the two cultivars. Although pectic enzyme treatment significantly increased juice yields, stilbene concentrations were not significantly higher than other juice extraction methods. In contrast to Carlos muscadine grape, where high skin stilbene concentration did not result in high juice concentration, Vitis labrusca grape juices had relatively high stilbene concentration when compared to muscadine juices. UV irradiation and cold storage had a significant effect on stilbene concentration of muscadine grape tissue. For Carlos muscadine grape, cold storage alone doubled skin stilbene concentration, but UV irradiation did not significantly change stilbene levels. In contrast, in Noble muscadine grape, UV irradiation increased skin stilbene concentration by 50%, but cold storage alone had no effect.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-01202006-082858 |
| Date | 20 January 2006 |
| Creators | LeBlanc, Mark Rene' |
| Contributors | Witoon Prinyawiwatkul, David Himelrick, Georgianna Tuuri, Paul Wilson, Jeff Kuehny, Charles Johnson |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-01202006-082858/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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