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dc.contributor.advisorBekhit, Alaa El-Din
dc.contributor.advisorMcConnell, Michelle
dc.contributor.authorCheng, Vern Jou
dc.date.available2013-01-17T00:23:57Z
dc.date.copyright2011
dc.identifier.citationCheng, V. J. (2011). Evaluation of the bioactivity of New Zealand wine by-products (Thesis, Master of Science). University of Otago. Retrieved from http://hdl.handle.net/10523/3665en
dc.identifier.urihttp://hdl.handle.net/10523/3665
dc.description.abstractEfficient extraction of phenolics from wine by-products has been of great interest to many researchers in order to maximise the activities exerted by the extracted bioactive compounds. In this study, different grape varieties of wine by-products (seeds, skin and pomace) were subjected to extraction process using solvents (i.e. aqueous acetone (Ace/w), aqueous ethanol (Eth/w) or aqueous methanol (Meth/w), 1:1 [v/v]) in order to study the effect of extraction solvent, fraction and variety on the yield of phenolic compounds, composition of phenolic compounds by LC-MS analysis and the biological activities of the extracts. The biological activities studied were: antioxidant (DPPH radical and superoxide anion), antibacterial (against Escherichia coli and Staphylococcus aureus) and antifungal (against Candida albicans) as well as in vitro anti-influenza viral activities. Furthermore, the mechanisms of antiviral action of extracts were investigated. Biological activities exerted by wine by-products (particularly antioxidant and antiviral activities) were relatively high compared to those reported to other foodstuffs in literature. There were significant effects (P < 0.001) for the extraction solvents, varieties and fractions of wine by-products on the activities. Overall, higher phenolic compounds and antioxidant activities were obtained using Ace/w extraction; however Meth/w extraction resulted in higher anti-influenza viral activity. Red grape varieties of wine by-products had an overall higher activity compared to white grape varieties. Seed extracts contained higher concentrations of flavan-3-ol compounds while skin extracts contained higher anthocyanins and flavonols. Pomace extracts contained moderate concentrations of all the compounds since pomace used was made up of both the seeds and skin. Seed extracts exhibited significantly better activities than pomace and skin extracts. All the extracts exhibited anti-influenza viral activities with the lowest effective concentration at 1 mg/mL and 10 mg/mL for seed and skin extracts, respectively. Wine by-product extracts suppressed influenza A virus infection through many modes of action. Seed extracts were able to inhibit viral infectivity in virus-bound cells but not skin extracts. Seed extracts also directly inhibited the infectivity of influenza A virus after short incubation of 30 min. Furthermore, pre-treatment of cells with extracts from wine by-products allowed the binding of extracts and inhibited virus adsorption to the cells. Results herein revealed considerable antioxidant and anti-influenza viral activity of the New Zealand vinification by-products, which can potentially be an inexpensive source of promising natural anti-influenza viral agents.
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectgrapes
dc.subjectwine by-products
dc.subjectantioxidant
dc.subjectantiviral
dc.subjectantimicrobial
dc.subjectbiological
dc.subjectextraction
dc.subjectinfluenza A virus
dc.titleEvaluation of the bioactivity of New Zealand wine by-products
dc.typeThesis
dc.date.updated2013-01-16T22:18:40Z
dc.language.rfc3066en
thesis.degree.disciplineFood Science
thesis.degree.nameMaster of Science
thesis.degree.grantorUniversity of Otago
thesis.degree.levelMasters
otago.interloanyes
otago.openaccessAbstract Only
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