The effects of different processing parameters (cold soak and percent alcohol (v/v) at dejuicing) on the concentrations of grape glycosides and glycoside fractions and glycosidase activities in selected yeast and lactic acid bacteria

Simple item page
dc.contributor.authorMcMahon, Heatheren
dc.contributor.committeechairZoecklein, Bruce W.en
dc.contributor.committeememberFugelsang, Kennethen
dc.contributor.committeememberClaus, George Williamen
dc.contributor.committeememberEigel, William N. IIIen
dc.contributor.departmentFood Science and Technologyen
dc.date.accessioned2014-03-14T21:51:25Zen
dc.date.adate1998-12-16en
dc.date.available2014-03-14T21:51:25Zen
dc.date.issued1998-12-03en
dc.date.rdate1999-12-16en
dc.date.sdate1998-12-14en
dc.description.abstractGrape-derived aroma and flavor precursors exist partially as non-volatile, sugar-bound glycosides. Hydrolysis of these compounds may modify sensory attributes and potentially enhance wine quality. Cold soak (prefermentation skin contact) at two temperatures and alcohol content (%, v/v) at dejuicing were monitored to determine effects on Cabernet Sauvignon glycoside concentration. Total, phenolic-free, and red-free glycoside concentrations were estimated by the quantification of glycosyl-glucose. Cold soak (5 days at 10° C) increased total glycosides by 77%, red-free glycosides by 80%, and phenolic-free glycosides by 96%. Ambient soak (3 days at 20° C) enhanced color extraction, and increased total glycosides by 177%, red-free glycosides by 144%, and phenolic-free glycosides by 106%. Wines produced by early pressing (10% sugar) had 25% more total and red-free glycosides than late press (0.25% sugar). After post-fermentation malolactic fermentation, total glycosides were 14% lower and phenolic-free glycosides were 35% lower. In a second study, the activities of a-L-arabinofuranosidase, b-glucosidase, and a-L-rhamnoyranosidase were determined in model systems for thirty-two strains of yeasts belonging to the following genera: Aureobasidium, Candida, Cryptococcus, Hanseniaspora, Hansenula, Kloeckera, Metschnikowia, Pichia, Saccharomyces, Torulaspora, and Brettanomyces (10 strains); and seven bacteria (Leuconostoc oenos strains). Only one Saccharomyces strain exhibited -glucosidase activity, but several non-Saccharomyces yeast species had substantial production. Aureobasidium pullulans hydrolyzed a-L-arabinofuranoside, b-glucoside, and a-L-rhamnoyranoside. Eight Brettanomyces strains had -glucosidase activity. Location of enzyme activity was determined for those species with enzymatic activity. The majority of -glucosidase was located in the whole cell fraction (66%), followed by the permeabilized fraction (35%), and extracellular production (2%). Aureobasidium pullulans was also capable of hydrolyzing grape glycosides.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-121498-094044en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-121498-094044/en
dc.identifier.urihttp://hdl.handle.net/10919/46209en
dc.publisherVirginia Techen
dc.relation.haspartetd.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectCabernet Sauvignonen
dc.subjectcold soaken
dc.subjectglycosidasesen
dc.subjectglycosidesen
dc.subjectyeasten
dc.titleThe effects of different processing parameters (cold soak and percent alcohol (v/v) at dejuicing) on the concentrations of grape glycosides and glycoside fractions and glycosidase activities in selected yeast and lactic acid bacteriaen
dc.typeThesisen
thesis.degree.disciplineFood Science and Technologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
etd.pdf
Size:
336.27 KB
Format:
Adobe Portable Document Format
Download

Collections

Masters Theses