Degree Type

Dissertation

Date of Award

2019

Degree Name

Doctor of Philosophy

Department

Agricultural and Biosystems Engineering

Major

Toxicology

First Advisor

Jacek A. Koziel

Abstract

Hybrid wine grape cultivars such as St. Croix (E.S. 283 x E.S. 193), Brianna

(‘Kay Gray’ x E.S. 2-12-13), Frontenac (‘Landot 4511’ x University of Minnesota 89),

La Crescent (‘St. Pepin’ x E.S. 6-8-25), Frontenac gris (single bud sport cane from

‘Frontenac’), Marquette (MN 1094 x Ravat 262) have been developed to be cold-hardy

and disease-resistant in order to thrive in the cold climates such as the upper Midwest.

Grape growers, area of grape production, wineries, and wine production has been

increasing since the early 2000. The Iowa wine industry generated a $420 million (USD)

economic impact in 2012. Cold-climate winemakers will encounter difficulties otherwise

not encountered in areas where vinifera thrive. These struggles include high titratable

acidity and low tannins, resulting in the perceptions of tartness and a lack of body and

mouthfeel. Data about aroma profiles from volatile organic compounds of these grapes

and wines are also lacking. To investigate the phenolic content of Marquette, Frontenac

and St. Croix grape skins and seeds, at veraison and harvest, pigments and anthocyanins

were exhaustively extracted, assayed by protein precipitation and bisulfite bleaching, and

analyzed by spectrophotometer. Total tannins (from skins and seeds) decreased from

veraison to harvest (0.62 mg catechin equivalents or CE per berry to 0.30 mg CE/berry).

Monomeric pigments accounted for over 50% of the total color at pH 4.9. Short and long

polymeric pigments accounted for less than 25% of the total color at pH 4.9. To

investigate the volatile organic compounds emitted in-vivo from Frontenac, Marquette,

St. Croix, and La Crescent during ripening, two novel SPME sampling devices were

developed and metabolites were analyzed by GC-MS. PCA analysis of these volatile

metabolites accounted for 26.8-79.9 percent of the variability, and a comprehensive

summary of these metabolites was reported. To investigate the effects of harvest time on

aroma profile of wines, berries of Marquette, Frontenac, Frontenac gris and Brianna were

harvested at different time points and research wines were made. Research wines were

analyzed by an automated headspace SPME-GCMS-olfactometry method, and a

comprehensive summary of these volatile organic compounds was reported.

Copyright Owner

Somchai Rice

Language

en

File Format

application/pdf

File Size

167 pages

Included in

Toxicology Commons

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