Industry-wide assessment and characterisation of problem fermentations
Date
2007-03
Authors
Journal Title
Journal ISSN
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Publisher
Stellenbosch : University of Stellenbosch
Abstract
In order to remain competitive in the international wine market, wineries need to increase
productivity and improve quality with the aid of available technologies. Problematic wine
fermentations directly impact both productivity and the quality of wine and therefore, by
reducing stuck and sluggish fermentations, less wine will be lost or downgraded. This
requires early identification and classification of problem fermentations with the use of high
throughput analytical tools and multivariate data analysis in order to take preventative
measures.
In this study, a non-directed, holistic approach was used to investigate the occurrence
of problem fermentations in the South African wine industry. Data obtained with various
analytical techniques was used for the purpose of multivariate data analysis. The use of
high throughput analytical techniques such as Fourier transform infrared (FT-IR)
spectroscopy proved extremely valuable as a fast screening method to monitor
fermentation progress. Principal component analysis of the spectral fingerprints obtained
with this technique indicated that all the fermentation problems occurred from the middle of
fermentation onwards. In addition, successful discrimination between control and problem
fermentations for different red and white cultivars was achieved. This demonstrates the
feasibility of this type of methodology to investigate and monitor fermentation.
Solid phase dynamic extraction (SPDE) headspace analysis was used to obtain a
volatile fingerprint of the fermenting must samples. Similarly to FT-IR spectra, successful
discrimination between problem and control fermentations was achieved with the use of
PLS-discriminant analysis. Discrimination between red and white cultivars was achieved
with headspace data. This excluded the data from tannin and colour compounds normally
used for this discrimination. SPDE coupled to gas chromatography mass spectrometry
(GC-MS) proved to be a novel and suitable analytical method for wine analysis, although
further method development is required.
A preliminary research and development strategy for evaluating FT-IR spectroscopy
for quantification purposes in fermenting must was established. Although these calibration
and validation results were preliminary, it was shown that the calibrations for fermenting
must under South African conditions need urgent attention.
In conclusion, this study illustrated the potential of using an alternative approach to
investigate stuck and sluggish fermentation with definite prediction possibilities for future
research endeavours.
Description
Thesis (MSc (Wine Biotechnology))--University of Stellenbosch, 2007.
Keywords
Dissertations -- Wine biotechnology, Theses -- Wine biotechnology, Wine and wine making, Fermentation