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Quantification of Sulphur Dioxide in Wine and Meat: Improvement of Methods for Accuracy and Efficiency

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Thesis is embargoed until 22 November 2026(4.85 MB)

Date

2023

Authors

Meiring, Pieter

Supervisor

Hamid, Nazimah

Item type

Thesis

Degree name

Master of Philosophy

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Publisher

Auckland University of Technology

Abstract

Sulphiting agents are used extensively in food and wine as preservatives to increase shelf life. As with most food additives, regulatory laws require the level of the sulphiting agent to be stated. Currently, the accredited testing methods for sulphites are restrictive due to their methodology and time needed to perform the tests. This study aims to investigate three methods for the determination of sulphur dioxide content and compare their results with the current gold-standard methods for testing for sulphur dioxide in food and wine. Two methods focused on improving upon the OIV method (Compendium of International Methods of Analysis for Total Sulfur dioxide [OIV-MA-AS323-04A2]; OIV, 2009) used for sulphur dioxide testing in wine. The first method utilises the titratable acidity method, investigating the possibility of adding hydrogen peroxide to convert sulphur dioxide and sulphites into sulphuric acid within wine. The difference in titratable acidity allowed for sulphur dioxide to be quantified without the need for distillation. The second method involved machine learning, successfully used spectral data points to classify wine samples in terms of their sulphur dioxide concentration. The third method involved the optimisation of the Monier-Williams method (AOAC Optimised Monier-Williams method 990.28) for testing for sulphur dioxide in food. Results revealed that the titratable acidity method provided faster quantification, although with reduced precision. Utilising percentage transmission results in a neural network model for sulphur dioxide quantification was found to be neither accurate nor precise but showed potential for basic classification of wine into high or low sulphur dioxide concentrations. Increasing the distillation temperature of the modified Monier-Williams method successfully reduced the distillation time from 105 to 75 minutes without any negative impact, as confirmed by recovery assays. All three methods investigated showed promise and warrant further research. Based on the significance of the findings, the modified Monier-Williams method through increasing distillation temperature appeared to have the most potential for further research.

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http://hdl.handle.net/10292/16971

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