Date of Award

1-1-2001

Degree Type

Thesis

Degree Name

Master of Science

Faculty

Faculty of Communications, Health and Science

First Advisor

Dr Mary C. Boyce

Abstract

Vanilla is a very important flavouring agent, it is used as a major ingredient in a number of food products. The taste and aroma results from a specific blend of components present in the extract. There are over 170 volatile components, which all contribute to the flavour of the extract. These volatile components can be present in trace amounts or in relatively high concentrations. The range and concentration of volatile components is somewhat characteristic of the vanilla extract and its origin. Due to the high cost and low availability of natural extract, nature-identical and synthetic flavourings are often used to flavour foods and beverages. As natural extracts are very expensive, compared to nature-identical and synthetic vanilla flavourings, there have been many attempts to adulterate them. There are many different methods available for the characterisation of vanilla extracts. These include high performance liquid chromatography (HPLC), isotope ratio mass spectrometry (IRMS), gas chromatography (GC) and thin layer chromatography. However, traditional methods for the extraction of volatile components from non-volatile components for GC analysis, in particular, are time-consuming and prone to sample loss and degradation. Solid phase micro-extraction (SPME) is a relatively new separation technique, which can be used in conjunction with HPLC or GC. The anolytes can be extracted from a variety of matrices using a fused silica fibre exposed to the headspace of the sample. This provides a simple and effective technique for the selective extraction of volatile and semi-volatile components from a sample containing non-volatile components. A SPME-GC method was developed to extract and analyse a range of natural extracts, nature-identical extracts and synthetic flavourings. Using a polyacrylate (PA) fibre, the volatile components were extracted at room temperature. No sample preparation was required (other than dilution). The SPME-GC method was used to qualitatively and quantitatively analyse a range of extracts and flavourings as well as food products. The method was also successfully compared to an existing HPLC method.

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