Suchergebnisse

Abstract
Diacetyl is a potentially harmful chemical that is used as an artificial flavouring in the food industry and may also be generated during processing of some natural products including coffee. In Europe, an 8-h time weighted average occupational exposure limit (TWA-OEL) of 20 ppb has been adopted for diacetyl, together with a short-term exposure limit (STEL) of 100 ppb. A new measurement method involving sampling on thermal desorption tubes and analysis by gas chromatography–mass spectrometry has been used to investigate potential exposure to diacetyl, and the related compound 2,3-pentanedione, at eight companies involved in the coffee industry including large- and small-scale manufacturers and coffee shops. A total of 124 static and personal samples were collected. In the majority of personal samples airborne concentrations of diacetyl were <5 ppb, with those at coffee shops generally <1 ppb. However, diacetyl concentrations in ~40% of the long-term personal samples, mainly originating from one site, were found to be in excess of the newly adopted European TWA-OEL of 20 ppb. Diacetyl concentrations up to 400 ppb were detected on the static samples, with the highest values occurring during grinding of roasted coffee beans. 2,3-Pentanedione was also detected in most of the samples at airborne concentrations around half of those for diacetyl. A significant number of other volatile organic compounds (VOCs) were also detected at sub-ppm concentrations, including acetoin, aliphatic carboxylic acids, aldehydes, ketones and esters, methylfuran, furfural and furfuryl-based alcohols and ketones, and nitrogen containing compounds, such as pyridines and pyrazines. In laboratory tests, diacetyl emissions generated during heating of whole beans were found to be significantly lower than those from heating the same beans after grinding. Diacetyl emissions from both ground and whole beans were also found to be significantly dependent on temperature.

Intro -- Cover Page -- Title Page -- Copyright Page -- Dedication -- Contents -- List of Figures -- List of Plates -- List of Tables -- Preface and Acknowledgements -- Introduction -- 1. Parish Distribution and Size of Properties -- 2. The Coffee Planters -- 3. Planting and Processing -- 4. Labour Management, Work Regimen and Resistance -- 5. Profitability and Decline -- 6. Emancipation and Labour -- Conclusion: Jamaican Coffee in the Age of Global Transformation -- APPENDICES -- Appendix 1. Parish Distribution of Coffee-Producing Properties in Jamaica, 1799 and 1836 -- Appendix 2. Frequency Acreage of Coffee Properties, 1832 -- Appendix 3. Frequency Number of Enslaved Workers on Coffee Properties, 1818 and 1832 -- Appendix 4. Enslaved Females Assigned to Field Work on Maryland Plantation, St Andrew, 1818 -- Appendix 5. Abandoned Coffee Plantations, 1832-1848 -- Appendix 6. Coffee Plantations in Production in Jamaica, 1899 -- Notes -- Bibliography -- Index.