CH4615 – Fragrance, Food and Colour Chemistry
Duration:
20 hours
Lecturers:
Dr R. A. Aitken and Dr R. J. Pearson*
*Module Convenor
Aims:
This module addresses three areas where applications of organic chemistry have been able to benefit society and give rise to important industries. The fragrance, perfumery and food flavouring industry will be covered from the early extraction of essential oils to the modern marketplace with an overview of the key structural features required for perfumes and flavours and some major manufacturing processes. The chemical constituents of food and reactions that occur when cooking will be considered with an emphasis on health effects and the molecular mechanisms that take place. The chemistry of organic dyes and pigments will be discussed including the historical development of colourants alongside a detailed look at the main compound classes, their synthesis and applications, and their environmental impact.
Objectives:
1. Know the historical development of flavour and fragrance chemistry; the extraction of ‘essential oils’. General requirements for a fragrance chemical in terms of molecular weight and functionality. Economics of extraction from natural sources vs. semi-synthetic and synthetic approaches. The concept of ‘nature identical’ materials and analytical methods to detect fraud.
2. Know the most important monoterpenes, their structures and interconversion. Synthetic routes used industrially. Sesquiterpenes and other less volatile fragrance compounds. Historical development of perfumes.
3. Know the fragrance compounds of animal origin: ambergris, musk and civet. Synthesis of the natural compounds and synthetic analogues – the nitro musks. Animal odour compounds for defence – the skunk.
4. Understand the use of food flavours and the link to fragrance. Aroma compounds from spices and fruits – aromatic compounds such as piperine, eugenol, vanillin, cinnamaldehyde, piperonal and coumarin; fruit flavours including aliphatic esters, raspberry ketone and strawberry furanone.
5. Explain the physical, chemical and biological basis of colour.
6. Appreciate the importance and history of colour chemistry, including historical examples of natural and synthetic dyes and pigments and how such examples helped revolutionise the colour industry.
7. Discuss and contrast the most important colorants, including azo, carbonyl and phthalocyanine dyes and pigments, and understand the synthetic strategies used in their production, and any toxicity or environmental issues.
8. Explain the mordanting process, fluorescence, luminescence, the valence-bond approach, bathochromic shifts, and other colour-related terminology.
9. Appreciate the importance of fastness properties and the applications of dyes and pigments, including those linked to cosmetics, biomedicine, food colouring, and chromic materials.
10. Understand the Maillard reaction, how it can be manipulated, the beneficial and problematic products formed, and its uses beyond cooking.
11. Appreciate the sulfur chemistry linked to cruciferous vegetables, garlic, and other alliums.