Fragrances and flavours industry

Crude turpentine is distilled to obtain refined products used in the fragrance and flavour industry. Only the unsaturated mono- and bicyclic terpenes are of interest for resin production. These are mainly a-pinene, p-pinene and dipentcne (D,L-limonene) (Fig. 17). D-Limonene is obtained by extraction of orange peel in citrus fruits. 

With several examples we could demonstrate that heterogeneous catalysts are becoming very valuable for the clean production of fine chemicals on the example of the fragrance and flavour industry. 

Pervaporation-assisted catalysis is a typical example of an operation eflide-ntly carried out in extractor-type catalytic membrane reactors. Esterification is by far the most studied reaction combined with pervaporation. " Esters are a class of compounds with wide industrial appUcation, from polymers to fragrance and flavour industries. Esterification, a reaction between a carboxylic acid and an alcohol with water as a by-product, is an equilibrium-limited reaction. So, this is a typical reaction that can be carried out advantageously in a extractor-type membrane reactor. By selectively removing the reaction product water, it is possible to achieve a conversion enhancement over the thermodynamic equilibrium value based on the feed conditions. 

As mentioned before (2.1.1) Arfmann et al. [133] studied the co-hydroxylation of the sesquiterpenes nerolidol and famesol and the related compounds neryl- and geranylacetone. This was done because co-hydroxylated sesquiterpenes are important intermediates in the synthesis of industrially used fragrances and flavours. Aspergillus niger ATCC 9142 and Rhodococcus rubropertinctus DSM 43197 were unable to hydroxylate nerylacetone or its -isomer geranylacetone, at the co-position of the molecule. Incubation of nerylacetone with Mucor circinelloides CBS 27749 for 25 hr resulted in seven transformation products, including one co-hydroxylation compound, in 3% yield [140]. 

The various applications of essential oils account for the great interest in their study. Such applications may be found in the cosmetic industry, as ingredients of fragrances, decorative cosmetic, fine fragrances and flavouring, in the food industry, as aromas and flavours, in the pharmaceutical industry, as active components of medicines and as antibacterials/antimicrobials, and in aromatherapy. At present, there are many studies in which they are used as intermediaries in fine chemistry reactions, among other applications. 

Essential oils (EOs) are secondary metabolites that plants usually synthesized for combating infectious or parasitic agents or generate in response to stress conditions [1]. EOs are aromatic components obtained from different plant parts such as flower, buds, seed, leaves and fruits, and they have been employed for a long time in different industries, mainly in perfumes (fragrances and aftershaves), in food (as flavouring and preservatives) and in pharmaceuticals (therapeutic action) [2]. 

Estimation of the volume of renewable resources involved in the flavour industry is very difficult. It is assumed that the total flavour and fragrance market... 

In 1874 Wilhelm Haarmann started to produce the first synthetic aroma chemical, vanillin [2-4]. Since then the flavour, fragrance and aroma chemical industry has shown rapid progress. In the beginning, perfumers created the first flavour formula with synthetic aroma chemicals. Over the years many different parameters, like the availability of natural products, the development of food industry and changes in consumers lifestyles, have led to a broad range of widely accepted flavourings. 

In recycled PP, 61 compounds were detected and 35 of them were identified. Many peaks showed very low separation levels making their identification difficult. In virgin and recycled PP the following compounds were identified Ethylbenzene and xylene were found only in the recycled resin. Present in both virgin and recycled PP were a large number of branched alkanes and n-alkanes between Qg and C25. Octadecanoic acid, methyl ester and dibutyl palmitate, which is a typical compound used in the cosmetic industry, were found only in the recycled PP. Amines such as hexamine, 3-ethyl and NIN"N" trimethyl dipropylene triamine were identified in both PP materials. Carboxylic acids and ketones were absent in both polymeric materials and so were fragrance or flavour compounds [113]. 

As can be seen from Table 5.2, nonylphenol ethoxylates have a steeply increasing cloud point for very little addition of ethylene oxide. Most industrial products have a rounded up/down value of ethylene oxide in their nomenclature. Thus, NP9 from one company could be actually NP9.25 and from another could be NP8.75. The cloud point for these two products could be 15° C different and in some applications, such as in solubilisation of a fragrance or flavouring, this could be crucial. This is almost certainly due to the sharp (compared to alcohol-based products) Poisson isomer distribution and also variable polyethylene glycol levels in different manufacturers products. Therefore, it is suggested that product should always be purchased on a cloud point specification and not to an EO number. 

Plants and plant extracts have been used as medicine, culinary spice, dye and general cosmetic since ancient times. Plant extracts are seen as a way of meeting the demanding requirements of the modem industry. In the past two decades, much attention has been directed to the use of near critical and supercritical carbon dioxide solvent, particularly in the food pharmaceutical and perfume industries. CO2 is an ideal solvent because it is non-toxic, non-explosive, readily available and easily removed from the extracted products. At present the major industrial-scale applications of supercritical fluid extraction (SFE) are hop extraction, decaffeination of coffee and tea, and isolation of flavours, fragrances and other components from spices, herbs and medicinal plants [1-4]. 

Plants represent a very important role in human nutrition, due to the large quantities of proteins, carbon hydrates, lipids, vitamins, antioxidants and mineral salts that its can supply. Sometimes the nutritional aspect can be associated with the flavour and fragrance of the extracts producing a high value products. In recent years one can observe an increase in research for natural sources, in particular from plant matrices, of additives with application in the food, cosmetic and pharmaceutical industries. 

Alkylarylethers have pleasant odors and flavours which made them valuable for the perfume and fragrance industries. They are also important precursors of agrochemicals, pharmaceuticals, antioxidants, etc. (32). Thus, anisole which results from phenol methylation is a precursor of Parsol, a solar protector (paragraph 14.2.). Vanillin results from gai acol transformation (3, 32) ... 

In 2001 it was estimated that the world merchant market for catalysts was worth ca. US 25 billion, divided roughly equally between refining, petrochemicals, polymers, environmental (20-25% each) and with about 11% being used in fine chemicals. Refining is about the production of fuels (Chapter 3, Box 2), petrochemicals cover many of the basic commodity chemicals and the monomers required for the polymer industries fine chemicals include pharmaceuticals and agrochemicals, as well as flavours and fragrances and environmental is about exhaust gas and waste product clean-up. Vehicle catalytic converters use catalysts, as does the production of the main tonnage polymers polyethylene, polypropylene, polystyrene, polyvinyl chloride and polyethylene terephthalate. 

The smell and taste of plants rely on aroma and fragrance compounds, many of which (besides fhe terpenoids) are derived from phenylpropanoid metabolism. In food and cosmetic industry, such fragrance and aroma compounds play an important economical role. Simple phenolic fragrance compounds are, e.g., eugenol, isoeugenol or (methyl)chavicol (Fig. 4.2), the biosynthesis of which has been clarified recently more complex compounds are phenolic esters. Evolutionary aspects of the bios)mthesis of flavours and scents have been reviewed by Gang (2005). 

They are widely used in the perfumery and cosmetics industry, as flavour and fragrance materials in the food industry as pharmacological substances and many others. 

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