Flavouring Raw Materials

Furthermore unexpected interactions may disturb the perception, for example 3-methyl cyclopent-2-en-2-ol-one (corylon) has a burnt, roasted, maple and coffee like character. 

Allyl hexanoate has a sweet, fruity, candy, pineapple like character. 

The combination of 9 parts corylon and 1 part allyl hexanoate is recognized by the majority of people as spicy, celery like. 

A professional description of flavours uses as precise descriptors as possible. Chemical analytical results are combined with sensory analysis of the identified components to assess the relative importance and contribution to the flavour profile. Key ingredients or character impact compounds (CIC) are important components sine qua non to impart the typical, product characteristic, flavour, e.g. anethol for anise, eugenol for clove, 3-methyl butyl acetate for banana or ethyl butyrate to improve the juiciness of orange juice. 

The characterization and description of raw materials is reversed to the description of food flavours and it depends strongly on the individual s experience, expertise, training and vocabulary. The flavouring raw materials are best described in view of then-potential use and in analogy to peculiarities of known products of natural or commercial origin. 

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The most common method to simultaneously dry and encapsulate flavours is the spray-drying technique (Fig. 21.11). For this technology, carrier materials like maltodextrin, starch and gum arabic are dissolved in water. As a next step, the liquid flavour raw material is emulsified in this slurry. Also non-volatile flavour components can be added. The slurry is atomised and dried in a spraydrying facility. 

Submerged fermentations are mostly operated in batch processes but can also be run continuously in certain cases (continuous fermentation). Batch fermentations may last up to 10 days. Following the fermentation the flavour raw material is extracted from the fermentation broth. In industrial fermentations typically cell counts of 10-30 g/1 are obtained. For a profitable cost/efficiency relation a product yield of 20-30 g/1 has to be achieved. Aerobe fermentations require oxygen transfer rates to the fermentation broth of about 100 mmol/1 per hour. Depending on the viscosity of the media 0.75-2.5 KW stirring power has to be applied for each m of fermentation broth. 

Micro-organisms also have a potential to form fruity components like alcohols, esters, lactones, ketones and terpenes. These substances are, however, also obtainable by chemical syntheses as well as by relatively simple extraction from the natural fruit. Additionally, fermented fruit flavours in many cases are not very typical for a certain fruit species and therefore may be used only as raw materials for compounded flavours. Presumably this is the reason why the corresponding processes have not yet been transferred onto an industrial scale. This is not true for the fermentative generation of well defined single substances which may serve as natural flavour raw materials for compounded flavours (cf. chapter 3.2.1.1.2). 

Traditional flavouring raw materials are produced under rather harsh conditions heat, distillation at high temperatures, concentration, extraction. These result in the destruction of all sensitive substances. Modem flavouring raw materials are produced under controlled and careful conditions low pressure, low temperature distillation, extraction with low boiling solvents or CO2, careful selection of fresh, high quality raw materials. Therefore sensitive substances survive the production process and influence the quality with all positive (flavour profile) and negative effects (stability). 

Most of the flavors data and descriptions mentioned in this article are taken from TRM - Flavour Raw Materials by BACIS and PMP - Fragrance Raw Materials by BACIS . 

In the production of antibiotics, sufficient growth of fungi in submerged cultures has created potential sources of biomass as SCP and as flavour additives to replace mushrooms the biomass contains 50-65% protein.1,5 Production of mushroom from lignocellulosic waste seems to be a suitable and economical process since the raw material is inexpensive and available in most countries. 

Replacement of organic solvents by water may be done for environmental, cost e.g. reduction in raw materials and VOC containment costs) or technical reasons. In the flavour and fragrance industry, where the presence of even trace amounts of volatile impurities can be detected by the expert nose , significant process costs are entailed in ensuring complete removal of solvent. If reactions can be carried out in water then these additional costs can be saved. As an example geraniol can be isomerized to the important fragrance intermediates a-terpinol and linalol in water at 220 °C (Scheme 5.9). 

These can be the natural material itself one example would be pieces of vanilla pod or an extract, e.g. vanilla extract. Extracts can be prepared in several ways. One is to distil or to steam distil the material of interest. Another is to extract the raw material with a solvent, e.g. ethyl alcohol. Alternatively, some materials are extracted by coating the leaves of a plant with cocoa butter and allowing the material of interest to migrate into the cocoa butter. These techniques are also used in preparing perfumery ingredients, indeed materials like orange oil are used in both flavours and perfumes. 

The major component of whey is lactose, and while there various uses for the protein in making protein concentrates these leave a surplus of lactose. Impure grades of lactose have been available to the food industry for some time. They are relatively successful in biscuits as a raw material for the Maillard reaction to produce pleasant colours and flavours. 

Essential oils occur mainly in aromatic plants. A few of them are found in animal sources, e.g. musk, civet and sperm whale, or are produced by microorganisms [1, 3, 6, 23, 25, 26, 29-33]. The Council of Europe describes essential oil as a product obtained from vegetable raw material [27]. Owing to a ban on animal-based flavour and fragrance materials, essential oils of trade are entirely of plant origin... 

Flavour of Spirit Drinks Raw Materials, Fermentation, Distillation, and Ageing... 

Table 10.1 gives a summary of the main by-products of fermentation by yeasts and other microbiological activities which can be identified in distilled spirits from different raw materials, like fruits, wine, grain, sugar cane, or other carbohydrate-containing plants. Since the sensory relevance of a flavour compound is related to its odour thresholds and odour quality. Table 10.1 presents also odour qualities and a review of threshold values of the fermentation by-products in ethanol solutions [9-10] and/or water [11-14] (Christoph and Bauer-Christoph 2006, unpublished results). 

Some of the volatile substances which are produced during fermentation, like acrolein, diacetyl, 2-butanol, allyl alcohol, or acetic acid, are a result of enhanced microbiological activities and may cause an unpleasant flavour (off-flavour) at certain levels thus, elevated concentrations of such compounds are markers for spoilage of the raw material, negative microbiological influences during or after the fermentation process, or a poor distillation technique. 

Table 10.2 presents a summary of odour qualities, odour thresholds in water, and concentrations of some selected volatile compounds, which are characteristic flavour impact compounds, owing to their typical flavour quality and their rather low odour thresholds. These compounds are not formed during fermentation but originate from the raw material and contribute significantly to the typical flavour of a fruit. The components summarised in Table 10.2 are important compounds in wine and different fruits and are discussed later. 

Distilled spirits are produced from different fermented plant materials grown all over the world. The most important criteria of quality and authenticity of each type of distilled spirits are the typical flavour composition originating from the raw material and/or the special techniques of fermentation, distillation, and ageing. In the following sections, specific flavour compounds and flavour-related technologies as well as peculiarities of the most important categories of distilled spirits are summarised. 

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