Flavourings continued

The plant cell culture technique of micropropagation of flavour-producing plants will be able to help with their agricultural cultivation and will relieve the pressure on the wild populations. Micropropagation will be able to propagate those plants where conventional propagation is difficult or will be to multiply elite stock. This may be required if demand for natural flavours continues to increase. 

Additionally, strong increases are predicted for ethnic offerings in meals. Seasonings remain spicy, new beverage flavours come from a variety of sources, and children s flavours continue to be popular. 

Like enzymes, whole cells are sometime immobilized by attachment to a surface or by entrapment within a carrier material. One motivation for this is similar to the motivation for using biomass recycle in a continuous process. The cells are grown under optimal conditions for cell growth but are used at conditions optimized for transformation of substrate. A great variety of reactor types have been proposed including packed beds, fluidized and spouted beds, and air-lift reactors. A semicommercial process for beer used an air-lift reactor to achieve reaction times of 1 day compared with 5-7 days for the normal batch process. Unfortunately, the beer suffered from a mismatched flavour profile that was attributed to mass transfer limitations. 

The restricted shelf life of liquid milk continues to be a problem that is often more influenced by the type of milk being sold rather than the pasteurisation technique. The shelf life of processed milk is determined primarily by the quality of the raw milk from the dairy herd. Increasing cell counts in the milk and a higher concentration of free fatty acids, contribute to rancidity in both liquid milk and milk products. Janzen (1972) reported that the 0-14 day shelf life of pasteurised milk is influenced by the somatic cell concentration in the raw milk and found that after 14 days any observed changes in the flavour and stability of the milk were attributable to microbial activity during storage. 

The application of ever improving analytical methods will continue to reveal new flavouring compounds, be they natural, nature identical or synthetic. Not only are ever more sophisticated analytical techniques available but also improved methods of data analysis. The new science of chemometrics has developed to cope with the situation where chromatograms with hundreds of compounds are obtained. 

Table 7.2 (continued) Key flavour compounds in stone fruits (Prunus spp.)... 

The aroma compounds from the tropical fruits described in this chapter can be very important for consumers and industry as they are exotic and extremely pleasant however, the production of these compounds by biotechnological processes should be emphasised since the extraction from the fruits is a hard task. Many tropical soils contain less nitrogen and phosphorus, have lower capacity to absorb fertilisers, and therefore have lower conventional productive capacity, but some tropical soils have been very intensively farmed and further intensification is possible in other areas. Thus, the evaluation of a sustainable agriculture in tropical regions requires a sophisticated approach including the estimation of the risk of microbial or insect infestations. As many fruits go directly to fresh markets or to immediate processing, a continuing supply of the flavour manufacturers in the future is not completely assured. 

Table 11 (continued) Simimary of most important aroma compounds in wine, excluding off-flavours, and the impact of grapes and microorganisms (modified according to [ 11 ])... 

An aliquot of the extract which was used for the first GC-O experiment is diluted with the solvent, usually as a series of 1+1 or 1+2 dilutions and each dilution is analysed by GC-O. This means that in each GC run the assessor records the retention time of each odour along with a descriptor of that odour. This procedure is continued until no odorants are perceivable. The highest dilution at which a compound can be smelled is defined as its flavour dilution (ED) factor. The ED factor is a relative measure, and is proportional to the OAV of the compound in air. 

Esters also constitute a group of important flavour compounds. They are the main aroma components found in fruits (apples, pears,. ..). For example, bananas contain 12-18 ppm acetates. The price of the pure flavour compounds, when isolated from fruit, can range between 10,000 and 100,000 US /kg In the past, research has been carried out by our group about the microbial production of fruity esters by the yeast Hansenula mrakii and the fungus Geotrichum penicillatum [10]. A fermentation was developed whereby fusel oil was continuously converted into a mixture of 3-methylbutyl acetate (isoamyl acetate) and 2-methylbutyl acetate, the character impact compounds of banana flavour. 

New product development is a constant activity for most soft drinks producers. For the most part there are few really new products alternative flavours and different forms of packaging are widespread and no doubt will continue to be so. 

A soft extract is produced initially as a liquid extract but the concentration stage is continued until the resultant extract has the moisture content of 30% or less. The extract has the texture of a thick paste or viscous syrup and is usually dark brown in colour and often caramelised in flavour. 

Soft drinks and fruit juices are produced in almost every country in the world and their availability is remarkable. From the largest cities to some of the remotest villages, soft drinks are available in a variety of flavours and packaging. The market for these products also continues to show a remarkable potential for growth. For example, the UK market alone showed an increase in consumption of some 7% in 2003 (over 2002) and, in the ten years since 1993, this same market grew from a consumption of around 9 billion litres to around 14 billion litres in a full year. 

---