Aroma compounds extracts

Gascons VF, Souchon I, Athes V, and Martin M, Air stripping membrane contactor applied to aroma compounds extraction Influence of heat and water transfers on aroma transfer. Euromembrane 2004, Hamburg, Germany, September 28-October 1, 2004. 

Accurate quantification is not straightforward as the amounts of different aroma compounds extracted are related to their partition ratio between the food and its headspace. Stable isotope dilution analysis using a labeled internal standard can be used [7]. 

Ultrafiltration of heterogenous colloidal suspensions such as citrus juice is complex and many factors other than molecular weight contribute to fouling and permeation. For example, low MW aroma compounds were unevenly distributed in the permeate and retentate in UF in 500 kd MWCO system (10). The authors observed that the 500 kd MWCO UF removed all suspended solids, including pectin and PE. If PE is complexed to pectate in an inactive complex, then it is conceivable that release of PE from pectin with cations will enhance permeation in UF. At optimum salt concentration, less PE activation was observed at lower pH values than at higher pH (15). In juice systems, it is difficult to separate the effect of juice particulates on PE activity. Model studies with PE extracts allows UF in the absence of large or insoluble particulates and control of composition of the ultrafilter. In... 

Bianchi, F., Careri, M., and Musci, M. (2005). Volatile norisoprenoids as markers of botanical origin of Sardinian strawberry-tree (Arbutus unedo L.) honey Characterisation of aroma compounds by dynamic headspace extraction and gas chromatography-mass spectrometry. Food Chem. 89,527-532. 

Aroma compounds, 11 517 Aroma extract dilution analysis (AEDA), 11 519-520... 

Pharmaceuticals are only a part of natural products derived from filamentous organisms. Filamentous fungi are also grown industrially for the production of natural products other than pharmaceuticals. Organic acids such as citric, itaconic and gluconic acids, carotenoids, taste and aroma compounds, and a variety of industrial enzymes such as amylases, lipases, dextranases and proteases are also extracted from these fungi. 

Pectinases and (3-glucanases are the only enzymes allowed in wine-making by European legislation. They are used as clarification and filtration agents and also to release aroma compounds that are mostly present in grape as nonvolatile glycosidic precursors. Pectolytic enzymes are also reported to increase extraction of phenolic compounds and wine color... 

The resinoids described above should be distinguished from prepared oleoresins (e.g., pepper, ginger, and vanilla oleoresins), which are concentrates prepared from spices by solvent extraction. The solvent that is used depends on the spice currently, these products are often obtained by extraction with supercritical carbon dioxide [223a]. Pepper and ginger oleoresins contain not only volatile aroma compounds, but also substances responsible for pungency. 

Aroma compounds of fresh banana from different countries (Martinique, Canary Islands, and Cote d Ivoire) were examined using the same extraction technique. As expected, differences in aroma composition were detected in the fruits of different origins. Isoamyl alcohol, isoamyl acetate, butyl acetate, and elemicine were detected by olfactometric analyses as characteristics of banana odour [7]. 

Volatile constituents of cupuacu were isolated by steam distillation-extraction of pulp or juice [2].The identification of volatile constituents was based on mass spectral analysis. The pleasant aroma compounds were mainly esters (Fig. 8.2). Targe amounts of ethyl butanoate and small amounts of ethyl acetate, butyl acetate, and butyl isobutanoate were described. 

More recently, several aroma compounds were isolated from cupuacu pulp by vacuum distillation, solid-phase extraction, and simultaneous steam distil-lation-extarction and were analysed by GC, GC-MS, and GG-O [8]. The olfaction of the extracts obtained by solid-phase extraction indicated linalool, a-ter-pineol, 2-phenylethanol, myrcene, and limonene as contributors of the pleasant floral flavour. In this study, the esters ethyl 2-methylbutanoate, ethyl hexanoate, and butyl butanoate were involved in the typical fruity characteristics. 

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. 

Aroma compounds in distilled spirits and liqueurs, their levels, odour attributes, and thresholds are most important for quality and authenticity. Using gas chromatography and mass spectrometry, especially the composition of volatile aroma compounds in distilled spirits has been widely investigated [4-8]. By direct injection of an alcoholic distillate it is possible to determine more than 50 components within levels between 0.1 and 1,000 mg L b special methods of extraction can be used to increase this number up to more than 1,000 volatile substances [6]. However, sensory analysis is still indispensable to describe and evaluate spirit drinks. 

Fig. 18.1 Systems used to absorb aroma compounds from samples for analytical purposes, a Traps loaded with various adsorbents [4]. b Solid-phase extraction (disk in a holder assembly) [5]. c Solid-phase microextraction (coated needle inserted in sample) [5]. d Twister (1 -cm length) [4]. (Courtesy of GERSTEL GmbH and Co. KG)...

In terms of specificity in isolation, one will also isolate food constituents that are not aroma compounds (e.g. pesticides, herbicides, PCBs, plasticisers, and some antioxidants). Since these compounds are typically present in foods at very low levels, they generally present few complications. The primary volatile that complicates the application of this methodology is water. In all cases, one obtains an aroma isolate that consists of volatiles in an aqueous solution . Thus, unless the amount of water is small and the subsequent analytical step is tolerant of some water, volatility-based techniques must include some water-removal process. This may be freeze-concentration, the addition of anhydrous salts, or solvent extraction. Distillation is often used to isolate aroma compounds from fat-containing foods. Since fat is not volatile (under isolation conditions), its presence does not prohibit the use of this methodology. 

Solvent extraction is an excellent choice for aroma-compound isolation from foods when applicable. Unfortunately, many foods contain some lipid material, which limits the use of this technique since the lipid components would be extracted along with the aroma compounds. Alcohol-containing foods also present a problem in that the choice solvents (e.g. dichloromethane and diethyl ether) would both extract alcohol from the product, so one obtains a dilute solution of recovered volatiles in ethanol. Ethanol is problematic since it has a high boiling point (relative to the isolated aroma compounds), and in concentration for analysis, a significant proportion of aroma compounds would be lost with the ethanol. As one would expect, the recovery of aroma compounds by solvent extraction is dependent upon the solvent being used, the extraction technique (batch or continuous), and the time and temperature of extraction. 

Adsorption (or absorption) involves passing an aroma-laden liquid (or gas) stream through a bed of adsorbent. Assuming that the adsorbent has a significant affinity for the aroma compounds of interest, they will be adsorbed onto the bed and concentrated. While for analytical purposes the bed is commonly thermally desorbed, it is more likely to be solvent-extracted in this application to recover the trapped volatiles. 

As mentioned in the introduction to this section, there is the opportunity to recover aroma compounds from baking or roasting exhaust gases. The patent literature contains numerous references to the recovery of aroma compounds using this approach, most commonly from cocoa, coffee, or tea processing. Aroma compounds from the roaster exhaust gases are either condensed in cryogenic traps [29-32] or collected on absorbents (e.g. charcoal [33]) and then solvent-extracted to obtain a concentrated aroma extract. The concentrated extract may be used to aromatise a similar product (e.g. soluble coffee) or may be used to flavour other products (e.g. coffee-flavoured ice creams). 

Recovery of aroma compounds from diluted aqueous streams (we are excluding from this discussion the recovery of aromas from vapour streams) may be of industrial interest under different circumstances recovery of complex aroma profiles and/or target aroma compounds from active biocatalytic processes recovery of complex aroma profiles and/or target aroma compounds from natural extracts and industrial process water (or effluent) streams. 

The world of aroma compounds is becoming more and more complex. In the early days people used aromatic products like fruit juices or fruit juice concentrates which were relatively weak and still close to the related foodstulf. Later, with more knowledge of separation techniques, infusions, extracts, oleoresins and absolutes ranging from weak to strong impact were used to impart aroma. Essential oils such as spice oils already had a very strong impact. Modern analytical technologies allowed the evaluation of the chemical compositions of extracts and essential oils, so that isolates either as powerful mixtures or even as single compounds could be obtained. 

Besides the structural elucidation of glycosides, research is focused on the application of glycosidases to liberate the aroma-active aglycons from their bound forms. The development of a continuous process of enzymatic treatment (simultaneous enzyme catalysis extraction) [50] opened the doors for the industrial large-scale production of aroma compounds from their non-volatile conjugates. 

Flavorzyme is a commercially available proteolytic enzyme preparation by Novo Nordisk Bioindustrials. It can be used to obtain a meat-like process flavouring from defatted soybean meal. With the help of aroma extract dilution analysis, Wu and Cadwallader [61] showed in their study of 2002 the presence of key aroma compounds of roasty, meat-like aroma in the enzymatically hydrolysed and heated hydrolysed protein, e.g. maltol, furaneol, methanethiol and furanthiol derivatives. 

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