Extraction supercritical fluid, flavors

Supercritical fluid extraction (SFE) has been widely used to the extraction processes in pharmaceutical industries. Besides application of SFE in phannaceuticals, it has been applied on a wide spectmm of natural products and food industries such as natural pesticides, antioxidants, vegetable oil, flavors, perfumes and etc [1-2]. 

Supercritical fluid extraction — During the past two decades, important progress was registered in the extraction of bioactive phytochemicals from plant or food matrices. Most of the work in this area focused on non-polar compounds (terpenoid flavors, hydrocarbons, carotenes) where a supercritical (SFE) method with CO2 offered high extraction efficiencies. Co-solvent systems combining CO2 with one or more modifiers extended the utility of the SFE-CO2 system to polar and even ionic compounds, e.g., supercritical water to extract polar compounds. This last technique claims the additional advantage of combining extraction and destruction of contaminants via the supercritical water oxidation process."... 

Another processing procediue that could involve supercritical fluid extraction with CO2 is the preparation of flavor concentrates from meat lipids for use in mixtures of other natural precursors for the preparation of tynthetic meat flavor additives that serve bofii as antioxidants that prevent warmed-over flavor (WOF) in cooked meat diuing storage and enhance the flavor of the natural products. 

Classical sample preparation methods such as distillation, soxhlet extraction are still used [839, 840], but specific techniques such as supercritical fluid extraction (SFE) [841], and increasingly in recent years, adsorption techniques such as solid phase micro-extraction (SPME) [841a] are also being used for isolation, separation, and identification of flavor and fragrance materials. 

Black pepper - [FLAVORS AND SPICES -SPICES] (Vol 11) -m carbonated beverages [CARBONATED BEVERAGES] (Vol 5) -extraction using SCFs [SUPERCRITICAL FLUIDS] (Vol 23)... 

Essential oils - [FLAVORS AND SPICES -FLAVORS] (Vol 11) - [FRUITJUICES] (Vol 11) - [OILS, ESSENTIAL] (Vol 17) - [TERPENOIDS] (Vol 23) -m carbonated beverages [CARBONATED BEVERAGES] (Vol 5) -esters m [ESTERS, ORGANIC] (Vol 9) -extraction using SCFs [SUPERCRITICAL FLUIDS] (Vol 23) -as food additive [FOOD ADDITIVES] (Vol 11) -hydroxybenzaldehydes m [HYDROXYBENZALDEHYDES] (Vol 13) -m natural resins [RESINS, NATURAL] (Vol 21) -in perfumes [PERFUMES] (Vol 18) -use m cosmetics [COSMETICS] (Vol 7)... 

S. B. Hawthorne, M. S. Krieger and D. J. Miller, Analysis of flavor and fragrance compounds using supercritical fluid extraction coupled with gas chromatography , Anal. Chem. 60 472-477 (1988). 

Based on its ability to enhance solvating power by increasing fluid density, supercritical fluid extraction offers an attractive alternative for fractionation of fats and oils. It works by the phenomena of selective distillation and simultaneous extraction, as has been shown by many researchers [3-5]. While the use of supercritical fluids in the extraction of numerous biomaterials has been reported, its commercialization has been limited to the decaffeination of coffee and tea and to the extraction of flavors from hops and spices. The chemical complexity of most food ingredients and their tendency to react and degrade at elevated temperatures, emphasize the difficulties of supercritical solvent selection. Carbon dioxide is the preferred supercritical solvent (its properties have previously been cited [6]). 

By now, nearly every chemist has had some introduction to the subject of supercritical extraction in one form or another, and it would seem that after scores of papers, newsreleases, and trade journal articles, only so much can be said about the background and early findings, the thermodynamic interactions between dissolved solutes and high pressure gases, the equations of state that can correlate and predict solubility behavior, the many applications of the technology (some of which are in flavors), the full scale coffee and hops extraction plants now in operation, etc. What, then, can a paper entitled "Supercritical Fluids - Overview and Specific Examples in Flavors Applications" give that s new -hopefully, a different development of the historical perspective... 

Some of the historical perspective is extracted (no pun intended) from a previous paper of the author ( 1 ) and is expanded with a chronological development of solubility phenomena based upon an additional compilation of recent work on naphthalene-supercritical solvent systems. The new data on flavor extraction and fractionation point out the most unique feature of supercritical fluid solvents, viz., their often-demonstrated selective dissolving power properties, a selectivity that is achieved because the dissolving power of supercritical fluids is pressure-dependent and can, therefore, be adjusted. 

Applications of Supercritical Fluids to the Extraction and Characterization of Flavors... 

In closing, this paper was not intended to represent an exhaustive process development effort in flavors extraction from natural materials nor a development of the quantitative analytical capabilities of supercritical carbon dioxide. However, even though the examples and the conditions of extraction were somewhat arbitrary, they point out some of the interesting features of the pressure dependent dissolving power properties of supercritical fluids. They can be further refined by virtue of more narrow ranges and ratios of pressure and temperature to accomplish still more narrow separations. 

Earlier, no emphasis was given to homogeneous catalysis in supercritical fluids, albeit the technique per se is now well established in extraction technology (e. g., for coffee, tea, hops, spices, and natural flavors). Incorporated in homogeneous catalyst processes [58-60], supercritical conditions can dramatically change the solubility profile of solvents and the reactivity of certain chemicals. 

In addition to extraction from solids, supercritical fluids can be used to extract aromatic molecules from liquids. Senorans et al. have utilized carbon dioxide to extract high-quality brandy aroma using a countercurrent supercritical fluid extractor. The aroma quality is influenced by the extraction conditions. Medina and Martinez studied alcohol removal from beverages using supercritical carbon dioxide, to produce beverages with low-alcohol content but sufficient flavor, because of three key benefits 1) water and salts are not appreciably removed by the carbon dioxide 2) proteins and carbohydrates are not extracted or denatured and 3) there is a good control in the aroma recovery. The alcohol removal efficiency increases with the extraction pressure raffinate alcohol concentration can be reduced up to 3 wt.% at 250 bar and 40°C, from 6.2 wt.% in the feed. " ... 

So far some very important aroma chemicals better known as flavor and fragrance chemicals used to be isolated and extracted from natural products such as essential oils, resinoids, extracts, etc. Solvent extraction, steam distillation or, more recently, supercritical fluid extraction using high pressure CO2 have been some of the important methods for isolation of the important flavor and fragrance chemicals. There is a wide range of aromatic chemicals both from natural sources or made by organic chemical synthesis which have been introduced in various finished products. They are never used in very pure form but are further formulated for specific... 

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