Steam distillation and extraction

Manzan, A.C. et al.. Extraction of essential oil and pigments from Curcuma longa [L] by steam distillation and extraction with volatile solvents, J. Agric. Food Chem., 51, 6802, 2003. 

Bierl [28] has described a procedure based on the micro-steam distillation and extraction technique for recovery and determination of low and medium-boiling chlorinated organic compounds. Recoveries of around 90%... 

D. Phenylpropargyl aldehyde. Twenty-nine grams (0.14 mole) of the acetal is added to 140 ml. of water containing 10 ml. of concentrated sulfuric acid, and the mixture is heated on a steam bath with occasional shaking for 30 minutes. The aldehyde is then steam-distilled and extracted from the distillate with two 250-ml. portions of ether. The ethereal solution is dried over 20 g. of anhydrous sodium sulfate, the solvent is removed, and the residue is distilled from a 100-ml. modified Claisen flask. The yield of phenylpropargyl aldehyde boiling at 114—117°/17 mm. and with 1.6032 is 13-15 g. (70-81%). 

A mixture of 2 mH (230 mg) of proline and 2 mM of various sugar or phosphate ester mixtures dissolved in 400 ml of distilled water was continously steam distilled and extracted according to (2). 

Cashew kernels possess pleasant taste and flavor and are eaten either raw or roasted with salt. The raw nuts, which are packed in flexible packages, are usually marketed as plain cashews. The roasted nuts are usually fried in vegetable oil to light brown colour, salted and packed in cans. The flavor characteristics of plain cashew nuts are enhanced as a result of oil roasting. A literature review revealed that the flavor constituents of plain or roasted cashew nuts have not been investigated previously. In the present study, the authors have attempted to isolate the flavor compounds by steam distillation and extraction and to identify them by GC and GC-MS techniques. Thirty six compounds have been identified for the first time. 

Wils et al. (25,26) previously reported an entirely different approach to TDG analysis. TDG in urine was converted back to sulfur mustard by treatment with concentrated HC1. The sample treatment is less straightforward than the methods described above, but analysis as sulfur mustard is facile. Urine, plus 2H8-TDG as internal standard, was cleaned up by elution through two C18 cartridges. Concentrated HC1 was added and the sample stirred and heated at 120 °C. Nitrogen was blown over the solution and sulfur mustard isolated from the headspace by adsorption onto Tenax-TA. The method was used to detect TDG in urine from casualties of CW attacks (see below). A disadvantage of this method is that it may convert metabolites other than TDG to sulfur mustard. This is supported by the detection of relatively high levels of analytes in urine from control subjects. Vycudilik (27) used a similar procedure, but recovered the mustard by steam distillation and extraction. 

The dividing line between natural and synthetic materials is far from clear-cut. The very basis of the distinction is questionable, since it assumes that no chemical changes occur in the course of processes such as steam distillation and extraction. It has long been known that this assumption is not correct. In addition there are gray areas between the two categories that can best be demonstrated by a few examples. 

Simultaneous Steam Distillation/Extraction An elegant apparatus was described by Nickerson and Likens ( 5) for the simultaneous steam distillation and extraction (SDE) of volatile components. This device has become one of the mainstays in the flavor field. In this apparatus, both the aqueous sample and water-immiscible solvent are simultaneously distilled. The steam which contains the aroma chemicals and the organic solvent are condensed together, and the aroma compounds are transferred from the aqueous phase to the organic phase. Typical solvents used are diethyl ether, pentane or a mixture thereof normal extraction times are one to two hours. 

Identified by Gianturco et al. (1966) in an aroma complex of coffee, and by Stoffelsma et al. (1968) after steam-distillation and extraction. Found also by Ho et al. (1993) in headspace of roasted coffee (0.17 ppm). 

Kato, K. Yoshimura, Y. Ito, Y. Oka, H. Nakazawa, H. Preparation of samples for gas chromatography/mass spectrometry analysis of phthalate and adipate esters in plasma and beverages by steam distillation and extraction. AO AC Int. 2002, 85, 719. 

Aromatic alcohols are insoluble in water and usually burn with a smoky flame. Their boiling points are comparatively high some are solids at the ordinary temperature. Many may be oxidised by cautious addi-tion of dilute nitric acid to the corresponding aldehyde upon neutralis-tion of the excess of acid, the aldehyde may be isolated by ether extraction or steam distillation, and then identified as detailed under Aromatic Aldehydes, Section IV,135. 

Neutralise the cold contents of the flask with 500-600 ml. of 40 per cent, aqueous sodium hydroxide solution, equip the flask for steam distillation and steam distil until about 1 litre of distillate is collected. The steam distillate separates into two layers. Add solid sodium hydroxide (< 100 g.) to complete the separation of the two layers as far as possible. Remove the upper (organic) layer and extract the aqueous layer with three 50 ml. portions of chloroform. Dry the combined organic layer and chloroform extracts with anhydrous potassium carbonate and distil the mixture through a short fractionating column (e.g., an 8 Dufton column) after a fore run of chloroform, followed by pyridine, collect the crude 4-ethylpyridine at 150-166° (49 g.). Redistil through a Fenske-... 

Aroma Distillate. Used by the flavor industry, aroma distillates are the product of continuous extraction of the plant material with alcohol at temperatures between ambient and 50°C followed by steam distillation, and, lastly, concentration of the combined hydro—alcohoHc mixture. On cooling, terpenes often separate from the aroma distillate and are removed. 

The sesquiterpenes found in essential oils have low volatilities compared with monoterpenes and so are isolated mainly by steam distillation or extraction, but some are also isolated by distillation or crystallization. Most of the sesquiterpene alcohols are heavy viscous Hquids and many crystallize when they are of high enough purity. Sesquiterpene alcohols are important in perfume bases for their odor value and their fixative properties as well. They are valuable as carriers of woody, balsamic, or heavy oriental perfume notes. 

Essential Oils. Volatile oils from plants are referred to as essential oils. The oils can be obtained through steam distillation, solvent extraction, or separation of the oils from pressed fmit. They consist of oxygenated compounds, terpenes, and sesquiterpenes. The primary flavor components of essential oils are oxygenated compounds. Terpenes contain some flavors but are often removed from the essential oil because they are easily oxidized (causiag off-flavors or odors) and are iasoluble. Essential oils are prepared from fmits, herbs, roots, and spices. 

The common methods of purification, discussed below, comprise distillation (including fractional distillation, distillation under reduced pressure, sublimation and steam distillation), crystallisation, extraction, chromatographic and other methods. In some cases, volatile and other impurities can be removed simply by heating. Impurities can also sometimes be eliminated by tbe formation of derivatives from which the purified material is regenerated (see Chapter 2). 

Purification as their N-acetyl derivatives is satisfactory for primary, and to a limited extent secondary, amines. The base is refluxed with slightly more than one equivalent of acetic anhydride for half to one hour, cooled and poured into ice-cold water. The insoluble derivative is filtered off, dried, and recrystallised from water, ethanol, aqueous ethanol or benzene (CAUTION toxic ). The derivative can be hydrolysed to the parent amine by refluxing with 70% sulfuric acid for a half to one hour. The solution is cooled, poured onto ice, and made alkaline. The amine is steam distilled or extracted as above. Alkaline hydrolysis is very slow. 

Gum turpentine is obtained from wounding living trees to get an exudate containing turpentine and rosin. Turpentine is separated from the rosin by continuous steam distillation and further fractionation. Wood turpentine comes from the extraction of stumps of pine trees using naphtha, and subsequent separation of rosin and turpentine by fractional distillation. Tail-oil turpentine is a byproduct of the Kraft sulphate paper manufacture. Terpenes are isolated from the sulphate terpentine and separated from the black digestion liquor. The composition of turpentine oils depends on its source, although a-pinene and p-pinene are the major components. 

To prepare heliotropin from isosafrol (which results from the isomerisation of safrol with alkalis), 5 parts of isosafrol are treated with a solution of 25 parts of potassium bichromate, 38 parts of cioncentrated sulphuric acid, and 80 parts of water. The reaction product is steam distilled and the distillate is extracted with ether, and the heliotropin obtained is purihed by means of alkaline bisulphite in the usual manner. 

Ionic liquids have been described as designer solvents [11]. Properties such as solubility, density, refractive index, and viscosity can be adjusted to suit requirements simply by making changes to the structure of either the anion, or the cation, or both [12, 13]. This degree of control can be of substantial benefit when carrying out solvent extractions or product separations, as the relative solubilities of the ionic and extraction phases can be adjusted to assist with the separation [14]. Also, separation of the products can be achieved by other means such as, distillation (usually under vacuum), steam distillation, and supercritical fluid extraction (CO2). 

A1C1, (0.8 g, 6 mmol) was added to a solution of the chloride 1 (1.6 g, 5.2 mmol) and a nitrile (6 mmol) in 1,2-dichlorobenzene and the mixture was heated at 120-130 C for 20 min. The mixture was cooled, made alkaline with dil aq NaOH and extracted with Et20. The solvents were removed by steam distillation and the residue was chromatographed (silica gel. EtOAc/petroleum ether 1 9) to give the yellow product (deep red if R = Ar). 

In 1976, Meluch and Campbell at General Motors obtained a patent10 for a steam hydrolysis depolymerization of PUR. High-pressure steam hydrolyzes flexible PUR foams rapidly at temperatures of 232-316°C to form diamines and polyols. The diamines are distilled and extracted from the steam and the polyols are obtained from the hydrolysis residue. In 1977, Bayer AG obtained a patent for a continuous PUR hydrolysis process using a specially designed extruder.11... 

Shen, S. et al.. Comparison of solid-phase microextraction, supercritical fluid extraction, steam distillation, and solvent extraction techniques for analysis of volatile consituents in Fructus amomi, J. AOAC Int., 88, 418, 2005. 

In liquid-solid extraction (LSE) the analyte is extracted from the solid by a liquid, which is separated by filtration. Numerous extraction processes, representing various types and levels of energy, have been described steam distillation, simultaneous steam distillation-solvent extraction (SDE), passive hot solvent extraction, forced-flow leaching, (automated) Soxh-let extraction, shake-flask method, mechanically agitated reflux extraction, ultrasound-assisted extraction, y -ray-assisted extraction, microwave-assisted extraction (MAE), microwave-enhanced extraction (Soxwave ), microwave-assisted process (MAP ), gas-phase MAE, enhanced fluidity extraction, hot (subcritical) water extraction, supercritical fluid extraction (SFE), supercritical assisted liquid extraction, pressurised hot water extraction, enhanced solvent extraction (ESE ), solu-tion/precipitation, etc. The most successful systems are described in Sections 3.3.3-3.4.6. Other, less frequently... 

Applications Simultaneous steam distillation-solvent extraction has been in use for many years [163]. Steam distillation combined with continuous liquid extraction is an efficient technique for the removal and isolation of volatile compounds in various matrices (environmental,... 

---