Likens-Nickerson apparatus

McGill, A.S. and Hardy, R. 1977. Artefact production in the Likens-Nickerson apparatus when used to extract the volatile flavourous components of cod. J. Sci. Food Agric. 28 89-92. 

As was mentioned earlier, distillation and subsequent solvent extraction remains popular in the aroma research area Q). In this method for aroma analysis, the Likens-Nickerson apparatus has been a standard for over 20 years (17, 18). The primary limitation of the Likens-Nickerson distillation/ extraction procedure has been its operation at reduced pressure. It is desirable to operate the system under vacuum in order to reduce the sample boiling point to minimize the formation of thermally induced artifacts. The fact that the solvent side of the distillation-extraction apparatus is also under vacuum makes it difficult to retain the solvent in the apparatus. Even modifications of the apparatus to include a dry ice/acetone condenser followed by a liquid nitrogen trap do not permit easy operation under vacuum. Problems arise in that the solvent or aqueous vapors reach the cryogenic traps, thereby eventually blocking the exit of the condenser. The need to minimize exposure of the sample to heat has resulted in the more frequent use of two step procedures. Very often, the sample is simply placed in a flash evaporator, a certain volume of distillate collected and the distillate is solvent extracted via either separatory funnel or a continuous extractor. In this manner, the distillation process and solvent choice are not conflicting processes. 

The simultaneous combination of steam distillation and solvent extraction, usually implemented by a Likens-Nickerson apparatus or its analogues, has also been widely used for the isolation of essential oil. The chemical composition of such essential oils will be analysed by GC-MS [40]. 

The SDK procedure was performed using a micro-version of a Likens-Nickerson apparatus [33] in the configuration for heavier-than-water solvents. The aroma components were extracted by steam distillation and the aqueous distillate was simultaneously extracted with dichloromethane. The organic extracts were analyzed by GC-FID and GC-MS. The DHS technique was carried out with adsorption on Tenax traps and thermal desorption with ctyofocusing of the volatile substances into the GC capillary column. 

DS Mottram, DJ Puckey. Artefact formation during the extraction of bacon volatiles in a Likens-Nickerson apparatus. Chem Ind 1978 385-386, 1978. 

A good example of the effect of pH98 is that observed on a xylose-lysine model system (1 M each, refluxed 1 h with diethyl ether in a Likens and Nickerson apparatus, initial pH 4.9, either kept at pH 5 with NaOH additions or left, when the final pH is 2.6) 54 and 28 volatiles were identified, respectively, 2-furaldehyde dominating with 52.2 and 99.9% (w/w). Total yield and number of nitrogen-containing compounds were greater at higher pH values of the former system, and monocyclic pyrroles, pyridines, and 2,3-dihydro-lH-pyrrolizines were identified only in that system. 

Frequently, steam distillation is combined with solvent extraction to obtain a more complete oil balance. The technique uses a Likens-Nickerson-type apparatus to isolate the oil as it is removed from the substrate, minimizing contact of the oil with the hot water [29]. Thermal artifact formation, though significantly reduced, is not completely eliminated by this technique [27]. A modification of the technique uses vacuum conditions to isolate the volatiles, thereby reducing the operating temperature to between 20°C and 40°C. It appears that this procedure more effectively eliminates some of the more commonly observed artifacts [30]. 

Alliin and deoxyalliin, two important nonvolatile flavor precursors of garlic, were reacted separately with inosine-5 -monophosphate (IMP) in an aqueous solution at pH 7.5 in a closed sample cylinder at 180 °C for one hour. The volatile compounds generated were isolated by using a modified Likens-Nickerson (L-N) distillation-solvent extraction apparatus, and analyzed by GC and GC-MS. 

Isolation of the Volatile Compounds. The total reaction mass was simultaneously distilled and extracted into diethyl ether using a Likens-Nickerson (L-N) apparatus. After distillation, 5 ml of heptadecane stock solution (0.0770 g in 200 ml diethyl ether) was added to the isolate as the internal standard. After drying over anhydrous sodium sulfate and filtering, the distillate was concentrated to about 5 ml using a Kudema-Danish apparatus fitted with a Vigreaux distillation column. It was further concentrated under a stream of nitrogen in a small sample vial to a final volume of 0.2 ml. 

Volatile compounds of garlic were collected using a Liken-Nickerson steam distillation and solvent extraction apparatus (Romer and Renner, 1974). The volatile compounds were determined using gas chromatography and then further examined by GC-MS. The... 

Steam distillation may be accomplished in several ways. The product may simply be put in a rotary evaporator (if liquid, or initially slurried in water if solid) and a distillate collected. This distillate would be solvent extracted to yield an aroma isolate suitable for GC analysis. The most common steam distillation method employs Simultaneous Distillation/Extraction (SDE may be called a Likens-Nickerson method). This is one of the oldest and most popular methods for obtaining aroma isolates. Chaintreau [31] has provided a very good review of this method and its evolution. An atmospheric pressure system is shown in Figure 3.4 (bottom). Vacuum systems must have joints that are air-tight, and all parts of the apparatus must be under rigid temperature control. 

An extraction combined with distillation can be achieved using an apparatus designed by Likens-Nickerson (Fig. 5.6). 

This chapter reviewed techniques that involve distillation and extraction procedures. These have the advantage of being simple and rapid, and they do not require a complex apparatus. For typical food products some version of the Likens-Nickerson distillation apparatus is probably the technique of choice for lipid materials, some high-vacuum distillation procedure is worth investigating initially. 

Different apparatus designs were proposed by several authors (Likens and Nickerson,... 

Flavor Extraction and Concentration. The apparatus used for the steam vacuum stripping consisted of a Nickerson-Likens extractor as modified by Schultz et al. (2). The sample/water slurry was maintained at a boil of 57-60°C (600-610 itm gauge pressure) for one hour. During this time, approximately 200 mL of water vapor and flavor volatiles vaporized, condensed, and were collected in the 250 mL flask. A needle-valve was attached to a glass tube in the second neck of the sample flask to admit a controlled stream of charcoal filtered air through the sample for even boiling under vacuum. 

A recently introduced microversion of the Likens and Nickerson SDE apparatus has been shown to be able to analyze polychlorinated biphenyls [ 41 ] and fatty acids [45 ] in aqueous samples. It has further been improved and studied for use with different kinds of solvents [42. ]. 

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. 

Isolation of volatile compounds by simultaneous steaia distillation-hexane extraction (SDE) Frozen burley tobacco stalks (1-4 kg) were cut perpendicular to the main axis into 0.5-cra sections and placed in a 12-L flask with 4 L of distilled water. The flask contents were steam distilled for 4 h in a continuous extraction apparatus of the type described by Likens and Nickerson... 

Microversions of the distillation-extraction apparatus, described by Likens and Nickerson, have also been developed as well for high-density (Godefroot et al., 1981) and low-density solvents (Godefroot et al., 1982). The main advantage of these techniques is that no further enrichment by evaporation is required for subsequent gas chromatographic investigation. 

Fig. 5.6. Apparatus according to Likens and Nickerson used for simultaneous extraction and distillation of volatile compounds.

Many foods contain components that are thermo-sensitive or labile and are changed by the application of heat resulting in artefact formation. One of the most commonly used extraction methods is simultaneous distillation-extraction (SDE). This method was first proposed by Likens and Nickerson in 1964 (16). Due to the high temperature used in atmospheric SDE, thermal artefacts may be generated during the extraction process and thus vacuum SDE systems have been developed to overcome the generation of thermal artefacts. One of the more recent vacuum SDE systems was developed by Maignial et al (10). This Static Vacuum SDE apparatus is an "easy-to-use device to isolate volatile... 

One of the most popular and valuable techniques in the flavor analysis fleld is the simultaneous steam distillation/extraction (SDE) apparatus first described by Likens and Nickerson (17). The apparatus provides for the simultaneous condensation of the steam distillate and an immiscible organic solvent. Both liquids are continuously recycled, and thus the steam distillable-solvent soluble compounds are transferred from the aqueous phase to the solvent. The advantages of this system include the following ... 

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