Drying methods, plant material

Many t)q)es of extraction procedures have been employed for the extraction of ginsenosides from fresh or dry ginseng plant material as well as from ginseng preparations. Characteristic for most of the extraction methods is the use of methanol or ethanol or different aqueous mixtures of these two solvents, which also clearly enhance the extraction performances of these compounds compared with pure methanol or ethanol at room temperature (Anderson and Burney, 1998 Christensen et ah, 2006 Euzzati, 2004 Lou et ah, 2006a). In order to enhance the recovery of... 

Trituration is the grinding of dried materials in a mortar with a pestle or adding Extracts to an inert powder. Powders are a favored type of poison among professionals. They easy to manufacture and dose, relatively easy to store and simple to administer in food or beverages. Dry powders can also be placed inside empty capsules made from a gelatin that dissolve in liquid. This method is preferred when time isn t an issue, since the drying of plant material takes some time. 

The methods for isolation of steroid saponins are similar to those of triterpenoid saponins. Since glycosides, as a class, are particularly prone to enzymatic or microbial degradation, processing of plant material needs to be started soon after collection to avoid delays. Air-dried powdered plant material is defatted and then extracted, either with cold or hot methanol or ethanol or with 50% aqueous ethanol or methanol at ambient temperature. Usually the extract is concentrated at reduced pressure, macerated with water, and partitioned successively using ethyl acetate and re-BuOH. Most of the saponin constituents are found in the n-BuOH soluble fraction. However, highly polar glycosides may be found in the aqueous layer. 

Various extraction methods for phenolic compounds in plant material have been published (Ayres and Loike, 1990 Arts and Hollman, 1998 Andreasen et ah, 2000 Fernandez et al., 2000). In this case phenolic compounds were an important part of the plant material and all the published methods were optimised to remove those analytes from the matrix. Our interest was to find the solvents to modily the taste, but not to extract the phenolic compounds of interest. In each test the technical treatment of the sample was similar. Extraction was carried out at room temperature (approximately 23 °C) for 30 minutes in a horizontal shaker with 200 rpm. Samples were weighed into extraction vials and solvent was added. The vials were closed with caps to minimise the evaporation of the extraction solvent. After 30 minutes the samples were filtered to separate the solvent from the solid. Filter papers were placed on aluminium foil and, after the solvent evaporahon, were removed. Extracted samples were dried at 100°C for 30 minutes to evaporate all the solvent traces. The solvents tested were chloroform, ethanol, diethylether, butanol, ethylacetate, heptane, n-hexane and cyclohexane and they were tested with different solvent/solid ratios. Methanol (MeOH) and acetonitrile (ACN) were not considered because of the high solubility of catechins and lignans to MeOH and ACN. The extracted phloem samples were tasted in the same way as the heated ones. Detailed results from each extraction experiment are presented in Table 14.2. 

In other isolation methods, where the ccmpound(s) was removed from the donor plants, the plant material was either dried or macerated prior to cold and hot water treatment. Soxhlet-type extraction was employed when organic solvents were used. Leaves and stems from the intact plants were extracted to collect the suspected volatile substances and those chemicals likely to be released by rain, mist... 

Carbon in soil and plant materials can be determined by wet- and dry-combustion methods [7, 8]. In both instances, soil and plant carbon is converted into carbon dioxide, absorbed in alkali and determined either by titration against a standard acid or by weighing. These methods involve large apparatus, are expensive and time consuming, and therefore cannot be adapted to the routine analysis of a large number of samples. 

In the Murphy and Riley [85] method 10ml of demineralized water and 2ml of concentrated nitric acid were added to 0.15-0.2g of dry sediment (predried at 103°C) or plant material in a 100ml Erlenmeyer Flask. After a preliminary oxidation by evaporation of water and nitric acid on a hot plate, 2ml of concentrated perchloric acid were added, and the sample was boiled until clear. After cooling, the sample was diluted to 100 ml and an aliquot was withdrawn for orthophosphate determination by the ascorbic acid reduction method of Murphy and Riley [85]. Blanks and standards were treated as samples. 

More successfully, the (S)-Hnl from Manihot esculenta has also been overexpressed in E. coli [41] and the lysate of the transformed cells showed an enzyme activity of 0.5 units per ml of the culture. A culture of 801 volume of the recombinant MeHnl followed by a short purification procedure [41] yielded 40,000 U. To obtain the equivalent amount of enzyme from the parent plant material would require the processing of 100 -200 kg of dried cassava leaves and thus this recombinant method for the production of MeHnl is a significant practical development. Hence, this recombinant MeHnl has allowed a study of (S)-cyano-hydrin production to be performed [41]. 

Details of the extraction methods for ficine (4) and isoficine (5) were not given. Phyllospadine (6) was isolated from the flavonoid-containing n-butanol-soluble extract from dried plant material (4). The alkaloids from Vochysia and Buchenavia were isolated by conventional procedures, utilizing acid-base extraction and subsequent column or thin-layer chromatography using silica gel or alumina (5,6). 

AOAC (Association of Official Analytical Chemists). 1990. Carotenes and Xanthophylls in Dried Plant Materials and Mixed Feeds. AOAC Method 970.64. In AOAC Official Methods of Analysis, 15th ed. (K. Helrich, ed.) pp. 1048-1049. AOAC, Arlington, Va. 

Pure salvinorin A is desirable because it permits one to experience intense psychedelic effects which are often elusive when using the whole plant material. In particular, when smoking dried Salvia divinorum leaf, many people fail to achieve more than a mild effect, although a few find this method quite satisfactory. 

Cahill et al. [241] have developed a simple and sensitive analytical procedure for determining the concentration of trifluoroacetic acid in plant, soil, and water samples. The analysis involves extraction of trifluoroacetic acid by sulfuric acid and methanol followed by derivatisation to the methyl ester of trifluoroacetic acid. This is accomplished within a single vial without complex extraction procedures. The highly volatile methyl ester is then analysed using headspace gas chromatography. The spike recovery trials from all media ranged from a low of 86.7% to a high of 121.4%. The relative standard deviations were typically below 10%. The minimum detectable limit for the method was 34 ng/g for dry plant material, 0.20 ng/g for soil and 6.5 ng/1 for water. 

In a standard official method [50], the plant material is prepared for analysis by either digestion with 60% wlw perchloric acid, 70% wlw nitric acid, 1 3 mlv, and digestion of the residue with 2 M hydrochloric acid, or by dry combustion at 500 °C followed by extraction of the residue with 6 M hydrochloric acid. The concentration of nickel in these extracts is determined by AAS at 232.0 nm employing either background correction, or by an AA spectrophotometric procedure involving formation of the nickel ammonium pyrrolidiniedithio-carbamate followed by chloroform extraction. 

In an official method [83] for determining zinc in plant material, the sample is digested with perchloric acid 60% nitric acid 70%, m/v 1 4, followed by 2 M hydrochloric acid. Alternatively, the plant material is dry ashed and the residue dissolved in 6 M hydrochloric acid. The extract is evaluated by AAS at the 213.9 nm emission line. See also Sect. 7.34.1,7.34.4 and 7.34.7. 

A further simplification has been reported (27) in which the dried plant material is extracted with three times its volume of a mixture of benzene, concentrated aqueous ammonia, and methanol in the ratio 100 1 1, respectively. Some five successive extractions appear to be adequate. The bases are separated from the combined benzene extract by shaking with 6% aqueous citric acid. The troublesome emulsions that are encountered in other procedures are largely avoided by this method. 

For many methods of elemental analysis, the organic constituents of plant material are eliminated either by dry ashing or by wet digestion (Sulcek and Povondra, 1989). Stoeppler (1991) has summarised the most frequently used decomposition methods for trace and ultratrace analysis of biological and environmental materials. 

Bauer (1999b) found that the alkamide, dodeca-2 ,4E,8Z, 1 OE/Z-tetra-enoic acid isobutylamide, level was influenced by the preparation method. Nonthermal preparations appeared to have slightly higher levels of the tested alkamide than thermally treated products. Thus, the drying process may not be the best method for preparing Echinacea products. Pressing of the plant material to obtain an expressed juice is a common preparation method however, preservation of the juice with ethanol is required. Direct ethanol extraction of the plant material can be used in place of the pressing operation. 

By the early part of the twentieth century, pure grades of volatile hydrocarbon solvents such as benzene and hexane became available through progress in petroleum-refining methods. They were found to be very useful for the extraction of fragrant plants and plant materials. If the plant material extracted is rich in waxes (as is generally the case with flowers, stems, and leaves), these are also taken up in the extract. After careful removal of the volatile solvent by distillation, a waxy concrete remains behind. This is then washed with alcohol to separate the fragrance materials, which are soluble in alcohol, from the insoluble waxes. An absolute is then produced by the removal of the alcohol by distillation, usually under reduced pressure. Certain plant materials that contain no water, such as resins or dried leaves and mosses, may be extracted directly with alcohol. The extracts obtained—often sticky, viscous, and resiny—are called resinoids. 

The methods employed for isolation of the alkaloids depend on the nature of the compounds, and specific conditions have frequently been devised for the selective isolation of particular types of compounds. Usually, fresh or dried plant material is extracted with dilute acid solution or with alcohol, and the extract obtained is further fractionated by extraction into organic solvents with variation of pH. Extraction columns (288), membrane processes (425), and ion-exchange materials (288-290) may be particularly useful for subfractionation or isolation procedures. For further identification and isolation of separate compounds, preparative thin-layer chromatography, (288, 291, 292, 426), liquid chromatography (293, 294), or gas chromatography may be used (202, 296, 297). Because some of the products reviewed in this chapter occur naturally in very small amounts, they have not been isolated in crystalline form. Gas chromatography-mass spectrometry (87, 213, 299), mass fragmentography (192), and mass spectrometry-mass spectrometry (301, 359) have proved to be particularly useful techniques for identification of trace alkaloids in complex mixtures. 

Pope et al. (1991) applied chemical-shift-selective imaging at microscopic resolution of various plant materials, including dried and undried fruits of fennel, to the study of selective imaging of aromatics and carbohydrates, water and oil. The non-invasive nature of the method gives it advantages over established methods of plant histochemistry, which involve sectioning and staining to reveal different chemical constituents. 

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