Water freeze drying

Water-containing plant materials need to be extracted with polar solvents such as acetone, methanol, or ethanol that can take up water. Freeze-dried plant tissues and freeze-dried juices can be directly extracted with diethyl ether, which contains traces of water and is more polar than light petrol or hexane. Pure light petrol or hexane are less suitable, because more polar pigments, such as Chi b or xantho-phylls, are only partially extracted from freeze-dried plant samples. A few drops of acetone or ethanol added to light petrol or hexane will, however, guarantee a complete extraction. This mixture will extract Chi a, Chi b, and all carotenoids—including xanthophyll esters and secondary carotenoids that are present in many fruits and juices—from the freeze-dried plant material. 

Two grams of HSPAN was added to 500 ml of water, the pH was adjusted from 9 to 6.5 with dilute hydrochloric acid, and 0.1 ml of Thermamyl 60L enzyme solution (Novo Enzyme Corp.) was added. The resulting mixture was heated at 95°C for 21 hr, and the clear yellow solution was exhaustively dialyzed against distilled water. Freeze drying yielded 1.235 g of polymer, which contained only about 5% residual carbohydrate (by infrared analysis). The number average molecular weight of this polymer was 44,000, as determined in 0.15N sodium chloride solution on a Melabs Model CSM-2 membrane osmometer equipped with a B-19 membrane (Schleicher and Schuell Co.). 

Freeze Drying. Freeze drying or lyophilization, with trapping of the volatiles that come over with the water vapor (31), would seem to have some advantages because of the mild conditions used. However, there is considerable selection of volatiles because the intact tissues act as a barrier to many volatiles whereas they are permeable to water. Freeze drying can also be considered a type of vacuum steam distillation. 

Due to the small size of the barnacles, three individuals from each level were combined for analysis of 8 C and 8 N in organic tissue matter. Samples were roughly broken using a mortar and pestle prior to immersion in 0.5 ml of sulphurous acid for 24 hrs to remove carbonates. A further 0.5 ml of acid was added and the samples left for another 24 hrs. The acid was removed and the samples were rinsed with deionized water, freeze-dried and then ground using a mortar and pestle. Samples of 4 mg from each level were weighed into tin... 

For the isolation of non-volatile water soluble compounds or biological materials from water, freeze drying is an effective technique. In this technique the water sample is frozen in a vial and the resulting ice sublimed away under vacuum. Organics are then solubilized in an organic solvent to separate them from the precipitated inorganic salts. 

Pool fractions containing receptor activity. Dialyze against water, freeze-dry, and analyze about 25% of the freeze-dried protein by SDS-PAGE. A 63-kDa band should be seen (a second band of 55 kDa is sometimes seen). 

The mixture was centrifuged. A portion of the supernatant was assayed for protein, and the remainder was equilibrated with 0.005 M sodium phosphate buffer, pH 7.0. Five ml of supernatant was applied to a 1 x 22-cm column of DEAE-cellulose in the same buffer. The column was washed with 150 ml of the 0.005 M phosphate buffer, pH 7.0, and renin was eluted with 100 ml of 0.2 M sodium phosphate buffer, pH 6.0, (4). The effluent was dialyzed against distilled water, freeze-dried, and the renin taken up in 2.5 ml of pH 7.4 saline phosphate buffer. The solution was dialyzed to pH 3.0 or to pH 7.4 as described for plasma (13), diluted in assay buffer and assayed for renin and angiotensinase. 

A series of copolymers of acrylic acid (AAc) and acrylamide (AAm), cross-linked with Bis, were either prepared or, as in the case of CO(AAc/AAm)V, purchased. Those synthesized in the laboratory were produced from freshly distilled AAc and AAm recrystallized from chloroform. The solution copolymerization and crosslinking, when carried to approximately 5% conversion, yielded an insoluble gel that was subsequently broken in a blender and forced through a 20-mesh screen, washed in 0.5N HCl, washed in distilled water, freeze-dried, and stored in a desiccator under vacuum. By controlling both the pH of the reaction medium and the feed ratio of the two monomers, the series of copolymers listed in Table II was prepared, the analysis being by the titration, with O.IN NaOH, of a suspension of the copolymer in O.IN HCl to determine the AAc content of the copolymer. 

Endo-exo ratios of the micelle-catalysed reactions have been determined by adding 0.25 mmol of 5.1c and 0.5 mmol of 5.2 to a solution of 5 mmol of surfactant and 0.005 mmol of EDTA in 50 ml of water in carefully sealed 50 ml flasks. The solutions were stirred for 7 days at 26 C and subsequently freeze-dried. The SDS and CTAB containing reaction mixtures were stirred with 100 ml of ether. Filtration and evaporation of the ether afforded the crude product mixtures. Extraction of the Diels-Alder adducts from the freeze-dried reaction mixture containing C12E7 was performed by stirring with 50 ml of pentane. Cooling the solution to -18 C resulted in precipitation of the surfactant. Filtration and evaporation of the solvent afforded the adduct mixture. Endo-exo ratios... 

Citric acid is used in carbonated beverages to provide tartness, modify and enhance flavors, and chelate trace metals. It is often added to jams and jellies to control pH and provide tartness. It is used in cured and freeze-dried meat products to protect the amino acids (qv) and improve water retention. Bakers use it to improve the flavor of fmit fillings in baked goods. Because citric acid is a good chelator for trace metals, it is used as an antioxidant synergist in fats and oils, and as a preservative in frozen fish and shellfish (7) (see Antioxidaisits). 

Lyophilization. LyophiLization is essentially a drying technology. Some dmgs and biologicals are thermolabile and/or unstable in aqueous solution. Utilization of freeze drying permits the production of granules or powders that can be reconstituted by the addition of water, buffered solution, or mixed hydrophilic solvents just prior to use, eg, certain antibiotic suspensions. 

Sublimation of ice crystals to water vapor under a very high vacuum, about 67 Pa (0.5 mm Hg) or lower, removes the majority of the moisture from the granulated frozen extract particles. Heat input is controlled to assure a maximum product end point temperature below 49°C. Freeze drying takes significantly longer than spray drying and requires a greater capital investment. 

Drying is an operation in which volatile Hquids are separated by vaporization from soHds, slurries, and solutions to yield soHd products. In dehydration, vegetable and animal materials are dried to less than their natural moisture contents, or water of crystallization is removed from hydrates. In freeze drying (lyophilization), wet material is cooled to freeze the Hquid vaporization occurs by sublimation. Gas drying is the separation of condensable vapors from noncondensable gases by cooling, adsorption (qv), or absorption (qv) (see also Adsorption, gas separation). Evaporation (qv) differs from drying in that feed and product are both pumpable fluids. 

Ultrafiltration (qv) (uf) is increasingly used to remove water, salts, and other low molecular-weight impurities (21) water may be added to wash out impurities, ie, diafiltration. Ultrafiltration is rarely used to fractionate the proteins because the capacity and yield are too low when significant protein separation is achieved. Various vacuum evaporators are used to remove water to 20—40% dry matter. Spray drying is used if a powdery intermediate product is desired. Tyophilization (freeze-drying) is only used for heat-sensitive and highly priced enzymes. 

Barium sulfate [7722-43-7] M 233.4, m >1580 . Washed five times by decantation with hot distilled water, dialysed against distd water for one week, then freeze-dried and oven dried at 105° for 12h. 

Sodium polyacrylate (NaPAA) [9003-04-7]. Commercial polyacrylamide was neutralised with an aqueous solution of NaOH and the polymer ppted with acetone. The ppte was redissolved in a small amount of water and freeze-dried. The polymer was repeatedly washed with EtOH and water to remove traces of low... 

Sodium poly(a-L-glutamate). It was washed with acetone, dried, dissolved in water and ppted with isopropanol at 5°. Impurities and low molecular weight fractions were removed by dialysis of the aqueous solution for 50h, followed by ultrafiltration through a filter impermeable to polymers of molecular weights greater the 10. The polymer was recovered by freeze-drying. [Mori et al. J Chem Soc, Faraday Trans I 2583 1978.]... 

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