Secondary extractives

Srinivas H, Swamylingappa B, Chand N. 1992. Secondary extraction of soybeans using hexane-acetic acid Effect on beany flavor removal and physiochemical properties. J Agric Food Chem 40 276-279. 

Concentrates are made by extracting water-soluble sugars and other compounds from defatted meals or flours. This is typically a secondary extraction, using acidic ethanol-water in a chain-type or basket-type continuous extractor for processing flakes, or acidic water extraction of flour in vats, followed by spray-drying (8). Acidic polar solvents are used at or near the isoelectric point of the protein to minimize its solubility and loss. The reextracted flakes may then be ground into a flour. Concentrates are more bland than defatted flours, but still contain the fiber components of the kernel. After extraction with acidic ethanol or water, concentrates... 

The sample mount also positions the sample properly for analysis. This includes. v and y lateral motion, z height, and angle with respect to primary beam and secondary extraction. It may vary from a simple mechanical mount to a sophisticated stage with stepping motors under computer control. 

A major problem associated with the characterization of the HMWHCs is the quantitative and qualitative separation of waxes from asphaltenes. Thanh et al. (1999) developed a method, subsequently modified (Hsieh et al. 2000), which involved the adsorption of the crude oil on alumina, followed by extraction of the alumina to remove the maltenes, including the HMWHCs, leaving the asphaltenes adsorbed to the alumina. The maltenes were subsequently separated into wax and non-wax fractions via acetone precipitation (Burger et al. 1981) and the asphaltenes were recovered by secondary extraction of the alumina. Characterization of the respective fractions demonstrated that the waxes were asphaltene-free and the asphaltenes were wax-free. 

Other extractants, especially tertiary amines, have been tested for some steps in reprocessing. The amines form organic soluble complexes with negatively charged metal complexes (used in uranium purification, 5.5.3). The use in the basic Purex cycle of a secondary extractive reag t can improve the decontamination factor ... 

While the above discussion has focused, in part, on several instances of rather striking species-related variations in organ accumulation after administration of labeled L-amino acids, it must be pointed out that these variations have not yet been studied in a highly systematic fashion. The time course of the radionuclide content of a given organ or tissue following administration of a labeled compound reflects the contributions of several distinct modes of label movement the rate of delivery of the injected compound to the tissue (which is, in turn, a function of the magnitude and distribution of cardiac output and the rate of systemic clearance of the compound from the blood) the fractional extraction of the compound by the tissue (which may depend, in part, on the rate of perfusion) the rate of release of the compound and of labeled metabolites from the tissue secondary extraction and retention... 

The classification of extractives is rarely made strictly according to substance classes. Therefore it can usually be divided into lipophilic and hydrophilic extractives due to the polarity (Table 9.4.4) or into primary and secondary extractives due to their biological function (Table 9.4.5). 

Heartwood contains very few or no primary extractives, but usually significantly more secondary extractives than sapwood. The secondary substances include almost all the other extractive classes, hence they have enormous structural variety including most different substance classes like alkaloids, quinones, fats, oils, saponins, terpenes, tropolones, waxes and a number of aromatic or phenolic compounds (stilbenes, lignans, flavonoids, tannins, etc.). The secondary substances play an essential role in the use of wood, for example the heartwood of most of the wood species is more durable than the sapwood. 

Secondary extractives substances for the protection against biological decay etc. 

The product quality sample extraction is normally 0.3 ml volume per target. It is transported to the SGB in a lead pig for shielded storage and use. An erroneously too large product quality sample extraction of 1.0 ml was hypothesized for hazard event purposes. A secondary extraction sample of 20 X X =10 ml) is taken from the 0.3 ml product quality sample extraction in the SGB for dilution to transfer the diluted product to the Hood. Product and product extraction samples are all the same concentration. 

There are usually three main stages in the working of an oilfield. The primary extraction corresponds to natural flow from oil wells. Only 5 or 10% of the oil can be extracted at this stage. Following this spontaneous production, a secondary extraction can retrieve a further 10 to 15%. This step involves either pumping, or drainage from the porous medium using water or gas. For this purpose, several wells are bored around the production wells (see Fig. 4.10). 

The high vacuum distillation of fresh food products uses product moisture to co-distill volatiles (Figure 3.4 top). Water is always the major part of the distillate and a secondary extraction is mandatory. Thus, an extraction is conunonly a part of this type of aroma isolation process. The primary sources of aroma profile distortion come from the distillation process and subsequent solvent extraction. 

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