Preparation for extraction

Storage For optimum extraction and quality of oil, the oil-bearing material should be stored so that it remains dry and at relatively low temperature. If it is wet, it should be processed as soon as possible after harvest. Oils in the presence of water can deteriorate rapidly, forming free fatty acids and causing greater refining loss. 

Grinding, rolling, or flaking. After dehulling, the meats are reduced in size, or flaked, to facilitate oil removal. Proper moisture content of the seeds is essential for flaking, and if the moisture level is too low, the seeds are conditioned, with water or steam, to raise the moisture to about 11%. For solvent extraction, flakes are commonly not less than 0.203-0.254 mm (0.008-0.010 inch), which can be solvent extracted efficiently with less than 1% residual oil. Thinner flakes tend to disintegrate during the solvent extraction process and reduce the miscella percolation rate. 

Expanders. Sometimes low shear extruders called expanders are used. This equipment has the capability to process both low- and high-oU content materials. The meats are fed into an extruder after dehulling, flaking, and cooking and are heated as they are conveyed by a screw press through the extruder barrel. The meats are under considerable pressure and temperature when they reach the exit of the extruder. The change in pressure as the material leaves the extruder causes it to expand and the oil cells are ruptured, releasing the oil, which is rapidly reabsorbed. The expanded collets produced are then cooled and extracted with solvent. 

---

The sohd can be contacted with the solvent in a number of different ways but traditionally that part of the solvent retained by the sohd is referred to as the underflow or holdup, whereas the sohd-free solute-laden solvent separated from the sohd after extraction is called the overflow. The holdup of bound hquor plays a vital role in the estimation of separation performance. In practice both static and dynamic holdup are measured in a process study, other parameters of importance being the relationship of holdup to drainage time and percolation rate. The results of such studies permit conclusions to be drawn about the feasibihty of extraction by percolation, the holdup of different bed heights of material prepared for extraction, and the relationship between solute content of the hquor and holdup. If the percolation rate is very low (in the case of oilseeds a minimum percolation rate of 3 x 10 m/s is normally required), extraction by immersion may be more effective. Percolation rate measurements and the methods of utilizing the data have been reported (8,9) these indicate that the effect of solute concentration on holdup plays an important part in determining the solute concentration in the hquor leaving the extractor. 

Place the Cig SPE column on the vacuum manifold, and prepare for extraction by washing the column sequentially three times with approximately 3-mL volumes of methanol and Optima water, respectively. Following the final water wash, allow a volume of liquid to remain on top of the resin bed, and avoid allowing the column to become dry before sample addition. 

A general flow sheet for direct solvent extraction of many row crop oilseeds is shown in Fig. 34.8. Initial quality of the seed, and its preparation for extraction, have the most effect on yield of extracted oil, subsequent required refinery operations, and yields of (saleable) neutral oil. Freshly harvested seed should be cleaned of trash, which may become ignited during drying, or harbor moisture that accelerates seed heating in storage. Oils of most good quality, dry, row crop... 

If the fish is not prepared for extraction at the time of collection, thaw it, and remove the head, skin, and fins. Remove the fat and viscera for separate handling. Cut off portions of the muscle tissue. Weigh out 20-gram samples of muscle and of fat-and-viscera for extraction. Re-freeze these samples. 

The first step in the analysis of antioxidant phytochemicals is extraction of the compounds Ifom the plant matrix. The means by which the samples are prepared for extraction is very important because, if it is not carefully performed, compounds can be chemically altered or degraded during the process. In general, sample preparation conditions should avoid oxidation, excessive exposure to high temperatures, enzymatic reactions, and other chemical changes to the target compounds. The first step is to select a representative sample of plant material that has been collected as recently as possible. If extraction cannot be performed immediately, it is recommended that samples be stored at refrigeration... 

S. To dilute a reaction mixture with many times its volume of water helps isolate a water-insoluble product from a synthetically useful, water-miscible solvent like lV,Ar-dimethylacetamide. It prepares for extracting only the desired product with a water-immiscible solvent. But, on a large scale, the volume of available reactors limits the quantity of starting ma-... 

Three types of processing systems are used to extract oil from oil-bearing materials expeller pressing, prepress solvent extraction, and direct solvent extraction. Only prepress solvent extraction and direct solvent extraction, which remove the oil from the conditioned, prepared seed with an organic solvent, will be discussed here (see Figure 14.10.1). Oil-bearing materials have to be prepared for extraction to separate the crude oil from the... 

The first step in preparing a solid sample for HPLC is usually homogenization in preparation for extraction [5]. Extraction of the relevant components of the solid can be accomplished by a variety of techniques including Soxhlet extraction, accelerated extraction methods, and supercritical flow [10]. Soxhlet extraction, which leaches a specific component from a sample by refluxing in an appropriate solvent, is the benchmark classical technique for extraction of small molecules from a matrix [5,10]. 

---