Hand press extraction

A novel device was designed to estimate the dislodgeability of dust-associated pesticide residues by skin contact (Edwards and Lioy, 1999). Called the EL Sampler , the device consists of a spring-loaded assembly that permits the sampling medium to be pressed lightly (12g/cm or 1160 Pa) onto the surface to be monitored. A 10-cm x 15-cm Empore C-18 extraction membrane was used for the sampling medium. The material was chosen after controlled experiments on particle adhesion showed it to pick up the same distribution of test dust particle sizes as the human hand. In studies in which the EL sampler was pressed onto polyethylene surfaces coated with house dust and then sprayed with a solution of pesticides in 2-propanol, the device was found to collect 35%, 31 %, 32% and 18 %, respectively, of chlorpyrifos, diazinon (0,0-diethyl 0-[6-methyl-2-(l-methylethyl)-4-pyrimidinyl] phosphorothioate), malathion and atrazine (6-chloro-A -ethyl-A -isopropyl-l,3,5-triazine-2,4-diamine). Parallel studies with human hand presses (full hand at 6.8 kg = ca. 6900 Pa) yielded collection efficiencies of 42 %, 29 %, 43 % and 21 %, respectively. 

Citms peel oils for small-scale use may be obtained by hand-pressing. Fmits are sliced, and mesocarp and albedo layers are peeled from the flavedo before handpressing. Peel oils are collected in brine solution on ice, and oil extract is centrifuged at 4°C. Afterwards, the supernatant is dehydrated with anhydrous sodium sulfate and filtered (5). The total final oil extract is about 1% of the flavedo by weight (6). 

Documented oil extraction dates back to 1650 b.c. when ripened olives were pressed by hand in Egypt using wooden pestles and stone mortars. The extracted ohve oil was hltered through goat hair filters and used as a lubricant. Sesame, hnseed, and castor oils were recovered in Egypt by hand pressing as far back as 259 b.c. (1). 

In the past, expression presses were used in many processes for extracting oil and juice, generally from seeds and fruits such as olives. Batch presses were typically used in these apphcations, and hand unloading of the pressed cake was often required. Batch presses that require hand unloading or extensive cleaning between pressings are rarely used now descriptions of various types are presented in earlier editions of this handbook. This section, therefore, describes mainly continuous presses. 

When the stuff is sufficiently bleached, tho clear liquid is pumped into a cistern for further use—it being a property of the liquid that it not only extracts but destroys the color, and, therefore, does not becomo impure by bleaching. On the other hand, the stuff or pulp is put into a strong iron box, and submitted to the action of a hydraulic press, which prepares it for the beating engine. 

External characters The genuine oil has normal colour and smell Large additions of terpenes weaken the colour oil extracted mechanically is more coloured than that pressed by hand... 

The low temperature in solvent extraction of oilseeds should produce a better oil than oil from the high-temperamre environment of screw-pressing. Solvent, however, extracts some nontriglycerides that are not pressed out by screw-pressing, so screw-press oil is generally of better quality than solvent-extracted oil. Although some animal fats are solvent extracted, most renderers full-press in screw-presses. Solvent extraction of oilseeds, on the other hand, is widely practiced. The section below is based primarily on research conducted with oilseeds. Some of it, however, would also apply to extraction of animal fats. 

In a first step, the apple and pear mash is separated from the solid matters and then fermented as pressed must. The mash of berries on the other hand, is in most cases fermented directly in order to extract the colourants. 

Few red wines need treatment for insufficient tannin since they ferment over the seeds and skins and possibly some stems so that they have ample opportunity to acquire the tannin they need. White wines, on the other hand, are almost invariably deficient in tannin as the pressing immediately after the crushing offers no opportunity for extraction. The amount of tannin required in the finished wine is very slight, most of the excess being consumed in precipitating the albuminoids of the freshly fermented wine. However, the presence of tannin helps ensure a sound fermentation and to clarify the wine afterward, so that a slight addition of tannin, say one part to 20,000 of white wine must is unobjectionable and almost invariably beneficial. 

Procedure. The method of acid extraction and demethylation of pectin from apple pomace at 60 C. was essentially that previously described (17), up to the point of clarification of the pectin extract. Prior to clarification, the temperature of the extract was raised to about 50 C. in order to aid dispersion of the pectinates. Following the clarification and removal of starch, the pectin was precipitated as calcium pectinate by adding 20% calcium chloride solution to the extract at room temperature. The quantity of calcium chloride was such that any excess of the salt did not give a further precipitate after the precipitated material had stood from 1 hour to overnight as a practical handling procedure. After the calcium pectinate had been filtered off through muslin by hand, the relative completeness of precipitation was estimated by determining the relative viscosity (Ostwald at 26 C.) of the liquid pressed out. A relative viscosity of 1.2 or less indicated practically complete precipitation. 

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