High-pressure pretreatment

Sila, D., Smout, C., Vu, S., and Hendrickx, M. (2004). Effects of high-pressure pretreatment and calcium soaking on the texture degradation kinetics of carrots during thermal processing. / Food Sci. 69, E205-E211. 

Ade-Omowaye et al. (2001) demonstrated that high-pressure pretreatment (400 MPa, 10 min) resulted in an increase in drying rate of paprika during subsequent dehydration. The pretreatment could be an alternative to chemical (NaOH or HCl) pretreatments, thereby minimizing adverse consequences of chemicals. 

The effect of high pressure on osmotic dewatering was studied by Rastogi et al. [89,90], It was shown that the treatment has a damaging effect on tissue and results in higher permeability to water and solutes. The process of osmotic dehydration is facilitated by high-pressure pretreatment. 

Fig. 23. Two types of hollow-fiber modules used for gas separation, reverse osmosis, and ultrafiltration applications, (a) Shell-side feed modules are generally used for high pressure appHcations up to - 7 MPa (1000 psig). Fouling on the feed side of the membrane can be a problem with this design, and pretreatment of the feed stream to remove particulates is required, (b) Bore-side feed modules are generally used for medium pressure feed streams up to - 1 MPa (150 psig), where good flow control to minimise fouling and concentration polarization on the feed side of the membrane is desired.

Measurable Process Parameters. The RO process is relatively simple ia design. It consists of a feed water source, feed pretreatment, high pressure pump, RO membrane modules, and ia some cases, post-treatment steps. A schematic of the RO process is shown ia Figure 2a. 

Most HW and LP steam boilers (i.e., those that operate below 15 psig) and many smaller high-pressure (HP) steam-raising boilers employ, at best, relatively simple methods of FW pretreatment and a basic internal chemical treatment program. Many times no pretreatment is provided. 

After a few minutes irradiation with a high pressure mercury lamp at about 50 C, a rather complete cover of grafted acrylic acid, acrylamide and other vinyl monomers could be obtained. In later experiments a continuous grafting method has been developed where a tape or a fiber bundle after suitable pretreatment is grafted by UV irradiation for a few seconds. Homopolymer formed is removed by washing and grafted polymer analyzed by dye absorption, IR reflection and ESCA spectroscopy. 

In this report we compare several properties of hepatic microsomal AHH activity in control and DBA-treated little skates (including metabolic profiles obtained from c-benzo(a)pyrene as elucidated by high pressure liquid chromatography [HPLC]), we describe the partial purification of two different forms of cytochrome P-450 (cytochrome P-448 and cytochrome P-451) from hepatic microsomes of DBA-pretreated little skates and we report polycyclic hydrocarbon-like induction in large numbers of winter flounder assayed in Maine during June, July, and August, which was quite different than data obtained with sheepshead examined in Florida during the same period. 

The plcint shown in Figure 1 consists of a water pretreatment plant and four sepairate blocks of "Permasep" units. All blocks cire fed by the Scime high pressure pump, cuid each block consists of 4-inch modules, reject-staged in a 2 to 1 ratio. The total conversion is about 70 percent — this means that cibout 70 percent of the feed water is converted to product, with 30 percent discarded as a brine stream. 

Deep well disposal involves injecting liquid wastes into a porous subsurface stratum that contains noncommercial brines [57]. The wastewaters are stored in sealed subsurface strata isolated from groundwater or mineral resources. Disposal wells may vary in depth from a few hundred feet (100 m) to 15,000 ft (4570 m), with capacities ranging from less than 10 to more than 2000 gpm. The disposal system consists of the well with high-pressure injection pumps and pretreatment equipment necessary to prepare the waste for suitable disposal into the well. 

Peeling, one of the most delicate pretreatments, is achieved industrially by abrasion, high-pressure steam, treatment with sodium hydroxide solution, or mechanically. Abrasion is effected by rough, moving surfaces which remove the outer surface of the product, but it has the drawback of considerable loss of raw material. Steam peeling consists of heating the product to... 

Most industrial reactors and high pressure laboratory equipment are built using metal alloys. Some of these same metals have been shown to be effective catalysts for a variety of organic reactions. In an effort to establish the influence of metal surfaces on the transesterification reactions of TGs, Suppes et collected data on the catalytic activity of two metals (nickel, palladium) and two alloys (cast iron and stainless steel) for the transesterification of soybean oil with methanol. These authors found that the nature of the reactor s surface does play a role in reaction performance. Even though all metallic materials were tested without pretreatment, they showed substantial activity at conditions normally used to study transesterification reactions with solid catalysts. Nickel and palladium were particularly reactive, with nickel showing the highest activity. The authors concluded that academic studies on transesterification reactions must be conducted with reactor vessels where there is no metallic surface exposed. Otherwise, results about catalyst reactivity could be misleading. 

Krauss and Stach (31) demonstrated that the hexavalent catalyst can be quantitatively reduced by CO at 350°C to divalent chromium. This material has no y-phase resonance but is active for ethylene polymerization, indicating that Cr(II) is definitely an active valence.1 These results have since been confirmed by several other laboratories, including this one (30). In fact, Hogan concluded, as early as 1959 from similar reduction studies, that the active species must be divalent. The CO-reduced catalyst polymerizes ethylene in a high-pressure autoclave much like its hexavalent parent, and produces almost identical polymer. Since the polymer properties are extremely sensitive to the catalyst pretreatment, this is a strong endorsement for the conclusion that Cr(II) is probably also the active species on the commercial catalyst after reduction by ethylene. 

Pretreatments of the electrode were carried out by soaking first in HC1 for 10 s and then in H,P0a for 5 min, followed by washing with de-ionized water. The RRDE was then set in a RRDE measuring system (Nikko Keisoku, model DPGS-1). The rotation rate of the electrode was usually 1000 rpm except where specially noted. Electrolytes were of reagent grade chemicals and twice distilled water. A 500 W super high pressure mercury arc lamp (Ushio... 

Suurmeijer, A. J. H., and Boon, M. E. 1999. Pretreatment in a high-pressure microwave processor for MIB-1 immunostaining of cytological smears and paraffin tissue sections to visualize the various phases of the mitotic cycle./. Histochem. Cytochem. 47 1015-1020. 

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