Vacuum drying encapsulation

Figure 5.19 Vesicle-encapsulated microtubes in bolaamphiphiles with oligoglycine head groups (33) observed using phase contrast light microscopy (a, b) in water at 25°C and (c) after vacuum drying. Reprinted from Ref. 53 with permission of Wiley-VCH.

Because the activity of dried yeast is reduced by exposure to oxygen, IADY is supplied vacuum packed or with an inert gas in the head space. PADY, which has the yeast encapsulated in fat, relies on an anti-oxidant for stability. PADY is essential for domestic bread machines. 

Although we do not have experience of this in our lab, it has been reported that similar encapsulation yields for DRVs may be obtained by drying down the SUV-solute mixture using other procedures, as drying nonfrozen mixtures at 20°C under vacuum, or under a stream of (at 20°C or 37°C). 

Ui The enzymatic charge offered for immobilization in U/g of support, U t the enzymatic charge theoretically immobilized in U/g of support, R1 the immobilization yield, defined as (C/rr/Ui)x 100, U i the measured immobilized enzyme activity, in U/g of biocatalyst, RA the activity recovered in the immobilized enzyme, defined as (Uei/[/it)=< 100, Note I gelation/encapsulation=45 °C, ethanolic/acid medium, 155 min, aging=18 h at 4 °C, drying=suck dried by vacuum, followed by a 24-h resting period in a desiccator All the results of this immobilization are the averages of duplicates. 

In the anhydrous microencapsulation, protein and excipients were suspended/dissolved in PLA/acetonitrile solution and then added to cottonseed oil to form an o/o emulsion with Span 85 as an emulsifier. Petroleum ether was then added to extract the acetonitrile and the microspheres were hardened. The microspheres were then recovered by filtration and dried under vacuum. As shown in Table 5 and Fig. 5, without the pore-forming PEG, only 36% BSA was released from PLA microspheres in 1-month of incubation with a total recovery (released-fall soluble and aggregated residue in polymer after release) of 76%. Blending in 30% of 35 kDa PEG with the PLA eliminated the BSA aggregation in polymer completely, with 82% of encapsulated BSA released in 1 month. The improved BSA stability in PLA/PEG microspheres could be attributed to a less acidic and more hydrophilic microenvironment in the polymer. As seen in Fig. 6, unlike PLGA 50/50, which caused a dramatic pH drop in the release medium after a 4-week incubation (41), a relatively neutral pH was retained in the release medium for both PLA and PLA/PEG microspheres. A slightly lower pH in the release medium incubated with PLA/PEG microspheres relative to that in PLA was also... 

Process selection around a core material is dependent upon core material properties such as thermal stability, viscosity if it is a liquid, particle size and shape if it is a solid, density, reactivity, and solubility. Processes such as spray chilling or spray coating can expose core materials to elevated temperatures for longer periods of time, compared to spray drying, as the mixture remains heated as it awaits pumping to an atomization nozzle. Other processes, such as coextrusion or some emulsion processes, can be carried out at or below room temperature. For example, ionic gelation coupled with coextrusion can be used to encapsulate oils or biological materials at or below room temperature." Processes like solvent evaporation can be operated under vacuum to remove the matrix solvent rather than the use of temperature. ... 

In solid state, CD in paste (powder, water) is mixed (kneading) with the product to encapsulate, with just the quantity of water, some of the complex paste is vacuum- or spray-dried (lemon oil, Bhandari et al., 1999). 

In the hydrophobic encapsulation experiments, phospholipid DPPE-DVBA was used as representative lipid. The encapsulation experiment was conducted at two separate temperatures, 55 °C and at 10 °C [DPPE-DVBA phospholipid (2.5 mg/temperature), 5 mg total]. DPPE-DVBA was dissolved in chloroform to form a homogenous solution, then the solvent was evaporated under a gentle stream of nitrogen. The thin layer was dried under vacuum for at least 3 h. The thin lipid film was covered with 0.05 M NaHCOa/O.l M NaOH. Lipid... 

From a processing standpoint, there are two types of PIC materials dry film and Uquid. The dry-fihn type is easily processed when manufactured with vacuum laminators, which provide good encapsulation with the fine conductors. A vacumn press is also available for a small-volume production. However, the cost per unit area is higher for the dry-fihn type than for hquid materials. 

Dehydration processes offer an economical, simple, and flexible means of producing encapsulated flavorings. Dehydration methods yield a particulate powder that contains active flavor ingredients uniformly distributed in the carrier matrix (matrix encapsulation). While any method of dehydration (tray, vacuum tray, freeze, or drum) can and is used for some applications, spray drying is by far the major process used for flavor encapsulation. 

Both the extrudates and fibers were encapsulate in a metal net and then etched in heptane at 90 °C for 1 hour to dissolve away ethylene butene copolymer. The remains were dried at vacuum oven at 60 °C for 1 hour, then the surfaces were coated with silver and observed in SEM. 

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