• Journal of the Korean Society of Food Culture
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• v.38 no.5
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• pp.356-364
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• 2023

This study compared the physicochemical properties of soybean curd residue and black soybean curd residue produced by hot air-drying and freeze-drying. Regardless of drying method, the crude protein, crude ash, crude fiber contents, pH, L, a, b color values and water soluble index were higher in soybean curd residue, whereas total polyphenol contents and antioxidant activity were higher in black soybean curd residue. Significant differences in water absorption index, oil absorption capacity and emulsion activity were observed between soybean curd residue and black soybean curd residue in freeze-drying. On the other hand, the emulsion stability was not significant difference in both hot-air drying and freeze-drying. The crude protein and crude fiber contents of soybean curd residue were not significant difference between hot-air drying and freeze-drying. Freeze-drying resulted in higher crude ash contents, pH, water absorption index, water soluble index, oil absorption capacity, emulsion activity and emulsion stability than hot-air drying. Hot-air drying have caused significantly higher water contents, water activity, total polyphenol contents and antioxidant activity in soybean curd residue than freeze-drying. In conclusion, soybean type and drying methods affect the physicochemical and quality characteristics of soybean curd residue, which could be important factors in the manufacture of processed foods.

• Macromolecular Research
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• v.9 no.5
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• pp.267-276
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• 2001

In order to endow with new bioactive functionality from demineralized bone particle (DBP) as natural source to poly(L-lactide) (PLA) synthetic biodegradable polymer, porous DBP/PLA as natural/synthetic composite scaffolds were prepared and compared by means of the emulsion freeze drying and solvent casting/salt leaching methods for the possibility of the application of tissue engineered bone and cartilage. For the emulsion freeze drying method, it was observed that the pore size decreased in the order of 79$\mu\textrm{m}$ (PLA control) > 47$\mu\textrm{m}$ (20% of DBP) > 23 $\mu\textrm{m}$ (40% of DBP) > 15$\mu\textrm{m}$ (80% of DBP). Porosities as well as specific pore areas decreased with increasing the amount of DBR. It can be explained that DBP acts like emulsifier resulting in stabilizing water droplet in emulsion. For the solvent casting/salt leaching method, a uniform distribution of well interconnected pores from the surface to core region were observed the pore size of 80 ∼70 $\mu\textrm{m}$ independent with DBP amount. Porosities as well as specific pore areas also were almost same. For pore size distribution by the mercury intrusion porosimeter analysis between the two methods, the pore size distribution of the emulsion freeze drying method was broader than that of the solvent casting/salt leaching method due to the mechanism of emulsion formation. Scaffolds of PLA alone, DBP/PLA of 40 and 80%, and DBP powder were implanted on the back of athymic nude mouse to observe the effect of DBP on the induction of cells proliferation by hematoxylin and eosin staining for 8 weeks. It was observed that the effect of DBP/PLA scaffolds on bone induction are stronger than PLA scaffolds, even though the bone induction effect of DBP/PLA scaffold might be lowered than only DBP powder, that is to say, in the order of DBP only > DBP/PLA scaffolds of 40 and 80% DBP > PLA scaffolds only for osteoinduction activity. In conclusion, it seems that DBP plays an important role for bone induction in DBP/PLA scaffolds for the application of tissue engineering area.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.186-193
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• 1996

Several chitosan beads were prepared by W/O emulsion and capillary extrusion methods. The surface structures were observed through SEM pictures, the surface areas were determined by BET method, the available amine contents were measured by picric acid titration method, and the results were correlated each other. The beads from W/O emulsion method were smaller in size but had higher hardness, surface area, and available amine contents than the ones from capillary extrusion method. Moreover, the surface area, available amine contents, apparent density and the hardness showed large differences according to the drying processes. As compared between the solvent dehydration and the freeze drying technique in W/O emulsion method, the former showed higher surface area, higher available amine contents and hardness than the latter. SEM pictures revealed that in case of solvent dehydration method, very small pores existed, whereas in case of freeze drying method, cell-like pores existed on the surface. The results of picric acid titration showed that the beads dried by solvent dehydration method were 10 times higher in amine contents than those from freeze drying method, and the amount of amine contents were increased as the surface area was increased. After fluorescamine was reacted with chitosan beads, the fluorescence labeled beads were observed through fluorescence microscope. The results showed that most of primary amine existed on the surface of beads and pores.

• Journal of Pharmaceutical Investigation
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• v.37 no.1
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• pp.51-55
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• 2007

Solid lipid nanoparticles (SLNs) have been regarded to behave similar to the vegetable oil emulsions because emulsions of lipid melts are formed before lipid droplets being solidified to turn into SLNs. Compared to lipid emulsion, however, it has been more difficult to obtain stable SLNs and needs more extensive considerations on stabilizer and manufacturing process. In the present study, we tried to prepare phosphatidylcholine-based trymyristin (TM) SLNs using high pressure homogenization method and optimize the manufacturing variables such as homogenization pressure, number of homogenization cycles, cooling temperature, co-stabilizer and freeze-drying with cryoprotectants. Nano-sized TM particles could be Prepared using egg Phosphatidylcholine and pegylated phospholipids ($PEG_{2000}$PE) as stabilizers. Based on the optimization study, the dispersion was manufactured by homogenization under the pressure of 100 MPa for more than 5 cycles, and solidifying the intermediately formed lipid melt droplets by dipping in liquid nitrogen followed by thawing at room temperature. In addition, TM SLNs could be freeze-dried and then redispersed easily without significant particle size changes after freeze drying with 10% and 12.5% sucrose or trehalose. The TM SLNs established in this study can be used as delivery system for drugs and cosmetics.

• Polymer(Korea)
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• v.25 no.3
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• pp.318-326
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• 2001

PLLA scaffold loaded with gentamicin sulfate (GS) was prepared by emulsion freeze-drying method for the prevention of infection and the improvement of wettability. i.e., the cell- and tissue-compatibility. GS-loaded PLLA scaffolds were characterized by scanning electron microscopy (SEM), mercury porosimetry and blue dye intrusion, and the GS release pattern was analyzed by high performance liquid chromatography (HPLC). GS-loaded PLLA scaffolds with porosity above 50%, medium pore size ranging from 30 to 57 ${\mu}{\textrm}{m}$ (with larger pore diameters greater than 150 ${\mu}{\textrm}{m}$), and specific pore area in the range of 35 to 75($m^2$ /g )were manufactured by varying processing parameter as GS concentration. It was observed that GS-loaded PLLA scaffolds were highly porous with good interconnections between pores for allowing cell adhesion and growth. These scaffolds may be applicable for scaffold as structures that facilitate either tissue regeneration or repair during reconstructive operations.

• Polymer(Korea)
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• v.31 no.6
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• pp.505-511
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• 2007

Poly(lactide-co-glycolide)(PLGA) and hyaluronic acid (HA) has been widely used as biocompatible scaffold materials to regenerate tissue. In this present study, we fabricated microporous PLGA and HA loaded PLGA scaffolds by a emusion freeze-drying method. In order to confirm that the release profile of cytokine or water-soluble drugs, we manufactured the granulocyte macrophage colony stimulating factor(GM-CSF) loaded PLGA and HA-PLGA scaffold. All scaffolds were characterized using scanning electron microscope(SEM), mercury porosimeter and wettability measurement. Cell proliferation and viability were assessed by a 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) test. The porosity of HA-PLGA scaffold was greater than 95% with the total pore area of $261\;m^2/g$. The HA-FLGA scaffold exhibited well interconnected pores to allow greater cell adhesion and prolixferation. It was proven by higher cell viability in the HA-PLGA scaffold than PLGA alone. This may be due to the enhanced natural properties and higher water retention capacity of HA.

• Polymer(Korea)
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• v.25 no.6
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• pp.893-901
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• 2001

We developed the nerve growth factor (NGF) loaded poly (L - lactide) (PLA) scaffolds by means of emulsion freeze drying method to the possibility for the application of the nerve regeneration of spinal cord disease and the degeneration in Alzheimer's disease. The release amount of NGF from NGF loaded PLA scaffold were analyzed over a 4 week period in vitro at phosphate buffered saline (PBS), pH 7.4, at $37^{\circ}C$. It can be observed the open cell pore structure of porous scaffolds and can be easily controlled the pore structure by the controlling of formulation factors resulting in the controlling of the release rate and the release period. The stability of NGF during the preparation of PLA scaffold was evaluated by comparing the released amounts of total NGF, assayed NGF enzyme - linked immunosorbent assay (ELISA). Released NGF has been found to enhance the neurite sprouting and outgrowth from pheochromocytoma (PC-12) cells. These results suggest that the released NGF from NGF loaded PLA scaffold such as conduit type can be very useful for the nerve regeneration in the neural tissue engineering area.