• Korean Journal of Materials Research
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• v.14 no.3
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• pp.218-223
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• 2004

P-type $\beta$-FeSi$_2$ with a nominal composition of $Fe_{0.92}Mn_{0.08}Si_2$ powders has been produced by mechanical alloying process. As-milled powders were spray dried and consolidated by atmospheric plasma thermal spraying as a rapid sintering process. As-milled powders were of metastable state and fully transformed to $\beta$-$FeSi_2$ phase by subsequent isothermal annealing. However, as-thermal sprayed $Fe_{0.92}Mn_{0.08}Si_2$ consisted of untransformed mixture of $\alpha$-$Fe_2Si_{5}$ and $\varepsilon$-FeSi phases. Isothermal annealing has been carried out to induce transformation to the thermoelectric semiconducting $\beta$-$FeSi_2$ phase. Isothermal annealing at $845^{\circ}C$ in vacuum gradually led to the thermoelectric semiconducting $\beta$-$FeSi_2$ phase transformation, but some residual metallic $\alpha$ and $\varepsilon$ phases were unavoidable even after prolonged annealing. Thermoelectric properties of $\beta$-$FeSi_2$ materials before and after isothermal annealing were evaluated. Seebeck coefficient increased and electric conductivity decreased with increasing annealing time due to the phase transition from metallic phases to semiconducting phases. Thermoelectric properties showed gradual increment, but overall properties appeared to be inferior to those of vacuum hot pressed specimens.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.177-187
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• 2014

Microbial phytases are enzymes with biotechnological interest for the feed industry. In this article, the effect of spray-drying conditions on the stability and activity of extracellular phytase produced by R. microsporus var. microsporus biofilm is described. The phytase was spray-dried in the presence of starch, corn meal (> $150{\mu}m$), soy bean meal (SB), corn meal (< $150{\mu}m$) (CM), and maltodextrin as drying adjuvants. The residual enzyme activity after drying ranged from 10.7% to 60.4%, with SB and CM standing out as stabilizing agents. Water concentration and residual enzyme activity were determined in obtained powders as a function of the drying condition. When exposed to different pH values, the SB and CM products were stable, with residual activity above 50% in the pH range from 4.5 to 8.5 for 60 min. The use of CM as drying adjuvant promoted the best retention of enzymatic activity compared with SB. Spray drying of the R. microsporus var. microsporus phytase using different drying adjuvants showed interesting results, being quite feasible with regards their biotechnological applications, especially for poultry diets.

• Food Science and Preservation
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• v.16 no.5
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• pp.719-725
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• 2009

We investigated the absorption characteristics of protein-bound polysaccharide powders of various molecular weights isolated from the mushroom Agaricus blazei Murill. The monolayer moisture content calculated using the GAB equation showed a higher level of significance than did the BET equation. The higher the water activity, the lower the isosteric heat of sorption. The fitness of the isotherm curve was shown to be in the order of the Khun, Oswin, Caurie and Henderson models. The prediction model equations for moisture content were established by use of ln(time), water activity, and temperature.

• Journal of Dairy Science and Biotechnology
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• v.40 no.3
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• pp.134-142
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• 2022

Protein-enriched dairy powder is widely consumed to promote muscle synthesis. Recently, in Korea, elderly people have also begun consuming protein powder products to prevent muscle loss. However, these protein-enriched powders have poor flowability and hydration properties because of the fine particles of spray-dried milk protein powder. Therefore, in this study, the fluidized bed agglomeration process was used to solve these problems. The rheological and physical properties of milk protein isolate (MPI)/skim milk powder (SMP) mixtures were effectively improved via fluidized bed agglomeration. The particle size of the MPI/SMP mixtures significantly increased from 35.7-58 ㎛ to 118-136 ㎛, the flowability level improved from fair (21.4-26.3) to good (15.7-16.3), and the cohesiveness level changed from intermediate (1.27-1.36) to low (1.18-1.19) after fluidized bed agglomeration. In addition, the wetting time of the agglomerated MPI/SMP mixtures was effectively reduced to 4.67-58.3 s by fluidized bed agglomeration. These findings may be useful for manufacturing protein-enriched dairy powders with good instant properties.

• Journal of the Korean Ceramic Society
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• v.36 no.6
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• pp.662-670
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• 1999

Porous alumina was fabricated from pressureless powder packing forming method using powders granulated by spray drying. It was investigated the pore size distribution of fabricated porous alumina. The results of microstructural observation showed that intraganular pore size and intragranular pore size. At 1700$^{\circ}C$ there were no intragranular pores but it showed homogeneous distribution of intergranular pore size. The bending strength and shrinkage increased as porosity decreased. In case of thermal shock resistance sudden decrease of bending strength to $\Delta$T was not shown because intergranular large pore prevented sudden crack propagation.

• Journal of the Korean Ceramic Society
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• v.36 no.6
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• pp.671-678
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• 1999

Porous ceramics were fabricated from pressureless powder packing forming method using mullite and cordierite powders granulate by spray drying. The bending strength and shrinkage of porous ceramics were increased and their porosity were decreased with increasing temperature. It showed homogeneous distribution of 2$\mu\textrm{m}$ intergranular pores of mullite at 1400$^{\circ}C$, 2.5$\mu\textrm{m}$ intergranular pores of cordierite at 1300$^{\circ}C$ respedtively. Above that temperature intragranular particles were sintered and sintering by intergranular necking was extremely proceeded. In the test of thermal shock resistance sudden decrease of bending strength to $\Delta$T was not shown because intergranular large pore prevented sudden crack propagation.

• Food Science of Animal Resources
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• v.42 no.6
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• pp.915-927
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• 2022

Recently, protein-fortified milk powders are being widely consumed in Korea to prevent sarcopenia, and the demand for high-protein food powders is continuously increasing in the Korean market. However, spray-dried milk proteins have poor flowability and wettability owing to their fine particle sizes and high inter-particle cohesive forces. Fluidized bed agglomeration is widely used to improve the instant properties of food powders. This study investigated the effect of fluidized bed agglomeration on whey protein isolate (WPI)-fortified skim milk powder (SMP) at different SMP/WPI ratios. The fluidized bed process increased the particle size distribution, and agglomerated particles with grape-like structures were observed in the SEM images. As the size increased, the Carr index (CI) and Hausner ratio (HR) values of the agglomerated WPI-fortified SMP particles exhibited excellent flowability (CI: <15) and low cohesiveness (HR: <1.2). In addition, agglomerated WPI-fortified SMP particles exhibited the faster wetting time than the instant criterion (<20 s). As a result, the rheological and physical properties of the WPI-fortified SMP particles were effectively improved by fluidized bed agglomeration. However, the fluidized bed agglomeration process led to a slight change in the color properties. The CIE L^* decreased, and the CIE b^* increased because of the Maillard reaction. The apparent viscosity (η_a,10) and consistency index (K) values of the rehydrated solutions (60 g/180 mL water) increased with the increasing WPI ratio. These results may be useful for formulating protein-fortified milk powder with better instant properties.

• Journal of Applied Biological Chemistry
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• v.50 no.1
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• pp.1-5
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• 2007

Chemical properties of spray-dried powders separated based on molecular weight from crude protein binding polysaccharide (CP-SD) of Agraricus blazei were examined. Contents of ${\beta}$-glucan in SD-1, SD-2 and SD-3 were 18.67%, 48.24%, and 37.15% respectively, and SD-2 (10-150 kDa) showed the highest molecular weight. Obtained ${\beta}$-glucans were not pure glucan, but was determined to be an acidic proteo-heteroglycan with a large amount of glucose (74.46-80.05%), galactose (8.91-15.2%), and mannose (4.9-5.46%). Composition of their amino acids was mainly aspartic and glutamic acids. FT-IR spectrum revealed SD-1, SD-2 and SD-3 were structures of ${\beta}$-1,3-glucans and ${\alpha}$-1,6-glucans at 890 and 930 $cm^{-1}$, respectively, signals of ${\alpha}$-1,6-glucans for CP-SD was not found. Useful CP-SD was recovered from A. blazei for preparation of three powder types as food materials.

• Food Science and Preservation
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• v.13 no.5
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• pp.555-562
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• 2006

This study was conducted to investigate the rheological properties of protein-bound polysaccharide powders (SD-1, 2, 3) using ultrafiltration (UF) and spray drying (SD) process from Agaricus blazei Murill. The calculated weight-average molar mass (Mw) in the positions at 29.7 mL (for SD-1), and at 27.8 mL (for SD-2), and at 18.7 mL (for SD-3) was $8.2{\times}10^3,\;9.6{\times}10^4$, and $5.9{\times}10^6g/mol$, respectively. As concentration increased the solution showed higher pseudoplasticity where the pseudoplasticity decreased as temperature increased. The flow behaviors of spray dried powder solutions were more fitted to Herschel-Bulkley equation than Power law equation. Apparent viscosity of SD-2 was more temperature-dependent than that of SD-1 and 3. However, the SD-3 tended to be more concentration-dependent than SD-1 and 2 as temperature increasing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.2
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• pp.209-214
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• 1984

To compare the keeping quality of freeze and spray dried red ginseng extract powders(RGEPs) and commercial dehydrated tea products, particle sizes and initial moisture contents of these products were measured, and the relationships between crude fat contents and moisture contents and/or densities were studied. Particle sires of RGEPs and commercial dehydrated tea products were below 100 mesh, and particle sizes of freeze dried products were higher than those of spray dried products. Initial moisture contents of freeze and spray dried RGEPz were 3.587 and 4.56f, and those of frecze and spray dried coffees were 2.17% and 3.52%, respectively. Crude fat contents of tang and ssanghwa tea were 4.12% and 0.62%, and densities of tang and ssanghwa tea were 0.89 g/ml and 0.59 g/ml, respectively. Absorption rates o( tang and ssanghwa tea were the lowest among these products, it was considered because of crude fat contents of tang and ssanghwa tea were higher than these of the other products, and densities of tang and ssanghwa tea were higher than these of the other products. Notwithstanding absorption rates of RGEPs were lower than those of coffees, to maintain lower keeping quality of RGEPs than that of coffees, it was considered that HGEPs are not only lower to coffees in crude fat contents but also in densities. A sinificant relationships were found between keeping Quality and crude fat content and/or density.