• Preventive Nutrition and Food Science
• /
• v.13 no.1
• /
• pp.28-32
• /
• 2008

Water vapor sorption by sodium alginate-based films may result in swelling and conformational changes in the molecular structure and affecting the water vapor barrier properties. Sodium alginate film specimens were dried in a vacuum freeze dryer and their moisture content was determined by an air-oven method. The water vapor absorption was determined at two different levels of water activities (0.727 and 0.995) and at three temperatures (10, 20, and $30^{\circ}C$), and kinetics were analyzed using a simple empirical model. Reasonably good straight lines were obtained with plotting of 1/($m-m_0$) vs 1/t. It was found that water vapor absorption kinetics of sodium alginate films were accurately described by a simple empirical model. The rate of water vapor sorption increased with increase in temperature and it showed temperature dependency following the Arrhenius equation. The activation energies varied from 49.18$\sim$149.55 kJ/mol depending on the relative humidity.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.27 no.5
• /
• pp.881-889
• /
• 1998

For the application of the commercially modified starch in frozen and retort foods, apparent viscosity and water loss were measured at each stages of heating, sterilization and freezing-thawing stages. Apparent viscosity showed the exponential increase with concentration and the slopes of apparent viscosity against concentration in the Firm-Tex(hydroxypropyl distarch phosphate), Hi-Flo(acetylated distarch adipate) and Colflo 67(acetylated distarch adipate) from waxy maize starch were higher than those of Amyloacetate M20(starch acetate) and X-amylo 250(distarch phosphare) from potato starch. In the presence of 1 or 2% NaCl, X-amylo 250 among modified starches showed the increase in water loss and the decrease in apparent viscosity, whereas Colflo 67, Hi-Flo and Firm-Tex were little affected by NaCl. In the presence of 1 or 2% sucrose, water loss and apparent viscosity of the modified starches were not affected. In the range of pH 4~8, water loss and apparent viscosity of the modified starches had no change but the differences were detected to some extent between each of heating, sterilization and freezing-thawing stages. In the apparent viscosity and water loss of the modified starches after 3 week storage from heating and sterilization, Hi-Flo, Amyloacetate M20 and X-amylo 250 were not changed at the storage period, and the overall acceptability of retort food containing the modified starches such as Firm-Tex and Amyloacetate M20 were favored more than others. In the apparent viscosity and water loss of the modified starches which have been frozen and thawed three times repeatedly, Colflo 67, Hi-Flo and Firm-Tex were not changed in freezingthawing, and the overall acceptability of frozen food containing Firm-Tex was most favored.

• Fisheries and Aquatic Sciences
• /
• v.11 no.2
• /
• pp.71-75
• /
• 2008

The shell of Reeve's turtle has been used as a traditional folk medicine in Korea. We produced a hot water extract from Reeve's turtle shell according to the traditional medical practice. To release bioactive peptides, the hot water extract was enzymatically hydrolyzed with various proteases, and the free radical scavenging activity of the hydrolysate was investigated against 1,1-diphenyl-2-picryl-hydrazyl (DPPH), hydroxyl and peroxyl radicals. The free radical scavenging activity of the enzymatic hydrolysates varied from 1 to 79% depending on the enzymes, free radical species, and concentration. The $EC_{50}$ values demonstrated that the enzymatic hydrolysates of hot water extract from the shell of Reeve's turtle are potential antioxidants.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.41 no.7
• /
• pp.1014-1019
• /
• 2012

This study was conducted to evaluate the heavy metal contents of mudflat solar salt, salt water, and sea water produced in the nationwide salt pan. In mudflat solar salt, moisture contents were significantly different (p<0.001) between regions, ranging from 7.357% to 14.862%. Arsenic (As) content ranged from 0.007 ppm to 0.497 ppm, cadmium (Cd) from 0.000 ppm to 0.101 ppm, plumbum (Pb) from 0.000 ppm to 0.191 ppm, hydrargyrum (Hg) from 0.006 ppb to 0.180 ppb, and copper (Cu) from 0.039 ppm to 4.794 ppm between regions, which were significantly different (p<0.001). Further, As, Cd, Pb, and Hg contents of sea and salt water were not in excess of their criterion points. Our results suggest that heavy metal contents of mudflat solar salt, salt water, and sea water produced in the nationwide salt pan were at safe levels. However, continuous management of heavy metal contamination, such as PVC met, is still necessary.

• Macromolecular Research
• /
• v.17 no.7
• /
• pp.528-532
• /
• 2009

The size and shape of free volume (FV) holes available in membrane materials control the rate of gas diffusion and its permeability. Based on this principle, a segmented, thermo-sensitive polyurethane (TSPU) membrane with functional gate, i.e., the ability to sense and respond to external thermo-stimuli, was synthesized. This smart membrane exhibited close-open characteristics to the size of the FV hole and water vapor permeation and thus can be used as smart food packaging materials. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), positron annihilation lifetimes (PAL) and water vapor permeability (WVP) were used to evaluate how the morphological structure of TSPU and the temperature influence the FV holes size. In DSC and DMA studies, TSPU with a crystalline transition reversible phase showed an obvious phase-separated structure and a phase transition temperature at $53^{\circ}C$ (defined as the switch temperature and used as a functional gate). Moreover, the switch temperature ($T_s$) and the thermal-sensitivity of TSPU remained available after two or three thermal cyclic processes. The PAL study indicated that the FV hole size of TSPU is closely related to the $T_s$. When the temperature varied cyclically from $T_s-10{\circ}C$ to $T_s+10^{\circ}C$, the average radius (R) of the FV holes of the TSPU membrane also shifted cyclically from 0.23 to 0.467 nm, exhibiting an "open-close" feature. As a result, the WVP of the TSPU membrane also shifted cyclically from 4.30 to $8.58\;kg/m^2{\cdot}d$, which produced an "increase-decrease" response to the thermo-stimuli. This phase transition accompanying significant changes in the FV hole size and WVP can be used to develop "smart materials" with functional gates and controllable water vapor permeation, which support the possible applications of TSPU for food packaging.

• Preventive Nutrition and Food Science
• /
• v.10 no.2
• /
• pp.111-117
• /
• 2005

Radical scavenging activity of water and methanol extracts of mulberry juice and cake prepared from mulberry fruit (Morus spp.) was evaluated using three in vitro assay systems. Mulberry fruits were homogenized with $0.5\%$ trifluoroacetic acid (TFA) in distilled water, filtered with cheeze-cloth and centrifuged to yield mulberry juice and cake. Mulberry juice was evaporated and solubilized in $0.5\%$ TFA in distilled water or $0.5\%$ TFA in $80\%$ aqueous methanol, followed by filtration and evaporation to obtain water (WMJ) and methanol (MMJ) extracts of mulberry juice. Mulberrry cake also was extracted with the above same solvents, and thereby finally obtaining water (WMC) and methanol (MMC) extracts of mulberry cake. Among four extracts, the MMC showed the most potent radical scavenging activity against DPPH radical $(IC_{50}=167.45\;{\mu}g/mL)$, and superoxide $(IC_{50}=36.18\;{\mu}g/mL)$ and hydroxyl radicals $(IC_{50}=467.08\;{\mu}g/mL)$. The WMC also exhibited stronger radical scavenging activity than those of two other mulberry juice extract, WMJ and MMJ. Meanwhile, the MMJ exerted stronger three radical scavenging activity than the WMJ. Total phenolic content of the water and MeOH extracts from mulberry cake was higher than that of the water and MeOH extracts from mulberry juice. Thus, these results suggest that the extracts of mulberry cake with high dietary phenolics may be useful potential source of natural antioxidant as radical scavenger.

• The Korea Journal of Herbology
• /
• v.24 no.1
• /
• pp.15-21
• /
• 2009

Objectives : This study was designed to investigate the effect of water extract from Paeonia Lactiflora Pasll. with medicinal herb on plasma lipid and glucose in rats fed high fat diet. Methods : Experimental groups were divided into control diet group(C), high fat diet group(HF), high fat diet and 5% water extracts from Paeonia Lactiflora Pasll. with medicinal herb group(HFE I), high fat diet and 10% water extract from Paeonia Lactiflora Pasll. with medicinal herb group(HFE II). Weight gain, food intake, food efficiency, plasma lipid concentration and glucose were determined for 10 weeks during high fat diet. Results : In this experiment, body weight and food efficiency were significantly increase in high fat diet. High fat diet group showed elevated levels of total cholesterol, LDL-cholesterol and free fatty acid. Consumption of 10% water extract Paeonia Lactiflora Pasll. with medicinal herb lowers level of total cholesterol, LDL-cholesterol and free fatty acid. But levels of plasma triglyceride, HDL-cholesterol and glucose did not affect by high fat diet and water extract Paeonia Lactiflora Pasll. with medicinal herb Conclusions : In these results, water extract Paeonia Lactiflora Pasll. with medicinal herb in high fat diet group decreased plasma total cholesterol, LDL-cholesterol and free fatty acid. Thus the Paeonia Lactiflora Pasll. with medicinal herb might be useful in the treatment of hyperlipemia.

• Food Science and Biotechnology
• /
• v.14 no.1
• /
• pp.108-111
• /
• 2005

To improve water-resistance and physical properties of sodium alginate film, effects of sodium alginate and plasticizer concentrations, divalent cation types and concentrations, and immersion time of films into divalent cation solutions on sodium alginate films were evaluated, based on elongation strength (ES), elongation rate (E), water vapor permeability (WVP), and water solubility (WS). Film made from 1.5% sodium alginate solution (w/w) had low WVP and WS, which are optimal characteristics for application of film preparation. Addition of plasticizer increased E and WS. Less than 2% $CaCl_2$ addition and 15min immersion time reduced WVP, WS, and E significantly (p<0.05). Sodium alginate films treated with $CuCl_2$, and $ZnCl_2$ solutions had lower WVP and WS, whereas $MgCl_2$ had no influence on improving water resistance of films.

• Korean Journal of Environmental Agriculture
• /
• v.39 no.4
• /
• pp.343-351
• /
• 2020

BACKGROUND: Irrigation water is known to be one of the major sources of bacterial contamination in agricultural products. In addition, anti-microbial resistance (AMR) bacteria in food products possess serious threat to humans. This study was aimed at investigating the prevalence of foodborne bacteria in irrigation water and evaluating their anti-microbial susceptibility. METHODS AND RESULTS: Surface water (n = 66 sites) and groundwater (n = 40 sites) samples were collected from the Gyeongi and Gangwon provinces of South Korea during April, July, and October 2019. To evaluate the safety of water, fecal indicators (Escherichia coli) and foodborne pathogens (E. coli O157:H7, Salmonella spp., and Listeria monocytogenes) were examined. E. coli isolates from water were further tested for antimicrobial susceptibility using VITEK2 system. Overall, detection rate of foodborne pathogens in July was highest among three months. The prevalence of pathogenic E. coli (24%), Salmonella (3%), and L. monocytogenes (3%) was higher in surface water, while only one ground water site was contained with pathogenic E. coli (2.5%). Of the 343 E. coli isolates, 22.7% isolates were resistant to one or more antimicrobials (ampicillin (18.7%), trimethoprim-sulfamethoxazole (7.0%), and ciprofloxacin (6.7%)). CONCLUSION: To enhance the safety of agricultural products, it is necessary to frequently monitor the microbial quality of water.

• Korean Journal of Food Science and Technology
• /
• v.20 no.3
• /
• pp.392-398
• /
• 1988

Gelatinized rice flours were prepared by drum drying at different moisture contents of slurry made from dry milled and wet milled rice flours. Milled rice samples were prepared from the Chuchung and the Samgang varieties. Degree of gelatinization of drum-dried rice flours revealed over 92% at 60% moisture content of wet milled rice flours and 80% moisture content of dry milled ones. With regards to amylogram and rheological properties, drum-dried rice flours prepared from wet milled raw materials showed higher viscosity than from dry milled ones. Increasing water contents in the slurry increased water absorption index(WAI) and decreased water solubility index(WSI). Hunter's color values of drum-dried rice flour at high moisture contents showed higher L values and lower b values. For the preparation of gelatinized rice flours by drum drying process, the higher water content caused more gelatinized network structure of rice starch in scanning electron micrographs. With regards to farinogram properties of dough with drum-dried rice flours and wheat flours in mixing ratio of 1 to 9 by weight, drum-dried rice flours made from wet milled raw rice flours revealed higher MTI than from dry milled ones.