Si-Kyung Lee

Quality Characteristics of Sponge Cake with Added Lotus Leaf and Lotus Root Powders

This study was conducted to evaluate the effect of lotus leaf and lotus root powder on the quality characteristics of sponge cake. Percentages of 4, 8 and 12% of two kinds of lotus powder were added to the batter based on flour content. Baking and cooling loss rate, volume and specific loaf volume, crumb color, texture, scanning electron microscopy (SEM) and sensory evaluation of the products were analyzed. The baking and cooling loss rate of the control was lower than cakes with added lotus leaf and lotus root powder. The volume of the control was the largest, and as the amount of lotus leaf and lotus root powder increased, volume and specific loaf volume became smaller. The lightness and yellowness values of the control were higher than those of the experimental cakes, and the loaves with 12% added lotus root powder showed the lowest value. Redness of the experimental cakes increased. In the textual property evaluation, hardness of the control and sponge cakes containing 4% lotus leaf, and lotus root powder appeared to have the lowest value. As the amount of lotus leaf and lotus root powder increased, hardness increased. Springiness showed the same tendency, but cohesiveness of the control revealed the lowest value. The structure of the cake crumb by SEM, revealed that the crumb cells and grains of the experimental cakes were opened and coarse, as the amount of lotus leaf and lotus root powders increased. In a sensory evaluation, sponge cakes containing lotus root powder were preferred rather than those with lotus leaf powder. As a result, good sponge cakes were prepared by adding 4% lotus leaf powder or 8% lotus root powder.

The Effects of Biopolymer Encapsulation on Total Lipids and Cholesterol in Egg Yolk during in Vitro Human Digestion

The purpose of this study was to examine the effect of biopolymer encapsulation on the digestion of total lipids and cholesterol in egg yolk using an in vitro human digestion model. Egg yolks were encapsulated with 1% cellulose, pectin, or chitosan. The samples were then passed through an in vitro human digestion model that simulated the composition of mouth saliva, stomach acid, and the intestinal juice of the small intestine by using a dialysis tubing system. The change in digestion of total lipids was monitored by confocal fluorescence microscopy. The digestion rate of total lipids and cholesterol in all egg yolk samples dramatically increased after in vitro human digestion. The digestion rate of total lipids and cholesterol in egg yolks encapsulated with chitosan or pectin was reduced compared to the digestion rate of total lipids and cholesterol in other egg yolk samples. Egg yolks encapsulated with pectin or chitosan had lower free fatty acid content, and lipid oxidation values than samples without biopolymer encapsulation. Moreover, the lipase activity decreased, after in vitro digestion, in egg yolks encapsulated with biopolymers. These results improve our understanding of the effects of digestion on total lipids and cholesterol in egg yolk within the gastrointestinal tract.

Physicochemical Characteristics and Antioxidant Capacity in Yogurt Fortified with Red Ginseng Extract.

The objective of this study was to investigate characteristics and functionality of yogurt applied red ginseng extract. Yogurts added with red ginseng extract (0.5, 1, 1.5, and 2%) were produced using Lactobacillus acidophilus and Streptococcus thermophilus and stored at refrigerated temperature. During fermentation, pH was decreased whereas titratable aicidity and viable cell counts of L. acidophilus and S. thermophilus were increased. The composition of yogurt samples was measured on day 1, an increase of red ginseng extract content in yogurt resulted in an increase in lactose, protein, total solids, and ash content, whereas fat and moisture content decreased. The pH value and cell counts of L. acidophilus and S. thermophilus were declined, however titratable acidity was increased during storage period. The antioxidant capacity was measured as diverse methods. During refrigerated storage time, the value of antioxidant effect was decreased, however, yogurt fortified with red ginseng extract had higher capacity than plain yogurt. The antioxidant effect was improved in proportion to concentration of red ginseng extract. These data suggests that red ginseng extract could affect to reduce fermentation time of yogurt and enhance antioxidant capacity.

Effect of Trehalose on Rheological Properties of Bread Flour Dough

This study was conducted to evaluate the effect of trehalose on the rheological properties of bread flour dough. Farinographic and viscographic properties, pH, total titratable acidity (TTA), and fermentation power were analyzed for flour dough rheology. Flour dough containing trehalose showed greater water absorption capacity and longer development time. However the stability, degree of softening, and farinograph quality number (FQN) were lower for the trehalosecontaining flour dough, however, these factors decreased with increasing amounts of trehalose. Trehalose did not affect the beginning of gelatinization temperature and maximum viscosity temperature of flour. The maximum viscosity was the lowest with 6% trehalose, the end of final holding period, breakdown and setback values decreased with increasing amounts of trehalose. Flour dough with 4% trehalose had the lowest pH value for 120 min fermentation at 30oC, and the highest TTA value. Addition of 4% and 6% trehalose showed larger fermentation volume of dough than the control. The results suggested that trehalose positively affected the rheological properties of flour dough such as bread volume, softness, and staling delay.

Effects of Fermented Pepper Powder on Body Fat Accumulation in Mice Fed a High-Fat Diet

We investigated the effects of non-pungent pepper powder fermented by Bacillus licheniformis SK1230 on the fat accumulation in mice. Four weeks of feeding a high-fat diet with fermented pepper powder resulted in a significantly decreased hepatic total-lipid level and increased serum HDL-cholesterol, and tended to lower the fat weight. These results suggest that fermented pepper powder inhibited fat accumulation and improved lipid metabolism in mice fed the high-fat diet.

Analysis of the Fluoroquinolone Antibiotic Resistance Mechanism of Salmonella enterica Isolates.

Quinolone-resistant Salmonella strains were isolated from patient samples, and several quinolone-sensitive strains were used to analyze mutations in the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE and to screen for plasmid-mediated quinolone resistance. Among the 21 strains that showed resistance to nalidixic acid and ciprofloxacin (MIC 0.125-2.0 μg/ml), 17 strains had a mutation in QRDR codon 87 of gyrA, and 3 strains had a single mutation (Ser83 → Phe). Another cause of resistance, efflux pump regulation, was studied by examining the expression of acrB, ramA, marA, and soxS. Five strains, including Sal-KH1 and Sal-KH2, showed no increase in relative expression in an analysis using the qRT-PCR method (p < 0.05). In order to determine the genes involved in the resistance, the Sal-9 isolate that showed decreased susceptibility and did not contain a mutation in the gyrA QRDR was used to make the STM (MIC 8 μg/ml) and STH (MIC 16 μg/ml) ciprofloxacin-resistant mutants. The gyrA QRDR Asp87 → Gly mutation was identified in both the STM and STH mutants by mutation analysis. qRT-PCR analysis of the efflux transporter acrB of the AcrAB-TolC efflux system showed increased expression levels in both the STM (1.79-fold) and STH (2.0-fold) mutants. In addition, the expression of the transcriptional regulator marA was increased in both the STM (6.35-fold) and STH (21.73-fold) mutants. Moreover, the expression of soxS was increased in the STM (3.41-fold) and STH (10.05-fold) mutants (p < 0.05). Therefore, these results indicate that AcrAB-TolC efflux pump activity and the target site mutation in gyrA are involved in quinolone resistance.

Physicochemical characterization of hydrolysates of whey protein concentrates for their use in nutritional beverages

Whey protein concentrates containing 50 and 60% protein were manufactured and were hydrolyzed for 0.5, 1, 2, 3, 4, and 5 h with 5 commercial enzymes (flavourzyme, protease A, protease M, protease S, and trypsin). Functional properties such as degree of hydrolysis (DH), non-protein-nitrogen (NPN), 5-hydroxymethyl-2-furfural (HMF), solubility, and free-sulfhydryl (FSH) levels were measured. In food applications functional efficiency of whey protein hydrolysates (WPHs) depended on hydrolysis time, protein composition and enzymatic specificity. WPHs treated with protease A were found to be suitable for applications that require extensively hydrolyzed (<2 h) WPHs, because they had high solubility, DH, HMF, and FSH contents. Proteases S and M hydrolysates delayed the Maillard reaction and had high DH in mild hydrolysates (≤2 h) of WPHs. Aggressive hydrolyzed WPHs of protease A, and mild hydrolysates of proteases S and M are preferred in beverage fortification for maximum functional efficiency.

Quality characteristics of Cheonggukjang containing Phellinus linteus extracts and antitumor effects in hep-2 and SK-MES cells

The quality characteristics of cheonggukjang containing Phellinus linteus extracts (PLE) and its cytotoxicity in Hep-2 and SK-MS-cells were investigated. Cheonggukjang containing 0.3% PLE showed the highest protease activity (7th aging day). The reducing sugar content and the amylase activity of cheonggukjang supplemented with 0.3% PLE increased immediately on the 1st aging day, and decreased slightly until the 15th aging day. All samples showed an increase in the amino-type nitrogen content. The dominant volatile compound detected using chromatography-mass spectrophotometry was 2,5-dimethyl pyrazine with the highest peak area value of 17.36% observed in cheonggukjang containing 0.3% PLE (3rd aging day). Cheonggukjang containing 0.3% PLE exhibited the best taste and acceptability with the least unpleasant odor. Cheonggukjang supplemented with PLE had a higher antitumor activity against SK-MES-1 and Hep-2 cells than a control. Hep-2 cells treated with a 10 mg/mL extract of cheonggukjang containing 0.3% PLE showed the highest growth inhibition rate of 84.74%.

Effect of Extrusion Process on the Change of Components in Ginseng

This study was carried out to investigate the effects of the extrusion process on the change of components in ginseng. The extraction yields from ginseng by distilled water extraction were highest in the extruded ginsengs, whereas it was lowest in the white ginseng. The contents of crude saponin were highest in the extruded ginseng, and they increased as the extrusion temperature was raised. The total contents of 11 kinds of ginsenosides increased in the order of red, white and extruded ginsengs. In particular, red ginseng showed higher contents of Rg1, Rg3 and Rb2, whereas Re was highest in white ginseng. In addition, the contents of Rg2, Rh1, Rh2 and Rg3 in the extruded white ginseng became higher. Free sugar contents were greatest in red ginseng. However, they were lowest in the extruded ginseng. White ginseng had a greater L value, whereas extruded ginseng demonstrated higher a and b values. In conclusion, the extraction yields, the contents of saponin, and ginsenoside-Rg2, Rh1, Rh2 and Rg3 were increased through the extrusion process.

Contamination Analysis of Heavy Metals in Commercial Feed for the Production of Safe-Animal Products

The safety of animal feed was evaluated by analyzing the levels of heavy metals (Pb, Cr, Cd, As, Se and Ag) in cattle, swine, and poultry feeds and the levels of Cu, Zn and P in swine feed. Feeds used in the analysis were produced in Korea from 2004 through the first half of 2007. The results of the study revealed that, with the exception of Cd, the concentration of heavy metals were much lower than the Minimum Regulation Levels (MRLs). However, the Cd concentration exceeded the MRL in 1 of 987 swine feed samples in 2005, as well as in 4 of 1,239 swine feed samples and 1 of 778 poultry feed samples in 2006. The levels of Cu, Zn and P in swine feed were compared with the swine breeding standard. The results of this analysis revealed that the Cu concentrations in the samples exceeded the MRL for growing pigs by 0.97%, and that for finishing and breeding pigs by 9.9%. In addition, the Cu levels (80.98 ppm for piglet, 44.82 ppm for growing pigs, 19 ppm for finishing and breeding pigs) in swine feed showed higher levels compared to 3.5-6.0 ppm, which is the Cu requirement for swine. Furthermore, the results of the Zn analysis revealed that the samples exceeded the MRL for piglets, growing pigs, and finishing and breeding pigs by 5.7%, 7.7%, and 9.3%, respectively. Finally, the average concentration of P in swine feed was 0.74%, which is almost the same as the phosphate requirement for swine.