Earticle

This study was to investigate the influence of pH on the antioxidant activity of melanoidins formed from glucose(Glc) and fructose (Fru) with lysine enantiomers in the Maillard reaction. Melanoidins formed from D-isomers were found tobe effective antioxidants in different in vitro assays with regard to the ferrous ion chelating activity, 1, 1-diphenyl-2-picryl-hydrazil(DPPH) radical scavenging activities, ferric reducing/antioxidant power (FRAP), and 2,2'-azinobis(3-ethylbenothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity. In particular, the chelating activity of these melanoidins ata pH of 7.0 was greater than those with pH of 4.0 and 10.0. The chelating activity and DPPH radical scavenging activity ofthe melanoidins formed from the Glc systems were higher than those of the melanoidins formed from the Fru systems.However, the FRAP and ABTS radical scavenging activity of these melanoidins were not different according to pH level, withexceptions being the Fru systems.

This study was conducted to develop a model to describe the effect of antimicrobials [potassium sorbate (PS),potassium lactate (PL), and combined PL and sodium diacetate (SDA, PLSDA)] on the growth parameters of Listeriamonocytogenes such as specific growth rate (SGR) and lag phase periods (LT) in air-dried raw sausages as a function ofstorage temperature (4, 10, 16, and 25oC). Results showed that the SGR of L. monocytogenes was dependent on the storagetemperature and level of antimicrobials used. The most effective treatment was the 4% PLSDA, followed by the 2% PLSDAand 4% PL and 0.2% PS exhibited the least antimicrobial effect. Increased growth rates were observed with increasing storagetemperatures from 4 to 25oC. The growth data were fitted with a Gompertz equation to determine the SGR and LT of the L.monocytogenes. Six polynomial models were developed for the SGR and LT to evaluate the effect of PS (0.1, 0.2%) and PL(2, 4%) alone and PLSDA (2, 4%) on the growth kinetics of L. monocytogenes from 4 to 25oC.

Tannase catalyzes the hydrolysis of gallic acid esters and hydrolysable tannins. Twenty-two Lactobacillus strainswith tannase activity were isolated from 7 types of kimchi. A polymerase chain reaction-based assay targeting the recA geneassigned all isolates to either Lactobacillus plantarum or Lactobacillus pentosus. The tannase activities of isolates measured inwhole cells and cell-free extracts varied even within each species. The activities of the isolates varied with the assay method,but both methods indicated that isolate LT7 (identified as L. pentosus) showed the highest activity. The results of thin layerchromatography and high performance liquid chromatography, respectively, showed that tannic acid and gallic acid degradedto pyrogallol in resting L. pentosus LT7 cells. Therefore, the putative biochemical pathway for the degradation of tannic acidby L. pentosus implies that tannic acid is hydrolyzed to gallic acid and glucose, with the formed gallic acid beingdecarboxylated to pyrogallol. This study revealed the possible production of pyrogallol from tannic acid by the resting cellreaction with L. pentosus LT7.

In order to determine whether peach contains compounds to regulate adipocyte differentiation, extracts of flesh/pericarp of yellow/white peach were prepared in water, ethyl acetate (EtOAc), or n-butanol solvent and determined for effectson adipocyte differentiation in C3H10T1/2 or 3T3-L1 cells. Interestingly, none of peach extracts has statistically significantstimulatory effect on the adipocyte differentiation in C3H10T1/2. Furthermore, the presence of EtOAc extract of white peachpericarp (WPP) was found to inhibit lipid accumulation in 3T3-L1 cells both by microscopic examination of Oil Red O-stained lipid droplets and by spectrophotometric quantification of extracted stain, indicating a significant inhibitory effect onadipocyte differentiation. The inhibition of lipid accumulation was accompanied by a significant decrease in the expressionlevels of adipocyte molecular markers-peroxisome proliferator-activated receptor γ, CAAT enhancer binding protein α, andfatty acid-binding protein. Thus, this study determined that WPP EtOAc extract contains the inhibitory compound(s) onadipogenesis.

The water extract of Saururus chinensis was investigated for oxygen radical absorbance capacity (ORAC),reducing capacity, metal chelating activity, and intracellular antioxidant activity using HepG2 cell. When 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) was used for the generation of peroxyl radicals in vitro, S. chinensis extract (SC-E)showed the strong and concentration-dependent scavenging activity through donating protons which could be explained by itsreducing property. When hydroxyl radicals were generated in vitro through the addition of Cu2+ and H2O2, SC-E demonstratedthe antioxidant activity depending on its concentration. In HepG2 cell model, most of intracellular oxidative stress generatedby AAPH was efficiently removed by SC-E. However, when Cu2+ without H2O2 was used as an oxidant in the intracellularassay, SC-E partially reduced the oxidative stress caused by Cu2+ in cellular antioxidant activity assay system. These resultsindicate that SC-E could be utilized for the development of functional foods as antioxidant resource in the near future.

The objective of this study was to evaluate the microbial safety of raw beef used to produce Korean beef jerky.The raw beef samples harbored large populations of microorganisms. In particular, psychrophilic bacteria were found to bemost numerous (9.2×103-1.0×105 CFU/g) in the samples. Mesophilic bacteria and anaerobic bacteria were present in averagenumbers (103-105 CFU/g). Spore-forming bacteria and coliforms were not detected below detection limit. Yeast and moldswere detected at 2.2×101-7.8×102 CFU/g in the raw beef. Ten samples of raw beef were analyzed for the presence ofpathogenic bacteria. Bacillus cereus was isolated from sample B, G, and H. The B. cereus isolates from raw beef samples wereidentified with 99.8% agreement according to the API CHB 50 kit.

The present study was conducted to investigate the effects of flowers ethanol extract of Elsholtzia splendens (ESE)on the antioxidant defence system in mice with 7,12-dimethylbenz(a)anthracene (DMBA)-induced oxidative stress. The ESEwas pre-administered orally to 2 groups of mice at 10 and 50 mg/kg body weight (BW) for 5 weeks. Subsequently, mice withpretreatment of ESE received DMBA intragastrically at a dose of 34 mg/kg BW twice a week for 2 weeks. In DMBA alonegroup, biomarkers of oxidative stress (TBARS value, carbonyl content, and serum 8-OH-dG) were significantly increased.Also, the antioxidant enzymes were down-regulated. ESE significantly restored the TBARS value and carbonyl content atboth doses, while a decrease in the elevated serum 8-OH-dG content was observed only at the higher dose. The DMBA-induced decreases in catalase and superoxide dismutase (SOD) activities were restored to nearly control levels by ESE.Glutathione peroxidase (GSH-px) and glutathione reductase (GR) activities, as well as the reduced glutathione (GSH)/oxidized GSH (GSSG) ratio, were significantly affected by ESE at the higher dose. These results suggest that ESE possessesantioxidant activity, which plays a protective role against DMBA-induced oxidative stress.

Titanium dioxide (TiO2) shows antibacterial effects when exposed to near ultra violet (UV) light. In this study,TiO2 photocatalytic continuous reactor was designed and applied to food-borne pathogens such as Vibrio parahaemolyticusATCC 17802, Salmonella choleraesuis ATCC 14028, and Listeria monocytogenes ATCC 15313. TiO2 films were prepared byconventional sol-gel dip-coating method using titanium tetra iso-propoxide (TTIP). The antibacterial activity of photocatalyticreactor with various flow rates and UV-A illumination time showed effective bactericidal activity. As the UV-A illuminationtime increased, survival rates of those bacteria decreased. After 60 min of UV-A illumination, the survival rates of V.parahaemolyticus and S. choleraesuis were less than 0.1%. However, that of L. monocytogenes was about 5% at that timepoint. These results present an effective way to exclude pathogenic bacteria from aqueous foods.

This study examined the effects of temperature, D-psicose concentration, pH, and various amino acids on theMaillard browning reaction of D-psicose and glycine mixture and compared browning color intensity with those of othersugars, such as sucrose, D-glucose, D-fructose, and D-tagatose. When D-psicose (0.1M) and glycine (0.1M) mixture washeated at 70-100oC for 5hr, the absorbance at 420nm increased with increasing reaction temperature and time. The Hunter a,b values, and color difference (∆E) increased with increasing D-psicose concentration and pH within the range of pH 3-7except at pH 6, while the L value decreased. The rate of Maillard browning reaction was in order of D-tagatose>D-psicose≒D-fructose>D-glucose>sucrose. The browning color intensity of the D-psicose-basic and non-polar amino acids mixtures washigher than that of the D-psicose-acidic amino acids.

Bootstrap method, a computer-intensive statistical technique to estimate the distribution of a statistic was appliedto deal with uncertainty and variability of the experimental data in stochastic prediction modeling of microbial growth on achill-stored food. Three different bootstrapping methods for the curve-fitting to the microbial count data were compared indetermining the parameters of Baranyi and Roberts growth model: nonlinear regression to static version function withresampling residuals onto all the experimental microbial count data; static version regression onto mean counts at samplingtimes; dynamic version fitting of differential equations onto the bootstrapped mean counts. All the methods outputted almostsame mean values of the parameters with difference in their distribution. Parameter search according to the dynamic form ofdifferential equations resulted in the largest distribution of the model parameters but produced the confidence interval of thepredicted microbial count close to those of nonlinear regression of static equation.

Propionibacterium acnes is the predominant organism in sebaceous regions of the skinand is thought to play animportant role in the pathogenesis of inflamed lesions. Antibacterial compounds against P. acnes were isolated from theethanol extract of Kaempferia pandurata Roxb. and identified as panduratin A and isopanduratin A. Minimum inhibitoryconcentration (MIC) and minimum bactericidal concentration (MBC) of panduratin A for P. acnes were 2 and 4µg/mL,respectively, while those of isopanduratin A were 4 and 8µg/mL, respectively. The time-dependent killing effect showed thatpanduratin A and isopanduratin A completely inhibited the growth of P. acnes at 4 and 8µg/mL in 48hr, respectively.Panduratin A and isopanduratin A demonstrated high antibacterial activities not only against P. acnes but also other skinmicroorganisms. The results suggest that panduratin A and isopanduratin A could be employed as natural antibacterial agentsto inhibit the growth of acne and skin disease causing microorganisms.

The inhibitory effects of naringenin, kaempherol, and apigenin on the production of cholesterol in HepG2 KCLB88065 and MCF-7 KCLB 30022 cells were evaluated. In this study, quercetin was used as a reference reagent. Afterincubation for 3 days, fat-soluble contents of both cell types were extracted by using the Folch method and the cholesterolcontents in both cultured cells were determined by high performance liquid chromatography. The concentration of cholesterolin untreated each tissue cells was 12.2±0.11 and 8.83±0.12mg/g of lipid, respectively. The total concentration of eachflavonoid was adjusted to 0, 35, or 350µM in the culture broth. As the results, the addition of 2% methanol and dimethylsulfoxide (DMSO) to the media (control for flavonoid solvents) did not significantly affect cell growth; however, DMSOcaused an increase in the production of cholesterol. Each flavonoid inhibited the production of cholesterol in both HepG2 andMCF-7 cells at the concentration of 35µM above. In addition, the inhibitory effect of kaempherol on the production ofcholesterol in these cells was greater than the other flavonoids tested and HepG2 cells are more sensitive to flavonoids thanMCF-7. From the results, the inhibitory effects of flavonoids on cholesterol production are different depending on the celltype.

The antibacterial activity of chitosan against Escherichia coli was investigated in the presence of NaCl, sucrose,and ethanol to assess the potential use of chitosan as a biopreservative in food products containing these components. Theinhibitory activity of chitosan decreased slightly upon the addition of NaCl and sucrose, respectively to culture brothcontaining 100ppm of chitosan (Mw 3,000), while the addition of ethanol enhanced the inhibitory activity of chitosan ongrowing cells. The addition of these components to non-growing cells prior to chitosan treatment demonstrated that NaClprotected the cells from the inhibitory activity of chitosan, while sucrose had no effect. Ethanol addition to non-growing cellsincreased cell death by chitosan treatment. Finally, binding of fluorescein isothiocyanate (FITC)-labeled chitosan to E. coliwas measured in the presence of the food components. The FITC-labeled chitosan binding to cells decreased upon NaCladdition, was not affected by sucrose, and increased following treatment with ethanol.

In this study, 50 rump samples of raw beef obtained from local Korean supermarkets were analyzed to surveymicrobial distributions. As results, mesophilic microorganisms ranged from (1.4±0.01)×102 to (1.6±0.05)×105 CFU/g, and totalcoliforms ranged from 0 to (1.3±0.04)×104 CFU/g. Major foodborne pathogens, including Listeria monocytogenes, Escherichiacoli O157:H7, and Salmonella spp., were not found among the samples. However, Staphylococcus aureus was isolated with 4%frequency. Other isolated microorganisms included Enterobacter amnigenus (4%), Enterobacter cloacae (24%), E. coli (24%),Listeria innocua (8%), Staphylococcus saprophyticus (56%), Staphylococcus xylosus (10%), and Staphylococcus warneri (8%).

The aprE2 gene from Bacillus subtilis CH3-5 was expressed in Bacillus licheniformis ATCC 10716 using aBacillus-Escherichai coli shuttle vector, pHY300PLK. The fibrinolytic activity of transformant (TF) increased significantlycompared to B. licheniformis 10716 control cell. During the 100hr incubation in Luria-Bertaini broth at 37oC, fibrinolyticactivity of B. licheniformis TF increased rapidly at the late growth stage, after 52hr of incubation, which was confirmed byzymography using a fibrin gel. pHY3-5 was stably maintained in B. licheniformis without tetracycline (Tc) in the media,60.9% of cells still maintained pHY3-5 after 100 hr of cultivation.

Tachioside (4-hydroxy-3-methoxy-phenyl-1-O-glucoside), a known phenolic glycoside, was isolated from variousbamboo species. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and Trolox equivalent antioxidantcapacity determined a significant antioxidant activity of tachioside which was comparable to L-ascorbic acid. Each culm andleaf extracts were tested and the culm of Phyllostachys bambusoides appeared to contain the highest amount of tachioside.

This study was performed to provide basic information that can be used to differentiate Korean ginseng (Panaxginseng C.A. Meyer) berry and seed from American ginseng (Panax quinquefolium L.) seed. Total ginsenoside contents ofKorean ginseng berry, Korean ginseng seed, and American ginseng seed were 9.09, 3.30, and 4.06%, respectively. Totalginsenoside content of Korean ginseng berry was about 2.2 to 2.7 times higher than those of Korean ginseng seed and Americanginseng seed. Particularly ginsenoside Re content of 4-year cultivated Korean ginseng berry (5.99%) was about 3.6 to 5.4 timeshigher than that of 4-year cultivated Korean ginseng seed (1.65%) and 4-year cultivated American ginseng seed (1.10%). Thecontents of total ginsenoside and ginsenoside Re of Korean ginseng berry were about 4.8 and 28 times higher, respectively, thanthose of 4-year cultivated Korean ginseng root. In general the contents of total ginsenoside and ginsenoside Re of Koreanginseng berry were significantly higher than those of Korean ginseng seed and American ginseng seed.

This study was conducted to examine the quality characteristics of soybean curd containing red paprika juice(RPJ) and green paprika juice (GPJ). The proximate compositions of RPJ showed higher levels of ash, carbohydrate, andvitamin C than GPJ. The yield of soybean curd was not significantly different with the level of RPJ and GPJ. However therewas a significant decrease in the pH and an increase in the acidity with the addition of RPJ and GPJ. The L, a, and b values ofsoybean curd containing RPJ and the L value of soybean curd containing GPJ were significantly different. The hardness andchewiness of soybean curd containing RPJ and GPJ increased significantly with the level of juice.

This study evaluated the effects of heat treatment on antioxidant activity of Rehmannia radix Libosch (RRL). RRLwas heated at various temperatures (110-150oC) for various times (1-5hr), and the total polyphenol, flavonoid content, andantioxidant activity were investigated. With increased heating temperature and exposure time, total content of polyphenol,flavonoid, as well as antioxidant activity increased. The highest total polyphenol and flavonoid contents were 21.65 and 3.56mg/g, respectively, these values were occurred after heating for 3hr at 150oC (RRL was 5.09 and 0.83mg/g, respectively).The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was highest value of 83.46% after heating for 3 hr at150oC. The 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) cation radical scavenging activity was highest valueof 20.43mg ascorbic acid (AA) eq/g after heating for 2hr at 150oC. There were highly significant differences in the totalpolyphenol, flavonoid content, and antioxidant activity among heating temperatures and times (p<0.001), with heatingtemperature having the greater effect.

Leuconostoc citreum HJ-P4 is a strain isolated for kimchi fermentation with its low temperature-adapted growthfeature and its high dextransucrase activity. The detailed characteristics of cell growth and dextransucrase activities wereinvestigated at various environmental conditions such as temperatures, pHs, salts, and raw ingredients. This strain showedalmost 2-fold higher maximal cell concentration (Xmax) than that of the type culture Leuconostoc mesenteroides B-512F at10oC. The Xmax of the strain was maximum at pH 7 and the cell growth was inhibited by salts in a dose-dependent mode up to7%. Addition of pepper (<6%), garlic (<10%), and ginger (<2%) in kimchi gave no inhibition effect on the growth of HJ-P4.Dextransucrase synthesized by this strain retained over 80% of its maximum activity at 10oC showing a comparable cold-adapted feature to its host microbe. This culture can be used as a starter culture in the industrial kimchi production givingdesirable functions and predominance at low temperature.