Earticle

This study was conducted to investigate the pasting and sensory properties of different commercial rice cultivars. All samples had adequate moisture content, and Gyeonggi Kosihikari had the lowest protein content (6.75%). Apparent quality of head rice ranged from 85.63 to 98.70% and amylose content was 21.51-26.54%. In a rapid visco analyzer examination, pasting temperature of Gyeonggi Kosihikari was the lowest (84.87). Breakdown of Gangwon Oade (43.64 RVU) was lower that of others, indicating the highest pasting stability. The setback of Jeonam Hitomebore was the lowest (81.56 RVU), suggesting slow deterioration. A texture analysis test showed that Gyeonggi Koshihikari had the lowest hardness and Chungnam Samgwang had the highest adhesiveness. Gyeonggi Koshihikari had the highest sensory scores for appearance, flavor, taste, texture and overall acceptability. These results indicate that Gyeonggi Koshihikari is the most adequate rice product among cultivars.

Free and bound aroma compounds in green and fermented teas treated with microbial-fermentation were analyzed using headspace-solid phase microextraction gas chromatography (GC) and GC-mass spectrometry. Aldehydes and ketones in green tea decreased during microbial fermentation, whereas linalool and geraniol increased in the fermented tea. After enzyme treatment, (Z)-3-hexen-1-ol increased significantly following enzymatic hydrolysis of both green and fermented teas. In addition, benzaldehyde, 3-hexenyl acetate, and geraniol also increased in green tea with enzyme treatment. Bound aroma compounds in the green and fermented teas increased at different levels of added enzyme. We demonstrated the enhancement of both green and fermented teas by enzyme treatment, which can lead to improvement in the flavor qualities of green and fermented teas.

This survey was conducted to monitor the safety of red ginseng products in Gwangju, in 2010. Among 100 samples, 37 were beverages, 5 were functional health foods on the market, and 58 were beverages from a tailor-made shop. All samples were negative for coliform bacteria. Aerobic plate counts were detected from 13 samples in the 58 tailor-made products but not detected in the other types of products. Benzoic acid was detected in 5 samples (range, 19.2- 543.0 mg/kg). Among heavy metals, lead was detected, ranging from 28.8-62.3 μg/kg, cadmium, from 1.15-4.18 μg/kg, and mercury from 0.10-0.18 μg/kg. Benzopyrene was not detected in any samples. Ginsenoside Rg1 and Rb1 were detected in 0.1-23.4 mg/90 mL of beverages and 12.1-66.8 mg/90 mL of functional health foods. These results indicate that red ginseng products are safe in terms of microbial contaminants and hazardous chemical compounds such as heavy metals and benzopyrene.

Changes in the flavor of muskmelons stored at different temperatures were examined to judge aroma patterns during storage. A mass-spectrometry based electric nose was used to distinguish the subtle differences in the muskmelon’s volatile compounds. The data were used for a discriminant function analysis (DFA), and then the partial least square algorithm was used for a quantitative analysis. Volatile components in the muskmelons increased with storage, and the first discriminant function score (DF1: r2=99.88%, F=3072.5) moved from a positive position to a negative position as the storage period increased. The proper point of maturity was anticipated as the 28th day at 0oC, 21st day at 4 and 7oC, and 14th day at 10oC. Also, using the DF1 score we could predict the general tendency (vitamin C, stem moisture, acidity) of the muskmelons. The electronic nose revealed that the major volatile compounds that changed during storage of the melons were ethyl ethyl acetate, butyl acetate, nonanol, dodecanoic acid, hexadecanoic acid and tricosane. The amount of volatile compounds detected increased during storage.

In this study, we set an optimum blanching condition as a pretreatment condition to freeze welsh onion (Allium fistulosum L.) for the purpose of preserving the cooking material for long-term usage. With higher blanching temperature and longer processing time, the Hunter color values and the hardness of welsh onion tended to decrease, which confirmed softening of the tissue. Compared to before blanching, total bacterial counts decreased to near 2 log scale, whereas coliforms were not detected or decreased to a 1-2 log scale. Blanching by heating at 100oC for 5 min decreased peroxidase inactivity to more than 94%, whereas only 47% of the inactivity was achieved at 80oC for 1 min. The sensory evaluation for the blanched and defrosted welsh onion showed that the group blanched at 80oC for 1 min was preferred significantly (p<0.05).

The quality characteristics and effects on the proliferation of human hepatoma HepG2 cells due to dropwort (Oenanthe javanica) extracts naturally fermented with fructooligosaccharides were investigated. Dropwort was fermented by steeping with the same weight of oligosaccaride at room temperature for 1 year, and then stored at 4oC for 1 or 2 more years. During the fermentation periods, total flavonoid content, Hunter’s color (a value), and viable cell counts decreased, but reducing sugars including glucose and fructose increased. HepG2 cell proliferation was inhibited significantly by the three extracts, but no effects were observed on Chang cells. In particular, the dropwort extract fermented for 1 year showed the highest inhibitory effect. These results demonstrate that the quality characteristics and anti-proliferative effects of dropwort were affected by fermentation period. It is concluded that dropwort extract fermented for 1 year showed the highest functional properties and quality.

This study was performed to examine the physicochemical characteristics of Korean traditional fermented liquor added with citron juice and the levels (3, 6 and 9%) of citron (Citrus junos) juice during two-step-brewing. The pH of traditional Korean fermented liquor added with citron juice increased after 3 days of fermentation and then the pH values decreased from the sixth day. pH increased again at the end of fermentation. Total acidity increased after 5 days of fermentation until the sixth day, then decreased rapidly but increased slightly up to 12 days. Alcohol content increased to 12.76-14.32% after 12 days of fermentation. As the amount of added citron juice increased, alcohol content decreased. Amino acids increased after 12 days of fermentation. A sensory evaluation appearance, flavor, sourness, sweetness, bitterness and overall acceptance of Korean traditional fermented liquor added with 6% citron showed higher values than those of the control.

Total 480 lactic acid-producing bacteria were isolated from five kinds of kimchi, and their antibacterial activity was tested against Salmonella enterica serovar Typhimurium, Bacillus subtilis, and Pseudomonas aeruginosa using an agar diffusion assay. Among them, 340 isolates showed a halo on MRS agar against one or more indicator strains, which were identified using multiplex PCR, an API 50CHL kit, and a 16S rDNA sequence analysis. As a result, 169 Lactobacillus plantarum, 20 Lactobacillus fermentum, two Lactobacillus paracasei ssp. paracasei, two Lactobacillus sp., and 15 Pediococcus sp. were identified. This may be the first report on the isolation of antibacterial Lactobacillus fermentum from kimchi.

The effect of the amount of water added during fermentation on the quality of takju (rice beer) was investigated. Takju was made by adding water 2-fold (A), 4-fold (B), 5-fold (C), and 6-fold (D), respectively, of the rice weight (w/w). Although the amount of takju increased in proportion to the amount of water added before fermentation, the amounts of B, C, and D were 1.17-1.19 times larger than the amount in A, and the total acidities of B, C, and D were 1.34, 1.40 and 1.46 times higher than those in A after adjusting alcohol content to 6%(v/v). Moreover, the sensory preferences for B, C, and D were higher overall than those for A, which was suggested to be due to the amount of sweet, sour, and bitter tastes as well as body in A. Different types of takju could be made by changing the amount of water added before fermentation.

Recent studies have revealed that collagen peptide (CP) plays a protective role in skin by improving the activity of antioxidants and acts as an inducer of skin regeneration by positive feedback. In this study, we focused on the beneficial effect of reinforcing the CP skin barrier. To evaluate the skin barrier, hairless mice were exposed to UVB irradiation and acetone-treatment, with or without oral administration of CP. The effects on skin appearance, trans-epidermal water loss, epidermal thickness, and cytokine content were measured using bioengineering and histochemical methods. In the CP treated group, the skin had better appearance and less damage than that of the control. Furthermore, in HaCaT cells, the amount of serinepalmytoyl transferase (SPT) mRNA increased by about 1.6-fold after treatment (CP, 100 mg/L), reflecting that CP can induce SPT expression and reinforce the recovery of skin barrier function. These results suggest that CP is not only an anti-wrinkling agent but also a potent candidate as an epidermal moisturizer.

Halocynthia roretzi is one of the most important cultured marine species on the southern coast of Korea. Samples were extracted using methanol (ME), ethanol (EE) and water (WE) to evaluate the antioxidant activities and antilipase activity in Halocynthia roretzi extracts. Antioxidant potentials of the samples were determined by poly-phenol content, flavonoid content, free radical scavenging activity, reducing potential, and chelating activity. The ME showed significant scavenging activity (1176 μg/mL IC50 for DPPH, and 895 μg/mL IC50 for ABTS assay). The IC50 for lipase inhibition activity was 12,021, 6,004, and 14,979 μg/mL in the ME, EE, and WE, respectively. In conclusion, Halocynthia roretzi extracts exhibited antioxidant activities and anti-lipase activity. These results suggest that Halocynthia roretzi extracts can be potentially used as a source of antioxidant and antiobesity agents.

Ginger (Zingiber officinale Rosc.) is a well known edible plant that is traditionally used to treat various illnesses related to inflammation and oxidative stress. Steam distillated ginger oil or water extract are mainly used for related products; however, it is unclear whether these fractions contain most of the bioactive compounds or the highest efficacy. This investigated the antioxidant effects of extracts prepared by supercritical fluid extraction (SFE). 6-Gingerol was the most abundant component in hexane fraction of ethanol extract from ginger. The antioxidative properties of SFE oil and Marc ethanol fractions were demonstrated using the 2,20-diphenylpicrylhydrazyl (DPPH) and 2,2'-azinobis 3-ethyl benzothiazoline-6-sulfonic acid (ABTS) radicals scavenging assays. A clear correlation was observed between total polyphenol contents and RC50 values in the Marc ethanol fraction. These results indicate that not only SFE oil but the marc after SFE could be good sources for the food industry.

From an analysis of the daily consumption per capita (g/capita/day) in the existing dataset of the Korea National Health and Nutrition Examination Survey 2008, the top seven fruit and vegetable juices (apple, grape, mandarin, orange, pineapple, pomegranate and tomato) commercially available on the Korean market were selected and analyzed. These juices showed a wide range of levels of total phenolics, total flavonoids, and antioxidant capacities. The daily per capita intake of total phenolics from juice consumption was 11.70 mg gallic acid equivalents and that of total flavonoids was 1.65 mg catechin equivalents. The daily per capita intakes antioxidant capacities were 10.42 mg vitamin C equivalents (DPPH assay) and 13.21 mg vitamin C equivalents (ABTS assay). Daily per capita intakes of total phenolics, total flavonoids, and antioxidant capacities were influenced by the compositional content and the daily consumption of fruit and vegetable juices.

Epigallocatechin-3-gallate (EGCG) is a polyphenolic compound frequently found in green tea, and its physiological actions have been extensively investigated. In the present study, changes in chemical stability and cytotoxic properties of EGCG in the presence of different types of antioxidants were investigated. The antioxidants used modulated the chemical stability of EGCG. Superoxide dismutase (SOD) significantly increased EGCG stability; EGCG was less stable in the presence of catalase. Ascorbic acid, N-acetylcysteine (NAC), and glutathione (GSH) stabilized EGCG concentration dependently. The H2O2 level generated from EGCG was decreased by catalase, SOD, and NAC but not by GSH. The cytotoxic effects of EGCG also decreased in the presence of NAC, catalase, and SOD. GSH, however, showed a complicated modulatory pattern according to the EGCG and GSH concentrations, and ascorbic acid rather enhanced EGCG toxicity. The results suggest that certain antioxidants could modulate the cytotoxic properties of EGCG in a cell culture system not only by removing reactive oxygen species but by modulating chemical stability and other factors, which should be considered carefully when studying reactive oxygen species-dependent mechanisms of EGCG.

Although bacterial outbreaks from ready-to-eat foods have increased, little information is available on microbial quality of sprouts in markets. Fifty sprouts and 30 salads were collected from wholesale markets. Total aerobic count (TAC), coliform, Escherichia coli, and some pathogens were detected. TAC for sprouts was 7.95 log CFU/g and 6.70 for salads, indicating that sprouts were more contaminated by 1 log CFU/g than that of salads. The numbers of coliform were 6.69 log CFU/g for sprouts and 5.42 for salads. E. coli was detected in 16 of 50 sprout samples at 2.38 log CFU/g and eight of 30 salads at 2.21 log CFU/g. Bacillus cereus was detected in 29 of 50 sprout samples and 16 of 30 salads, and the counts were mostly <3 log CFU/g. Salmonella, Staphylococcus aureus, Listeria monocytogenes, Campylobacter jejuni, and Clostridium perfringens were not detected. Therefore, although pathogens may not be a high risk for these foods, the high TAC and E. coli contamination require improved production and distribution methods, particularly for sprouts.

We evaluated the quality characteristics of fresh-cut produce (potato, sweet potato, carrot, radish, zucchini, cucumber, and green bell pepper) washed with sodium hypochlorite, which were vacuum packaged, and stored at 4 and 10oC. The L-values of the fresh-cut potato and sweet potato decreased during storage. Lower PPO activities of potato and sweet potato were observed at 4oC than those at 10oC and development of potato and sweet potato browning was delayed at 4oC. Total aerobic count and coliform increased continuously at 10oC during storage. Diced zucchini and shredded sweet potato had the greatest reduction in hardness among the fresh-cut produce during storage. Differences in the rate of quality change were observed according to the kinds and cut types of produce. Thus, a quality maintenance period for each type of fresh-cut produce must be determined, which will lead to the safe use of fresh cut produce in foodservice establishments.

The objective of this study was to determine the extent to which acetaldehyde (AA) and formaldehyde (FA) migrated from polyethylene terephthalate (PET) bottles into mineral water during storage at 25 and 35oC for 240 days. Generally, AA and FA were observed to migrate more at 35oC than at 25oC. The amount of FA in the samples irradiated under UV lamps was higher than in those stored in the dark over the storage period and vice versa for AA. Using a triangular test, the sensory panels distinguished a difference between one sample and the other two mineral water samples that had been exposed to UV lamps after 60 days of storage at 35oC (p<0.05). At this time, FA and AA concentrations were measured at 267.4 and 515.3 g/L, respectively. After 120 days, an independent mineral water sample from the other two samples in all treatments could be distinguished by the panel members at a significance level of p<0.001.

To study the effect of freezing rate on the quality of freeze-dried rice porridge, freeze-dried rice porridge products were prepared with rice porridge pre-frozen at three different temperatures of −20, −40, and −70oC. The porridge properties such as microstructure, mechanical properties, textural properties, and rehydration rate were determined. Scanning electron microscopy images indicated that fewer air cells were obtained with a larger size of freeze-dried rice porridge frozen at −20oC compared with that frozen at −40 and −70oC. In contrast, quick frozen products at −70oC had more dense texture with higher mechanical strength, whereas slow frozen products exhibited higher rehydration rates than those of quick frozen products. In conclusion, the proper choice of pre-freezing temperature plays a decisive role when preparing freeze-dried rice porridge with optimum quality and convenience.

The effects of nonthermal plasma treatments against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes living on polystyrene (PS), sausage casings, and smoked salmon were investigated. Inoculated PS, casings, and salmon were treated with nonthermal plasma generated with helium (5 L/min) or with both helium (5 L/min) and oxygen (100 mL/min) at 60 Hz and 30 kV/cm for 2, 5, or 10 min. S. Typhimurium exhibited the highest sensitivity to the helium-used treatment. The greatest reduction (3.9±0.8 log CFU/cm2) was observed with L. monocytogenes on PS after the treatment with the mixed gas for 5 min. The treatment with the mixed gas inhibited L. monocytogenes on casings and salmon by 0.5±0.3 log CFU/cm2 and 1.0±0.3 log CFU/g, respectively. Different treatment times did not result in different reductions of L. monocytogenes on both casings and salmon. The types of treatment gas and material of contamination need to be considered for evaluating the antimicrobial effects of nonthermal plasma treatments.

The aim of this study was to evaluate the antimicrobial activities of leek and garlic extract juice and powder against Escherichia coli, Salmonella enteritidis, and Staphylococcus aureus in a single strain and a mixed strains system. Garlic juice and powder showed higher antimicrobial activity against Sta. aureus than that of E. coli or S. enteritidis. The antimicrobial activities of the leek and garlic powders decreased with increasing temperature and time, but stabilized at various pHs. The antimicrobial effects of mixtures of various ratios between the leek and garlic extracts increased with an increase in garlic extract content. No synergistic effects by the leek and garlic mixtures were observed. In a mixed strains system, the antimicrobial effects of leek and garlic powder were similar to those in a single strain system.