• The Korean Journal of Mycology
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• v.40 no.4
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• pp.244-253
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• 2012

The effect of fermented Rhus verniciflua stem bark (FRVSB) extract on the microbial count, enzyme activity, concentrations of free amino acids and organic acids, and physiochemical properties of doenjang (soybean paste) was evaluated during brine fermentation. The FRVSB extract increased the total free amino acid concentration by 1.3-3.1-fold on the $42^{nd}$ day of brine fermentation. After the filtration of brine, the following microbial counts were obtained in the doenjang: bacteria, $0.3{\times}10^8-12.0{\times}10^8$ cfu/g; mold, $3.0{\times}10^4-21.0{\times}10^4$ cfu/g; yeast, $1.0{\times}10^4-2.0{\times}10^4$ cfu/g; Escherichia coli, not detected; and Bacillus cereus, $3.0{\times}10^2-25.0{\times}10^2$ cfu/g. The FRVSB extract addition enhanced the protein and starch degrading activity by 13.8-26.0% and 16.1-35.1%, respectively. The extract increased the total free amino acid content by 1.4-3.0-fold. Lactic acid, acetic acid, and pyroglutamic acid were the predominant organic acids in doenjang. Moreover, the proximate composition, pH, moisture, ash, salt, and amino nitrogen content were increased.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.277-284
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• 2012

The objective of this study was to investigate and evaluate microbial contamination levels of leafy greens (perilla leaf and lettuce) and its distributing conditions at different seasons (Feb, May, Aug, and Nov of the year 2011) in order to provide insight into any potential health hazards associated with consumption of these commodities. Leafy greens were collected from a farm located in Geumsan, Chungnam and wholesale markets (WM) and traditional markets (TM) located in Suwon. At the same time, temperature and relative humidity fluctuations experienced by the leafy greens during distribution from the farm to the distribution center were measured by a data logger. The contamination levels of perilla leaf and lettuce were determined by analyzing total plate count. Coliform groups, Bacillus cereus, Escherichia coli, Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes and Staphylococcus aureus were determined. The contamination levels of total aerobic bacteria, coliform groups and B. cereus in both vegetables sampled during May and August found to be higher than those sampled during February and November. E. coli O157:H7, Salmonella spp., L. monocytogenes were not detected in the vegetables analyzed in this study. There were no significant trends between samples at WM and TM in the contamination levels. Relative humidity of vegetables distributed from the farm to the distribution center showed over 90% during distribution regardless of measured seasons. In the case of background microflora on leafy greens, the density was significantly increased at 20, 30 and $37^{\circ}C$ during storage of 24h. E. coli O157:H7 and B. cereus inoculated on the leaves also showed similar increases in the storage tests. The microbial contamination levels determined in this study may be used as the fundamental data for microbial risk assessment.

• Food Science and Preservation
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• v.21 no.5
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• pp.676-687
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• 2014

This study investigated the quality changes in cabbage brined with deep sea water salt and in a commercial brined cabbage product. The subject cabbages were separated into two groups: those manufactured in the Lab (ML) and the commercial brined cabbage product (CP). Each group had three brining treatments: with sun-dried salt (S, CS), refined salt (R, CR), and deep sea water salt (D, CD). The salinity level of the ML group was 2.1~2.3%, higher than that of the CP group (1.1~1.5%). The total plate count (TPC) was detected as 5.0 log CFU/g with the S, R, and D treatments at Day 7, but the growth rate of the TPC with the CS, CR, and CD treatments was faster than that with the S, R, and D treatments (6.9~7.7 log CFU/g). A lactic acid bacteria (LAB) level of 5.0~6.6 log CFU/g was also detected in the S, R, and D samples, but only 7.0~7.6 log CFU/g was detected in the CP groups at Day 14. The instrumental hardness levels of the cabbage brined with the deep sea water salts (D and CD) were 3,971 g and 3,932.4 g, respectively, which were significantly higher than those of the samples that were salted with sun-dried salt and refined salt (p<0.05). As for the sensory attributes, S, D, and CD maintained their marketability scores until the end of the storage period for all the properties. CD presented the highest total free amino acid (478.9 mg%), glutamic acid (107.0 mg%), citric acid (428 mg%), and sodium (189 ppm) contents.

• Food Science and Preservation
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• v.19 no.6
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• pp.951-956
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• 2012

In this study, the effects of the use of a starter on radish soaked at $4^{\circ}C$ for 28 days using two kinds of domestic sun-dried salt (white and gray salt) were determined. As a result, the moisture contents of the radish soaked with white and gray salt were 7.93 and 4.50%, respectively. The salinity levels were found to be equal (90%). No significant difference was found between the two groups in terms of the mineral contents of the salts therein ($37812.41{\pm}1922.95$ and $39755.13{\pm}1205.70$ mg/100 g, respectively). However, iron and zinc contents of gray salt were higher than those of white salt while the calcium, potassium, and magnesium contents were lower than those of white salt. After the addition of the starter, the sugar content increased, the pH decreased, and the total acidity rapidly decreased compared with the non-starter group during fermentation. The total microorganism count of the two groups increased during the fermentation period of 28 days. From the initial fermentation for 7 days, the lactic acid bacteria in the non-starter group increased while those in the leuconostoc starter group steadily increased within the whole fermentation period. The Leuconostoc spp. in non-starter group increased, but that in the starter group decreased to pH 4.0 on day 14.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.233-238
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• 2004

Foxtail Millet Takju was treated with heat ($65^{\circ}C/30\;min$) (HT) or high hydrostatic pressure ($27^{\circ}C/400\;MPa/10\;min$) (PT), and changes in microbial count, enzyme activity, and quality were determined during 30-day storage at 10 and $25^{\circ}C$. Total viable cellcount remained constant, while lactic acid bacteria and yeast were not detected in HT and PT Takjus. Relative activities of ${\alpha}-amylase$ in PT Takju significantly increased by 169.7% at 3 days storage, then decreased to 137.7 and 68.7% at 10 and $25^{\circ}C$, respectively, at 30 days. Relative activities of glucoamylase in HT Takju showed reversible change, and were 36.5 and 54.3% at $10\;and\;25^{\circ}C$, respectively, at 30 days storage. Activities in PT Takju increased with storage period, 158.2% at 30 days storage at $10^{\circ}C$. Titratable acidity in untreated Takju increased, while those in HT and PT Takjus remained almost constant during 30 days storage. Reducing sugar content in untreated Takju showed no change, while that in HT Takju increased gradually, reaching 2.9% at 30 days, whereas that in PT increased sharply after 3 days, reaching 4.8% at 30 days. Sensory evaluation showed sourness and bitterness were low, and sweetness and overall acceptance were high in PT Takju after 30 days storage at $10^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.743-749
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• 2012

Black soybean paste (BSP) is a bealmijang manufactured with barley flour and black soybeans. This study investigated the quality characteristics of BSP prepared with Bacillus subtilis HJ18-4 (HJ18-4). ${\alpha}$-Amylase and protease activities of BSP rapidly increased on day 6 and day 9, respectively, ($41.45{\pm}0.3-42.72{\pm}0.16$, $21.84{\pm}0.24-23.11{\pm}0.35unit/g$) after which the activities were constant or decreased slightly. Amino type nitrogen contents increased until day 23 ($173.78{\pm}3.51-195.63{\pm}1.51mg\;%$), whereas ammonia type nitrogen sharply decreased on day 9. On day 30, lactic acid bacteria counts were higher compared with the initial count ($7.91{\pm}0.05-8.17{\pm}0.02log\;CFU/g$). Meanwhile, B. cereus and total aerobic counts in HJ18-4 added BSP were lower than that in the control. These results implied that BSP could be edible after 30 days of fermentation, and the addition of HJ18-4 in meju could contribute to the safety of the black soybean paste by the inhibition of B. cereus growth.

• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.104-110
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• 2013

This study assessed hazards at the harvest stage of strawberry farms which may cause risk to humans. A total of 216 samples were collected from 6 strawberry farms (soil culture farms: A, B, C; nutriculture farms: D, E, F) located in Western Gyeongnam. The collected samples were subjected for sanitary indicator bacteria (aerobic plate count, coliforms and Escherichia coli), major foodborne pathogens (E. coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Bacillus cereus), and fungi. The levels of APC and coliform in the soil culture farms were 1.0-6.9 and 0.4-4.6 log CFU/g (leaf, mL, hand or 100 $cm^2$), respectively. The samples obtained from the nutriculture farms were contaminated with the levels of 0.8-4.9, and 0.2-2.6 log CFU/g (leaf, mL, hand or 100 $cm^2$) of APC and coliform. However, E. coli was not detected in any samples. In major foodborne pathogens, S. aureus was detected at the level of ${\leq}$3.3 log CFU/hand in workers' hand samples and B. cereus was detected at the levels of 0.4-4.1 log CFU/g (hand or 100 $cm^2$) in soil, plants and workers' hygiene. L. monocytogenes, E. coli O157:H7 and Salmonella spp. were not detected. Fungi were detected at the levels of 1.0-5.2 and 0.2-4.4 log CFU/g (leaf, mL, hand or 100 $cm^2$) in soil culture and nutriculture farms, respectively.

• Food Science and Preservation
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• v.19 no.4
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• pp.470-476
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• 2012

Enzymatic action and microbial growth degrade the quality of fresh-cut lettuce. Browning, a bad smell, and softening during storage are the major forms of quality deterioration. Health-oriented consumers tend to avoid foods treated with chemicals to maintain their freshness. This study was conducted to evaluate the change in the quality of fresh-cut lettuce with combined low-temperature blanching (LB) and ultrasonication (US). The optimum condition was selected using the response surface methodology (RSM), through a regression analysis with the following independent variables; the ultrasonication time (X1), blanching temperature (X2), blanching time (X3), and dependent variable; ${\Delta}E$ value (y). It was found that the condition with the lowest ${\Delta}E$ value occurred with combined 90s US and $45^{\circ}C$ 90s LB (US+LB). The combined treatment group (US+LB) was stored at $10^{\circ}C$ for 9 days with the control group and each single-treatment group, with low-temperature blanching and ultrasonication. Overall, the US+LB group had a significantly high $L^*$ value, which indicates significantly low $a^*$, $b^*$, ${\Delta}E$, browning index, PPO, and POD activity values, and a low total bacteria count (p < 0.05). The US+LB group also had the highest sensory score (except for aroma and texture; p > 0.05).

• Applied Biological Chemistry
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• v.11
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• pp.1-27
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• 1969

More than thirty kinds of sea food pickles have been eaten in Korea. Out of these salted yellow tail pickle, salted clam pickle, salted oyster pickle, and salted cuttlefish pickle were employed for the analysis of their components, identification of main fermenting microbes, and determination of enzyme characteristics concerned. Also studied was the effect of enzymic action of microbes, which are concerned with the fermenting of pickles, on the production of flavorous 5'-mononucleotides and amino acids. The results are summarized as follows: 1. Microflora observed in the pickles are: (a) Total count of viable cells after 1-2 months of pickling was found to be $10^7$ and that after 6 months decreased to $10^4$. (b) Microbial occurence in the early stage of pickling was observed to be 10-20% Micrococcus spp., 10-20% Brevibacterium spp., 0-30% Sarcina spp., 20-30% Leuconostoc spp., ca 30% Bacillus spp., 0-10% Pseudomonas spp., 0-10% Flavobacterium spp., and 0-20% yeast. (c) Following the early stage of pickling, mainly halophilic bacteria such as Bacillus subtilis, Leuconostoc mesenteroides, Pediococcus halophilus and Sarcina litoralis, were found to exhibit an effect on the fermentation of pickle and their enzyme activities were in direct concern in fermentation of pickles. (d) Among the bacteria participating in the fermentation, Sarcina litoralis 8-14 and 8-16 strains were in need of high nutritional requirement and the former was grown only in the presence of purine, pyrimidine and cystine and the latter purine, pyrimidine and glutamic acid. 2. Enzyme characteristics studied in relation to the raw materials and the concerned microbes isolated are as follows: (a) A small amount of protease was found in the raw materials and 30-60% decrease in protease activity was demonstrated at 7% salt concentration. (b) Protease activity of halophilic bacteria, Bacillus subtilis 7-6, 11-1, 3-6 and 9-4 strains, in the complete media decreased by 10-30% at the 7% salt concentration and that of Sarcina litoralis 8-14 and 8-16 strains decreased by 10-20%. (c) Proteins in the raw materials were found to be hydrolyzed to yield free amino acids by protease in the fermenting microbes. (d) No accumulation of flavorous 5'-mononucleotides was demonstrated because RNA-depolymerase in the raw materials and the pickles tended to decompose RNA into nucleoside and phosphoric acid. (e) The enzyme produced in Bacillus subtilis 3-6 strain isolated from the salted clam pickles, was ascertained to be 5'-phosphodiesterase because of its ability to decompose RNA and thus accumulating 5'-mononucleotide. (f) It was demonstrated that the activity of phosphodiesterase in Bacillus subtilis 3-6 strain was enhanced by some components in the corn steep liquor and salted clam pickle. The enzyme activity was found to decrease by 10-30% and 40-60% at the salt concentration of 10% and 20%, respectively. 3. Quantitative data for free amino acids in the pickles are as follows: (a) Amounts of acidic amino acids such as glutamic and aspartic acids in salted clam pickle, were observed to be 2-10 times other pickles and it is considered that the abundance in these amino acids may contribute significantly to the specific flavor of this food. (b) Large amounts of basic amino acids such as arginine and histidine were found to occur in salted yellow tail pickle. (c) It is much interesting that in the salted cuttlefish pickle the contents of sulfur-containing amino acids were exceedingly high compared with those of others: cystine was found to be 17-130 times and methionine, 7-19 times. (d) In the salted oyster pickle a high content of some essential amino acids such as lysine, threonine, isoleucine and leucine, was demonstrated and a specific flavor of the pickle was ascribed to the sweet amino acids. Contents of alanine and glycine in the salted oyster pickle were 4 and 3-14 times as much as those of the others respectively. 4. Analytical data for 5'-mononucleotides in the pickles are as follows: (a) 5'-Adenylic acid and 3'-adenylic acid were found in large amounts in the salted yellow tail pickle and 5'-inosinic acid in lesser amount. (b) 5'-Adenylic acid, especially 3'-adenylic acid predominated in amount in the salted oyster pickle over that in the other pickles. (c) The salted cuttlefish pickle was found to contain only 5'-adenylic acid and 3'-adenylic acid. It has become evident from the above fact that clam and the invertebrate lack of adenylic deaminase and contain high content of adenylic acid. Thus, they were demonstrated to be the AMP-type. (d) 5'-Inosinic acid was contained in the salted yellow tail pickle in a significant concentration, and it might be considered to be IMP-type. 5. Comparative data for flavor with regard to the flavorous amino acids and the contents of 5'-mononucleotides are: (a) A specific flavor of salted yellow tail pickle was ascribed to the abundance in glutamic acid and aspartic acid, and to the existence of a small amount of flavorous 5'-inosinic acid. The combined effect of these components was belived to exhibit a synergistic action in producing a specific fiavor to the pickle. (b) A specific flavor of salted clam pickle has been demonstrated to be attributable to the richness in glutamic acid and aspartic acid rather than to that of 5'-mononucleotides.