• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.752-755
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• 2003

The antimicrobial activity of fresh garlic juice against Escherichia coli O157:H7 was investigated. When E. coli O157:H7 was cultured for 18 hr in the trypticase soy broth containing 1%, 3%, and 5% garlic juice, viable cell number of E. coli O157:H7 was reduced to $2.3{\times}10^2\;CFU/mL$ at 5% from $7{\times}10^8\;CFU/mL$ at the non-treated culture, respectively. The inhibitory effects of the ground beef treated with 3%, 6%, and 10% garlic juice against E. coli O157:H7 was significantly enhanced with approximate 2 log-reduction compared to that of ground beef without garlic. There was no significant difference in the inhibition of E. coli O157:H7 among the groups with different amounts of garlic juice (p<0.05). These results suggest that garlic juice may function well as a natural preservative in food system.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.614-620
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• 1994

The effects of growth temperature and nutritional components on the synthesis of poly-3-hydroxybutyric acid, PHB, by filamentation-suppressed recombinant Escherichia coli XL1-Blue (pSYL107) were studied. After culturing XL1-Blue(pSYL107) for 48 hours in complex medium at 30$\circ$C, 7Al g/l of PHB could be obtained with the PHB content and PHB yield of 82% and 0.371 g PHB/g glucose, respectively. Lower concentration of PHB(3.2 g/l) was obtained when cultu- red at 37$\circ$C, which seemed to be due to the instability of this strain having amplified FtsZ activity. The PHB concentration of 3.75 g/l was obtained after culturing 60 hours in R medium supplemen- ted with 20 g/l glucose at 30$\circ$C, which was more than twice higher than that obtained with XL1-Blue(pSYL105). This suggested that the enhancement of PHB synthesis by suppressing filamenta- tion was more significant in a defined medium than complex medium. PHB synthesis could be further enhanced by supplementing a small amount of various complex nitrogen sources. When 5 g/l of beef extract was added to a defined medium, PHB concentration, PHB content, and PHB yield obtained after 60 hours of cultivation at 30$\circ$C were 7.46 g/l, 86%, and 0.375 g PHB/g glucose,respectively.

• Food Science of Animal Resources
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• v.36 no.2
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• pp.159-169
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• 2016

Animal muscles are stored for specific period (aging) at refrigerated temperatures, during and after which the living muscles start to convert into meat and thus, attain certain superior properties in the final product. Proteolysis, lipolysis, and oxidation are the major biochemical processes involved during the postmortem aging of meat that affect the tenderness, juiciness, and flavor, as well as sometimes may introduce certain undesirable traits. This review analyzes the role of pre- and post-mortem factors that are important for aging and their effect on the chemical and physical changes in the “dry- and wet-aged meat.” Thus, if the meat processing manufacturers optimize the effects of aging for specific muscles, the palatability, color, and the shelf life of the aged meat products could be significantly enhanced.

• Food Science of Animal Resources
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• v.18 no.2
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• pp.97-106
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• 1998

Antioxidant enzymes such as catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) are known to inhibit oxidative reactions by incativating compounds responsible for the formation of ree radicals. SOD transforms superoxide radical into hydrogen peroxide which is precursor to active free radicals. CAT reduces hydrogen peroxide to water. GSH-Px reduces hydroperoxides to corresponding alcohols. Antioxidant enzyme activities of muscle are different by animal species age, stress and exercise, muscle type and part, conditions of post mortem, storage and processing which are related to oxidative deterioration I muscle foods as well as oxidative defence in living systems. Antioxidant enzyme systems are enhanced rather than weakened in aging skeletal muscle. Red muscle contains higher antioxidant enzyme activity than white muscle. The antioxidant enzyme activities of poultry are higher in leg than in breast, and those of beef are higher in redder and more unstable muscles. It is clear that the effectiveness of the antioxidant enzyme in muscle foods seems to be influenced by meat processing operations. Both GSH-Px and CAT are inactivated by heat processing NaCl also influence the efficiency of the antioxident enzymes since its presence diminishes their catalyitc activity.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.2
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• pp.229-236
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• 2007

This study was conducted to determine effects of different selenium (Se) sources on performance, carcass characteristics, blood measures (whole blood Se concentration and plasma glutathione peroxidase (GSH-Px) activity), and Se concentrations in tissues of finishing Hanwoo steers (Korean native steers). Twenty finishing Hanwoo steers (average body weight=536${\pm}$23.4 kg, average age=approximately 20 months) were allotted to treatments in four groups of five steers per pen for 16 weeks preceding slaughter. Treatments were control (CON), spent mushroom composts from Se-enriched mushrooms (Se-SMC), selenized yeast (Se-Y), and sodium selenite (SS). Dietary Se levels of all treatments except CON were 0.9 mg Se/kg on the dry matter basis. Body weight was measured at the first and final day of trial, and blood samples were collected to analyze whole blood Se concentration and plasma GSH-Px activity at 2, 4, 8, and 16 weeks. At the end of trial, steers were slaughtered to collect muscle and liver samples for their Se analyses, and carcass data were recorded. In terms of dry matter intake, body weight gain and carcass characteristics, no significant differences among treatments were observed. Whole blood Se concentrations were significantly higher (p<0.05) for Se-SMC and Se-Y treatments than for CON at each collection period, with no significant difference between SS and CON. For weeks 2 and 8, there was no significant difference for whole blood Se concentration between Se-SMC and Se-Y, but for weeks 4 and 16, Se-Y treatments were significantly higher (p<0.05) than Se-SMC. No differences were observed for plasma GSH-Px activity between Se-SMC and Se-Y. The Se concentrations in hind leg and liver were significantly different among treatments (p<0.05) and those in both tissues ranked the greatest in Se-Y, followed by Se-SMC, SS, and CON treatments. However, tissue Se concentration for SS was not different from that for CON. These results showed that feeding organic Se sources such as Se-SMC and Se-Y enhanced Se concentration in tissues, while SS, the most common supplement of inorganic Se, was inefficient in Se deposition. Even though Se-Y had a higher Se concentration in tissues than Se-SMC, replacing Se-Y with Se-SMC in diets of beef steers would be an inexpensive way to increase Se concentration in beef.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.10
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• pp.1279-1286
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• 2007

We investigated the effects of conjugated linoleic acid (CLA) on the fatty acid composition in the plasma and liver, and the expressions of delta-5 desaturase (D5D) and fatty acid desaturase2 (FADS2) genes in ICR male mice using two different sources of fats in the diets. The experimental groups were divided into four groups: beef tallow (BT) and fish oil (FO), BT with CLA supplementation (BTC), and FO with CLA supplementation (FOC) groups. Ten mice in each group were fed with the experimental diets for 4 weeks. All mice were fed experimental diets containing 12% of total dietary fat (w/w) either with or without 0.5% CLA (w/w). Fatty acid compositions were analyzed in the plasma and liver using gas chromatography. The levels of D5D and FADS2 expression were analyzed by RT-PCR in the liver The results showed that CLA participates competitively with C18:2 in the elongation and desaturation processes, leading to significant increase in the levels of C20:4 and C22:6 in BTC group (p<0.05). The expression levels of D5D and FADS2 were higher in BT and BTC group than those of FO and FOC group. In particular, the expression of D5D gene was greatly upregulated in BTC group. Furthermore, the conversion ratios from C18:2 to C20:4 in the liver were higher in BTC group than those in other groups. Thus our results suggest that increased expressions of DSD and FADS2 genes may be responsible for the enhanced CLA effects on the desaturation in the BT containing saturated fatty acids rather than the FO rich in n-3 PUFA.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.9
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• pp.1267-1278
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• 2009

Three beef steers fitted with permanent cannulae in the rumen and duodenum were used to determine the effects of protein supply from soyhulls (SH) and wheat bran (WB) on ruminal metabolism, blood metabolites, nitrogen metabolism, nutrient digestion and concentrations of soluble non-ammonia nitrogen (SNAN) in ruminal (RD) and omasal digesta (OD). In a 3${\times}$3 Latin square design, steers were offered rice straw and concentrates formulated either without (control) or with two brans to increase crude protein (CP) level (9 vs. 11% dietary DM for control and bran-based diets, respectively). The brans used were SH and WB that had similar CP contents but different ruminal CP degradability (52 vs. 80% CP for SH and WB, respectively) for evaluating the effects of protein degradability. Ruminal ammonia concentrations were higher for bran diets (p<0.01) than for the control, and for WB (p<0.001) compared to the SH diet. Similarly, microbial nitrogen and blood urea nitrogen were significantly increased (p<0.05) by bran and WB diets, respectively. Retained nitrogen tended (p<0.082) to be increased by SH compared with the WB diet. Intestinal and total tract CP digestion was enhanced by bran diets. In addition, bran diets tended (p<0.085) to increase intestinal starch digestion. Concentrations of SNAN fractions in RD and OD were higher (p<0.05) for bran diets than for the control, and for WB than for the SH diet. More rumendegraded protein supply resulting from a higher level and degradability of CP released from SH and WB enhanced ruminal microbial nitrogen synthesis and ruminal protein degradation. Thus, free amino acids, peptides and soluble proteins from microbial cells as well as degraded dietary protein may have contributed to increased SNAN concentrations in the rumen and, consequently, the omasum. These results indicate that protein supply from SH and WB, having a low level of protein (13 and 16%, respectively), could affect ruminal metabolism and nutrient digestion if inclusion level is relatively high (>20%).

• KSBB Journal
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• v.14 no.2
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• pp.241-247
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• 1999

Experimental studies were carried out to optimize the culture conditions of Corynebacterium diphtheriae for the production of diphtheria toxin. A new media which does not contain any meat digest products was selected. The main ingredient of new medium was enzymatic digests of casein known as NZ-Case. In fermenter experiments, the toxin production was increased with the increase of cell growth. The optimum initial pH of media, air flow rate and agitation speed were 7.0, 0.22, vvm and 400 rpm, respectively. The contents of iron and calcium-phosphate precipitate were important for maximal cell growth and toxin production. The optimum concentration of iron was 0.3 mg/L and calcium-phosphate precipitate could serve in gradual supply of iron to maintain the optimal culture condition which is required for enhanced yield of toxin production. In potency test, the potency of toxoid from fermentor culture was higher than that from static culture. When diphtheria toxin is produced by fermentor culture, it is possible to produce higher levels of toxin and better toxoid quality in terms of safety, yield, productivity and immunity.

• Journal of Biosystems Engineering
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• v.40 no.2
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• pp.145-152
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• 2015

Purpose: The inability to adequately judge the efficacy of cleaning and sanitation procedures in deli departments is a recognized food safety concern. In a prior study, our research group demonstrated that visual inspection of cleaned produce processing surfaces could be enhanced through the use of a portable fluorescence imaging device that detected residual produce residues. Methods: To explore the feasibility of using fluorescence imaging to similarly detect residual deli residues, spectra of American, Cheddar, Provolone, and Swiss cheeses and of processed chicken, ham, roast beef, and turkey were acquired using a laboratory hyperspectral imaging system. Circular punches of these commodities were placed onto stainless steel and high density polyethylene coupons for imaging. The coupon materials were selected to represent common surfaces found in deli departments. Results: Analysis of hyperspectral fluorescence images showed that cheeses exhibited peaks in the blue-green region and at around 675 nm. Meats exhibited peaks in the blue-green region with one of four ham and one of four chicken brands exhibiting peaks at around 675 nm, presumably due to use of plant-derived additives. When commodities were intermittently imaged over two weeks, locations of spectral peaks were preserved while intensity of peaks at shorter wavelengths increased with time. Conclusion: These results demonstrate that fluorescence imaging techniques have the potential to enhance surface hygiene inspection in deli departments and, given the immediate availability of imaging results, to help optimize routine cleaning procedures.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.53-60
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• 2000

Strain BH5 was isolated from naturally fermented Kimchi and identified as a bacteriocin producer, which has bactericidal activity against Micrococcus flavus ATCC 10240. Strain BH5 was identified tentatively as Lactococcus lactis by the API test and some characteristics. Lactococcus lactis BH5 showed a broad spectrum of activity against most of the non-pathogenic and pathogenic microorganisms tested by the modified deferred method. The activity of lacticin BH5, named tentatively as the bacteriocin produced by Lactococcus lactis BH5, was detected at the mid-log growth phase, reached its maximum during the early stationary phase, and decreased after the late stationary phase. Lacticin BH5 also showed a relatively broad spectrum of activity against non-pathogenic and pathogenic microorganisms as tested by the spot-on-lawn method. Its antimicrobial activity on sensitive indicator cells was completely disappeared by protease XIV or ${\alpha}$-chymotrypsin. The inhibitory activities of lacticin BH5 were detected during treatments up to 100$^{\circ}C$ for 30 min. Lacticin BH5 was very stable over a pH range of 2.0 to 9.0 and was stable with all the organic solvents examined. The cell concentration and bacteriocin production in strain BH5 were maximum when grown at 30$^{\circ}C$ in a modified MRS medium supplemented with 0.5% tryptone, 1.0% yeast extract, and 0.5% beef extract as nitrogen sources. It demonstrated a typical bactericidal mode of inhibition against Micrococcus flavus ATCC 10240. Lacticin BH5 was purified through ammonium sulfate precipitation, ethanol precipitation, and CM-Sepharose column chromatography. The apparent molecular mass of lacticin BH5 was estimated to be in the region of 3.7 kDa, by the direct detection of bactericidal activity after SDS-PAGE. Mutant strain NO141 which was isolated by nitrosoguanidine mutagenesis produced about 4 fold more bacteriocin than the wild type.