• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.991-996
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• 1995

Effects of high hydrostatic pressure on microorganisms and browning enzymes in Angelica keiskei juice were investigated using response surface methodology. The optimum process condition for maximum reduction of total aerobes was $5700\;kg_f/cm^2$ (558.6 MPa) pressure and 7.16 min process time, and 3.44 log cycle reduction of total aerobes was predicted at the optimum condition. E. coli, initially $8.8{\times}10^3\;CFU/ml$, was completely inactivated by high hydrostatic pressure at all process conditions ($3800{\sim}6700\;kg_f/cm^2\;pressure;\;3{\sim}17\;min\;process\;time$). Polyphenol oxidase and peroxidase were partly inactivated by the high hydrostatic pressure. It was also indicated that inactivation of microorganisms and browning enzymes by hydrostatic pressure is dependent on pressure rather than process time.

• Korean Journal of Food Science and Technology
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• v.33 no.2
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• pp.226-230
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• 2001

High hydrostatic pressure was applied to Foxtail Millet Takju to investigate the effects of high pressure on inactivation of microorganisms and enzymes. Total bacteria, lactic acid bacteria and yeast in untreated Takju were $6.8{\times}10^7,\;1.3{\times}10^8\;and\;8.4{\times}10^7\;CFU/mL$, respectively. Total bacterial count in Takju reduced to $2.2{\times}10^5\;CFU/mL$, while lactic acid bacteria and yeast were sterilized completely when heated at $65^{\circ}C$ for 30 min. Lactic acid bacteria and yeast decreased with the increase of treatment pressure, and pressurization of 400 MPa for 10 min at room temperature sterilized completely the lactic acid bacteria and yeast in Takju. Total bacteria were not sterilized with pressurization of even 600 MPa at room temperature. Total bacteria were completely sterilized at $66^{\circ}C/400\;MPa/60\;min\;and\;66^{\circ}C/600\;MPa/10\;min$. Pressurization of Takju caused a partial inactivation of ${\alpha}-amylase$, and after pressurization at 600 MPa for 10 min at room temperature, 73.2% of the original activity remained. The activity of glucoamylase increased with the increase of treatment pressure. Treatment at $66^{\circ}C/400\;MPa/10\;min$ reduced the activity of ${\alpha}-amylase$ by 59.7% and glucoamylase by 20.5%. ${\alpha}-Amylase$ was inactivated to less than 1.2% of the original activity at $66^{\circ}C/600\;MPa/30\;min$.

• Food Science of Animal Resources
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• v.32 no.1
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• pp.1-5
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• 2012

The objective of this study was to examine the effects of a combined treatment regarding antimicrobial food ingredients and high pressure processing (HP) on the inactivation efficiency of Escherichia coli and Listeria monocytogenes inoculated into ground pork. Ethanol extracted from garlic, leeks, onions, and ginger powder was prepared. Half of the prepared powder was irradiated at 5 kGy to see the effect of pasteurization before addition. The prepared food ingredients were added into radiation-sterilized ground pork (1%, w/w), and inoculated with E. coli and L. monocytogenes. The samples were vacuum-packed and applied with HP at 0.1 (control), 300, 450, and 600 MPa. Microbial log reduction increased with the increase of pressure up to 600 MPa. With minor exceptions, overall efficiency of HP treatment with regards to inactivation of pathogens increased. Inoculated microorganisms showed approximately 7-8 Log reductions by 600 MPa, except for L. monocytogenes treated with garlic (5.7 Log reductions). The E. coli reduction in ground pork mixed with ethanol extracted garlic showed the highest efficiency (1.86) compared to leeks (1.25-1.31), onions (1.17-1.44), and ginger (1.50-1.82) when treated at an HP of 450 MPa. There was no evidence for the advantage of pasteurization concerning the food ingredients before addition of antimicrobial food ingredients and HP. Results demonstrate that the combination of antimicrobial food ingredients and HP treatment may help improve the efficiency of sterilization in meat systems.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.593-599
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• 1996

The effects of high pressure on alliinase and on flavor of garlic (Alliiium sativum L.) were investigated. After pressurized at 150 MPa, 300 MPa, and 500 MPa for 10 min, the activities of purified alliinase were reduced approximately 30%, 80%, and 100%, respectively, while the enzyme activities of pressurized garlic cloves were reduced 0%, 7%, and 100%, respectively. This indicated that the intact garlic has a protective effect against pressure-inactivation of alliinase. Alliinase was more effectively inactivated when high pressure treatment was carried out at high ($>40^{\circ}C$) or low temperature ($>10^{\circ}C$) than ambient temperature. Pressure treated garlic at 500 MPa had little pungency and sulfuryl odor compared to raw garlic indicating that high-pressure processing can be used to produce garlic without pungent flavor.

• YAKHAK HOEJI
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• v.50 no.2
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• pp.111-117
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• 2006

Cardiac chambers serve as mechanosensory systems during the haemodynamic or mechanical disturbances. To examine a possible role of fluid pressure (FP) in the regulatien of atrial $Ca^{2+}$ signaling we investigated the effect of FP on L-type $Ca^{2+}$ current $(I_{Ca})$ in rat ventricular myocytes using whole-cell patch-clamp technique. FP $(\sim40cm\;H_2O)$ was applied to whole area of single myocytes with electronically controlled micro-jet system. FP suppressed the magnitude of peak $I_{Ca}$ by $\cong25\%$ at 0 mV without changing voltage dependence of the current-voltage relationship. FP significantly accelerated slow component in inactivation of $I_{Ca}$, but not its fast component. Analysis of steady-state inactivation curve revealed a reduction of the number of $Ca^{2+}$ channels available for activity in the presence of FP. Dialysis of myocytes with high concentration of immobile $Ca^{2+}$ buffer partially attenuated the FP-induced suppression of $I_{Ca}$. In addition, the intracellular $Ca^{2+}$ buttering abolished the FP-induced acceleration of slow component in $I_{Ca}$ inactivation. These results indicate that FP sup-presses $Ca^{2+}$ currents, in part, by increasing cytosolic $Ca^{2+}$ concentration.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1221-1226
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• 2003

High hydrostatic Pressure was applied to Foxtail Millet Yakju to investigate the effects of high pressure on inactivation of microorganisms and enzymes. Total bacteria, lactic acid bacteria and yeast in untreated Yakju were $1.5{\times}$10$^4$,1.9${\times}$10$^4$ and 1.4${\times}$10$^4$ CFU/mL, respectively. Total bacterial count was reduced to 4.1${\times}$l0$^2$ CFU/mL, while lactic acid bacteria and yeast were sterilized completely in Yakju heated at $65^{\circ}C$ for 15 min. Lactic acid bacteria and yeast decreased greatly with the increase of treatment pressure, and were sterilized completely in Yakju treated at more than 300 ㎫ for 10 min/$25^{\circ}C$. Total bacteria were not completely sterilized with pressurization of even 600 ㎫ at room temperature and reduced to 2 log cycle even at $65^{\circ}C$. Total bacteria decreased by 2∼3 log cycle with the increase of treatment time from 10 to 60 min at $25^{\circ}C$/300 ㎫. Pressurization of Yakju caused a partial inactivation of $\alpha$ -amylase and glucosamylase, and the activities of $\alpha$ -amylase and glucoamylase decreased by 18.1% and 21.1%, respectively at $25^{\circ}C$/600 ㎫/10 min. Activities of $\alpha$ -amylase and glucoamylase decreased with the increase of temperature, and 22.2% and 32.1% of the original activity were remained with the treatment at $65^{\circ}C$/300 ㎫/10 min, respectively. Enzyme activities decreased slightly with the increase of treatment time at $65^{\circ}C$/300 ㎫.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.57-62
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• 2012

In this study, the inactivation efficiency of Mycobacterium marinum was evaluated in buffered water (pH 7) using a low pressure ultraviolet (LP-UV) lamp, ultrasonic (US), and UV/US sequential processes. In the UV alone process, 3 log inactivation of the M. marinum was achieved with a UV dose of $120mJ/cm^2$. However, a tailing phase was later observed because M. marinum has a high tendency for cell aggregation. Even though the M. marinum was not inactivated in the US alone process, the hydrophobicity decreased and turbidity increased due to the crumbling of the cell aggregation. Among the candidate processes which were UV alone, US-UV sequential process and UV-US-UV sequential process, the US-UV sequential process showed the highest synergistic effects for M. marinum inactivation. Consequently, US is a very useful process as a UV irradiation pre-treatment to inactivate M. marinum in water.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.790-795
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• 1996

Citrus juice was treated with supercritical carbon dioxide $(SC-CO_{2})$ as an alternative to heat for pectinesterase (PE) inactivation to minimize undesirable changes in flavor, color and ascorbic acid loss caused by the current heat treatment, and the effect of temperature $(40,\;50,\;60^{\circ}C)$, pressure (138, 276 bar) and process time $(5{\sim}130\;min) $ on PE activity was determined. PE in temperature control samples was inactivated by 54% at $40^{\circ}C$ after 130 min, 84% at 50% after 60 min and 83% at $60^{\circ}C$ after 30 min treatment compared to the original juice. PE inactivation in $(SC-CO_{2})$ treated samples at 138 bar was 83% at $40^{\circ}C$ after 130 min, 88% at $50^{\circ}C$ after 20 min and 87% at $60^{\circ}C$ after 10 min. %PE inactivation due to pressure was higher at low temperature and lower at high temperature. Higher temperature, Pressure and longer process time resulted in higher %PE inactivation. Nonlinearity in the curves of PE inactivation at different temperatures and pressures indicated that at least two forms of PE existed in citrus juice with different stabilities.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.1102-1105
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• 2008

The structural change and leakage of cellular substances of Saccharomyces cerevisiae attributed by high hydrostatic pressure (HHP) treatment were observed with scanning electron microscopy (SEM). S. cerevisiae (ATCC16664) was inoculated in apple juice for 10 min at $23^{\circ}C$ and the apple juice treated at 138, 207, 276, 345, and 414 MPa pressure for 30 sec at $23^{\circ}C$. Increased of roughness, elongation, wrinkling, and pores on yeast cell surfaces, the yeast cell walls were severely damaged by HHP treatment from 276 to 414 MPa. Inactivation of S. cerevisiae by HHP is dependent on structural changes on the cell walls observed with SEM.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.3
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• pp.232-237
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• 2009

Norovirus surrogate (feline calicivirus) was inactivated by treatment at 50,000 psi for 60 sec by 6.8-$log_{10}TCID_{50}mL^{-1}$. Tissue obtained from oyster (digestive gland, gill and mantle) was qualitatively destroyed and distorted by treatment at pressure greater than 5,000 psi for 60 sec. High pressure treatment induced progressive changes in the color of the oyster adductor muscle. High pressure treatment effectively reduced norovirus surrogate but induced conformational changes in the tissue and color of oyster flesh.