Takashi Ohmori

Effects of high hydrostatic pressure on characteristics of pork slurries and inactivation of microorganisms associated with meat and meat products.

Pork slurries inoculated with various test microorganisms were prepared and subjected to high hydrostatic pressure at 1000 to 6000 atm for 10 min at 25 degrees C to examine for the pressure effects on characteristics of the slurries and the inactivation of the microorganisms associated with meat and meat products. Pressure treatment at higher than 3000 atm caused coagulation and discoloration of the pork slurries. Harder and more white coagulants were obtained by increasing the pressure. Pressure treatment at 3000 to 6000 atm killed all the microorganisms tested by more than 6-log colony-forming units (cfu)/g except Bacillus cereus spores. Gram-negative microorganisms were more labile to pressure than Gram-positive ones. Campylobacter jejuni, Pseudomonas aeruginosa, Salmonella typhimurium and Yersinia enterocolitica were inactivated at pressures higher than 3000 atm; Escherichia coli, Saccharomyces cerevisiae and Candida utilis at pressures higher than 4000 atm; Micrococcus luteus, Staphylococcus aureus and Streptococcus faecalis at 6000 atm. Only less than one-log cfu/g of B. cereus spores were inactivated at 6000 atm. Ultraviolet absorption spectra and acridine orange staining suggested that E. coli became permeable and leaked cytoplasmic RNA at lower pressure than S. aureus. From the present findings, the authors propose high hydrostatic pressure treatment as a promising means of preparing wholesome meat and meat products.

Simultaneous Determination of Residual Veterinary Drugs in Bovine, Porcine, and Chicken Muscle Using Liquid Chromatography Coupled with Electrospray Ionization Tandem Mass Spectrometry

A simple and rapid method using liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC/MS/MS) for the simultaneous determination of 130 veterinary drugs and their metabolites in bovine, porcine, and chicken muscle was developed. The drugs (1 to 10 ng/g, in muscle) were extracted from bovine, porcine, or chicken muscles with acetonitrile-methanol (95:5, v/v), and the extracts were delipidated with n-hexane saturated with acetonitrile. The extracts were evaporated, dissolved with methanol, analyzed by liquid chromatography with gradient elution on a C18 column, and determined by electrospray ionization tandem mass spectrometry. The detection limits ranged from 0.03 to 3 ng/g. The quantitation limits ranged from 0.1 to 10 ng/g. One hundred eleven, 122, and 123 drugs from bovine, porcine, and chicken muscle respectively showed recoveries between 70 and 110%.

Inactivation of herpes viruses by high hydrostatic pressure

The effects of high hydrostatic pressure on herpes simplex virus type 1 (HSV-1) and human cytomegalovirus (HCMV) were examined. Pressure at more than 300 MPa for 10 min at 25 degrees C inactivated these virions and drastically inhibited their infection to cultured cells, and at greater than 400 MPa, reduced infective titers of HSV-1 and HCMV by more than 7 and 4 logs, respectively. Electron microscopic examination illustrated coincidentally that high pressure at 300 MPa damaged the virus envelope and prevented the virus particles from binding to the cells. The findings suggest that treatment at high hydrostatic pressure is promising as a means of inactivating HSV-1, HCMV and other enveloped viruses.

Chicken Collagen Hydrolysate Protects Rats from Hypertension and Cardiovascular Damage

We previously reported that chicken collagen hydrolysate (CCH) has strong angiotensin I converting enzyme (ACE) inhibitory activity and antihypertensive effects on spontaneously hypertensive rats. Here, we investigated the chronic therapy effects of CCH on blood pressure and vascular relaxation in a cardiovascular damage model of Wistar-Kyoto rats induced by N-nitro-l-arginine methyl ester (L-NAME). Following co-treatment with CCH for 4 weeks, the increment of systolic blood pressure was suppressed significantly. At 8 weeks, the vasorelaxation of thoracic aorta increased significantly, and cardiovascular damage was ameliorated. The concentration of soluble intercellular adhesion molecule-1 (ICAM-1) in blood was reduced significantly by long-term administration of CCH, whereas the nitric oxide concentration was increased significantly at 1 hour post-treatment. The results suggest that beneficial effects of CCH result from antihypertensive function, but also from inhibition of cardiovascular damage to the endothelial cells via its ACE inhibitory activity and regulation of nitric oxide and ICAM-1, which suggests that CCH may be useful as a medicinal food for patients with cardiovascular disease.

Effects of a Chicken Collagen Hydrolysate on the Circulation System in Subjects with Mild Hypertension or High-Normal Blood Pressure

We investigated the effects of a chicken collagen hydrolysate (CCH) on the circulation system in humans. A total of 58 subjects with either mild hypertension (systolic blood pressure (SBP) of 140-159 mmHg or diastolic blood pressure (DBP) 90-99 mmHg) or high-normal blood pressure (SBP 130-139 mmHg or DBP 85-89 mmHg) were assigned to two groups, one involving a placebo and the other, the test food (including CCH of 2.9 g/d). The parameters related to each subjects circulation system were monitored over the study period of 18 weeks. The Δbrachial-ankle pulse wave velocity (baPWV), an indicator of arterial stiffness and marker of vascular damage, was significantly lower in the test food group than in the placebo group during the treatment period. The blood pressure in the test food group was also significantly lower than that in the placebo group, while the serum nitrogen oxide was higher in the test food group after the treatment. These results suggest that CCH exerted modulatory effects on the human circulation system.

In Vitro and in Vivo Anti-platelet Effects of Enzymatic Hydrolysates of Collagen and Collagen-related Peptides

Collagen-related peptides, Gly-Pro-Arg and its analogues, were examined for their inhibitory effects on platelet aggregation induced by the addition of ADP. Human platelet aggregation was suppressed by more than 50% with each of Gly-Pro-Arg and such Gly-Pro-Arg-containing peptides as Gly-Pro-Arg-Gly, Gly-Pro-Arg-Gly-Pro, Gly-Pro-Arg-Pro-Pro, and Gly-Pro-Arg-Pro-Pro-Pro at a concentration of 0.3 mm. The inhibitory effects of these peptides were about 10 times higher in human PRP than in rat PRP. Other Gly-Pro-Arg analogues such as Sar-Pro-Arg, Gly-Pro-Lys, Gly-Ala-Arg, and Ala-Gly-Pro-Arg had no inhibitory effect at a concentration from 0.1 to 0.8 mm even in human PRP. Intravenous and oral administrations of Gly-Pro-Arg and enzymatic hydrolysates of collagen suppressed the decrease in platelet count for endotoxin-induced DIC in rats. Collagen itself has been regarded as a potent inducer of platelet aggregation, but these findings suggest that collagen-related peptides and enzymatic hydrolysates of collagen prevent platelet aggregation.