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51.
Inactivation Kinetics of Food Poisoning Microorganisms by Carbon Dioxide and High Hydrostatic Pressure 总被引:2,自引:0,他引:2
The inactivation kinetics of food poisoning microorganisms using a combined treatment of carbon dioxide (CO2) with high hydrostatic pressure (HHP) was investigated. Staphylococcus aureus, Fusarium oxysporum, and Fusarium sporotrichioides were totally inactivated by a combined treatment of carbonation and HHP at 500 MPa. Bacillus subtilis, a spore forming bacteria, were not completely inactivated after the combined treatment. The microorganisms treated by carbonation and HHP were exponentially reduced in a pressure range and the Dp ‐value, the Zp‐value, and the activation volume were determined. UV absorbing materials leaked from injured cells. Morphological changes of the cells were observed by scanning and transmission electron microscopy. 相似文献
52.
二氧化氯对苹果表面Listeria monocytogenes杀菌效果的研究 总被引:4,自引:0,他引:4
利用A PI Listeria鉴定系统对从榨汁苹果表面分离的Listeria monocytogenes疑似菌落进行了鉴定,并将原料清洗与杀菌过程相结合,通过4因素中心组合试验设计(CCD),以杀菌效果(以杀菌效率的负对数表示,即logNN )为响应值,研究二氧化氯溶液浓度、杀菌温度、处理时间和杀菌液pH 等因素对杀 0菌效果的影响,用数学方法描述二氧化氯对苹果表面Listeria m onocytogenes的杀菌规律。结果表明:二氧化氯浓度对杀菌效果影响最大,杀菌液pH 次之,杀菌温度影响最小,延长杀菌时间对杀菌效果的影响不显著,二氧化氯溶液浓度、杀菌温度和pH 之间对杀菌效果有协同作用,建立的数学模型其预报结果与实测结果拟合基本一致,相对误差在 5.0% 以内。 ± 相似文献
53.
Differences in properties of myofibrillar proteins from bovine semitendinosus muscle after hydrostatic pressure or heat treatment 总被引:1,自引:0,他引:1
Eun‐Jung Lee Yun‐Ji Kim Nam‐Hyouck Lee Seok‐In Hong Katsuhiro Yamamoto 《Journal of the science of food and agriculture》2007,87(1):40-46
Hydrostatic pressure (HP) and heat treatments of myofibrillar proteins have both been shown to induce protein denaturation, but different gel formation properties result from these treatments. To characterise differences in the properties of proteins resulting from HP or heat treatment, Ca‐ and Mg‐ATPase activities (ATP, adenosine triphosphate) and protein solubility in 0.1 and 0.6 mol L?1 KCl buffers (pH 7) were evaluated in this study. The inactivation rate of Ca‐ATPase of myofibrillar proteins (Mf) induced by HP was slower than that of Mg‐ATPase at each of the tested pressures. However, the inactivation rate of Ca‐ATPase induced by heating was faster than that of Mg‐ATPase at each of the tested temperatures. The level of soluble proteins in Mf suspension induced by HP in 0.1 mol L?1 KCl buffer increased with increasing pressure up to 400 MPa and then decreased slightly at 500 MPa. However, the level of soluble proteins in Mf suspension induced by heat treatment in 0.1 mol L?1 KCl buffer increased with increasing temperature up to 55°C. According to the results of sodium dodecyl sulfate polyacrylamide gel electrophoresis, the levels of soluble myosin heavy chain and actin in Mf suspension induced by HP in 0.6 mol L?1 KCl buffer decreased simultaneously at pressures higher than 300 MPa. The level of soluble MHC in 0.6 mol L?1 KCl buffer decreased gradually with increasing temperature, but there were no changes in the level of soluble actin in 0.6 mol L?1 KCl buffer with increasing temperature up to 50°C. These results showed that the mechanism of HP‐induced protein denaturation was different from the mechanism underlying heat‐induced protein denaturation. Copyright © 2006 Society of Chemical Industry 相似文献
54.
55.
Inactivation of Nisin by Glutathione in Fresh Meat 总被引:2,自引:0,他引:2
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to determine the fate of nisin in meat products. Nisin in 0.02N HCl was added to fresh and cooked meat and meat juice and samples were stored at 4 °C overnight. Residual nisin solutions and meat juice and meat extract supernatants were analyzed for antimicrobial activity and for nisin. Nisin was recovered from cooked meat extract and cooked meat juice; however, only nisin bound to a food component was detected in fresh meat extract. Mass spectra for raw meat and juice showed a signal 307 Da greater than the mass of nisin. Results indicated that nisin was likely inactivated in raw meat by an enzymatic reaction with glutathione. 相似文献
56.
S.E. Smith J.L. Maurer A. Orta-Ramirez E.T. Ryser D.M. Smith 《Journal of food science》2001,66(8):1164-1168
ABSTRACT: In 19.1% fat ground beef, Escherichia coli 0157:H7 was less heat- resistant at ≥58°C than the Salmonella typhimurium DT104 and Salmonella senftenberg , but at 55°C the D value was similar to DT104 strains and higher than an eight-strain Salmonella cocktail. Inactivation of E. coli 0157:H7 was more temperature-dependent than the cocktail and DT104 strains. E. coli and DT104 strains were more heat-resistant in beef containing 19% fat than 4.8% fat. The cocktail was more thermally stable in stationary as compared to log phase. Freezing of inoculated raw meat decreased heat resistance of the cocktail. The pathogenic strain, growth phase of the organism, state of the meat (fresh or frozen) and meat composition must be considered when designing protocols to verify thermal processes. 相似文献
57.
Use of linear, Weibull, and log-logistic functions to model pressure inactivation of seven foodborne pathogens in milk 总被引:1,自引:0,他引:1
Chen H 《Food microbiology》2007,24(3):197-204
Survival curves of six foodborne pathogens suspended in ultra high-temperature (UHT) whole milk and exposed to high hydrostatic pressure at 21.5 degrees C were obtained. Vibrio parahaemolyticus was treated at 300 MPa and other pathogens, Listeria monocytogenes, Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Salmonella enterica serovar Typhimurium, and Staphylococcus aureus were treated at 600 MPa. All the survival curves showed a rapid initial drop in bacterial counts followed by tailing caused by a diminishing inactivation rate. A linear model and two nonlinear models were fitted to these data and the performances of these models were compared using mean square error (MSE) values. The log-logistic and Weibull models consistently produced better fits to the inactivation data than the linear model. The mean MSE value of the linear model was 6.1, while the mean MSE values were 0.7 for the Weibull model and 0.3 for the log-logistic model. There was no correlation between pressure resistance and the taxonomic group the bacteria belong to. The order, most to least pressure-sensitive, of the single strains tested was: V. parahaemolyticus (gram negative)相似文献
58.
59.
Luciano J. Quitão-Teixeira Ingrid Aguiló-Aguayo Afonso M. Ramos Olga Martín-Belloso 《Food and Bioprocess Technology》2008,1(4):364-373
The effects of high-intensity pulsed electric fields (HIPEF) on oxidative enzymes and color of fresh carrot juice were studied.
A response surface methodology (RSM) was used to evaluate the effect of pulse polarity (mono or bipolar mode), pulse width
(from 1 to 7 μs), and pulse frequency (from 50 to 250 Hz) on color and peroxidase (POD) inactivation of carrot juice treated
by HIPEF. The total treatment time and the electric field strength were set at 1,000 μs and 35 kV/cm, respectively, at a temperature
below 35°C. The physicochemical characteristics of carrot juice were measured. There was a linear relationship between electrical
conductivity and temperature of the carrot juice. The results showed that HIPEF-treated carrot juice at 35 kV/cm for 1,000 μs
applying 6 μs pulse width at 200 Hz in bipolar mode led to 73.0% inactivation of POD. The color coordinates did not change
significantly. Therefore, HIPEF was effective in POD inactivation and carrot juice color preservation. 相似文献
60.
This study was carried out to determine some of the biochemical properties of pectin methylesterase (PME) from black carrot. The enzyme showed very high activity in a broad pH range of 6.5–8.5, with the optimum pH occurring at 7.5. The optimum temperature for maximal PME activity was found to be 55 °C. NaCl enhanced PME activity, particularly at 0.2 M. Km and Vmax values for black carrot PME using apple pectin as substrate were found to be 2.14 mg/ml (r2 = 0.988) and 3.75 units/ml, respectively. The enzyme was stable between the temperatures of 30–50 °C/5 min whereas it lost nearly all of its activity at 70 °C/5 min. Ea and Z values were found to be 196.8 kJmol−1 (r2 = 0.996) and 2.16 °C (r2 = 0.995), respectively. 相似文献