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Dong P.,China Agricultural University | Dong P.,National Engineering Research Center for Fruits and Vegetables Processing | Dong P.,Key Laboratory of Fruits and Vegetables Processing | Dong P.,German Institute of Food Technologies DIL | And 5 more authors.
Frontiers in Microbiology | Year: 2015

Ultra high pressure homogenization (UHPH) opens up new areas for dynamic high pressure assisted thermal sterilization of liquids. Bacillus amyloliquefaciens spores are resistant to high isostatic pressure and temperature and were suggested as potential surrogate for high pressure thermal sterilization validation. B. amyloliquefaciens spores suspended in PBS buffer (0.01 M, pH 7.0), low fat milk (1.5%, pH 6.7) and whole milk (3.5%, pH 6.7) at initial concentration of ~106 CFU/mL were subjected to UHPH treatments at 200, 300 and 350 MPa with an inlet temperature at ~80 °C. Thermal inactivation kinetics of B. amyloliquefaciens spores in PBS and milk were assessed with thin wall glass capillaries and modeled using first-order and Weibull models. The residence time during UHPH treatments was estimated to determine the contribution of temperature to spore inactivation by UHPH. No sublethal injury was detected after UHPH treatments using sodium chloride as selective component in the nutrient agar medium. The inactivation profiles of spores in PBS buffer and milk were compared and fat provided no clear protective effect for spores against treatments. Treatment at 200 MPa with valve temperatures lower than 125 °C caused no reduction of spores. A reduction of 3.5 log10 CFU/mL of B. amyloliquefaciens spores was achieved by treatment at 350 MPa with a valve temperature higher than 150 °C. The modeled thermal inactivation and observed inactivation during UHPH treatments suggest that temperature could be the main lethal effect driving inactivation. © 2015 Dong, Georget, Aganovic, Heinz and Mathys. Source

Zhang Y.,China Agricultural University | Zhang Y.,National Engineering Research Center for Fruits and Vegetables Processing | Zhang Y.,Key Laboratory of Fruits and Vegetables Processing
Innovative Food Science and Emerging Technologies | Year: 2013

This study was carried out to evaluate the effect of high hydrostatic pressure on microbiological and physical qualities changes of bay scallop (Argopecten irradians) during storage time at - 18 C. High hydrostatic pressure (HHP), at pressure levels from 150 to 400 MPa was used for shucking bay scallop. 100% detachment of adductor muscle was observed when scallops were treated at 200 MPa/3 min and 350 MPa/0 min. HHP-shucked scallops obtained higher yield (17.26% higher for tissue and 3.48% higher for adductor muscle) than manual shucking samples (P < 0.05). HHP shucking produced reductions in the aerobic plate count and coliform. Moreover, HHP-shucked adductor muscles showed significantly higher pH (6.14 to 6.40), moisture (78.95% to 80.47%) and thawing drip loss (4.41% to 9.67%) than control (P < 0.05). The hardness of HHP-shucked adductor muscles increased, while the springiness showed no difference changes. Furthermore, the HHP shucking significantly increased L* value (52.40 to 53.96) of adductor muscles, while a* (- 2.05 to - 4.15) and b* values (0.18 to - 4.68) decreased (P < 0.05). At the end of frozen storage (150 days), most of quality parameters showed no significant changes. In addition, the HHP-shucked adductor muscles presented better sensory attributes. In short, HHP as an effective shucking method showed a broad prospect for application in scallop processing industry. Industrial relevance This research paper which presented a fair comparison of high pressure shucking and hand shucking on bay scallops, could provide information about shucking attributes and biochemical stability of adductor muscles under frozen storage time which are quite scarce. The available data are provided for the evaluation and application of HHP in the bivalve processing industry, and criteria for commercial production of high quality scallop adductor muscle with safety requirements could be established. Crown Copyright © 2013 Published by Elsevier Ltd. All rights reserved. Source

Li L.,China Agricultural University | Feng L.,Key Laboratory of Fruits and Vegetables Processing | Hua C.,China Agricultural University | Chen F.,China Agricultural University | And 3 more authors.
International Journal of Food Microbiology | Year: 2010

This study investigated the inactivation of total aerobic bacteria (TAB), lactic acid bacteria (LAB), yeasts in sour Chinese cabbage (SCC) treated by high hydrostatic pressure (HHP). The pressure level ranged from 200 to 600MPa and the treatment time were 10-30min. All samples were stored at 4, 27 and 37°C for 90days. The pressure level of 200MPa had no significant impact on these microorganisms. The counts of TAB were significantly reduced by 2.7-4.0log10CFU/g at 400MPa and 4.2-4.5log10CFU/g at 600MPa from 6.2log10CFU/g; the counts of LAB were also reduced by 2.4-4.3log10CFU/g at 400MPa from 7.0log10CFU/g and LAB was completely inactivated at 600MPa; the counts of yeasts were reduced by 1.5-2.0log10CFU/g at 400 and 600MPa from 4.2log10CFU/g. Storage temperatures significantly influenced the microbial proliferation in HHP-treated SCC depending on the pressure levels. The surviving TAB and LAB at 400MPa equaled initial counts after 15-day storage at 27 and 37°C, whereas they were inhibited at 4°C up to 60days. The surviving TAB at 600MPa did not grow. Yeasts at 400 and 600MPa decreased below detectable level after 2days at all the three storage temperatures. From the microbial safety point of view, the result indicated that HHP at 600MPa could be used as an alternative preservation method for SCC. © 2010 Elsevier B.V. Source

Wang D.,Tianjin University of Science and Technology | Wang D.,Beijing Academy of Agriculture and Forestry Sciences | Wang D.,China Agricultural University | Li X.,Tianjin University of Science and Technology | And 4 more authors.
European Food Research and Technology | Year: 2011

1-(2′-Hydroxybenzene-1′-carboxy-ethyl) pyrrole (P-Tyr) was synthesized to study its effect on garlic greening. The puree of freshly harvested garlic bulbs turned green after being soaked in solutions of P-Tyr, and with increasing concentration, the green color of the puree became deeper. The thermal stability of P-Tyr was studied by differential scanning calorimetry. Thermodynamic analysis showed that the conversion of P-Tyr followed an Arrhenius relationship, where the delta enthalpy (H) and activation energy (Ea) were 399. 102 J/g and 82. 137 ± 3. 243 kJ/mol, respectively. Furthermore, the relationships between the degree of conversion of P-Tyr and time or temperature were reported. This study demonstrated that the evaluated P-Tyr is stable over a wide range of temperatures and time. © 2010 Springer-Verlag. Source

Wang J.,China Agricultural University | Wang J.,Engineering Research Center for Fruits and Vegetables Processing | Wang J.,Key Laboratory of Fruits and Vegetables Processing | Hu X.,China Agricultural University | And 5 more authors.
International Journal of Food Microbiology | Year: 2010

In this paper, the ultrasonic inactivation efficacy of Alicyclobacillus acidiphilus DSM14558T and Alicyclobacillus acidoterrestris DSM 3922T inoculated into apple juice was investigated at power level from 200 to 600W for treatment time from 1 to 30min. The survival ratio of A. acidiphilus DSM14558T and A. acidoterrestris DSM 3922T decreased with the time of exposure to ultrasounds and with their power. Weibull distribution function, log-logistic model, modified Gompertz equation and biphasic linear model were used to describe the experimental data and the fitness of the models was assessed by the adjusted correlation coefficient (adj-R2) and the root mean square error (RMSE). The results showed that, for A. acidiphilus DSM14558T, the Weibull distribution function described well the characteristic of ultrasonic inactivation, while for A. acidoterrestris DSM 3922T, the adequate one was the biphasic linear model. Alicyclobacilli had a much higher resistance to ultrasonic treatments in apple juice than in buffer, which indicated that the resistance of alicyclobacilli to ultrasound varied significantly depending on their environment; A. acidoterrestris DSM 3922T, with the greatest microbial reduction of 4.56 log cycles at 600W for 30min, seemed more sensitive to ultrasonic treatments than A. acidiphilus DSM14558T. © 2010 Elsevier B.V. Source

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