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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

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

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

Su G.,China Agricultural University | Su G.,Engineering Research Center for Fruits and Vegetables Processing | Gao H.,Shanghai University | Wang Z.,China Agricultural University | And 10 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering

In order to explore the correlation between organic acids and adulterated apple juice and in turn to take control of apple juice quality to ensure food safety. A total of 340 apple samples from 14 different planting areas on 19 different varieties were collected throughout the main cultivation areas in China, high performance liquid chromatography (HPLC) was applied to detect organic acids profiles in apple juices. Adulterated juice samples at 75%, 50% and 25% (w/w) were prepared by adding water, L-malic acid and sucrose to adjust pH and total soluble solids (TSS) normal value. Binary logistic regression was adopted on the basis of organic acids in both authentic and adulterated apple juices to establish a predictive model to distinguish authentic and content-mislabeled apple juices. The accuracy and stability of the model were about 87.4% and 94.51% respectively. Statistic results indicate that the model works well and can be used as quality control guide. Therefore, apple juice has very distinct organic acids profiles that can be used as fingerprints for evaluating authenticity. Source

Wu M.,China Agricultural University | Wu M.,Engineering Research Center for Fruits and Vegetables Processing | Wu M.,Key Laboratory of Fruits and Vegetables Processing | Hu X.,China Agricultural University | And 11 more authors.
International Journal of Food Science and Technology

Bitter gourd (Momordica charantia), a commonly consumed vegetable in South Asia, eastern-South Asia, China, Japan, Korea peninsula, Caribbean Sea isles etc., is used as an adjunct in the management of diabetes mellitus. In this study, in order to find the effective ways of producing bitter gourd freeze-dried powder, the concentrated juice of bitter gourd was produced through enzymatic process (EP), ultra filtration (UF), reverse osmosis and vacuum concentration technology. Results indicated that total saponins, total sugar and pH value in bitter gourd juice were almost unchanged after EP and after UF (P ≥ 0.05). However, UF decreased the turbidity and improved transmittance of juice (P < 0.05). When compared with the vacuum concentration alone, the combined process of reverse osmosis followed by vacuum concentration had 3.33 folds of production efficiency and 1.725 times of vitamin C content in concentrated juice. With freeze-drying microscope system, the eutectic point of the freeze-dried product of bitter gourd juice was detected to be -37.5 °C, which was important to optimise lyophilisation parameters. The freeze-drying microscope system was more accurate than the conventional electric resistance method in detecting the eutectic point of freeze-dried product. © 2010 The Authors. International Journal of Food Science and Technology © 2010 Institute of Food Science and Technology. Source

Gong W.-X.,China Agricultural University | Gong W.-X.,Key Laboratory of Fruits and Vegetables Processing | Gong W.-X.,Engineering Research Center for Fruits and Vegetables Processing | Li S.-Y.,China Agricultural University | And 17 more authors.
Gaoya Wuli Xuebao/Chinese Journal of High Pressure Physics

The activity of polyphenol oxidase from red raspberry treated at 600 MPa for 45 min is even up to 40%, indicating strong pressure resistance. In order to further inactivate polyphenol oxidase from red raspberry, the combination effect of high hydrostatic pressure and metal ions on polyphenol oxidase activity was investigated. The change of polyphenol oxidase activity treated at 400 and 600 MPa after adding metal ions was revealed. The activity of raspberry polyphenol oxidase gradually decreases with the pressure increasing and/or the holding time extending with/without adding metal ions. Fe2+, Mn2+ (both inhibited polyphenol oxidase) and Cu2+ (activated polyphenol oxidase) in combination with pressure have synergistic effects, Ca2+ (inhibited polyphenol oxidase) combined with pressure has antagonistic effect, and Zn2+ (not change polyphenol oxidase activity) has no synergistic/antagonistic effect. Source

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