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Li L.,Tianjin University of Science and Technology | Ban Z.,Jinan Fruit Research Institute | Ban Z.,Xinjiang Agricultural University | Li X.,Tianjin University of Science and Technology | And 2 more authors.
International Journal of Food Science and Technology | Year: 2012

The effect of different modified atmosphere packaging conditions, 75kPa O 2 (high-oxygen atmosphere, HOA), 3.0kPa O 2+5.0kPa CO 2 (low-oxygen atmosphere, LOA) and passive atmosphere (PA) on the antioxidant properties of ready-to-eat honey pomelo slices stored at 4°C was investigated. Both ascorbic acid content and antioxidant capacity underwent a significant depletion under HOA in comparison with LOA and PA. Total phenolic content among the samples stored under HOA and PA decreased significantly, but not for LOA. Moreover, HOA was more effective in maintaining the firmness of the slices. The hue angle values among different packaging atmosphere conditions were significantly affected, but chroma values were not. Both high oxygen and low oxygen concentrations inhibited the growth of spoilage microorganism of honey pomelo slices. © 2012 The Authors. International Journal of Food Science and Technology © 2012 Institute of Food Science and Technology.


Han W.,Shandong University | Gu J.,Shandong University | Gu J.,Jinan Fruit Research Institute | Cheng Y.,Shandong University | And 3 more authors.
Applied and Environmental Microbiology | Year: 2016

Alginate lyases are important tools for oligosaccharide preparation, medical treatment, and energy bioconversion. Numerous alginate lyases have been elucidated. However, relatively little is known about their substrate degradation patterns and productyielding properties, which is a limit to wider enzymatic applications and further enzyme improvements. Herein, we report the characterization and module truncation of Aly5, the first alginate lyase obtained from the polysaccharide-degrading bacterium Flammeovirga. Aly5 is a 566-amino-acid protein and belongs to a novel branch of the polysaccharide lyase 7 (PL7) superfamily. The protein rAly5 is an endolytic enzyme of alginate and associated oligosaccharides. It prefers guluronate (G) to mannuronate (M). Its smallest substrate is an unsaturated pentasaccharide, and its minimum product is an unsaturated disaccharide. The final alginate digests contain unsaturated oligosaccharides that generally range from disaccharides to heptasaccharides, with the tetrasaccharide fraction constituting the highest mass concentration. The disaccharide products are identified as ΔG units. While interestingly, the tri- and tetrasaccharide fractions each contain higher proportions of ΔG to ΔMends, the larger final products contain only ΔMends, which constitute a novel oligosaccharide-yielding property of guluronate lyases. The deletion of the noncatalytic region of Aly5 does not alter its M/G preference but significantly decreases the enzymatic activity and enzyme stability. Notably, the truncated protein accumulates large final oligosaccharide products but yields fewer small final products than Aly5, which are codetermined by its M/G preference to and size enlargement of degradable oligosaccharides. This study provides novel enzymatic properties and catalytic mechanisms of a guluronate lyase for potential uses and improvements. © 2015, American Society for Microbiology.


Li L.,Tianjin University of Science and Technology | Li X.,Tianjin University of Science and Technology | Ban Z.,Jinan Fruit Research Institute | Ban Z.,Xinjiang Agricultural University | Jiang Y.,University of Leeds
International Journal of Food Properties | Year: 2014

Antioxidants are usually considered with regard to plant defense mechanisms due to the oxidative stress or their importance for human health or both. A comprehensive study in the present research was made to determine the variation in contents of antioxidants and their metabolites (such as ascorbate and glutathione) and enzymes activities of Red Fuji apple pulp and peel tissue during cold storage (0 ± 1°C). Results showed that the majority of antioxidant metabolites were maintained in the reduced state, reduced ascorbate and glutathione, mainly localized in apple peel tissue. Strong or very strong correlations between hydrogen peroxide content and superoxide dismutase activity (r = 0.822 and 0.959), reduced/oxidized ascorbate ratio and monodehydroascorbate reductase activity (r = 0.966 and 0.984) as well as reduced/oxidized glutathione ratio and glutathione reductase activity (r = 0.969 and 0.924) were discovered. These results highlight that apple peel tissue could be selected to explore antioxidant mechanism and defense metabolism of apple fruit. Copyright © Taylor and Francis Group, LLC.


Li L.,Tianjin University of Science and Technology | Li X.,Tianjin University of Science and Technology | Wang A.,Tianjin University of Science and Technology | Jiang Y.,Tianjin University of Science and Technology | And 2 more authors.
International Journal of Food Science and Technology | Year: 2013

Changes in qualities of 'Red Fuji' and 'Golden Delicious' apples in response to different heat treatments (45 and 60 °C) following cold storage were investigated. Quality indices including firmness, titratable acidity, total phenolic content, antioxidant capacity, colour parameters and microstructure were measured. Results indicated heat treatment at both temperatures for 3-h hastened loss of titratable acidity in 'Red Fuji' and 'Golden Delicious' apples, but maintained firmness in both cultivars. However, heat treatment at lower temperature (45 °C) best maintained total phenolic compounds and antioxidant capacity in 'Red Fuji' apples throughout storage, whereas there was no difference between heat treatments in 'Golden Delicious' apples. Examination by scanning electron microscope (SEM) revealed that the effect of heat treatment at different temperatures on 'Red Fuji' and 'Golden Delicious' apples was structurally different. Apple tissue that had been heat treated at elevated temperature (60 °C) for 3 h was associated with fractured cell walls and collapse of cells. © 2012 The Authors. International Journal of Food Science and Technology © 2012 Institute of Food Science and Technology.


Wang R.,Northwest Agriculture and Forestry University | Wang R.,Jinan Fruit Research Institute | Zhou Y.,Northwest Agriculture and Forestry University | Zhang J.,Northwest Agriculture and Forestry University
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2012

In order to investigate the effects of temperature on electrical parameters for 'Huoshi' persimmon fruit, variation of electrical parameters with temperature of intact 'Huoshi' persimmon fruit was studied over a frequency range from 100 Hz to 3.98 MHz with LCR meter and parallel plate electrode. Frequency and temperature characteristics of electrical properties were also illuminated by biology and electromagnetism theories. The results showed that fruit impedance, inductance and low frequency (f ≤ 15.8 kHz) conductance varied in exponential form with the increase of frequency. As the fruit temperature rised from 10°C to 40°C, fruit impedance decreased from 28% at 3.98 MHz to 38% at 1 kHz, the inductance 30% at 3.98 MHz to 38% at 1 kHz, while the capacitance increased from 43% at 3.98 MHz to 56% at 1 kHz, and the conductance had an increasing trend. Linearly correlation equations were built between fruit temperature and electrical parameters for the prediction of electrical parameter values at different temperatures. Frequency properties of fruit electrical parameters were attributed to the in-homogeneity of fruit structure, penetrating capacity variance of the electric field to the flesh and the variation of dominant dielectric loss factors at different frequency ranges, while the ionic conduction accounted for the temperature behavior of the electrical parameters.

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