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Jiang Z.-T.,Tianjin University of Commerce | Wang Y.,Tianjin University of Commerce | Chen S.-H.,Tianjin University of Commerce | Guan W.-Q.,National Engineering Technology Research Center for Preservation of Agricultural Products
Journal of Essential Oil-Bearing Plants | Year: 2011

Volatile oil of Origanum majorana L. grown in China was separated by using hydrodistillation (HD). The chemical components of the oil were identified by GC-MS technique and comparison of retention indices with those of C8-C40 standard alkanes. Forty components were characterized, representing 94.5 % of total volatile oil. Major components are terpinen-4-ol (33.0 %), caryophyllene oxide (11.9 %), p-cymene (6.8 %), α-terpineol (6.7 %) and spathulenol (6.0 %). © 2011, Har Krishan Bhalla & Sons. Source

Kou X.,Tianjin University | Liu X.,Tianjin University | Li J.,National Engineering Technology Research Center for Preservation of Agricultural Products | Xiao H.,Tianjin University | Wang J.,Tianjin University
Journal of the Science of Food and Agriculture | Year: 2012

Background: Aroma is one important fruit sensory attribute influenced by the volatile constituents related to species, variety and technological treatments. We analysed the variations of volatile compounds in five pear cultivars and investigated their changes related to different pear organs, different ripening stages, 1-MCP treatment and ultra-high-pressure pasteurisation. Results: Considerable variations exist in the quantity of 10 volatile compounds among five pear cultivars. Their levels generally showed an increasing trend when collected at later harvest time in Ya pear. In Whangkeumbae pear, most volatile compounds reached their maximum levels in skin and pulp. After treating pears with 42 μmol L -1 1-methylcyclopropene (1-MCP), the levels of volatiles remained basically unchanged or only slightly increased in Ya pear during a shelf life of 21 days. When Huangguan pear juice was pasteurised by using ultra-high pressure, the levels of volatiles significantly changed during the shelf life. Conclusion: The volatile compositions of five different Chinese pear cultivars differ considerably. The levels of these volatiles vary along with ripening stages and pear tissues. A moderate concentration of 1-MCP could keep the levels of volatile compounds basically unchanged during storage and ultra-high-pressure pasteurisation could change the levels of volatiles significantly during the following shelf life. © 2011 Society of Chemical Industry. Source

Chen X.,China Agricultural University | Mu W.,China Agricultural University | Peter S.,University of Trnava | Zhang X.,China Agricultural University | Zhu Z.,National Engineering Technology Research Center for Preservation of Agricultural Products
Journal of Food and Nutrition Research | Year: 2016

In this work, 10 treatments of Kyoho grapes were preserved to analyse the effects of constant concentrations of sulfur dioxide (SO2) and temperature on the quality evolution of table grapes to provide references for the preservation technology improvement and the shelf life prediction. With the increase in SO2 concentration and the decrease in temperature, the peak time of soluble solids content was delayed or the rising stage disappeared. The addition of SO2 elevated the apparent activation energy of brown stain, which made the rate of the increase in brown stain more sensitive to temperature. The addition of SO2 showed an effect of inhibition and delay, together with low temperature, on the accumulation of saccharides in table grapes in the early storage. The change in pH value in an environmental range, which is a common situation in actual cold-chain logistics, showed a trend of monotone decrease and could be described by using a unified model. The evolution of pH value and brown stain could be used as reference indices for the shelf life prediction of table grapes in corresponding surroundings. © 2016 National Agricultural and Food Centre (Slovakia). Source

Huang Y.-F.,Nankai University | Huang Y.-F.,National Engineering Technology Research Center for Preservation of Agricultural Products | Li Y.,Nankai University | Jiang Y.,Nankai University | Yan X.-P.,Nankai University
Journal of Analytical Atomic Spectrometry | Year: 2010

The use of magnetic microspheres and nanoparticles for sample extraction in analytical chemistry has received increasing interest. However, previous magnetic particle-based solid-phase extraction (SPE) is usually performed in a batch mode. In this work, we report magnetic immobilization of amine-functionalized magnetite (Fe3O4) microspheres (AF-MMPs) onto the inner walls of a knotted reactor (KR) for on-line SPE coupled with ICP-MS for speciation analysis of trace chromium. A tubular magnet is sufficient to immobilize AF-MMPs onto the inner walls of a KR without the need for any frits or plugs. Sensitive speciation analysis of trace CrIII and CrVI in water was achieved based on selective on-line SPE of either CrIII and CrVI under controlled pH conditions on an AF-MMPs magnetically immobilized KR integrated into a flow injection system with on-line ICP-MS detection without the need for extra oxidation/reduction. On-line SPE of 2.4 mL aqueous solution gave an enhancement factor of 96 for CrIII and 47 for CrVI, a detection limit of 1.5 ng L -1 for CrIII and 2.1 ng L-1 for CrVI at a sample throughput of 23 h-1. The precision (RSD) for eleven replicate measurements of 100 ng L-1 CrIII and Cr VI was 1.9% and 4.5%, respectively. The batch-to-batch reproducibility (RSD) for three parallel prepared AF-MMPs packed KRs for the SPE of CrIII and CrVI at 100 ng L-1 was less than 5.5%. One AF-MMPs packed KRs can be used for at least 75 cycles of preconcentration without significant loss of extraction efficiency. The developed method was successfully applied to the speciation analysis of trace CrIII and CrVI in drinking water samples. © 2010 The Royal Society of Chemistry. Source

Chen X.,China Agricultural University | Zhu Z.,National Engineering Technology Research Center for Preservation of Agricultural Products | Zhang X.,China Agricultural University | Mu W.,China Agricultural University | Fu Z.,China Agricultural University
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2015

As an important research direction of food sector, shelf life prediction has become a hot topic worldwide. The related research literatures were summarized, the research mechanism and research progress of food shelf life prediction were reviewed, and the related research ideas and research methods were clarified. Five types of research methods were analyzed and compared, including the method based on chemical kinetics, the method based on growth kinetics of microbial, the method of back propagation (BP) neural networks, the method of Weibull hazard analysis and the method based on temperature such as Q10 model. Quality indexes and research models used in different kinds of foods' shelf life prediction, such as meat, aquatic product, fruits and vegetables, which were proved to be available to achieve good results, were summarized. Finally, the status of food shelf life prediction research was analyzed and its development tendency was presented in the respects of research mechanism, study object and its surroundings, research applications and dynamic monitoring. Analysis indicates that food shelf life prediction tends to be more accurate and utility. ©, 2015, Chinese Society of Agricultural Machinery. All right reserved. Source

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