Severity: Warning
Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
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File: /var/www/html/application/helpers/my_audit_helper.php
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Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
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Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
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Function: getPubMedXML
File: /var/www/html/application/controllers/Detail.php
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Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
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Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
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Function: require_once
Severity: Warning
Message: Attempt to read property "Count" on bool
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File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3100
Function: _error_handler
File: /var/www/html/application/controllers/Detail.php
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Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
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Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
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Function: require_once
A novel headspace gas chromatography-mass spectrometry (HS GC-MS) method was developed for analysis of volatile compounds in onion (Allium cepa L. var. cepa, 'Recas'). MS was operated using full scan mode and selective ion monitoring (SIM) mode in order to quantify some specific compounds with increased sensitivity relative to full scan mode. The limits of detection and quantitation ranged from 0.01 to 0.10 μg/g and from 0.02 to 3.83 μg/g fresh weight, respectively, for studied compounds. The procedure allowed the identification of eighteen compounds and quantitation of nine compounds in the volatile fraction of onion, belonging mainly to di-, and trisulfides and aldehydes. These methods were applied to evaluate how high-pressure (HP) as a processing technology affects onion volatile compounds, responsible in part of the onion biological activity. Onion samples were treated at T1: 200 MPa/25°C/5 min, T2: 400 MPa/25°C/5 min and T3: 600 MPa/25°C/5 min (treatments). In addition, the difference among diced, freeze-dried and pulverized onions (groups) was studied, in order to select the process more adequate for better preserving volatile compounds. The results obtained in full scan mode showed that both main factors (group and treatment) had a significant effect (P<0.001). There were also significant differences between groups and treatments for all compounds, being the main effect of group more marked by HS GC-MS using selective ion monitoring (SIM) mode. For 2-methyl 2-pentenal, dimethyl trisulfide, and methyl propyl trisulfide it has been observed an increase in freeze-dried and pulverized onion samples compared with diced samples regardless the HP treatment. However, freeze-drying and pulverization processes affected the stability of propionaldehyde, 1-propanethiol, hexanal, dipropyl disulfide, and dipropyl trisulfide, diminishing their content regardless the HP treatment. HP at 200 and 400 MPa/25°C/5 min were the least detrimental treatments to the total fraction of volatile compounds, not affecting or even increasing the levels of some volatile compounds.
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http://dx.doi.org/10.1016/j.talanta.2012.10.022 | DOI Listing |
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