The contents of total phenolics and extractable condensed tannins in the leaves, twigs and stem bark of Canarium album were determined. The structural heterogeneity of condensed tannins from stem bark was characterize...The contents of total phenolics and extractable condensed tannins in the leaves, twigs and stem bark of Canarium album were determined. The structural heterogeneity of condensed tannins from stem bark was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF MS） and nuclear magnetic resonance （NMR） analyses The results show the predominance of signals representative of procyanidins and prodelphinidins. In addition, epicatechin and epigallocatechin polymers with galloylated procyanidin or prodelphinidin were also observed. The tannins were screened for their potential antioxidant activities using l,l-diphenyl-2-picrylhydrazyl （DPPH） and ferric reducing/antioxidant power （FRAP） model systems. Tannins extracted from leaves, twigs and stem bark all showed a very good DPPH radical scavenging activity and ferric reducing power.展开更多
This study proposed a strategy based on simple chemical derivatization coupled with neutral loss scan tandem to electrospray ionization source of mass spectrometer (NLS-ESI-MS/MS) for rapid and sensitive detection of ...This study proposed a strategy based on simple chemical derivatization coupled with neutral loss scan tandem to electrospray ionization source of mass spectrometer (NLS-ESI-MS/MS) for rapid and sensitive detection of free fatty acids (FFAs) in coldpressed rapeseed oils without sample purification and enrichment. The method was applied to investigate contents of FFAs and their changes in cold-pressed rapeseed oil pretreated by microwave. Results showed that main FFAs in rapeseed oil control samples were myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). The highest content of C18:1 was 7163.69 nmol/g and C18:2 was 5221.18 nmol/g among 8 oil samples. FFAs generally increased after microwave pretreatment except C14:0 in oil sample of ‘Xinyou 17’ and ‘Suyou 6’. C18:1 and C18:2 significantly changed (P<0.05) after microwave pretreatment. With this established simple,practical and reliable analysis approach, changes of FFAs would be monitored to ensure safety and quality of edible oils. A powerful tool is provided for thermal degradation mechanism research of edible oils.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30671646)the Program for New Century Excellent Talents in University, China (No. NCET-07-0725)the Program for Innovative Research Team in Science and Technology in Fujian Province University, China
文摘The contents of total phenolics and extractable condensed tannins in the leaves, twigs and stem bark of Canarium album were determined. The structural heterogeneity of condensed tannins from stem bark was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF MS） and nuclear magnetic resonance （NMR） analyses The results show the predominance of signals representative of procyanidins and prodelphinidins. In addition, epicatechin and epigallocatechin polymers with galloylated procyanidin or prodelphinidin were also observed. The tannins were screened for their potential antioxidant activities using l,l-diphenyl-2-picrylhydrazyl （DPPH） and ferric reducing/antioxidant power （FRAP） model systems. Tannins extracted from leaves, twigs and stem bark all showed a very good DPPH radical scavenging activity and ferric reducing power.
文摘This study proposed a strategy based on simple chemical derivatization coupled with neutral loss scan tandem to electrospray ionization source of mass spectrometer (NLS-ESI-MS/MS) for rapid and sensitive detection of free fatty acids (FFAs) in coldpressed rapeseed oils without sample purification and enrichment. The method was applied to investigate contents of FFAs and their changes in cold-pressed rapeseed oil pretreated by microwave. Results showed that main FFAs in rapeseed oil control samples were myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). The highest content of C18:1 was 7163.69 nmol/g and C18:2 was 5221.18 nmol/g among 8 oil samples. FFAs generally increased after microwave pretreatment except C14:0 in oil sample of ‘Xinyou 17’ and ‘Suyou 6’. C18:1 and C18:2 significantly changed (P<0.05) after microwave pretreatment. With this established simple,practical and reliable analysis approach, changes of FFAs would be monitored to ensure safety and quality of edible oils. A powerful tool is provided for thermal degradation mechanism research of edible oils.
