Unfolding of Poly-L-glutamic Acid by Microbubbling of Supercritical Carbon Dioxide
The conformational changes in α-helical poly-L-glutamic acid caused by microbubbling supercritical CO2 were investigated with circular dichroism spectra. After microbubbling using a micropore filter at 35 and 30 MPa for 30 min, α-helix content decreased to 37%, while without the filter it was 68%. The α-helix structure was significantly decomposed by a high density of CO2. No important changes were observed in heating, autoclaving, or pH-lowering.
Inactivation of Oxidoreductase Containing Metals by Supercritical Carbon Dioxide.
食品の劣化や褐変に関与する金属含有の酸化還元酵素を中心に,酵素に対する超臨界二酸化炭素(SC-CO2)の影響を調べた.各種酵素の水溶液にSC-CO2を圧力10-20MPa,温度35℃で0-120分および20時間導入したところ,カタラーゼ,ペルオキシダーゼ,ポリフェノールオキシダーゼは,SC-CO2処理により容易に活性が低下した.その効果は時間が長くなるほど,また圧力が高いほど顕著であった.一方,リパーゼやピルビン酸デカルボキシラーゼはSC-CO2処理による著しい活性の低下は見られなかった.以上より,酵素の種類によりSC-CO2に対する感受性が異なることが明らかとなった.このことは,SC-CO2処理の条件(温度や圧力)を適当に選択することにより,食品中の特定の酵素だけを失活させることが可能なことを示唆した.
Essential Oil Profiles of 168 Perilla Cultivars by Head Space Solid Phase Micro-extraction Gas Chromatography Mass Spectrometry
Abstract In order to comprehensively elucidate the chemical biosynthesis in Perillla (commonly used in traditional herbal medicine), an untargeted analysis based on Gas chromatography-Mass spectrometry was done to reveal the metabolites from 168 different species of Perilla, with 73 components were identified. The results based on the 168 samples, which can be classified into five chemotypes, reveals that different genetic background have a significant influence on the metabolic synthesis of Perilla. The results of heat map for the components of different species and the principal component analysis are implying that the Perilla chemotypes are clustered for characteristic compounds. This study, which used optimized solid-phase microextraction conditions to investigate volatile oil composition, expanded our knowledge of metabolic pathways in Perilla. The differences between chemotypes provide a scientific basis for distinguishing between Perilla species, which not only can improve the testing standards for essential oils from Perilla herbs, but also can be beneficial to Perilla breeding.