RESUMO
Effect of electron beam irradiation on microbial growth and qualities of vacuum-packaged Korean ginseng and red ginseng during storage was investigated. Korean ginseng and red ginseng were treated at irradiation doses of 0, 2, 8, and 16 kGy. After treatment, samples were individually vacuum-packaged and stored at 20 degrees C. Microbial growth results of the irradiated samples presented that populations of total bacteria, yeast and mold, and total coliforms were decreased by 2 to 3 log CFU/g. The pH values of the samples were not significantly different among treatments. Thiobarbituric acid-reactive substance values of the samples increased during storage. Electron beam treatment caused negligible changes in Hunter's color L, a, and b values among the samples. Sensory evaluations like color and odor of the samples exhibited that there were no significant changes among the samples. During storage, content of saponin, a leading compound in ginseng, was not affected by irradiation. These results suggest that electron beam treatment should be useful in extending shelf lives of Korean ginseng and red ginseng.
Assuntos
Irradiação de Alimentos/métodos , Conservação de Alimentos/métodos , Panax/efeitos da radiação , Adulto , Cromatografia em Camada Fina , Contagem de Colônia Microbiana , Feminino , Microbiologia de Alimentos , Embalagem de Alimentos/métodos , Humanos , Lipídeos/efeitos da radiação , Masculino , Odorantes/análise , Oxirredução/efeitos da radiação , Panax/química , Panax/microbiologia , Pigmentos Biológicos , Doses de Radiação , Saponinas/efeitos da radiação , Paladar , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Substâncias Reativas com Ácido Tiobarbitúrico/efeitos da radiação , VácuoRESUMO
The degradation of ginsenosides in American ginseng (Panax quinquefolium) extracts during microwave and water (oil) bath heating (conventional heating) was investigated. Both the 50% ethanol-water extracts and the aqueous extracts were boiled in a modified laboratory microwave oven and in a water (or oil) bath, respectively. The neutral ginsenosides (Rb(1), Rc, Rd, and Re) and malonyl ginsenosides (m-Rb(1), m-Rc, and m-Rd) were determined by reverse-phase high-performance liquid chromatography. The results showed that the degradation of ginsenosides in 50% ethanol-water extracts was a first-order reaction. The malonyl ginsenosides were much less stable than the corresponding neutral ginsenosides, with the rate constant value of the malonyl ginsenosides being 3-60 times that of the neutral ginsenosides. At the same temperature, the effect of microwave heating on the degradation of ginsenosides was the same as that of conventional heating.
Assuntos
Panax , Plantas Medicinais , Saponinas/química , Culinária , Ginsenosídeos , Temperatura Alta , Micro-Ondas , Panax/efeitos da radiação , Extratos Vegetais , Saponinas/efeitos da radiaçãoRESUMO
The transient photodichroism induced by a 0.80 sec plane-polarized light flash in a rhodopsin-digitonin mixture at about -70 degrees C was compared with a theoretical description of the effect. It was concluded that the transient dichroism is entirely due to rotational diffusion of the pigment molecules. When the rhodopsin-digitonin micelles are assumed to be rotationally symmetric it was found from the observed relaxation time that the axial ratio is probably less than 2. The initial photodichroism after each flash as a function of the number of flashes was shown to obey an equation derived for the photochemical equilibrium reaction between rhodopsin, lumirhodopsin, and isorhodopsin. The absolute quantum efficiency of the transition of rhodopsin to lumirhodopsin was found to be equal, within experimental error, to the quantum efficiency of bleaching rhodopsin at room temperature.
