Drying and rehydration of oyster mushroom

Dehydration and rehydration processes of Pleurotus ostreatus fruiting bodies were investigated in this work. Mushroom samples were dehydrated at 40, 50 and 60 ºC, using drying air with relative humidity of 75 percent. The rehydration was investigated at different temperatures of immersion water (25, 55 and 85 ºC) and different immersion times (30, 75 and 120 minutes). The best rehydration occurred for the samples dried at 40 ºC. The rehydration could be done in water at room temperature, during 30 minutes. Water sorption isotherms of samples were determined at 30, 40 and 50 ºC. Both GAB and BET models satisfactorily represented the experimental data of moisture sorption of dried mushrooms.

Processos de desidratação e de rehidratação de cogumelos da espécie Pleurotus ostreatus foram avaliados neste trabalho. Os cogumelos foram desidratados a 40, 50 e 60 ºC, com umidade relativa do ar de 75 por cento. O processo de rehidratação foi avaliado para diferentes temperaturas de água de imersão (25, 55 e 85 ºC) e diferentes tempos de imersão (30, 75 e 120 minutos). A melhor temperatura de secagem foi 40 ºC, levando em consideração a melhor rehidratação dos cogumelos desidratados nesta temperatura. A rehidratação pode ser feita em água a temperatura ambiente, por 30 minutos. Isotermas de sorção de umidade de amostras foram determinadas a 30, 40 e 50 ºC.Tanto o modelo de GAB quanto o de BET representaram satisfatoriamente os dados experimentais de isoterma de sorção de umidade.

Studies on the hygroscopicity of glucosamine sulfate powder / 中国海洋药物

Objective To study the hygroscopicity of glucosamine sulfate powder.Methods Hygroscopic studies were conducted on glucosamine sulfate powder at 5℃ and 30℃ used gravimetric method,determined the equilibrium moisture content(EMC) and drew the moisture sorption isotherms.The experimental values were regressed using the BET model,calculated the monolayer moisture content.Results At 30℃,when water activity exceeded 0.43,samples agglomerated,browned and lose adsorbed water,EMC declined;At 5℃,the isotherm had typical ob-S shape,the EMC increased with water activity raising.At 30℃ and 5℃,the monolayer moisture content were 4.8633,5.5740g/100g respectively.Conclusion At 5,30℃ the appropriate aw for storage appeared to be below 0.3056,0.2784,respectively.