3 resultados para Thermostability

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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Xylanolytic enzymes produced by Lentinula edodes UFV70, cultivated in eucalyptus sawdust/rice bran medium, were stable at 50, 60 and 65 degrees C for 21 hours, losing only 15-25% activity. Fungus incubation at 50 degrees C for 12 hours and at 65 degrees C for 24 hours increased the amount of xylose produced.

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Xylanolytic enzymes produced by Lentinula edodes UFV70, cultivated in eucalyptus sawdust/rice bran medium, were stable at 50, 60 and 65ºC for 21 hours, losing only 15-25% activity. Fungus incubation at 50ºC for 12 hours and at 65ºC for 24 hours increased the amount of xylose produced.

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Hybrid materials were prepared by combining clay mineral (montmorillonite SWy-2 and saponite SapCa-1) and dyes extracted from the acai (Euterpe oleracea Mart.) fruit, which contains mainly anthocyanins from the 3-glucoside class, to increase the stability of the dye and facilitate its handling and storage. Clay minerals are common ingredients in therapeutic and pharmaceutical products and acai phytochemicals show disease prevention properties. The extract of the acai fruit was mixed with water suspensions of layered silicates in different proportions. The dyeclay hybrids presented incorporated organic material in amounts up to 24 wt.-%. X ray diffractometry and vibrational (FTIR and Raman) and electronic spectroscopic data showed that flavylium cations were successfully intercalated between the inorganic layers. Mass-coupled thermogravimetric analysis (TGA-MS) data showed a significant gain in the thermostability of the organic species in relation to anthocyanins in the extract. MS curves related to CO2 release (m/z = 44) are ascendant above 200 degrees C when the dye cations are confined to the inorganic structure. The radical scavenging activity of the hybrid materials was monitored by electron paramagnetic resonance (EPR) toward the stable radical DPPH (1,1-diphenyl-2-picrylhydrazyl) and compared to the activity of the acai extract. In addition to the fact that interaction with clay minerals improves the stability of the acai dyes against heat, their properties as radical scavengers are preserved after intercalation. The improvement in the properties of the nutraceutical species by intercalation by using biocompatible inorganic structures can be valuable for human therapy.