Water sorption isotherms of Beauveria bassiana (Bals.) Vuill. Conidia

• Autor(a) principal: Silva,Roberta Z. da
• Data de Publicação: 2003
• Outros Autores: Neves,Pedro M.J.O., Yamashita,Fábio, Santoro,Patrícia H.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Neotropical entomology (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2003000200023
• topic: Entomopathogenic; biological control; storage; water activity; moisture

One of the requirements for successful commercial production of biological control agent is the maintenance of viability for long periods at room temperature, increasing shelf life. The water activity (Aw) is an important parameter to study the stability in the storage of dehydrated products but its determination demands equipments not always available. The water sorption isotherms correlate the Aw with the moisture of a product; adsorption isotherm is important to define the packaging system, and desorption isotherm the drying process. The objective of this study was to determine the sorption isotherms of Beauveria bassiana conidia and adjust them using a mathematical model. The adsorption and desorption were determined by gravimetric technique at 25°C and data were adjusted by the BET model. During desorption, conidia initially presented high moisture content (98% in dry basis) and Aw (0,93); from 98% to 50% a low reduction in Aw was observed, because the water was in a free form. When moisture was around 50%, a small reduction on moisture resulted in a great decrease in Aw, because the water was in a bound form. The adsorption curve showed that when moisture varied from 9% to 50% a small increment in conidia moisture resulted in a high increment in Aw. The BET model adequately represented the sorption isotherms of B. bassiana conidia, being useful to define the ideal moisture to storage this biological control agent.