Spray-drying microencapsulation of Trichoderma harzianum conidias in carbohydrate polymers matrices

Microencapsulation of biological control agents in biopolymer matrices by spray-drying is a valuable alternative to produce formulations with extended shelf-life. In this work, Trichoderma harzianum conidia were microencapsulated in: maltodextrin DE10 (MD10), maltodextrin DE20 (MD20), gum Arabic (GA), and a 1:1 weight blend of MD10-GA. The effect of spray-drying inlet and outlet air temperatures, and the activation energy (E-a) of the biopolymers on the survival of T. harzianum conidia was evaluated. The highest conidia survival after spray-drying (86%) and after 8 weeks of storage at 4 degrees C (40%), were obtained with the MD10-GA biopolymer matrix (with the highest E-a =31.6 kJ mol(-1)). Such survivals were 11 and 330-fold times higher than those of non-encapsulated conidia, respectively. The evolution of reactive oxygen species (ROS), as a measure of oxidative stress, during storage at 29 degrees C was assessed. An inverse relationship was found between the conidia survival and ROS concentration during storage. (C) 2012 Elsevier Ltd. All rights reserved.