Microencapsulating aerial conidia of Trichoderma harzianum through spray drying at elevated temperatures

Conidia of Trichoderma harzianum produced from either solid or liquid fermentation must be dried to prevent spoilage by microbial contamination, and to induce dormancy for formulation development and prolonged self-life. Drying conidia of Trichoderma spp. in large scale production remains the major constraint because conidia lose viability during the drying process at elevated temperatures. Moreover, caking must be avoided during drying because heat generated by milling conidial chunks will kill conidia. It is ideal to dry conidia into a flow-able powder for further formulation development. A method was developed for microencapsulation of Trichoderma conidia with sugar through spray drying. Microencapsulation with sugars, such as sucrose, molasses or glycerol, significantly (P < 0.05) increased the survival percentages of conidia after drying. Microencapsulation of conidia with 2% sucrose solution resulted in the highest survival percentage when compared with other sucrose concentrations and had about 7.5 × 1010 cfu in each gram of dried conidia, and 3.4 mg of sucrose added to each gram of dried conidia. The optimal inlet/outlet temperature setting was 60/31 °C for spray drying and microencapsulation. The particle size of microencapsulated conidia balls ranged from 10 to 25 μm. The spray dried biomass of T. harzianum was a flow-able powder with over 99% conidia, which could be used in a variety of formulation developments from seed coatings to sprayable formulations.

Microencapsulating aerial conidia of Trichoderma harzianum with 2% sucrose solution through spray drying at an inlet/outlet temperatures of 60/31 °C significantly improved the survival percentage.Figure optionsDownload as PowerPoint slideResearch highlights
► Sugar microencapsulation protected conidia of Trichoderma harzianum during spray drying.
► 2% sucrose microencapsulation resulted in 7.5 × 1010 cfu/g.
► The optimal inlet/outlet temperature was 60/31 °C for spray drying.
► The particle size of microencapsulated conidia balls ranged from 10 to 25 μm.
► The spray dried biomass of T. harzianum was a flowable powder with over 99% conidia.