Drying of Epicoccum nigrum conidia for obtaining a shelf-stable biological product against brown rot disease

Abstract

Aims: The effects of freeze-drying, spray-drying and fluidized bed-drying on survival of Epicoccum nigrum conidia were compared. Methods and Results: Viability of E. nigrum conidia (estimated by measuring its germination) was 100% after fluidized bed-drying and freeze-drying, but it was determined that skimmed milk must be added in the case of freeze-drying conidia. Addition of other protectants (Tween-20, peptone, sucrose, glucose, starch and peptone + starch) to skimmed milk before freeze-drying did not improve the conidial viability which was obtained with skimmed milk alone. Glycerol had a negative effect on the lyophilization of E. nigrum conidia. Epicoccum nigrum conidia freeze-dried with skimmed milk, or fluidized bed-dried alone maintained an initial viability for 30 and 90 days, respectively, for storage at room temperature. Epicoccum nigrum conidial viability after spray-drying was lower than 10%. Conclusions: The best method to dry E. nigrum conidia was fluidized bed-drying. Conidia without protectants dried by this method had 100% viability and survived for 90 days at room temperature. Significance and Impact of Study: This paper deals with methods for the potential formulation of a biocontrol agent which is being tested for eventual commercialization.

The science, development, and commercialization of postharvest biocontrol products

“…Fluidized bed-drying is a costeffective method of drying that can be used to dry heat-sensitive microorganisms because the drying temperatures are relatively low. Fungi such as E. nigrum (Larena et al, 2003) and P. frequentans (Guijarro et al, 2006), the yeast-like fungus, A. pullulans (Mounir et al, 2007), and the yeast, C. sake CPA-2 (Usall et al, 2009) have all been successfully dried using fluidized bed-drying. In contrast, liquid formulations are the simplest way to stabilize the viability of microbial cells.…”

Evaluación de la Estabilidad y Viabilidad de Dos Cepas Probióticas Microencapsuladas por Lecho Fluidizado

“…Estos resultados fueron similares a los obtenidos por otros autores con el mismo método, quienes obtuvieron viabilidades en el rango de 95% y 96%. (Schell y Beermann, 2014;Strasser et al, 2009;Larena et al, 2003). (2014) sugieren que los azúcares de bajo peso molecular pueden estabilizar la membrana y las cadenas de proteínas de las células, mediante la sustitución de las moléculas de agua con enlaces de hidrógeno molecular durante los procesos de secado.…”

“…Diversas investigaciones han realizado estudios comparativos de tres métodos más comunes para la microencapsulación de probióticos; liofilización, secado por aspersión y pulverización en lecho fluidizado ( Guijarro et al, 2006;Larena et al, 2003;). El secado por congelamiento o también denominada liofilización es una de las técnicas más importantes, convenientes y exitosas para la preservación a largo plazo de microorganismos probióticos (Chávez y Ledeboer, 2007;Strasser et al, 2009), sin embargo resulta ser muy costoso y laborioso para ser desarrollado a escala industrial (Augustin y Hemar, 2009); el secado por atomización en contraste al liofilizado permite procesar grandes volúmenes de solución, su principal desventaja son sus altas temperaturas de proceso que pueden afectar drásticamente a la supervivencia de los microorganismos y por ende reducir significativamente la eficiencia (Silva et al, 2014).…”

Maximizing the Shelf Life of Monoxenically Produced Carrier-Based Am Fungal Bio-Inocula for Maintaining Its Long-Term Viability

“…Non-availability of good quality and appropriate carrier materials can affect shelf life of the beneficial microbial inoculants. Drying process, moisture content, storage conditions plus storage temperature are also important determinants of the shelf life of microbial inoculants or formulations and can affect their activity pre-or post-application [17][18][19][20][21].…”