Development of a Bioactive Food Additive for Controlling of Fungal Growth

Fresh foods have a great importance in human nutrition. However, they are marketed with greatly reduced shelf life mainly due to fungal spoilage. In this work, cell wall degrading enzymes produced by Trichoderma asperellum T00 (TCWDE) were immobilized onto cashew gum polysaccharide (CGP) in order to evaluate the potential use of this material as food additive aiming to increase the shelf life by inhibiting fungal growth. Results from factorial design (32) evidenced that the best conditions for TCWDE immobilization was achieved with 20 min of reaction using 1 mmol L-1 of NaIO4. On these conditions it was observed 91% of retention yield for NAGase (30.1 ± 0.38 U mL-1), 41% for chitinase (0.67 ± 0.05 U mL-1), and 24% for β-1,3-glucanase (0.017± 0.001 U mL-1). CGP/TCWDE was effective for growth inhibition of Aspergillus fumigatus and Penicillium sp. and the inhibition mechanism seems to involve changes in the cell wall of those microorganisms. Finally, the CGP/TCWDE presented high stability after drying, maintaining enzymatic and biological activity after 200 days of storage at room temperature (25 ºC).