Shelf life improvement of the biocontrol agent Candida sake CPA-1 by suitable package and storage conditions

Abstract

Agrochemical companies are increasing their interest in the production of biopesticides based on biocontrol agents (BCAs), mainly due to the need to reduce the synthetic fungicide application and the consequent benefits for the environment and for human health. The efficacy of the BCA Candida sake CPA-1 has been demonstrated against the main postharvest diseases on pome fruit, and B. cinerea and sour rot in grapes control on field. Recently, two effective fluidised-bed spray-dried formulations based on C. sake CPA-1 and biodegradable compounds were described as an effective biocontrol product. However, the maintenance of the effectiveness and survival of these formulations during a long shelf life is a crucial aspect to the success of its marketing. For this reason, the aim of this study was to select the best packaging and storage conditions to maintain a long shelf life of two fluidised-bed spray-dried C. sake CPA-1 formulations. Viability and aw (water activity) of CPA-1 formulations stored in different packages (bottles and bags), temperatures (− 20 °C and 4 °C) and atmospheric conditions (vacuum and air) were tested for 22 months. Both formulations maintained their initial viability (around 4 × 109 CFU ml−1) when they were stored at − 20 °C regardless of the packages or atmospheric conditions. In contrast, the viability of CPA-1 formulations stored at 4 °C differed between bags and bottles. Both formulations could be stored for at least 21 months at − 20 °C, and only one formulation could achieve a one-year shelf life stored in bottles at 4 °C. C. sake CPA-1 formulations stored for 12 months at the most suitable conditions significantly reduced B. cinerea on grapes by 25 to 56%.