Stepwise Screening of Natural Substances for Control of Postharvest Aflatoxigenic Fungi in Maize and Peanut Agroecosystems

PASSONE, M.A.; GIRARDI, N.S.; ETCHEVERRY, M.

Agricultural Research Updates. Volume 7

Nova Science Publishers

Año: 2014;

Fungi are significant destroyers of foodstuffs during storage resulting in a reduction in quality and quantity, as well as rendering them unfit for human consumption due to the potential for fungi to produce mycotoxins. The indiscriminate use of different synthetic antimicrobials in recent years to minimize such losses has encountered major problems not only due to their adverse side effects on consumers but also for the development of resistance by microorganisms. Hence, there must be optimization of alternative methods for pests and diseases control that produce minimal damage to the environment and human health and with different action mechanisms on the target cell to avoid the development of resistance by microorganisms. Currently, different plant products have been formulated for large scale application in eco-friendly and biorational management of storage pests and are being used as botanical antimicrobials because plants generate a wide variety of compounds. Amongst plant products the essential oils (EOs) derived from aromatic plants have been well studied during the last two to three decades as a potential candidates against different microbes. The aim of this chapter is to summarize the results of the screening carried out in our laboratory from the last six years on in vitro and in situ studies regarding the effects of plant-derived products for controlling Aspergillus section Flavi growth isolated from maize and peanut storage agroecosystems. Data from research works on the mode of action mode of these metabolites inside the fungal cell are discussed in this chapter. Comparisons of antifungal and antiaflatoxigenic effects by contact and volatile assays of selected EOs are analyzed. Furthermore, an analysis on how the stress factors derived from the presence of EOs and the modifications of water activity (aW) modifications ofin culture medium and kernels affect the secondary metabolism of the fungus, specifically aflatoxin synthesis, is developed. Finally, the influence of abiotic external factors such as temperature, sunlight, UV light and time on the EO antifungal stability of EOs, the chemical composition and the residual levels in the substrate of the two most effective EOs are also covered in the present chapter.