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The control of micro-organisms responsible for pre- and postharvest diseases of agricultural products, mainly viruses and fungi, is a problem that remains unresolved, together with the environmental impact of the excessive use of chemicals to tackle this problem. Current efforts are focused on the search for efficient alternatives for microbial control that will not result in damage to the environment or an imbalance in the existing biota. One alternative is the use of natural antimicrobial compounds such as chitosan, a linear cationic biopolymer, which is biodegradable, biocompatible and non-toxic, has filmogenic properties and is capable of forming matrices for the transport of active substances. The study of chitosan has attracted great interest owing to its ability to form complexes or matrices for the controlled release of active compounds such as micro- and nanoparticles, which, together with the biological properties of chitosan, has allowed a major breakthrough in the pharmaceutical and biomedical industries. Another important field of study is the development of chitosan-based matrices for the controlled release of active compounds in areas such as agriculture and food for the control of viruses, bacteria and fungi, which is one of the least exploited areas and holds much promise for future research., (© 2013 Society of Chemical Industry.)

Contamination of agricultural products by toxigenic fungi and the presence of mycotoxins cause serious economic damage, and toxic effects to humans and animals. In this study the effect of chitosan as a natural alternative for the control of the fungus Aspergillus parasiticus was evaluated. Chitosans were obtained from chitin previously extracted from shrimp heads using chemical (CS) and biological (CB) processes. The chitosan yields were 5.74 and 6.20% for CS and CB methods, respectively, with an amount of residual protein and ash below 1%, low molecular weight and degree of deacetylation of 80-82%. Chitosan showed fungistatic activity against A. parasiticus, with 6.71 and 10.66 g L (CI) of CS and CB, respectively, being required to delay fungal growth by 50% at 122 h. Chitosan (CI) inhibited both radial growth up to 122 h, and germination of spores before 8 h higher than 50%. Chitosan also increased the average diameter of the spores and hyphae ( P ≤ 0.05), reduced the septation process and increased the number of mitotic divisions of spores during germination. However, compared with control, chitosan decreased ( P ≤ 0.05) aflatoxin B1 production at 8 days but increased ( P ≤ 0.05) the total aflatoxins production by A. parasiticus. Copyright © 2011 Society of Chemical Industry Contamination of maize by Aspergillus parasiticus and its mycotoxins cause economic and environmental damages. Chitosan affected fungal morphogenesis; however, it did not inhibit aflatoxin B1 production in corn grain. [ABSTRACT FROM AUTHOR]