Mouldy fruits and vegetables as a source of mycotoxins: part 2

Although chemical control is still the main way to reduce the preharvest and postharvest incidence of mycotoxigenic fungi, the worldwide tendency to reduce chemical use, and the emergence of resistant strains, have accelerated the search for non-chemical strategies. Those applied at the postharvest stage include heat treatments, biological control, and modified-or controlled-atmosphere storage. It is now evident that combinations of treatments are more efficient than individual treatments applied alone. Most of the studies on mycotoxins in fruits are focused on patulin (produced mainly by Penicillium expansum) in apple products, and ochratoxin A (produced mainly by Aspergillus carbonarius) in grapes and in wines. Patulin levels can be significantly reduced by washing and sorting apples, and trimming away rotten tissues. Other treatments for patulin reduction have been associated with its ability to react readily with compounds containing sulphydryl groups. Other additives that reduce patulin levels are ascorbic acid and B-complex vitamins. The rate of ochratoxin A reduction during fermentation depends, among others, on the yeast used for fermentation and the type of wine produced. During vinification, ochratoxin A is also reduced by binding to the solid residues of grapes. Alternaria mycotoxins may be produced naturally in a variety of fruits and vegetables and their processed products. At least two of these mycotoxins, alternariol and alternariol monomethyl, were shown to be stable in heated apple juice. In some apple cultivars, Alternaria occurs in the core and the damage is hidden. Contamination with mycotoxins is recognized as an unavoidable risk, but three major components are involved in the attempt to minimize the risk: Good Agricultural Practices, Good Manufacturing Practices, and Hazard Analysis Critical Control Points. In many countries, regulatory measures have been taken to limit the presence of mycotoxins in fruits and vegetables. Several factors may influence the establishment of national and regional mycotoxin limits and regulations.