Information about mould and mould disease
Patulin (PAT) is probably the best-known toxin associated with fresh fruits like apples, pears, apricots, peaches and grapes. Its production in grapes has been associated with mouldy berries and with fruits infected during prolonged cold storage; it has been detected in peaches, apricots, cherries, blackcurrants and olives and an outbreak of diarrhoea in children in Sweden was attributed to the consumption of blueberries with a high patulin content.
Patulin (C7H6O4) is a relatively uncomplex lactone, derived mainly from species of Penicillium, Aspergillus, Paecylomyces and Byssochlamys. It also can, however, be produced by species of Stemphylium, Alternaria, Fusarium, Trichoderma, Trichothecium, Mucor and Phialophora, which are all capable of inducing postharvest diseases in fruits and vegetables. The major producer of patulin in nature is P. expansum, commonly known as the blue mould pathogen of apples and other deciduous trees.
Patulin can be isolated as colourless to white crystals. It melts at about 110 ºC and sublimes in high vacuum at 70-100 ºC. It is soluble in water, methanol, ethanol, acetone, and ethyl or amyl acetate and less soluble in diethyl ether and benzene. It is susceptible to alkaline hydrolysis, reduced by SO2 and by fermentation.
Patulin is highly toxic to plant and animal cells, and can react with terminal sulfhydryl groups of proteins and polypeptides present in food. It was found to inhibit protein and RNA synthesis, and was shown to produce persistent breaks in single and double strands of DNA in Escherichia coli. It can cause oxidative damage to DNA in human cells also inhibit the activity of numerous enzymes, mainly as a consequence of its strong affinity to sulfhydryl groups. It has an inhibitory effect on several biochemical parameters, such as AT-Pase, alkaline phosphatase, aldolase and hexokinase activity.
Exposure of humans to patulin via consumption of infected products may result in severe toxicosis, including mutagenic, teratogenic, hepatotoxic?, nephrotoxic?, neurotoxic and genotoxic effects; its acute effects include nausea, vomiting and other gastrointestinal traumas that accompany kidney damage. At high doses patulin was found to exhibit immunosuppressive properties. Patulin produce by Aspergillus clavatus is known to have cause a severe mycotoxicosis? in farm stock fed of malting by products.
At present, there are no published toxicological or epidemiological data to indicate whether consumption of patulin is harmful to humans. However, there is a desire to limit patulin levels in apple products since infants and young children are major consumers of these foods and the effects of long-term exposure to patulin are not yet known. Many countries, including the United States, have set regulatory limits for patulin in apple products of 50 mg/L or less (van Egmond, 1989; U.S. Food and Drug Administration, 2001; Drusch and Ragab, 2003). Current UK limits include a guideline level of 50 µg/kg patulin in apple juice.
The optimum growth temperature for P. expansum is near 25C, but there are reports of growth of the organism at 3C (Pitt, 2002). Minimum water activities? for spore germination are 0.82-0.83.
P. expansum has a very low requirement for oxygen; the organism was found to grow at atmospheric oxygen levels of less than 2 percent. Carbon dioxide concentrations of up to 15 percent have been found to stimulate growth of the organism.
The optimum temperature for patulin production has been reported in the range of 23-25C. Although patulin production tends to decrease as temperature is decreased, patulin can be produced at low temperatures (0-4C). Consequently, refrigerated storage is not practical to inhibit patulin production in fruit.