Patulin: the whats, whys and hows
Patulin has been in the spotlight in the last few weeks, with several brands and major retailers recalling apple juice products from supermarket shelves. Patulin is a mycotoxin that is associated with health concerns. But how does patulin get into apple juice, what is considered ‘safe’, and which products may be at risk?
What are mycotoxins?
Mycotoxins are organic contaminant compounds that accumulate in infected foodstuffs as a consequence of a fungal attack. They are produced by filamentous fungi as secondary metabolites. Fungal contamination may affect crops grown under warm and humid conditions.
Are mycotoxins dangerous?
Mycotoxins are toxic and carcinogenic. They can cause renal, pulmonary, neurologic, hematologic and immunologic toxic effects; however, this is dependent on the level of ingestion, frequency of ingestion and specific mycotoxin consumed1. Common symptoms following acute mycotoxin exposure include vomiting, nausea and gastrointestinal disturbances2. These symptoms usually appear quickly after consuming food contaminated with mycotoxins.
How are they detected?
Mycotoxins may accumulate to levels that are harmful to human health without having any adverse effect on the appearance, flavour or appearance of the food. There are several test methods available to detect mycotoxins, including immunochemical-based techniques such as ELISA and chromatographic-based techniques such as HPLC and GC3.
What is patulin?
Patulin is a mycotoxin that commonly affects pome fruit (apples and pears), but has been found in a variety of other fruits and food commodities.
Patulin may be produced by over 60 filamentous fungal species. Penicillium expansum is the main source of patulin contamination in apples and pears. This organism causes fruit decay in the form of blue mould and a soft, brown fruit rot; but patulin contamination at harmful levels may occur without these physical defects.
How does patulin get into apple juice?
Fruit juice is typically produced using fruit of a lower grade than that which we are used to seeing on our supermarket shelves. Apples are sorted before being processed into juice, to ensure that those which do not meet the quality criteria are removed. However, patulin contamination may not always be visible, so some contaminated fruit may make its way into processing.
Fruit-juice processing factors such as homogenisation, pulping, pasteurisation, clarification, centrifugation and concentration may have a reducing effect on patulin levels in a fruit juice4,5. However, these controls have limited effects. They are incapable of eliminating and/or significantly reducing the levels of patulin in a product, due to the great heat stability of P. expansum in acidic environments6. Thus, if the initial levels of patulin contamination are too high, these control measures will not be enough to lower patulin levels to a level considered safe.
The only way to avoid patulin contamination is by good agricultural pre-harvest, harvest and post-harvest practices that limit infection by P. expansum. These may include the application of fungicides and biocontrol agents, the use of induced resistance, taking care not to damage fruit during the harvest, rejecting fruit that has fallen to the ground and fast post-harvest cooling6.
Irradiation, especially UV irradiation, and high hydrostatic pressure have been shown to have a promising effect on reducing and eliminating patulin without any adverse effect on quality of food products5,7.
What is considered ‘safe’ regarding patulin contamination?
Under the South African Foodstuffs, Cosmetics and Disinfectants Act, 1972 (Act 54 of 1972), and the Regulations Governing Tolerance for Fungus-Produced Toxins in Foodstuffs, (R. 1145 of 2004) as amended, apple juice and apple juice ingredients in other beverages are deemed to be contaminated, impure or decayed if they contain more than 50 µg/L of patulin.
Which products may be at risk?
History shows that pure apple juice products (100%) are at the greatest risk of patulin contamination. Although most fruit juices contain apple juice, the risk of patulin exceeding the regulatory limits in these products may be lower, as the apple juice portion is diluted with other juices. However, this depends on the specific product.
Besides apple products, patulin contamination has been reported in figs, grapes, apricots, pears and peaches; some vegetables, cereals and cheeses; and also in some seafood4. It is always best practice to perform routine quality tests, to best manage the risks that may be associated with a specific product.
For more information on patulin, mycotoxins, or the testing of these compounds, contact FACTS.
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