Updated – 14 October 2021
Fruit juice processing, as for any food processing, has certain inherent food safety risks. One such risk is the potential presence of a toxin called patulin, produced by certain fungi, mainly Penicillium expansum, when related to apples. The generic name for a fungal toxin is “mycotoxin”. Patulin is but one example of a mycotoxin.
How does patulin enter the juice?
The fungus itself is present on the surface of the fruit and is a common storage-rot fungus of apples. Care must be taken to limit the amount of fruit that enters the juicing process that visibly shows fungal growth, spoilage, or damage. The patulin is produced by the fungus whilst present on the apples. Therefore, the patulin is pre-formed and enters the juicing process via the apples. Fruit juices and concentrates (including Appletiser and the bases for Liquifruit and Woolworths juices) are pasteurized to kill off any microorganisms that could cause foodborne disease (food poisoning) and that could cause spoilage of the product, such as yeasts. which are commonly associated with unpasteurized juices. However, the heating temperatures used for pasteurization do not destroy the patulin. Using higher temperatures is impractical as the higher temperatures would affect certain desirable quality attributes of the product, making the juice undesirable for the consumer.
Is it necessary to have a zero-tolerance for patulin?
In most cases when it comes to food safety, a certain level of either a substance or a microorganism is tolerated by humans without causing disease. Several international organizations and food safety authorities conduct research, gather information and conduct risk assessments. The latter includes considering the age of the individual, any underlying conditions, frequency of ingestion of the food or beverage under consideration, portion size and more. At the end of such a risk assessment, a maximum permitted level of that substance/microorganism in that particular food is often developed.
The Codex Alimentarius Commission (CAC) is an international standards-setting organization under the auspices of the FAO and WHO. The CAC has indeed published a standard (CODEX STAN 193-1995) that specifies a maximum level of 50 micrograms per kilogram (µg/kg) of patulin in apple juice. This is the same as saying 50 parts per billion.
What is the safety level?
Most importantly, patulin does not accumulate in the body and taking consumption patterns into consideration, JECFA (Joint Expert Committee on Food Additives), an FAO/WHO body, established a PMTDI (provisional maximum tolerable daily intake) of 0.4 µg/kg body weight per day.
They reached this decision as follows: The PMTDI of 0.4 µg/kg body weight was established based on a NOEL (no observed effect level) of 43 µg/kg body weight per day and an additional safety factor of 100.
What does this mean?
Interpreting these figures is important. This means that at a level of 43 µg/kg body weight per day, there is no observed effect of harm or damage done for example to functionality, growth, development and lifespan of the organism in question (in this case, humans). Following this, JECFA added an additional safety margin of a factor of 100, which then provides for a 100-fold lower level than the NOEL. This essentially means that 0.4 µg/kg body weight per day is a 100-fold lower level than the level of patulin that shows no observed negative effect in the human body, thereby creating a large safety margin.
Is patulin regulated in South Africa?
South Africa does indeed regulate patulin in apple juice. The maximum permitted level follows that of the CAC i.e. not more than 50 micrograms per litre of apple juice and apple juice ingredients in other beverages.
What about other countries?
The European Union (EU) follows the same maximum permitted level for apple juice for general consumption of 50 µg/kg, but specifies a stricter maximum permitted level of patulin in apple juice (and other solid apple products) for infants and young children, of 10 µg/kg.
Is patulin dangerous for humans?
Very few reports indicate any direct carcinogenic (cancer-causing) ability of patulin in humans. Hence it is currently classified as group 3 by the IARC (International Agency for Research on Cancer) as it is not considered carcinogenic to humans. In vivo animal studies show interaction of patulin with the gastrointestinal tract, causing an inflammatory reaction. Similar disturbances have been reported in humans, including nausea and vomiting. It can also be mutagenic i.e. causing DNA damage in animals as well as being teratogenic (affecting unborn animal foetus). However, it is important to note that these effects have occurred in animal models and also when very high levels of patulin have been administered to those experimental animals, via direct injection into the peritoneum as opposed through diet. In one example, 1-3.75 mg/kg (parts per million or milligrams, which are 1000x higher than micrograms or parts per billion), was administered to the animal in this way. Under these circumstances, one would definitely expect such high doses to have a negative effect on the animal. Such very high levels are, however, unlikely to be found in commercially manufactured juices within a HACCP-based Food Safety Management System.
Furthermore, one must consider the intake of patulin through the diet and into the stomach as opposed to having it injected directly into one’s gut. Few studies have been conducted by giving patulin orally to animals, yet, in those too, the levels were very high, for example, 10 and 20 mg/kg (parts per million) which is 10 000 and 20 000 µg/kg (parts per billion) respectively.
In other studies (2017) where yeast cells were exposed to very high levels of patulin, it caused a significant growth defect, but when the patulin was washed out, the yeast cells were able to resume normal growth, so the effect of the patulin was reversed.
More recent studies indicate that drinking green tea and chewing on green tea leaves may have a beneficial effect in reducing potential toxic effects of patulin on the liver.
Certain studies have shown that patulin may indeed have a therapeutic effect for some conditions as it may have clinically useful properties. Therefore, ongoing research is being conducted to better understand this potential development.
Copyright 29 September 2021 Anelich Consulting
