One of the most exciting things about being a dweller of an African city is the delicious seasonal fruit such as mazhanje and sweet yellow mangoes you find weighing down their sellersҠvehicles when the fruits are in season.
Fresh fruits and vegetables are naturally good for our health. They contain compounds such as vitamin C in oranges and lycopene in tomatoes and watermelons which protects the body against disease. Fruits and vegetables, however, may be contaminated with bacteria and chemicals during production and distribution that may be harmful to the health of consumers.
Fruits and vegetables that are eaten raw are particularly of concern because bacteria are not killed say through cooking. Even when the fruits and vegetables are cooked, the temperature will not be high enough to kill the bacteria but will preserve the nutritional value.
It is therefore important to ensure that fruits and vegetables do not become contaminated with bacteria and harmful chemicals in the first place. We present a few guidelines based on the standard for hygienic practice for fruits and vegetables of the Codex Alimentarius Commission. The Codex Alimentarius Commission is a joint WHO/FAO United Nations Agency which was established for the development of international food standards based on risk assessment and risk analysis principles.
Soil is a source of biological and/or chemical contamination; hence it is important to know how the land was previously used. For example, faeces of both humans and animals may contain dangerous bacteria such as Salmonella and E.coli. If sewage spilled onto the land or if the land was used to house animals, it means the land may contain harmful bacteria and the soil needs to be tested before use.
Also, if the land was used for disposal of toxic industrial waste, the soil may contain heavy metals such as mercury which may accumulate in the plants and harm those who eat them. The soil will need to be tested to make sure it is not contaminated with harmful chemicals before use. The Codex Alimentarius Commission standard for hygiene in production of fruits and vegetables recommends that access of both domestic and wild animals to the land where crops are growing should be prevented so they do not contaminate the crops with their faeces.
Agricultural Inputs and Chemicals
It is advisable that only approved chemicals for fruits and vegetables should be used during production to avoid the risk of harmful chemicals accumulating in the produce. An agronomist can advise farmers on the proper chemicals to use. Agricultural inputs (for example, seed and fertilizer) for fruits and vegetables should also be sourced from a credible manufacturer who has procedures in place to make sure the inputs are not contaminated with bacteria or harmful chemicals.
Record-keeping is very important in any agricultural activity. It is important to keep records of chemicals applied to crops, when they were applied, which crop has been sprayed, the pest or disease against which the chemical was being used, and method and frequency of application. There is also need for records on harvesting to ensure that time between application and harvesting is adequate.
Mixing of chemicals should not result in contamination of land and water. For example, mixing should not be done in open spaces where chemicals can spill onto the ground and go further to flow with rain water and mix with irrigation water or even the domestic water supply. It is very important not to use containers of chemicals for other purposes such as storing of harvested fruit. Empty containers should instead be disposed of as recommended by the manufacturer.
Water may be a source of bacterial or chemical contamination, for example, if it has been contaminated with agricultural chemicals or sewage. It is therefore important that the microbiological and chemical quality of water should be tested to make sure it is safe and suitable for use as irrigation water. If any contamination is found, testing establishments can offer advice on corrective action (if any)) farmers can take to ensure their water is safe before using it to irrigate their plants. Otherwise the water source must be condemned.
Safe water should also be used to wash fresh fruits and vegetables after harvesting. We sometimes assume that once we remove the visible dirt such as soil, the produce is safe for consumption when in actual fact the contamination we cannot see if we use unsafe water is often the most dangerous. It is very important to be careful of the quality of water we use for this purpose.
Although manure is ideal for organic farming, we cannot always assume it is safe for use because it consists of faecal matter which may contain harmful bacteria. Measures to eliminate harmful bacteria in manure should therefore be practised. The Codex Alimentarius Commission standard for hygiene in production of fruits and vegetables recommends composting, pasteurization, heat drying, Ultra Violet irradiation, alkali digestion and sun drying.
However, many small-scale farmers do not have the capacity to employ these measures therefore they need to use alternative corrective measures which minimize the risk of microbial contaminants such as maximizing time between application and harvesting of fresh fruits and vegetables.
Another possible source of contamination may be the people handling the fruits and vegetables. For example, people may carry bacteria in their ears, noses and mouths and even on the skin. It is important for handlers of fruits and vegetables during and after harvesting to be hygienic by making sure they wash their hands before handling produce and preventing behaviour such as blowing their nose, sneezing into their hands or onto the produce and spitting in the handling area.
Protective clothing such as overalls which cover up skin, hairnets which prevent hair falling onto produce and masks which cover the mouth is advisable to minimize the risk of contamination. Handlers of fresh fruit and vegetables should be encouraged not to handle produce while they are suffering from illnesses such as diarrhoea, vomiting, colds and flu.
Harvesting, Handling, Packaging and Transport
Fresh fruit and vegetables unsuitable for human consumption should be removed during harvesting so they do not contaminate other fruits and vegetables. A good example is what happens with soft rot in tomatoes where an infected tomato will damage the whole batch if allowed to come into contact with other tomatoes.
Good practice to prevent the spread of disease is not only to remove visibly infected fruit but to also go further and wash the rest of the fruit in water with a very small amount of Jik (as per instructions on the bottle) and drying the fruit by spreading it out in one layer on drying racks which are clean and disinfected before packaging.
Containers previously used for potentially hazardous materials (e.g. rubbish of manure) and hazardous materials (chemicals) should not be used for holding fresh fruits and vegetables or have contact with packaging material.
Packaging material may come in the form of what is referred to as primary packaging, which is in direct contact with the fruit or vegetables (such as punnets or plastic bags), or secondary packaging which holds packaged produce and prevents it from being crushed and damaged.
Sometimes fruits and vegetables may be placed directly into wooden or plastic trays which normally serve as secondary packaging. Packaging is important to protect fruits and vegetables from being contaminated once they have been harvested and washed and while they are being transported.
An ideal scenario would be to package produce in both primary and secondary packaging then transporting them in covered refrigerated trucks to maintain their quality. However, this is not always economically viable particularly for small-scale farmers. In such cases contamination may be prevented by placing washed and drained produce in pallets which have been thoroughly cleaned and sanitized (by wiping down with a solution of Jik) and transporting the trays in covered (so produce does not get contaminated by, for example, polluted air or water splashes) but well ventilated trucks (which allow circulation of air).
Where possible, there should be a particular vehicle dedicated to transport of fresh fruits and vegetables so they do not get transported in vehicles that transport hazardous substances such as chemicals and rubbish. Transporters of fruits and vegetables should also avoid transporting people and other goods in the vehicle while transporting fresh produce as they may be contaminated.
Every Zimbabwean has a role to play in ensuring that the fresh fruit and vegetables we eat do not harm our health. The principles outlined above will be of assistance in achieving this goal as a nation.