Package 1 - What are the potential hazards in fruits & vegetables?

1) Water/ Agriculture water (for growing the vegetables)

Water of inadequate quality has the potential to be a direct source of contamination and a vehicle for spreading localized contamination in the field, facility, or transportation environments. Wherever water comes in contact with fresh produce such as vegetables, its quality dictates the potential for pathogen contamination. If pathogens survive on the produce, they may cause foodborne illness.

Water can be a carrier of many microorganisms including pathogenic strains of Escherichia coli, Salmonella spp., Vibrio cholerae, Shigella spp., Cryptosporidium parvum, Giardia lamblia, Cyclospora cayetanensis, Toxiplasma gondii, and the Norwalk and hepatitis A viruses. Even small amounts of contamination with some of these organisms can result in foodborne illness.

Agricultural water quality will vary, particularly surface waters that may be subject to intermittent, temporary contamination, such as waste-water discharge or polluted runoff from upstream livestock operations.

*Factors to consider/take note:
- Identify the source and distribution of water used and be aware of its relative potential for
being a source of pathogens.
- Maintain wells in good working condition
- Review existing practices and conditions to identify potential sources of contamination.
- Be aware of current and historical use of land.
- Consider practices that will protect water quality.
- Consider irrigation water quality and use.

2) Anti-microbial chemicals

Anti-microbial chemicals are usually added in processing water (water used during the post-harvest handling of fruits and vegetables). The effectiveness of an anti-microbial agent depends on its chemical and physical state, treatment conditions (such as water temperature, acidity [pH], and contact time), resistance of pathogens, and the nature of the fruit or vegetable surface. Example of anti-microbial agents:

Chlorine
Commonly added to water at 50 - 200 ppm total chlorine, at a pH of 6.0 - 7.5, for post-harvest treatments of fresh produce, with a contact time of 1 - 2 minutes.

Ozone
Used to sanitize wash and flume water in packinghouse operations. Ultraviolet radiation may also be used to disinfect processing water.

Quoted from: http://www.foodsafety.gov/~dms/prodguid.html

All chemical substances used, which is in direct/indirect contact with foods must be in accordance with the local authorities (AVA – in Singapore, FDA- in USA). Anti-microbial chemical levels should also be routinely monitored and recorded to ensure that they are maintained at appropriate concentrations. Washing of vegetables & fruits (before packing) with some anti-microbial chemicals needs to be followed by a clean water rinse to remove any treatment residues.

3) Pesticides

Pesticides are use to prevent pests from growing in vegetables farms. However, pesticides also contain chemicals that can be harmful to human’s health if the amount of pesticides used is over-concentrated or vegetable surfaces are not thoroughly washed where residues of pesticides are still present. Therefore, it is important that vegetables are thoroughly washed clean before they are being packed.