In Summary
- Food business must ensure that personnel and visitors do not contaminate fresh produce, by implementing appropriate procedures, including hygiene codes.
- Personnel should be appropriately trained in their specific roles and responsibilities for hygiene during fresh produce production.
- Validation of handwashing standards is recommended.
- Studies have found that the lowest bacterial transfers were achieved when workers washed and dried their hands, put on gloves, and then sanitised the gloved hands.
Personal Hygiene and the Role of Training
Businesses should aim to minimise the risk that personnel or visitors contaminate fresh produce by direct contact. Informing staff and visitors about the risks of cross contamination through training, signing in sheets and clear signs, lets them know what is expected from them. It is important to check periodically that any such procedures are being applied. The expectations for personal hygiene are often common sense, but businesses may be unclear as to the degree of detail that should be covered. There is a small amount of research in this area which focusses mainly on the persistence of human pathogens on the surfaces of hands and produce after cleaning and sanitation. Clear guidance on expectations of good hygiene is given by the Codex Alimentarius Commission (CAC). CAC functions worldwide under the FAO/WHO Food Standards Programme for all foods including fresh produce.
There are two codes of practice that cover fresh produce and personal hygiene standards:
- Recommended International Code of Practice - General Principles of Food Hygiene (CAC/RCP 1-1969, Rev. 4-2003) (CAC, 2003b) - which covers all food.
- The Code of Hygienic Practice for Fresh Fruits and Vegetables (CAC/RCP 53-2003) (CAC, 2003a) - with particular attention paid to general hygienic practices for the primary production and packing of fresh fruits and vegetables (particularly for those intended to be consumed raw).
The following are recommended by CAC:
Workers known or suspected of being ill with a food transmissible illness should be kept out of food handling areas (for an undefined time). There is an expectation that workers should report illness to management – although no system is suggested to implement this approach.
Workers who directly handle fresh produce should have a high degree of personal cleanliness. Hands should be washed before handling fresh produce, after breaks, after using the toilet and after handling a potential contaminant (see advice below). Suitable, appropriate, protective clothing should be worn and any cuts should be covered with waterproof dressings. It is a good practice that when wound coverings are used by workers in direct contact with fresh produce, that the issue of the dressings are recorded and then checked at end of production.
Behaviour that poses a risk of contaminating fresh produce, and that should be stopped, is described – smoking, spitting, chewing gum, eating, sneezing and coughing. In addition, it is advised that personal effects such as jewellery and watches should be kept out of production areas.
Training
The General Principles of Food Hygiene (CAC, 2003b) requires that all workers should be aware (after training) of their roles and responsibilities for hygiene during fresh produce production. The level of training required should be based on the workers’ role in processes that affect the risks associated with pathogen contamination, potential for post contamination growth, and any further processing.
Codex also provides a list of topics that should be covered when training staff, those suggested includes:
- personal health and hygiene
- hand washing
- use of toilet facilities.
- fresh produce handling
The effectiveness of training should be assessed, and periodic refresher training should be used to maintain an awareness of hygiene issues.
More detail on implementing personal hygiene standards can be found in the Red Tractor Fresh Produce Standard.
The importance of effective handwashing in the control of cross-contamination is described in the below example (Monaghan and Hutchison, 2016).
If the fingers of an unwashed human hand are pressed into a non-selective agar plate which supports the growth of microorganisms, and the plate is incubated at 25oC for 48 hours then typically, results similar to the picture shown below are observed.
Unwashed human hands harbour a wide variety of surface microorganisms. Some of these organisms could be human pathogens with the potential to cause an outbreak of foodborne illness.
In order to reduce as much as possible a worker's hands transferring contamination to food; it is necessary to wash the hands of workers who touch food as frequently as possible.
If only water is used when washing hands, a small and insignificant reduction in the numbers of microorganisms on the skin surface is typically observed as shown in the picture on the left.
Washing hands in plain tap water is not a very effective way of controlling skin surface microorganisms in food processing establishments.
The benefits of using liquid soap and water are shown in the picture below.
Compared with an unwashed hand there is a significant reduction in skin-surface microorganisms when washing in soapy water.
Soaps are detergents and they tend to act by removing the oil from the surface of human skin that microorganisms live in. In addition, soap can directly dissolve the membranes that form the outer layer of some bacteria directly causing their deaths.
In the picture on the left, the areas occupied by the white bacteria have diminished compared with the pictures above indicating that soap has reduced the viability of the white bacteria.
In contrast, the reddish coloured microorganisms appear largely unaffected by the soap.
When an alcohol gel is used to sanitise a hand after washing in soapy water, it is difficult to recover many microorganisms from the skin surface.
In combination, hands properly and frequently washed in soapy water which are then sanitised with an alcohol gel can adequately control the contamination of foods from the hands of workers (Monaghan and Hutchison, 2016).
The validation of hand washing
It is straightforward for food business operators to validate a hand or glove washing procedure. NB: where re usable gloves are used (not disposables), workers hands should be washed fully prior to putting gloves on and then gloves fully washed. In many companies, effective washing is undertaken as part of an employee's training. The validation process can be as simple as the one depicted above where an employee’s hands are tested by pressing into agar plates before and after washing and sanitation. The process is repeated until the employee is able to wash their hands to remove all or the majority of contamination from them. Alternatively, the actual counts from hands can be quantified if hands are swabbed with a diluent-soaked swab. Counting bacterial numbers is more precise and obtains a more representative result than pressing hands onto agar. This is because the swab can be used to sample in difficult to clean areas of the hand such as the webbing in-between fingers and underneath fingernails. If bacterial numbers are known, statistical processes can be used to determine if significant reductions in bacterial numbers have been achieved. General information on comparing reductions in bacterial numbers using statistical methods is available on the help page dealing with the validation of sanitisers.
The use of gloves, alcohol gels and the importance of drying hands
Montville et al (2001) investigated the use of gloves versus bare hands for the transfer of bacteria to lettuce and back onto hands. The study demonstrated that low levels of bacteria can pass from food through gloves to hands and from hands through gloves to food. The findings are in broad agreement with much of the established literature that indicated a glove may not be a complete barrier to microorganisms. Thus, effective hand hygiene prior to putting on gloves is critical. A 0.01% transfer was observed from food to hands and from hands to food when subjects wore gloves, and a 10% transfer was observed without a glove barrier. Consequently, a general conclusion of the work was that gloves may reduce both bacterial transfer from food to the hands of foodservice workers and in subsequent transfer from hands back to food.
Todd et al (2010) reviewed the effectiveness of hand washing procedures with an emphasis on sanitising chemicals and alcohol gels. In summary, alcohol gel is effective against Gram-negative bacteria if there is light soil on hands. The majority of human bacterial pathogens associated with fresh produce are Gram-negative, with the only notable exception being Gram-positive Listeria monocytogenes. However, if there was more than a light soiling of the hands, then alcohol gel and other sanitising chemicals were concluded to be not particularly effective. Antimicrobial soaps were as good or better than alcohol gel when hands were more heavily contaminated. Instant sanitisers had no remaining effect, unlike some antimicrobial soaps that retained antimicrobial activity after the hygienic action had been completed, e.g. after hand washing. The review discussed the role of wipes, which are widely used for the quick clean-up of hands in places where there is no water available. Antiseptic wipes are not a solution for every situation and are not effective in the presence of more than a light soil load or against most enteric viruses. A later study by de Aceituno et al., (2016) also concluded that hand washing using soap and water was more effective than alcohol gel at removing soil from harvesting worker's hands but concluded that washing was not particularly effective at reducing bacterial numbers on hands. de Aceituno et al., (2016) noted there were benefits for using alcohol gels in places where water for handwashing was unavailable.
References
CAC, 2003b. Code of Hygienic Practice for Fresh Fruits and Vegetables (CAC/RCP 53-2003).
