Hygiene in food preparation
68
Basic Food Safety for Health Workers
KEY POINTS
l Application of general rules governing food hygiene can improve
food safety.
l WHO’s Ten Golden Rules for Safe Food Preparation summarize
the most important aspects of food hygiene.
l More detailed rules are required for mass catering than for
domestic food preparation.
l Hygiene rules govern physical, operational and personal factors.
l Health workers can play an important role in educating food
handlers in food hygiene.
l General rules suffer from a lack of specificity.
l Microbiological testing of food, while specific, is ineffective
as a routine tool for assuring food safety.
l Application of procedures that are both preventive and specific such as
HACCP are the most effective way of protecting food safety.
67
Hygiene in food preparation
other organisms that might indicate the oped. The most commonly implemented
presence of pathogens. This is a totally of these is known as the system of
unrealistic option for domestic and small- Hazard Analysis and Critical Control
scale food preparation and, while at first Point (HACCP).
sight appealing, it has been discredited HACCP involves the systematic evalua-
even for large-scale food production. It tion of a specific food processing or
is now almost universally recognized that preparation procedure to identify hazards
microbiological testing of food products associated with ingredients or the
on its own is an ineffective and expen- processing procedure itself and to find
sive way of trying to achieve an accept- out how those hazards can be control-
able level of food safety assurance. led. It then decides which steps in the
Microbiological testing can be very costly process are essential to controlling haz-
and only gives information after the ards so that attention can be focused on
event, when the problem has already them.
arisen. It may also give a false sense of While this system was first applied to
security since microorganisms will not be commercial food processing, it can also
spread uniformly throughout a food and be applied to any operation where food
samples taken may not show the pres- is handled or processed for consumption.
ence of pathogens even though the food It is also replacing traditional regulatory
is contaminated. Even when pathogens approaches. Many countries now recog-
are detected, this will not necessarily in- nize HACCP in their food safety regula-
dicate where the problem arose and how tions and their enforcement procedures
it can be solved. Without this informa- are being adapted to ensure that food in-
tion, the same problem is likely to recur dustries apply HACCP in a systematic
again and again. way.
A far better approach is to control micro- The full rigours of a HACCP system, as
biological quality at source, during pro- outlined in Appendix 3, are probably not
duction or preparation, so that safety is feasible or even necessary in households,
built into the product. Put simply, it is but the essence of the approach —
much better to prevent a problem from identifying hazards and the key steps that
arising than try to remedy the situation will ensure their control is useful both at
after it has. Food hygiene rules attempt the level of the household and more
to do this but lack the specificity required. generally in health education campaigns
To overcome this problem, new preventa- and courses.
tive approaches have had to be devel-
66
Basic Food Safety for Health Workers
leave the worker financially worse off as
it would then be a disincentive to the The Hazard
honest disclosure of any symptoms.
A person suffering from diarrhoea should Analysis and
not be allowed to handle open food. If
food is to be handled by a person with Critical Control
spots or infected cuts or skin lesions,
these should be covered with a water- Point (HACCP)
proof dressing.
system
It is not necessary for a food handler to
have an overt infection in order to pose
a threat to food safety. The asymptomatic Where general rules of good food
carriage of Staphylococcus aureus on the hygiene are followed, they establish a
skin, in the nasopharynx and hair folli- baseline of good practice in food
cles has already been described. Activi- preparation that can play an important
ties that encourage hand/mouth contact role in ensuring food safety. The strength
such as smoking or the chewing of gum, of such rules lies in their general
tobacco, betel nut or finger nails can also applicability, but this can also be a source
therefore lead to food contamination and of weakness. In attempting to cover all
must be avoided. The same also applies circumstances, some rules may seem
to the tasting of food during preparation. vague, or even irrelevant or unrealistic
Similarly, food handlers should not spit, in certain situations, and to some this can
sneeze or cough over food, or pick their appear to devalue the whole approach.
nose, ears or any other parts of their body. Individual food preparation activities,
both domestic and on a larger scale, have
Many of the basic rules of food hygiene their own characteristics: they do not all
are already observed as part of traditional
produce the same products, and they use
religious or cultural habits that go back
different raw materials, different
thousands of years, but the reasons for processes and different equipment. What
their importance in terms of food safety
food handlers really want is guidance on
are often not clearly understood. It is easy
food safety related to their own specific
for lapses to occur resulting in a threat to operations. Precisely how should they
food safety. Education of food handlers
store their raw materials? What are the
in basic food hygiene is important so that
most important areas to clean and when
rules are not seen as pointless irritants (sweeping a dusty floor, for instance, is
dreamed up by bureaucrats. If food
cleaning but it can actually increase
handlers understand the reasons for the
contamination of exposed food)? How
rules, this will encourage them to apply long should the food be cooked? In what
the rules rigorously and consistently. For
order should ingredients be added? These
the general population, basic food hygiene
and many other questions are often of
education can focus on WHO’s Ten golden great relevance to food safety and require
rules but more detailed training is required
specific answers.
for food handlers in mass catering. In this
educational process, the health worker One approach to checking the safety of
can play a significant role. This is one of particular foods would be to test them to
the issues addressed in Chapter 7. see if they contain specific pathogens or
65
Hygiene in food preparation
to ensure that all parts reach a tempera- in food is not just aesthetically objection-
ture of at least 70oC. Precooked foods able but may also be a source of patho-
should be stored outside the temperature gens.
danger zone of 10–60oC and those served
hot should be reheated to 70oC before
consumption.
Personal factors:
If frozen meat and poultry are not com- personal
hygiene and training
pletely defrosted before cooking, some
parts may not get hot enough to kill the
pathogens present.
As indicated in Chapter 3, the food
When dishes containing a mixture of handler can often be a major source of
cooked and raw ingredients are being contamination. There are several good
prepared, it is important to cool the hygienic practices that he or she should
cooked component before mixing with observe.
the other ingredients. Failure to do this
could lead to a temporary rise in tempera- Hands should be washed regularly with
ture during which microbial growth can soap in clean water, but especially before
occur. starting to handle food, after going to the
toilet or changing a baby, and after
The other major objective of hygienic handling raw food, food waste or
food handling is to avoid contamination, chemicals. In all these activities the hands
particularly of cooked or ready-to-eat may become contaminated with
foods. Physical measures such as the pathogens or toxic chemical residues that
exclusion of vermin from the premises can then be transferred to the food. It is
contribute to this, as do a number of easier to keep hands clean if finger nails
operational procedures such as keeping are kept short and jewellery such as rings
food covered as much as possible. are removed as dirt can become lodged
The liquid that accumulates during the under these and may be difficult to
defrosting of frozen meat is likely to remove.
contain pathogenic microorganisms. It Food handlers should avoid coughing into
must not be allowed to drip on other their hands or touching their hair, nose
foods stored below it and great care must or mouth while handling food without
be taken in disposing of it. Any washing their hands afterwards.
equipment or surfaces contaminated
during defrosting must be thoroughly Routine medical and microbiological ex-
cleaned and disinfected. amination of food handlers is not gener-
ally recommended but if food handlers
Cooked food should be kept well are suffering from an illness that includes
separated from raw food to reduce the symptoms such as jaundice, diarrhoea,
risk of cross-contamination. vomiting, fever, sore throat, skin rash or
Touching cooked foods with bare hands skin lesions such as boils or cuts, they
should be avoided wherever possible as should report this to their supervisor be-
even clean hands can carry pathogenic fore starting work. It may then be neces-
microorganisms. Ideally, hair should be sary for them to be assigned temporarily
covered or at the very least tied back to some other task which does not in-
when one is working in a kitchen. Hair volve handling food. This should not
64
Basic Food Safety for Health Workers
clean. In commercial food processing this confusion between poisonous substances
is overcome by using an antimicrobial and food materials. Rubbish and waste
agent (a disinfectant or sanitizer) as well should also be stored away from the food
as a detergent to clean food contact sur- preparation area.
faces. This can be expensive and unnec- The importance of not leaving food for
essary at the household level. Heat is the extended periods at temperatures in the
most effective antimicrobial agent and danger zone at which microbial growth
thorough washing with hot water (more can occur has been referred to earlier. The
than 80oC), perhaps with a small amount equipment used to cool food is of
of detergent, will clean a surface and kill obvious importance here. For example,
those microorganisms that are not easily shallow trays allow faster cooling of
removed (Figure 5.1). Frequent cleaning foods and are preferable to deeper
is also important since dried and en- containers. Cold storage equipment
crusted residues are much harder to re- should be well maintained and checked
move. regularly to ensure it operates at the
Cloths used for cleaning can rapidly ac- correct temperature. If cold storage
cumulate a large population of microor- equipment is overloaded this will slow
ganisms, particularly when left moist, and down the cooling process and the food
their use can actually increase contami- will spend longer in the temperature
nation rather than reduce it. They should danger zone.
therefore be changed every day and Similarly, cooking equipment should be
boiled before re-use. adequate for its intended use, well
We have already seen how raw foods can maintained and checked regularly to
act as a source of pathogens. It is confirm that it is functioning correctly.
important, therefore, that the layout of To allow good personal hygiene, the
the premises and equipment should allow premises must have adequate and
foods to be stored and handled without hygienic toilet facilities separated from
contact between raw and cooked prod- the food production area, as well as
ucts, either directly or via equipment. adequate hand-washing facilities.
The food should also be protected from
Operational factors:
other sources of contamination such as
soil, insects, rodents and other animals
hygienic handling
(wild or domesticated). For this reason,
food should not be placed on or near the
ground in open containers. As far as
possible, the premises should be of food
protected to prevent pests entering. This
is sometimes very difficult in the A large part of the hygienic handling of
foods relates to the correct use of
household so storing foods in tightly
sealed containers is an effective second temperature in the control of
line of defence. microorganisms — avoiding
temperatures where microbial growth is
Facilities should also be available for possible and, where appropriate, ensuring
storing dangerous or toxic substances that temperatures are sufficiently high to
such as disinfectants and insecticides kill microorganisms. For example,
outside the kitchen area in a clearly perishable foods should normally be
marked location. This will minimize the stored refrigerated at <10oC. Food that
risk of accidents occurring as a result of are cooked should be cooked thoroughly
63
Hygiene in food preparation
Figure 6.1 Principle components of food hygiene
Physical factors: A first requirement is that the working
environment should be well lit, well ven-
premises and tilated and tidy as this will encourage
good working practices and promote food
equipment safety. The working environment should
also be clean and easy to clean. Microor-
Ideally, food preparation premises should ganisms can grow on any scrap or parti-
be purpose built and sited in an area that cle of food remaining on food contact
is free from objectionable odours, smoke surfaces or lodged in some crack or crev-
and dust, is located away from rubbish ice and this can act as a source of con-
tips, and is not prone to events such as tamination. While most microorganisms
flooding. In practice one usually has a will be associated with food particles that
more limited choice about the building can be removed by thorough physical
to be used and its location, but it should cleaning, it should be remembered that a
be of sound construction and well surface may appear physically clean al-
maintained. though it may not be microbiologically
62
Basic Food Safety for Health Workers
Chapter 6
Hygiene
in food
preparation
Chapter 3 describes the principal sources work, in hospitals and educational
of food contamination and these are establishments, at social gatherings and so
mentioned again in the discussion of the on. The scale of mass catering means that
safety of particular food commodities in breakdowns in good hygienic practices can
Chapter 4. Clearly it is important to be have far more serious consequences in
aware of specific problems associated terms of the number of people affected
with certain foods. However, in many and, sadly, events involving mass catering
cases, food safety can be enhanced by a often feature prominently in many national
number of general measures, regardless statistics on outbreaks of foodborne
of the food materials being handled. The illness. For these reasons a more extended
most important of these have been for- list of food hygiene requirements directed
mulated by WHO as a set of Ten golden at mass catering is given here. The reader
rules for safe food preparation. These are pre- is also referred to other WHO publications
sented in Appendix 2. These give guid- dealing specifically with this topic. (See
ance to the general population on the bibliography) Many of the rules apply to
essential principles of safe food prepara- food preparation at all levels, though some
tion. are excessive and inappropriate to food
preparation in the home. Some instances
Though the Ten golden rules apply equally of this are highlighted.
to all food preparation activities, catering
on a larger scale is a more complex
operation than preparing food for the Rules of good hygienic practices in food
immediate family and requires more preparation deal broadly with three dif-
detailed rules. It involves preparing larger ferent areas: physical factors relating to
quantities of food for more people mainly the premises and equipment used, opera-
using paid employees, special premises and tional factors relating to the hygienic han-
equipment. It is also becoming increasingly dling of food, and personal factors relat-
important as more people eat food that ing to questions of personal hygiene and
has been prepared outside the home, at training (Figure 6.1).
61