|Commercial Kitchen Planning Hygiene
| Hygiene aspects
The aspect of hygiene is surely the most delicate to face
in that, as already stated, the kitchen is a true and proper
laboratory where the oper ation of transforming food into
dishes to be served is strictly connected to the manual
activities of the employees.
The kitchen, as a laboratory for the preparation and transformation
of food, must be very diligent and careful to adhere to
strict hygiene regu lations. The problem is, that often
such rules are not known by all the employees, or can be
interpreted in different ways by the person dele gated to
make sure that these rules are adhered to. A banal example
one of these rules is the following: the separation in cold
rooms of fruit and vegetables from cold cuts and cooked
foods from raw foods etc.
However, many restaurants do not utilise any of these criteria
in the con- 11 servation of food, the only rule followed
is the one of “where there is
In reality, the problem is very serious. There are many
areas in the kitchen where dirt can easily build up and
the same cleaning methods for all these areas is often insufficient
to guarantee correct hygiene and sterili sation. The washing
of crockery is often carried out negligently and sited in
areas where the proliferation of and the contamination by
bacteria is facilitated.
However, often, the primary problems arise from employees
who can be possible sources of dangerous contamination from
outside. It is hard to imagine the amount of micro-organisms
which can be brought into the kitchen on the clothes especially
when changing rooms or exits and entrances are not suitably
positioned, or people are required to use the same corridors
used by wait- ers or chefs in service.
But, even if personal hygiene is often down to the diligence
and atten tiveness of employees, that of the equipment and
the kitchen itself is not, yet it is necessary and indispensable.
Consequently, the problems, first seen, of space, functionality
and labour, (it can happen that an employee, due to lack
of space and the necessity for speed, may not clean a work
table and starts preparing or even cut ting products already
cooked, with disastrous results), have a more or less equal
effect on the accumulation of dirt in the kitchen and on
lems derived from it.
Dangerous sources of bacteria proliferation are located
in the most inac cessible, often neglected, areas of the
kitchen, (e.g. under tables, under fridges or the cooking
block), or hidden areas such as the join between two tables,
between two machines, where dirt can enter and accumulate.
The equipment can often limit cleaning even more, by being
too near the floor, too cumbersome or difficult to move,
therefore not allowing a thor ough cleaning of the environment.
Often, however, human reticence adds itself to the equation
and aggra vates the situation. Poor stocking, superficial
cleaning of pantries and col drooms, the keeping of cooked
and raw food together and maybe even one above the other
in the same fridge without separators, the conserva tion
of meat and fish together, are only some examples of other
To summarise, three types of dirt can be identified as being
present in the process of preparation and service in the
| 1. Environmental contamination
2. Food residues
12 3. Bacteria proliferation
Environmental contamination: under this heading can be
grouped all the types of pollution derived from operations
carried out in
unhygienic environments and/or by personnel that have not
regulations. The main contaminating agents are as follows:
• Colon bacteria
• Yeast and mould
• Streptococcus salivanius-mitis
The main areas of risk are presented by:
• Poor levels of cleaning.
• Lack of physical separators for cooked and raw foods,
as well as other foods.
• Conservation in unsuitable and/or unclean containers.
• Lack of knowledge of the problems on the part of
| Food residues: under this heading the possibilities of
contamination from work residues, be it on the worktop or
employees themselves, can be
considered. A single contact is all it takes for contamination
Bacteria proliferation: this subject area
is vast and merits an exten sive study all to itself, however
for our purposes it is sufficient to understand the factors
of growth and risk, as well as the important links with
the cool ing of food once it is cooked.
A Time - This has a very important role, bacteria proliferation
substantial ly functions exponentially, as can be seen in
the diagram below, which shows the importance of the rapid
elimination of possible pollutants and in particular food
B Availability of mediums for growth - The substances
needed for bac terial growth differ from bacteria to bacteria
and can range simply from the presence of water, oxygen,
carbon dioxide, to the necessity for nitro gen, energy,
C Temperature - Amongst the different factors effecting
the growth and development of bacteria, temperature is without
doubt one of the most important.
Most bacterial species grow and multiply in the range of
temperature from 15°C to 40°C. Such germs are called
mesophile and the optimum tem perature for this species
is 35°C to 40°C.
At this optimum temperature these micro-organisms have a
short term “lag phase” and “generation
time”, whilst the logarithmic development phase 13
takes place quickly, in some cases in the brief space of
25-30 minutes from the point of contamination.
As a result of this behaviour, at an optimum temperature,
the number of mesophile can increase notably in only a few
hours. On the other hand at a non-optimum temperature there
is a “lag phase”, a “generation time”
and a “lag growth phase” that last longer and
Every single strain of bacteria has a maximum and a minimum
temperature, above or below which it will not develop. Therefore,
in the chilling and con servation of food, it is of key
importance to pass through this proliferation stage as quickly
as possible. To achieve this, it is necessary to have equip
ment and devices that are not present in many kitchens and
even considered as necessary. (These important but relatively
unknown appliances and devices will be discussed later in
more depth in the pre sentation of the new blast chillers).
D Oxygen - Micro organisms can generally be divided into
two groups depending on whether or not they need oxygen
for development. Anaerobic micro-organisms such as clostridium
can grow and develop in the absence of oxygen (for example
in canned goods) whereas aerobic micro-organisms require
here is however, also a third group of bacteria which can
grow in the presence or absence of oxygen. This group includes
species like staphy lococcus and coliform bacteria.
Temperature of bacteria development
| E Acidity - Most bacteria have an optimum
pH value for development on
a neutral culture. However, some types of bacteria can develop
alkaline environments (pH 11) and others in acidic environments
|F Humidity - Without doubt this is one of the main factors
growth of bacteria. High humidity generally favours bacterial
is why correct humidity levels are so important in fridges
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