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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 of
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 the prob-
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 aggra-
To summarise, three types of dirt can be identified as being present in the process of preparation and service in the kitchen:

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 followed
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 the staff.

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 to occur.


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 residues.

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, amino-acids etc.

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 occur later.

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 sometimes not
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 oxygen.

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 in distinctly alkaline environments (pH 11) and others in acidic environments (pH13).

F Humidity - Without doubt this is one of the main factors affecting the growth of bacteria. High humidity generally favours bacterial growth, this is why correct humidity levels are so important in fridges and coldrooms.
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