Background
Catering
systems are complex sociotechnical organizations involving both people and
machinery in the production and service of food. Such systems have the key
purpose of transforming a diverse combination of ‘inputs’ into desired
‘outputs.’ Systems need to maximize their interdependence with the environment
within which they exist. The objective for the management of any system is to
find ways of ensuring its long-term survival and growth, often by seeking gains
in efficiency and effectiveness in producing its outputs. Different types of
catering systems have evolved in recent years as a result of efforts to achieve
these goals. These developments have brought with them further technological
challenges related to the provision of safe, nutritious, quality food products.
Emergence of Catering Systems
It has been noted that the ‘systems’ approach to management involves viewing organizations ‘holistically’ in order to gain a better insight into these complex situations, rather than merely focusing on individual parts or problems. Systems theory has been applied to a wide range of organizational contexts and has proven valuable in solving problems particularly where the situation is unpredictable and issues causing concern are ill defined or vague. It has been suggested that ‘systems’ terminology was first applied to food production and service operations during the 1950s. The terms ‘catering systems,’ in common use in the UK, and ‘food service system,’ more frequently used in the USA, can be said to have been coined as a result of the ‘systems approach’ being applied to those operations that undertook the production of food and its service to consumers.
A simple
definition of the term ‘catering system’ that has been proposed is that it
refers to ‘a particular method of organizing the production and service of
food.’ It is contended that the application of a systems approach involves
defining and describing food production and service operations using
‘systems concepts.’ This enables the
component parts, or subsystems, of an operation to be identified and the
efficiency of their interaction assessed. Undertaking such a ‘systems analysis’
facilitates the application of ‘problem-solving’ methodologies, which can
generate design solutions for the optimization of system performance.
Utilization of these techniques, and awareness of the nature of organizations
as being complex groups of ‘subsystems’ that need to be monitored and modified
according to how efficiently they fulfil their specified objectives, can hence
be referred to as ‘systems management.’
Catering
systems may be described as systems that have objectives relating to the
production and/or service of food products to specified groups of consumers.
Such systems normally receive a combination of inputs, which include:
1. fully,
part, or unprocessed food items;
2. adequate
numbers of appropriately skilled people;
3.
sufficient equipment and machinery;
4. any
necessary financing.
The inputs
form the components of a complex set of ‘subsystems’ that act to produce outputs
required by the environment within which the system exists. The activity of the
subsystems must be ‘managed’ effectively to ensure that they exhibit unity of
purpose and exploit potential synergies within the system. The broad aim of any
system is to fulfill demand for its outputs with maximum efficiency on a
continuous basis. Through effective management that takes account of feedback
from the market and environment, and also of ‘feed-forward’ from the manager’s
knowledge and experience of similar operations, the system’s continued
existence and growth are ensured.
Different
views have been put forward by management and systems theorists over the years
about the most important focus for managers of sociotechnical systems. In
essence, these contentions may be summarized as follows:
The
long-term survival of a system will depend on how well it ‘interacts’ with its
environment, that is to say, how efficiently it acquires appropriate inputs and
how ideally the output it produces match the current and potential demands of
the environment. The efficiency with which a system works, and therefore
thrives, will depend on ensuring that its subsystems work harmoniously towards
common goals that contribute to, and are congruent with, the objective/s of the
organization. Catering systems, therefore, have been defined either in terms of
the markets that they serve, that is against the context of their environment,
or in terms of the differentiation in their internal processes or subsystems.
There follows a brief summary of the classifications that can be applied to
catering systems in relation to these perspectives.
Catering Systems Defined in Terms of Their
External Environment
Catering organizations, as with all ‘systems,’ interact with their environment. In an ideal world, a catering system will produce the exact outputs the ‘environment’ demands in terms of both quantitative and qualitative requirements. A key task in managing such systems involves matching systems output to the requirements of the environment in such a way as to maximize the systems potential to do work. Thus, catering systems have typically been classified in terms of the sector of the environment they serve. The two major sectors into which catering systems are divided are the ‘Cost Sector,’ which, broadly speaking, incorporates all not-for-profit catering activities, and the ‘Profit Sector,’ which includes all profit-orientated organizations.
The ‘Cost
Sector’ typically includes all catering systems in the following subsectors:
1. Healthcare, e.g., hospitals;
2. Education, e.g., schools and colleges;
3. Business and Industry, e.g., staff-feeding
operations;
4. Public Services, e.g., the police and armed
services.
In 1996,
the value of purchases (which equate with sales) in this sector, in the UK, was
almost £1.5 billion, ‘Healthcare’, ‘Education,’ and ‘Business and Industry’
sectors each having similar values of £460–475 million. The ‘Profit Sector’
includes catering systems in the subsectors listed below:
1. Hotels;
2. Restaurants;
3. Fast Food;
4. Cafes and Takeaways;
5. Public Houses;
6. Travel Organizations (e.g., on-board
and in-flight catering);
7. Leisure Operations.
In 1996,
the value of purchases in the profit sector was over £6 billion, and sales were
in excess of £18 billion. The Hotel sector alone accounted for £4.7 billion
sales, with Public Houses being the second largest subsector having sales just
less than £4 billion. These figures serve to confirm the economic importance of
catering systems to the UK economy, which reflects a global pattern in the
developed world.
Catering Systems Defined by Their Subsystemic
Differentiation
Catering
systems may be defined in terms of the differences in the subsystems they
contain. Subsystems can be defined in many ways, depending on the analysis
being undertaken. In the example of ‘process subsystems’ alone, the possible
permutations that can be identified mean that there are potentially innumerable
variations in operational systems. Attempts have been made to resolve these
variations into viable ‘generic’ groups. There are essentially three major
classifications of catering systems into which the minor ‘generic’ variations
may all be fitted. These can be summarized as follows:
‘Cook–serve’/Integratedfood-servicesystems,where
both the preparation of food and its service are an integral function carried
out in a single operation, and there is little delay between preparation and
food service. The majority of the catering industry still operates conventional
systems of this kind. Food-manufacturing systems, where the production of food
and meals is separated or ‘decoupled’ from the service of meals. Such systems
encompass the use of chilling and freezing methods to preserve the food and in
the past have been referred to as ‘technological catering systems.’
Meals-assembly/food-delivery systems, a recent systems development, in which
little or no actual food preparation takes place in the system and the
operation focuses on the assembly, regeneration, and service of meal.
Cook–Serve Catering Systems
The
cook–serve or integrated catering system represents the conventional approach
to catering. These systems operate over a short time scale with the minimum
feasible period or ‘time buffer’ between cooking and food service. Where food
is cooked to order, or produced in small batches to suit expected demand, it is
quite easy to minimize the ‘time buffer,’ but this can be more difficult where
food is made in bulk quantities for large numbers such as in institutional food
services. The period, over which food is held hot, which, according to UK
legislation, must be at a temperature above 63 oC, is largely dictated by the
logistics of serving individual customers in each situation.
In
cook–serve systems, should food need to be held hot for any appreciable period,
time- and temperature- dependent changes occur that reduce both the sensory and
nutritional properties of food. Adverse sensory changes can affect the color,
texture, and flavor of foods. Losses in heat-labile vitamins such as thiamin
and vitamin C also occur. In research, the loss of vitamin C (as measured using
the ‘Fluorimetric method’) has frequently been used as an indicator of food
quality, as its destruction is time- and temperature-dependent and is
accompanied by losses in sensory qualities.
Extended
cooking times and hot holding period cause substantial losses not only in
cook–serve systems but also in the other systems discussed. It can be imputed
that cook–serve systems in many areas of catering have their limitations. This
is particularly the case in large-scale institutional catering such as in the
healthcare sector. Large hospital food service operations formerly using
traditional cook–serve methods and experiencing associated quality problems
owing to extended hot holding before service, have been at the forefront of the
change to food-manufacturing and delivery systems.
Food-manufacturing Systems
Food-manufacturing
systems avoid prolonged hot holding of foods as they incorporate a substantial
‘time buffer’ between cooking and food service. This is achieved by chilling or
freezing the prepared meals followed by appropriate storage. In this case, a ‘time
buffer’ is effectively used to ‘decouple’ the production subsystems of the
operation from food assembly and service.
In
food-manufacturing systems, food items are prepared in quantity in a large
kitchen or centralized production unit, then chilled or frozen usually in
multiportion packs, in effect preserving food until required. Products can be
regenerated in the required amounts in a satellite kitchen, or using
specialized reheating equipment close to the point of service (e.g., in large
institutional operations) or within individual units (e.g., in an aeroplane’s
galley kitchen in in-flight catering). This approach minimizes the time food is
actually hot-held as it should take only the time required to serve food to
customers immediately after regeneration, which will minimize potential
deterioration.
Meals-assembly/Food-delivery Systems
Food-delivery
systems take the concept of ‘decoupling’ to a logical conclusion in that the
manufacturing subsystems are completely removed. Food products are ‘bought in’
from specialist manufacturers producing frozen menu items for assembly and
regeneration in simple kitchens consisting essentially of reheating equipment,
or close to the consumer using specially designed heated trolleys. These
catering systems, which do not require the traditional kitchen, may be referred
to more aptly as ‘meals assembly systems’ as they only consist of the storage,
assembly, regeneration, and service subsystems.
The length
of the ‘time buffer’ in these systems is determined by the preservation
technique used, being up to 5 days for standard chilled foods and a year for
frozen foods. Thus, the time buffer decouples production from service and
potentially preserves food quality. This potential can be lost if the food is
subjected to another period of hot holding after regeneration. UK guidelines
recommend that it should take no longer than 15 min for meals to be served
after regeneration is complete. Whilst the food-manufacturing approach aims to
improve efficiency by decoupling the major subsystems, ‘meals assembly’
actually simplifies a catering system by removing the preparation and cooking
subsystems completely. This allows the caterer to focus on food service and the
monitoring of food safety and quality.
Preservation Methods in Food-manufacturing and
Meals-assembly Catering Systems
Cook–Freeze
Freezing is
a reliable method of preservation as it includes the barrier of the latent heat
plateau seen in any time/temperature graph during the thawing of frozen food.
This phase change provides a safety factor against temperature abuse, although
any partially thawed foods at the surface could potentially cause food-safety
and sensory problems. A variation of this is the cook–freeze–thaw system
introduced because, once thawed, the food can be treated as for cook–chill.
However, the system can be potentially hazardous unless the temperatures are
tightly controlled.
Cook–Chill
Cook–chill
systems have gained acceptance through consumer preference for minimally
processed foods. These are, however, more susceptible to temperature abuse in
only having a small barrier to temperature change. Precise temperature control
is necessary throughout the whole system.
Sous Vide
Sous vide
is a specialist form of cook–chill system in which product shelf-life is
extended from the normal 5 days up to as long as 42 days. Sous vide cooking is
semicontinuous when operated on a large scale but discontinuous in smaller
operations. There are particular concerns that all systems employing this
method must have appropriate technical expertise to ensure that all the
processing equipment and operating procedures are adequately designed so that
products receive sufficient heat treatment.
Questions
about food safety and quality in sous vide operations have been raised. Food is
cooked in sealed plastic bags under a partial vacuum, which slows the rate of
heat transfer and could result in underprocessing. This has led to concerns
that psychrotrophic pathogens, such as Listeria monocytogenes, Yersinia
enterocolitica, Clostridium botulinum, and the like could survive. The most
hazardous of these is Clostridium botulinum, some strains of which produce a
toxin at temperatures as low as 3.3 oC. Although the vegetative cells of
Clostridium botulinum are destroyed by heat treatment of not less than 70 oC
for 2 min at the coldest spot, foods should be heated to 90 oC for 10 min to
ensure destruction of spores.
Concerns
about the safety of vacuum-packaged and modified atmosphere-packaged products
have led the Advisory Committee on the Microbiological Safety of Food in the UK
to issue a Code of Practice that recommends the use of additional hurdles and
the application of the HACCP technique in the manufacture of all such products.
The retention of most of the original juices within the package after cooking
has led to claims that sous vide processed foods have enhanced sensory
qualities. This claim has not been fully supported by research findings to
date.
Further Developments in Cook–Chill
As there is
doubt that chilled storage alone can assure the safety of sous vide products,
recent work has focused on the formulation of products with additional hurdles.
This involves the combination of several factors together, which collectively
ensure the microbial safety of food, even though each hurdle on its own might
be insufficient to maintain safe food. Examples of hurdles are low water
activity, low pH, use of modified atmospheres, irradiation, added organic acids
and protective cultures. The incorporation of such adjuncts provides hurdles to
microbial growth and can also impact positively on safety, nutritional, and
sensory aspects. Research indicates that cook–chill produces a product that is
inferior in sensory qualities to that produced in cook–serve systems in ideal
conditions, but better than that produced in the nonideal or abused situations
often found in catering systems.
Meals-Assembly Techniques
In this
type of system, menu items are prepared and processed by food manufacturers to
a specification prepared by a caterer. Typically, these menu items will include
main courses, vegetables, and puddings, plus accompaniments such as sauces. The
meals are chilled or frozen, and packaged in bulk foil containers suitable for
use in commercial catering operations. After delivery to the catering unit,
food is stored appropriately until requisitioned. Meals are then assembled,
regenerated usually using forced-air convection ovens, and served. Meals
assembly represents a radical change in catering systems. By the year 2000,
such systems were being used by almost a fifth of UK NHS hospitals as well
being more widely adopted within the profit sector, particularly by pub and
fast-food operations.
This type
of system has proven popular in healthcare catering, because it offers cost
savings by reducing the need for skilled labor and expensive plant and
equipment. The meals-assembly system allows the catering manager to concentrate
on food-service techniques and monitoring methods, in particular to control
time and temperature factors. A quality-management approach is essential for
both the manager’s own operation and for their suppliers, the food
manufacturers. The final quality of food produced using these new systems is
governed by the control of time–temperature parameters throughout the system.
Potentially, regeneration is the stage that can affect food quality most
adversely, as primary cooking is common to all.
Regeneration
In a
meals-assembly system, regeneration usually involves a standard reheat cycle in
which a mixed load of chilled or frozen meals is regenerated in a specially
designed oven. This means that food can be under- or over-heated as different
foods have different thermal characteristics. Owing to food-safety concerns
food, is often effectively overheated, with core food temperatures at the end
of regeneration in excess of 80 oC being usual. The time spent at this
temperature level is particularly detrimental to food quality, causing both
heat-labile vitamin losses and sensory losses. There is often potential to
reduce the severity of the regeneration process whilst still maintaining
safety, yet preserving sensory and nutritional quality, but reliable control
and monitoring methods are vital.
Various
types of equipment can be used for regenerating assembled meals, the most
common currently being forced-air convection ovens. Forced-air convection
technology gives a fast regeneration time owing to constant air velocity and
even temperature distribution. Hot-air convection currents being forced to
circulate the oven cavity by a fan achieve this. These currents remove the
steam layer from the surface of the food quickly and enable heat to reach the
food directly, thus causing a rapid rise in temperature. The heating effect can
be enhanced further by the incorporation of steam injection into the oven
cavity. The latent heating effect of condensing steam on the surface of the
food package promotes faster reheating.
The use of
microwaves in regeneration is less common but can be successfully combined with
forced-air convection technology. Microwaves alone are better for reheating
chilled, rather than frozen, foods because of the different absorbency of
microwaves by ice and water, which can cause thermal runaway, leading to hot
spots and cold spots in the product. This can still occur in chilled products
because of different dielectric properties in foods of varying compositions.
The newer systems of food manufacture and food delivery require strict control
throughout heat processing to ensure food safety and maintain consistent
quality. New approaches to equipment design include the application of
computational fluid dynamics and the use of model-based control design.
Food-safety Issues in Catering Systems
Temperature
control in catering systems is imperative, and monitoring systems have
consequently been developed in recent years. Larger units can have
computer-controlled temperature-monitoring devices, whereas smaller operators
generally rely on making manual checks and keeping manual records. Failure to
control time and temperature remains a problem responsible for the majority of
foodpoisoning cases caused by the catering industry. In the UK, there is a mandatory
requirement for caterers to identify the steps in the system where hazards can
arise and put appropriate control and monitoring measures in place. This
relates to the implementation of Hazard Analysis Critical Control Point (HACCP)
techniques. Caterers are encouraged to develop modified HACCP approaches based
on the Assured Safe Catering methods, but this is expected to be a slow process
that will take place over several years.
There is a
need to address the safety of individual foods as caterers continue to cause
outbreaks of food poisoning owing to the use of contaminated fresh shell eggs.
The UK Government has recommended that caterers should make use of heat-treated
egg products, pasteurized to eliminate Salmonella enteritidis. Systems used in
the catering industry can be seen as a continuum of the techniques used in the
food manufacturing industry and therefore can employ similar methods of
control. For example, the concept of quality management can be usefully
applied. As more food-manufacturing techniques are adopted, and encouraged by
regulatory authorities, these techniques should accompany the HACCP approach so
that safety and quality issues are both addressed.
Catering Systems in Conclusion
There is a
need for further research to confirm claims of improved sensory qualities,
safety, and nutritional values in food manufacturing and meals assembly
systems. Quality changes can occur rapidly, but many variables affect the end
result that is often product-specific. The lack of control and standardization
in both the catering industry and experimental methods makes comparisons
between studies difficult. The fact that technological innovations in catering
systems have not introduced new methods of food production but rather, as some
have noted, introduced systems of food preservation has not been proven to have
had a positive impact on food quality predicted, as a matter of course.
Generally
cook–serve catering systems still predominate throughout the food-service
industry. It has been found that increased size, certainly in the healthcare
sector, tends to dictate whether or not food-manufacturing systems have been
adopted. However, recent surveys have indicated that around three-quarters of
hospitals in the USA and almost the same proportion in the UK still operate
conventional food-service systems.
In recent years, the emergence of food-delivery/meals-assembly systems has offered the opportunity for many smaller catering operations to adopt this type of system. Whilst this development means that catering systems can provide a wider menu with less skilled staff and reduced equipment needs, it has been observed that quality suffers if regeneration of products is poorly controlled and if the aesthetics of meals assembly and customer service expectations are overlooked. It is pertinent to recall that the term ‘catering system’ emerged from the application of systems theory to the management of food-service operations. It should not be forgotten, therefore, that the systems approach is ‘holistic,’ and that any innovation that affects one or more subsystems will also affect the rest of the system, its inputs, and the efficiency and effectiveness with which it produces its outputs.
By A G Smith and A West, in the book 'Encyclopedia of Food Science and Nutrition',
Academic Press, Editor-in-Chief: Benjamin Caballero (Johns Hopkins University,
USA). Editors: Luiz C Trugo, (Federal University of Rio de Janeiro) and Paul M
Finglas,(Institute of Food Research Norwich Laboratory, UK), p.975-981. Digitized, adapted and illustrated to be posted by Leopoldo Costa.
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