3.24.2012

CATERING SYSTEMS


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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