Case Method in the Teaching of Food Safety


  • Alfredo Gallego,

    Corresponding author
    • Cátedra de Higiene y Sanidad, Facultad de Farmacia y Bioquímica Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
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  • María S. Fortunato,

    1. Cátedra de Higiene y Sanidad, Facultad de Farmacia y Bioquímica Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
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  • Susana L. Rossi,

    1. Cátedra de Higiene y Sanidad, Facultad de Farmacia y Bioquímica Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
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  • Sonia E. Korol,

    1. Cátedra de Higiene y Sanidad, Facultad de Farmacia y Bioquímica Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
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  • Juan A. Moretton

    1. Cátedra de Higiene y Sanidad, Facultad de Farmacia y Bioquímica Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
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One of the fundamental aims of education is the integration of theory and practice. The case method is a teaching strategy in which students must apply their knowledge to solve real-life situations. They have to analyze the case described and propose the best possible solution. Although the case may be written, the use of new information and communication technologies can develop the case plan in ways that would achieve greater realism and widen the possibilities for discussion. This paper describes our experience in implementing the case method to teach food safety in the Chair of Hygiene. At first this methodology was used to improve the teaching of good practices in food preparation, later practical work was implemented where small groups of students designed and carried out the microbiological analysis of suspected food. This practical work was presented online as a multimedia activity; students were given face-to-face and on-line tutoring. Evaluation was based both on students’ performance and on a survey they had to answer. More than 92% of students regarded the methodology used for the understanding of the unit as sound. Professors collaboration on providing guidance and multimedia presentation were also positively assessed. The bringing together of face-to-face and virtual tasks and small-group discussion of cases under professors guidance contributed to making good use of the positive aspects of this methodology in order to improve the understanding of problems which do not always have a single answer.


The case method is a teaching strategy in which students must apply their knowledge to solve real-life situations. This methodology becomes very attractive from many points of view when we take into account that one of the fundamental aims in education is to achieve the integration of theory and practice through an adequate implementation of teaching and learning strategies that efficiently connect knowledge with the real world ( 2012).

The use of the case method in education may be traced back to medieval times, when it was employed for solving moral or religious problems (Florio 2011). Christopher Langdell, Law Professor in the Harvard Law School, is recognized for having introduced the technique in the modern Univ. (Walsh 2008). To be more precise, Harvard Univ., particularly its Business School, holds the best application record, though nowadays several universities have courses that employ this technique, and they also have specific areas the aim of which is widening the pedagogical basis of the method. Moreover, several databases compile cases from different spheres of human knowledge in order to facilitate its application to education (ITESM 2011; GCHERA 2012).

Carl Christensen, defined case “as a partial, historical, clinical study of a situation which has confronted a practising administrator or managerial group. Presented in a narrative form to encourage student involvement, it provides data—substantive and process—essential to an analysis of a specific situation, for the framing of alternative action programmes and for their implementation, recognizing the complexity and the ambiguity of the practical world.” Thus it is a method of learning based on active participation and cooperative or democratic discussion of a situation faced by a group of managers (Asopa and Beye 2001).

Even though any subject matter could be addressed by this methodology, its use has been very clearly focused on certain disciplines as Law, Business, Management and Ethics. One of the advantages of the method is its application to real-life problems, which are usually unique because of the myriad of variables involved, and for which a single answer does not necessarily exist, but each possible answer should be analyzed considering the multiple factors present. Therefore it is not surprising that especially social sciences have made use of the case method to their advantage. However, this methodology has proven to be a useful tool in many of the areas of a hard science, particularly in medicine, where the uniqueness of each situation is also a relevant characteristic. Currently there are examples of its use in other fields, including food science (NCCSTS 2012).

To be effective, a case has to present students with a situation analogous to situations they can find in real life, in order for them to take decisions similar to those that they should take in their professional lives (Fernandez March 2007). The case should have a real background, irritate or trigger a willingness to discuss, and concomitantly fulfill a scheduled learning objective (Tärnvik 2007).

The case approach is a tool that allows us to activate the student's prior knowledge base (Brooke 2006). Adherents of the case method argue that it fosters critical and reflective thinking and facilitates students openness to multiple perspectives. Critical thinking has become the most prized student outcome at all levels of education. Although most educators give lip service to the importance of teaching critical thinking, few can clearly define it, and fewer still can demonstrate that they are teaching it. (Milner 2009).

In spite of the fact that the operation and functioning of this methodology is different depending on the discipline under consideration, it generally consists of some kind of analysis of a real or hypothetical situation, an examination of the different forms of scrutiny and alternatives available and an evaluation and discussion of possible correct solutions, sometimes trying to find the best one (Toller 2010). For businessmen, the primary tasks were making and implementing decisions, often in the face of considerable uncertainty. Much less time and attention would be devoted to underlying theories or principles (Garvin 2003). In food science it is necessary for the student to have sufficient knowledge of the different food-borne diseases (FBD) in order to act to prevent them.

A characteristic feature of the method is that, in the absence of a single correct answer (although there may be more and less appropriate answers) what the professor has to assess is the process that students follow to reach a solution (UPM 2008). Because of this, the success of the case study method is critically dependent upon student preparation and professor's knowledge of this didactic technique for its implementation.

Indeed, at the Harvard Business School, there was a Law School grad familiar with the technique, which pushed for the full inclusion of the case method at the Business School, where it was altered and adapted to a business perspective (Walsh 2008).

For years, the “technology” of cases remained static. They were written documents consisting of text, tables, and illustrations. Currently the use of new information and communication technologies (ICT) are transforming cases in ways that produce greater realism, and new possibilities for their discussion (Garvin 2003).

One of the major problems that we experienced in recent years in the teaching of food safety was the carrying out of practical work in large groups, which hinders the possibility for each student to be trained in performing techniques individually, thus missing the goal of practical work and leading to the loss of motivation among students. Other issues, such as hazard identification in the preparation of food or the analysis of FBD outbreaks, are presented only in a theoretical way, without adequate practice which makes it difficult for the student to reach meaningful learning.

In order to promote students’ participation and motivation, the case study methodology was used for teaching parts of the unit. This paper describes our experience.

Materials and Methods


Public Health is a course dictated in the fourth academic year of the Pharmacy degree course. Entering students have a basic knowledge of biology, microbiology, and chemistry. Classes last 3 hours each and meet twice a week. The number of students per class is between 30 and 60. For practical work, students are divided into 5 groups, each group occupying a laboratory bench.

Subjects addressed in the Food Safety Unit include the description of the physical, chemical, and biological hazards that can potentially be found in food; the discussion of the most important Food-borne Diseases (FBD), their prophylaxis and epidemiology, and the study of retrospective and prospective methods to assure food safety. Practical work consists of microbiological analyses of food samples.


The proposal was implemented over 2 consecutive years.

The first year our objective was applying the method with the sole purpose of improving the teaching of good elaboration practices. We worked on 5 different cases describing outbreaks of FBD.

The material students received was:

  • A brief outline of the event by way of introduction.
  • A description of the outbreak recording number of people affected, symptoms, time of onset of symptoms and suspected foods. For each food a detailed description of its preparation was included as well as a description of both facilities and personnel involved.
  • Photos showing relevant aspects of the facilities, procedures or personnel.
  • A video interviewing one of the people affected indicating what he considers important details.
  • A guide to the tasks to be performed.
  • Journal articles where similar cases were reported.

The case material was given to students 1 week before discussion. It was also available on the Internet. In addition, all material, including text, photos, and a transcript of the interview, was available in a printed version for those students who wished to photocopy it.

Students were divided into 5 groups, and each group was assigned a case. During the week dedicated to solving the case, students could receive face to face or virtual tutoring via email.

On the day appointed for the presentation each group should present to the class the case on which they had worked and should propose a solution that would be discussed by class and group members. As an additional task, students gave the professor a written version which included a proposal to perform laboratory analyses to confirm or reject the proposed hypothesis.

The encouraging first-year results we obtained made us extend the experience to the next year and include practical work, which had only been hinted at before.

The number of cases was substantially increased in order for students to work in 2-member groups. In addition, the time spent on the unit was increased so that students, apart from developing a theoretical solution, could propose and carry out a laboratory analysis, and based on the results obtained, draw a conclusion.

All laboratory work had to be done by the students themselves, which meant that attendance days had to be increased. The time for tutoring was also increased because students had to agree in advance with the professor on the tasks they would perform in the laboratory, to prepare the material for each group.

To allow all students to read the questions their fellow students had asked in the tutorials, a Facebook group was created, which tried to list all class queries.

Finally, as in the previous year, there was a sharing of results.

Figure 1 shows a diagram of the different activities conducted.

Figure 1.

Diagram of the different activities.

Summary of the cases discussed

The following is a brief description of the 10 cases that were used in the classes

Salad bar

The case concerns an FBD outbreak presumably caused by consumption of salads in a fashionable neighborhood restaurant that features a free salad bar. There were 22 affected customers, mostly local office employees. The symptom was diarrhea with abdominal pain in some cases and it appeared 18 hours after the consumption of salads. Only 1 person had fever.

Birthday party

The case presents data from an outbreak of diarrhea occurred in a poor outlying area close to a stream visibly contaminated. The infection was attributed to the ingestion of hot dogs and fruit juices at a children's birthday party. Eleven children were affected. The symptoms were diarrhea and sometimes vomiting. Most of the children had a fever of around 39 degrees Celsius. Ten cases were ambulatory and none was hospitalized.

White bread sandwiches

The case focuses on an FBD presumably caused by eating contaminated white bread sandwiches. The total number of people affected was 36; 35 of them received outpatient medical care, and 1 remained hospitalized for 5 days. Symptoms appeared between 12 and 24 hours after consumption. Those affected had fever, suffered from prostration, in all cases they had diarrhea and abdominal pain, and in some cases they vomited.

Homemade cakes

The case describes an outbreak of FBD presumably caused by the consumption of homemade cakes. The total number of people affected was 41; 15 of them received outpatient care at health centers. No one required hospitalization. Consumption took place at the inauguration of an engraving exhibition in an art gallery that doubles as a bar. The cakes had been purchased and delivered to the gallery. Those affected suffered from vomiting and diarrhea in all cases. No one had a fever. Some people also reported hypotension. The onset of symptoms was sudden within a few hours after consumption (2 to 4 hours).

Street burgers

An outbreak of FBD presumably originated in the consumption of contaminated hamburgers or sausages in a street food stall. The total number of people affected was 23, of which 22 received outpatient medical care, just one 75-year-old man remained hospitalized for 5 days. Symptoms appeared between 12 and 24 hours after consumption. People affected suffered from a fever, prostration, in some cases vomiting and in all cases diarrhea and abdominal pain.

Takeaway sushi

The outbreak has been linked to the consumption of prepared sushi bought in a supermarket. A total of 22 people were affected by intense prostration, diarrhea and vomiting. In no case was a fever recorded. A total of 12 people received outpatient care while an old person had to be hospitalized for 48 hours. Symptoms appeared between 3 and 7 hours after consumption, and there were no sequela aftereffects.

Pies and sausage sandwiches

The case considered is that of an FBD presumably caused by eating pies or sausage sandwiches. The suspected place was a club that held a meeting to raise funds for graduates of a local school. A total of 23 people were affected. None required hospitalization. Symptoms appeared 10 hours after eating the food. They were cramps and diarrhea. No patient developed a fever.

Summer camp

There was an outbreak of diarrhea in a summer camp. There were 29 cases of diarrhea in a 48-hour period. All cases occurred among children attending the camp. The outbreak was initially related to products consumed in the buffet lunch at the club: bangers and mash and fresh fruit. But there were some doubts about the cause because 8 children that had diarrhea did not have lunch at the club that day. Symptoms appeared between 12 and 36 hours after consumption. Affected children had profuse watery diarrhea, gastrointestinal discomfort and sometimes vomiting and fever.

None of the children required hospitalization.

A green chicken

A person filed a complaint about a chicken sold in poor condition in a neighborhood shop, the chicken skin was noticeably green. Analyses of the product have shown a high content of aerobic mesophilic bacteria as the only deviation. The complainant claims to have used parts of the product before he realized its state. None of the people who ate the product showed discomfort or symptoms of food poisoning. Because of this unusual situation we have been contacted to evaluate the whole process and determine both the possible source of pollution and the measures to take.

Washing vegetables

In a restaurant an FBD outbreak occurred which was related to contaminated salads. The microorganism responsible for the outbreak was not identified, whereas a high amount of coliforms was found in raw ready-to-eat leafy vegetables. Advice on the development of procedures that ensure safe-food production has been sought.

All the cases included examples of the most frequent FBDs detected in our country. Case solution is open. While, in some cases, there was some reasonable certainty about the food and the microorganism responsible, in others the likely cause could not be clearly established. Moreover, in some cases there were doubts over food being actually responsible for the outbreak. Some of the cases were directly dealt with by the students to design safety procedures for food elaboration.

Evaluating the case-study approach

At the end of the second year an anonymous survey had to be answered by the students to evaluate the proposal. The aim was to gather data about the following points:

  • Was the subject presentation as a case study more advantageous than that of conventional practical work?
  • Which of the materials supplied were thought of as more useful?
  • Was the complementary bibliography consulted?
  • Were the tutorials implemented useful?
  • Which was the best way in consulting a professor: a face-to-face or online consultation?

There was additional space which allowed students to make comments.

We have to bear in mind that the other practical work of the subject was carried out using a conventional approach, therefore students could utilize this as a basis to evaluate the new proposal.

As there were also doubts about students’ facility to accede to the Internet, they were asked whether they had bought printed material or they had consulted material online.

The degree of achievement in the practical work students themselves proposed as well as the degree of elaboration and participation in the concluding expositions were also used to gauge engagement with the experience.


The methodology employed was rated positively by most students.

In the survey conducted at the end of the subject, over 92% of students felt that the methodology was beneficial for the understanding of the unit. The students especially emphasized the willingness of professors to provide mentoring and guidance while carrying out practical work. The multimedia presentation of the material and the use of new communication technologies were also assessed.

Comparing with other units passed in a traditional way, the advantages highlighted included the possibility the students had of developing their own laboratory tasks as well as the multimedia problem presentation. The space of tutoring was also assessed, although most students chose to attend face to face discussion meetings instead of dealing with the questions on line, in the forum created for that purpose.

Following conventional procedure, the microbiological examination of food was performed only on the days and times set for the class. The assistant professor carried out any task that had to be done between classes, then he stored samples in the refrigerator. In the new scheme, students carried out all tasks. If one task stood outside the scheduled time frame, they agreed with the professor upon a time to complete the task. This voluntary participation of students outside the established hours, for the purpose of carrying out further testing, was one of the positive examples of the motivation that was achieved.

Students also selected the food sample that they were going to analyze and the type of analysis they would perform. Final results were shared in the last day: Both attendance and the interest in the presentation shown by all were satisfactory. Students used electronic tools for presentations, and benefited from bibliography on suggested links or found by the students themselves in scientific journals.

In sharing results not only were we able to present the case resolution but also the different pathways each group followed to solve it, pointing out errors committed and solutions found.

Survey results are shown in Figure 2.

Figure 2.

Survey results.

From the professors’ standpoint the new methodology was critized because of the greater effort that practical work demanded. It should be noted that there was a great change of scheme. Formerly there were 5 groups per class working on a set schedule, where the necessary equipment was known beforehand. In the new methodology there were about 20 groups working per each class. Each one defined with their professor the necessary materials (even the food sample to be analyzed). They also agreed upon dates outside the schedule, in order to perform complementary tasks. The success of tutorials to promote students’ learning without revealing a patterned answer to the problem also depended to a high degree on the personal ability and commitment of each professor to the method used.


Volpe (2011) cites Wang Yang-ming, a fifteenth-century Chinese philosopher:

‘Knowledge is the beginning of practice; doing is the completion of knowing. Men of the present, however, make knowledge and action two different things and go not forth to practice, because they hold that one must first have knowledge before one is able to practise.”

Precisely, one of the main advantages of the case method is that it allows the combination of theory and practice in order to produce graduates able to find an expert solution which is tailored to personal and social context to any particular problem (UPV 2006). In a teaching situation, case studies can help the student achieve competence, whereas context-independent facts and rules will bring the student just to beginner's level (Flyvbjerg 2006).

As stated this paper describes the application of the case method to study food hygiene issues. We believe that the methodology can be particularly useful for hazards identification in food processing and for FBD outbreaks analysis. In the cases dealt with, special care was taken so that that they should represent plausible situations. Episodes similar to the reported fictitous outbreaks, have indeed occurred in our country. The places described, also fictitious, are representative of identifiable real places here.

Students’ acceptance may constitute a barrier to the case method implementation (Herreid 2005). However, our proposal was considered as more interesting than conventional practical work by the vast majority of students. Working in small groups and the fact that they themselves had to design new techniques and obtain materials helped to strengthen the links between students and the development of practical work.

In addition, forming small groups to solve cases helped to promote collaborative learning between students, learning which goes beyond a simple task division: it means the joint construction of the answer (Stahl et al. 2006).

To further this approach, the work of the professor as tutor is also necessary. Helping to learn is not just a question of putting forward information or setting tasks to be done by the student. It is, essentially, to continually accompany the learning process and offer the student encouragement and support at the time when that encouragement and support may be needed (Onrubia 2005).

This experience was designed combining face-to-face and online tasks, so as to benefit from the positive aspects both approaches have. In this respect, Webb et al. (2005) have suggested that when implementing the case discussion method, a hybrid approach to the use of technology could be better than either a pure online or a pure in-class approach.

Herreid (2005) points out that sometimes the professors themselves may become a barrier to technique implementation. Not all professors felt at ease with the proposal. We believe this may be a weak point of the methodology. The role of the professor as a tutor is absolutely central. Both the absence of an answer from the professor as well as the immediate provision of the correct answer, which does not give the group the possibility of thinking, discussing the question or even making their own mistakes, may devoid the proposal of all sense.

Another problem we met with was that not all cases had the same degree of complexity. A challenge for the future is to modify those cases, which, for different reasons, proved to be less adequate.

In discussion pedagogy, students share the teaching task with the instructor and one another. All teach, and all learn (Christensen 1991). As professors, one of the lessons we learned from this experience was that, despite some drawbacks, we have shown that it is possible to attempt to use an even more personalized teaching also in large groups. Another positive development was that by moderating the discussions generated in the presentation of the cases, many opportunities arose to discuss facts that hardly ever have been present in traditional lectures. And when we say this we mean not only strictly technical but also social aspects.

The core of the teaching task is trying to understand what happens in any educational situation (Contreras Domingo 2010). In that sense, one of the main contributions of this experience is the further reflection on the difficulties encountered and the results obtained with the aim of improving our teaching.


Students assessed the implementation of the case method possitively, this can be inferred both from their answers to the surveys carried out as well as from their attendance in order to fulfill assignments outside of scheduled class time. Final case presentation and results comparison were useful in order to share individual and class experiences. Combining face-to-face and online activities and discussing cases in small groups under the guidance of tutors also contributed to the full and very positive application of this methodology.