Case study 4 Food safety in the home: a review and case study

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1 Case study 4 Food safety in the home: a review and case study William H. Sperber This case study is an example to illustrate application of food safety management and is provided without any liability in its application and use. INTRODUCTION While all links in the farm-to-table food supply chain are important, the last link the point of consumption seems to be the most important because it is the last opportunity to assure the safety of a food before it is eaten. There are many points of consumption in the last link, including restaurants, institutional settings such as schools and hospitals, and the home. Restaurants and institutions can usually provide significant assurance of food safety because the food is usually prepared and served by trained personnel. In contrast, the home environment is much more vulnerable to food safety mistakes and the occurrence of foodborne illnesses because those handling and serving the food are typically untrained and often unaware of the potential hazards. Often, they are children or ignorant adults and work in a confined space that may include pets and infant children. Furthermore, the principal food safety controls in the home refrigeration, cooking and baking are not always used properly. It is most important to recognise, particularly in the home, that the consumer has a significant role in food safety, a role that is shared with the many participants in the food supply chain. Recognising that a lack of knowledge contributed to the spread of many infectious diseases and foodborne illnesses in the home, an online resource, the International Scientific Forum on Home Hygiene, was established in 1997 to promote health by means of improved hygiene in the home. A detailed report on progress during its first 10 years is a most helpful resource for consumers (Bloomfield et al., 2009). Additional efforts to increase consumer understanding have been initiated by the UK Food Standards Agency, whose goal is to promote kitchen hygiene in order to reduce foodborne illnesses in the home by 20% over the next 5 years (FSA, 2009). This review and case study will provide information for educators and consumers to make them more aware of the potential foodborne hazards in the home, practical means of hazard control, and specific control measures that could be established. Ideally, some potential hazards could be managed in the home environment, similar to the management of hazards in foodprocessing facilities by means of HACCP and prerequisite programmes. Food Safety for the 21st Century: Managing HACCP and Food Safety Throughout the Global Supply Chain Carol A. Wallace, William H. Sperber and Sara E. Mortimore 2011 Carol A. Wallace, William H. Sperber and Sara E. Mortimore. ISBN:

2 304 Food Safety for the 21st Century POTENTIAL HAZARDS The wide range of microbiological, chemical and physical hazards that can be found through the food supply chain can often be encountered in the home kitchen. Potential microbiological hazards include the following: Salmonella and Campylobacter in raw meat and poultry Listeria monocytogenes in cooked, ready-to-eat (RTE) meats and soft cheeses E. coli O157:H7 in raw ground beef, raw milk and juices, and fresh produce Clostridium botulinum in improperly cooled foods, e.g. soups and baked potatoes Clostridium perfringens in dressed, roasted poultry and gravies Bacillus cereus in improperly cooled, cooked rice and potatoes Staphylococcus aureus in custard or crème-filled cakes Salmonella in pet food Both B. cereus and S. aureus produce heat-stable toxins that survive reheating of previously cooked foods. Potential chemical hazards include the following: Allergens Cleaning chemicals Pesticides and rodenticides Potential physical hazards include the following: Broken glass Other foreign material The potential introduction of hazards into a prepared food can be heightened by several environmental factors, including the presence of pets and infants in the household, combined with inadequate hand-washing by the food preparer after handling the pet or changing diapers, etc. Accumulated dust on the floor is a common cause of infant botulism (Nevas et al., 2005). While not directly a food safety issue, this important fact emphasises the need to maintain a clean kitchen. Cross-contamination from raw to cooked foods can result from inadequate hand-washing or using, without adequate washing or disinfection, the same utensils to handle raw and cooked or RTE foods. For example, a cutting board used to prepare raw poultry can contaminate fresh salad ingredients with Salmonella or Campylobacter if it is not properly washed after being exposed to the raw poultry. Of course, such potential sources of cross-contamination are not limited to the home kitchen. The public health issues related to handling of raw meat and poultry and fresh produce in the same food preparation area are a major concern in retail and food service establishments that prepare food for consumption. POTENTIAL CONTROL MEASURES Several common-sense practices will minimise the possibilities of a foodborne illness originating in the home, but they are not always easy to implement:

3 Case study 4: Food safety in the home: a review and case study 305 Use clean (potable) water for preparing foods, especially when rehydrating foods such as dried milk for consumption without heating. In many regions, limited access to potable water is a major public health issue. Clean and disinfect bottles used for infant feeding before filling with properly heated milk or infant formulas. Maintain allergen controls if a family member has a food allergy. Be aware of food allergies that visitors may have. Do not store toxic chemicals in the kitchen or in other areas where foods are stored. No pets are allowed on tables or countertops. Cross-contamination control, e.g. hand-washing and separate utensils for raw and cooked food handling. The principal control measures available to ensure food safety in the kitchen are refrigeration, heating by cooking, baking or frying, sanitation and personal hygiene (Marchiony, 2004). Refrigeration Providing proper refrigeration of perishable foods begins when foods are purchased. Perishable foods should be refrigerated at 4 C or below as soon as possible, or within 2 hours of purchase. Attention should be given to the product s recommended shelf-life date so that it would be consumed before spoilage could occur. Care must be taken to promptly refrigerate leftover foods in order to prevent the growth of spoilage or pathogenic micro-organisms. A very good, and widely taught, guideline for holding foods is that cold foods should be stored at or below 4 C and hot foods should be stored at or above 60 C to prevent the growth of pathogens. This is an important consideration during holidays when family meals are served to large groups of people. Leftovers should be placed directly into refrigeration at 4 C within 2 hours of serving; it is not recommended to cool foods at room temperature before refrigeration. Large quantities of food that would require many hours to reach refrigeration temperature should be divided into smaller portions so that they will be properly chilled within several hours. Leftovers should be reheated to 74 C, if necessary, and consumed within 2 days of refrigerated storage. Family members may disagree on whether a refrigerated food is on the verge of spoilage or not. A wise saying applies in this case when in doubt, throw it out. Some people, in the interest of saving money, have died of botulism after eating leftover food that was either questionable or obviously spoiled. Refrigeration temperatures should be verified periodically with a reliable thermometer. It would be a public health service if refrigerator manufactures build reliable thermometers into the refrigeration unit such that the interior and door temperatures could be monitored. It is known that the door temperatures are substantially higher than the interior temperatures of household refrigerators. Therefore, items that do not spoil rapidly, such as condiments, acidic beverages or high-salt foods, should be stored in the door, rather than more perishable foods (Godwin et al., 2007). Many frozen foods need to be thawed before cooking. These should not be thawed at ambient temperatures, as pathogens could grow on the warming food surface while the interior of the food remains frozen. Preferably, frozen foods should be thawed in the refrigerator or under cold running water. They can also be thawed in a microwave oven, provided that they are cooked immediately after thawing.

4 306 Food Safety for the 21st Century Heating In preparing processed foods for home serving, the manufacturers label instructions should be followed for cooking, baking, microwaving or frying the product. It is the responsibility of food processors to validate that the food preparation instructions will have a sufficient margin of error to ensure the safety of the product. Usually, the heating process required to yield an organoleptically acceptable food is substantially higher than that needed to kill vegetative forms of pathogenic micro-organisms, thus providing the margin of safety. Raw meat and poultry products must be cooked to a minimum centre temperature in order to ensure food safety. The recommended centre temperatures are (Marchiony, 2004): 71 C raw ground beef, beef and pork 74 C raw ground poultry, leftover foods 82 C whole poultry or pieces It is highly recommended that an accurate meat thermometer be used to measure the centre temperature before serving. This is especially important with ground meats; if not adequately cooked, the centre of the ground products can potentially contain pathogenic micro-organisms that had been on the meat surface before grinding. Sanitation and personal hygiene Many opportunities for contamination and cross-contamination exist in the kitchen (Walter et al. 2007). Elimination of the causes of contamination, when applied in millions of kitchens worldwide, will reduce the burden of foodborne illness. Examples of causes of contamination include the following: Contact of raw and cooked foods Unclean kitchen counters and utensils Inadequate hand-washing, e.g. after handling raw foods, changing diapers, taking out garbage and visiting the bathroom Preparing food when ill Improper use of dish towels Playing with pets while preparing foods Smoking, sneezing or coughing while preparing foods Many of the potential contamination problems in the kitchen can be minimised or eliminated by using prerequisite programmes, to extend the use of this term from the rest of the food supply chain, such as cleaning and sanitising, and by altering food consumption patterns. Moreover, some control measures could be established and monitored as critical control points (CCPs) in the home kitchen. POTENTIAL CCPs IN THE HOME Simple but effective CCPs could be established in each home kitchen to create awareness of potential hazards and their means of control. Examples of home CCPs and control measures include the following: Controlled refrigeration temperatures. Controlled cooking temperatures.

5 Case study 4: Food safety in the home: a review and case study 307 Removal of target allergens when susceptible individuals are known or expected to be present. Preventing consumption of raw milk and raw purchased juices, raw cake batter and unbaked cookie dough. Restricted or prohibited consumption of certain types of food by immunocompromised individuals. For example, pregnant women should not consume soft or surface-ripened cheeses, pre-cooked RTE meat and poultry products, unless the latter have been reheated to 74 C before consumption. EDUCATION Creation of a home HACCP plan or food safety plan would be a good educational device for the entire family, with an added benefit for society as a whole many of the children in families will spend part of their early life in part-time jobs in the food service industry, preparing and serving a vast number of meals outside the home. If these children learned proper food safety procedures in the home, they would be better prepared to use safe food-handling practices when working outside the home. Education would include basic information about foodborne hazards, means of control and susceptible consumers, as described above. Education for food safety in the home should begin in the primary school so that good practices are learned at a young age (this happens in the UK see Chapter 4). A number of techniques can be employed to continually reinforce the early learning: public service announcements by radio, television or print media, public health agency websites, academic extension services, etc. Family members who participate in food safety awareness training will be better prepared to use safe food-handling practices in the home, to the point of actually using CCPs in the home, or creating a simple home HACCP plan. Friendly competitions could be arranged in schools to encourage students to create the best HACCP plan, CCP or other food safety practices. TV cookery show hosts could be educated to eliminate the poor practices which many currently use, and instead help to educate their viewers on the good practices needed in the kitchen and why. Education of home appliance manufacturers could also be beneficial. For example, refrigeration units should have built-in, reliable thermometers that would facilitate observing and recording interior temperatures without opening the door, as mentioned previously. Optical scanners by which consumers could retrieve food safety information either from in-store displays or from label encryptions could be developed (Mortimore and Wallace, 1998). CASE STUDY Background A typical suburban Hill City, Kansas (USA), family has been stricken by a number of illnesses during the past several years, most or all of which may have been foodborne illnesses resulting from foods prepared in their home. The Knight family father, Winston, age 61; mother, Margaret, age 35; daughter, Penelope, age 12; and son, Charles, age 10 can recall three recent episodes in particular that seem to have been food related: 1. Three of the family members began vomiting within 2 hours of eating a meal that included Himalayan Nut Pilaf. Penelope, the only member who did not become ill, had not eaten the Pilaf.

6 308 Food Safety for the 21st Century 2. All family members experienced repeated diarrhoea within 14 hours of eating a winter holiday meal that included a dressed and roasted 4 kg goose. Because this meal was a family tradition, all members ate heartily. 3. Two family members and three of four visiting neighbours experienced simultaneous vomiting and diarrhoea within 1 day of feasting at an outdoor barbeque that included grilled chicken and Caesar salads. ORIGIN OF THE KNIGHT FAMILY HOME FOOD SAFETY PROGRAMME The Knight family s growing awareness that some of their memorable bouts of illness might have been associated with food-handling practices was gradually reinforced with information gained by each family member from different sources. Margaret s suspicions were raised while watching a public television programme about the causes and nature of foodborne illnesses. Penelope and Charles learned simple facts about safe food handling in their school s health classes. In particular, they learned about the importance of proper refrigeration temperatures. Winston learned more about foodborne illness symptoms than he imagined possible after Googling diarrhoea, eating chicken ( RETROSPECTIVE ANALYSIS OF PREVIOUS ILLNESSES The Knight family began to discuss their newfound information about food-handling practices and began to develop hypotheses about the unexpected and, at the time, mysterious illnesses that had affected them and their neighbours. Additional online searching and attempted reconstruction of events surrounding the potentially incriminated meals and suspect foods led them to the following conclusions: 1. It seemed rather clear that the first series of illnesses involved the Himalayan Rice Pilaf, as it had not been eaten by Penelope, the only family member who had not become ill. Margaret recalled cooking rice the evening before the Pilaf was prepared and served. She spooned the hot cooked rice into a rectangular plastic storage dish, which she covered and placed in the refrigerator door. It is likely that the episodes of vomiting were caused by the growth of Bacillus cereus in the rice, which required many hours to cool below ambient temperature. B. cereus spores are normally present in rice. The spores survive the cooking process and are able to grow rapidly if the rice is not consumed or adequately chilled within several hours. During growth, B. cereus produces a heat-stable emetic toxin, which induces vomiting within several hours of consumption. 2. The dressed goose served for the holiday meal had been purposely roasted at an oven temperature lower than the recommended 163 C to retain the succulence of the meat. Winston learned online that C. perfringens, also a spore-forming micro-organism, was often the cause of diarrhoeal illness in meat and poultry products, particularly those involving dressing or gravy. It can grow very rapidly at temperatures up to about 50 C in foods that are roasted too slowly or held too long during serving. Following growth, it produces spores in the food. After consumption, the spores germinate in the host s intestine and produce toxins,

7 Case study 4: Food safety in the home: a review and case study 309 which cause diarrhoea typically within 8 24 hours. In this episode, the family s illnesses could have been caused by the growth of C. perfringens in the dressing during slow roasting, or in the gravy, which had been made from the goose drippings and held for many hours at ambient temperature during the long holiday meal. 3. Reconstruction of the third illness episode led to two plausible causes; perhaps both were involved to differing extents in the five illnesses. The same tongs had been used to handle raw and grilled chicken pieces. It is possible that grilled chicken could have been recontaminated with Salmonella or Campylobacter, both common contaminants of raw poultry. It is perhaps more likely that the Caesar salad was the cause of the illnesses, as it was made with two potential sources of contamination. Whole chickens were cut on a cutting board that was not washed and disinfected before being used to cut salad ingredients. Furthermore, the salad dressing was prepared with fresh, raw egg yolks, which have frequently been responsible for illnesses caused by Salmonella Enteritidis. Salmonella infections are typically characterised by vomiting and diarrhoea, while Campylobacter infections do not always involve vomiting. Therefore, it is more likely that the illnesses were caused by Salmonella, though it could not be determined whether the raw chicken or raw egg yolks were responsible for the contamination. In any case, both are serious food-handling mistakes which need to be prevented. KNIGHT FAMILY FOOD SAFETY TEAM AND ACTION PLAN Equipped with this knowledge about foodborne illnesses and their likely mistakes that caused the illnesses, the Knight family agreed to work together to avoid future occurrences. Each member assumed responsibility for specific aspects of the resulting family action plan: Penelope became the team leader. She wanted to be the keeper of the collected data, which she intended to use in a school project. She was also responsible to monitor refrigerator temperatures at least weekly and make adjustments when necessary. Charles agreed to monitor cooking and roasting temperatures as necessary, and to supervise prompt and proper refrigeration of foods. Margaret agreed to monitor food-handling practices and regularly clean and sanitise kitchen counters to minimise opportunities for food contamination. Winston agreed to continue online monitoring of safe food-handling information and to inform the entire family about useful practices. At this writing, the Knight family has experienced no additional known cases of foodborne illness. CONCLUSION While the above case study is a mostly fictional example of a family and its home food safety plan, the authors believe that it can be effectively used to promote the possibilities of improving safe food-handling practices in the home, the ultimate link in the food supply chain.

8 310 Food Safety for the 21st Century REFERENCES Bloomfield, S.F., M. Exner, G.M. Fara, K.J. Nath, E.A. Scott and C. Van Der Voorden (2009) The global burden of hygiene-related diseases in relation to the home and community. (accessed 19 Nov 2009). Food Standards Agency (FSA) (2009) Domestic sector hygiene research program (B20). (accessed 23 October 2009). Godwin, S.L., F.-C. Chen, E. Chambers IV, R. Coppings and D. Chambers (2007) A comprehensive evaluation of temperatures within home refrigerators. Food Protect. Trends 27, Marchiony, A. (2004) Food-Safe Kitchens. Pearson/Prentice Hall, Upper Saddle River, New Jersey. Mortimore, S. and C.A. Wallace (1998) HACCP: A Practical Approach, Second Edition. Aspen Publishers, Inc., Gaithersburg, Maryland, p Nevas, M., M. Lindström, A. Virtanen, S. Hielm, M. Kuusi, S.S. Arnon, E. Vuori and H. Korkeala (2005) Infant botulism acquired from household dust presenting as sudden infant death syndrome. J. Clin. Microbiol. 43, Walter, C. M., R.H. Schmidt, K.R. Schneider and J. Cornell (2007). Home food safety practices of government employees in Osceola County, Florida. Food Protect. Trends 27,