Microbiological Quality and Safety in Dairy Industry

Module 3. Plant hygiene and sanitation

Lesson 14
PERSONNEL HYGIENE

14.1 Introduction

Everyone has the right to expect the food he/ she consumes is safe and suitable for consumption. Food poisoning is a serious health problem and can cause severe illness and even death. In addition, outbreaks of food borne illness damage trade and tourism, lead to loss of earnings, unemployment and litigation. Food spoilage is wasteful, costly and adversely affects trade and consumer confidence. Increase in international food trade and foreign travel have brought important social and economic benefits. Eating habits have undergone a major change worldwide during the past three decades. These opportunities have also made the world population vulnerable for spread of diseases over the globe very fast, if not handled hygienically. Hence, effective hygiene control is vital to avoid adverse effects on human health and economy due to food borne illness and spoilage.

Personnel handling milk and milk products constitute one of the most important sources of microbial contamination including potential pathogens in these products. Hence, personnel hygiene plays a very significant role in influencing the microbiological quality of the milk and milk products which, in turn, may affect the health of the consumers. If the personnel handling of these delicate food stuffs are not well acquainted with the codes of hygiene practices, they can in advertently introduce lots of undesirable microorganisms merely by touching. This can be achieved by adopting food hygiene principles throughout the food chain and HACCP based approach. All stakeholders including producers, manufacturers, food handlers and consumers have a responsibility to assure that food is safe and suitable for consumption. Both government and industry have the responsibility to provide safe and suitable milk and milk products for consumers practicing principles of food hygiene.

14.2 Food Handlers

Any person who directly handles packaged or unpackaged food, equipment and utensils or food contact surfaces and is therefore expected to comply with food hygiene requirements. Food handlers are potential sources of microorganisms that cause illness and food spoilage. Parts of the body that contribute to the contamination of food include the skin, hands, hair, eyes, mouth, nose, naso-pharynx, respiratory tract, and excretory organs. These parts are contamination sources as carriers, through direct or indirect transmission, of detrimental microorganisms.

14.2.1 Carrier

A carrier is a person who harbours and discharges pathogens but does not exhibit the symptoms of the disease. Carriers are divided into three groups:

14.2.2 Convalescent carriers

After recovering from an infectious disease, continue to harbour the causative organism for a variable length of time, usually less than 10 weeks.

14.2.3 Chronic carriers

People continue to harbour the infectious organism indefinitely, although they do not show symptoms of the disease.

14.2.4 Contact carriers

People acquire and harbour a pathogen through close contact with an infected person but do not acquire the disease.

14.2.5 Pathogenic bacteria associated with food handlers

14.2.5.1 Streptococci

These organisms, commonly harboured in the human throat and intestines, are responsible for a wider variety of diseases than other bacteria. They are also frequently responsible for the development of secondary infections.

14.2.5.2 Staphylococci

The most important single reservoir of Staphylococci infection of humans is the nasal cavity. Equally important to the food industries are those who possess the pathogenic varieties of the organism as part of their natural skin flora. These people are a constant threat to consumer safety if they are permitted to handle food products.

14.2.5.3 Intestinal microorganisms

This group of organisms includes Salmonella, Shigella, Escherichia coli, cholera, infectious hepatitis and infectious intestinal amoebas. These microorganisms are of public health concern because they can contribute to serious illness.

14.3 Personal Contamination of Food Products

The intrinsic factors that affect microbial contamination by people are as follows.

14.3.1 Body location

The composition of the normal microbial flora varies depending on the body area. The face, neck, hands and hair contain a higher proportion of transient microorganisms and a higher bacterial density. The exposed areas of the body are more vulnerable to contamination from environmental sources. When environmental conditions change, the microbial flora adapt to the new environment.

14.3.2 Age

The microbial population changes as a person matures. This trend is especially true for adolescents entering puberty. They produce large quantities of lipids known as sebum, which promotes the formation of acne caused by Propionibacterium acnes.

14.3.3 Hair

Because of the density and oil production, the hair on the scalp enhances the growth of microbes such as S. aureus and Pityrosporum.

14.3.4 pH

The pH of the skin is affected through the secretion of lactic acid from the sweat glands, bacterial production of fatty acids, and diffusion of carbon dioxide through the skin. The approximate pH (5.5) for the skin is more selective against transient microorganisms than it is against the resident flora. Factors that change the pH of the skin (soap, creams, etc.) alter the normal microbial flora.

14.3.5 Nutrients

Perspiration contains water soluble nutrients (i.e., inorganic ions and some acids), whereas sebum contains lipid (oil)-soluble materials such as triglycerides, esters, and cholesterol. The role of perspiration and sebum in the growth of microorganisms is not fully understood.

14.4 Methods of Disease Transmission

14.4.1 Direct transmission

Many diseases are transmitted through direct transfer of the microorganisms to another person through close contact. Examples are diphtheria, scarlet fever, influenza, pneumonia, smallpox, tuberculosis, typhoid fever, dysentery and venereal diseases. Respiratory diseases may be transferred via atomized particles extruded from the nose and mouth when a person talks, sneezes, or coughs. When these particles become attached to dust, they may remain suspended in the air for an indefinite length of time. Other people may then become infected upon inhaling these particles. Wall mounted no-touch hand sanitizer may be a good alternative to prevent such incidences of direct bodily touch.

14.4.2 Indirect transmission

The host of an infectious disease may transfer organisms to vehicles such as water, food, and soil. Lifeless objects, other than food, capable of transmitting infections are doorknobs, telephones, pencils, books, washroom fittings, clothing, money, and knives. Intestinal and respiratory diseases such as salmonellosis, dysentery and diphtheria may be spread by indirect transmission. To reduce the transfer of microorganisms by indirect transmission, wash basins should have foot-operated controls instead of hand-operated faucets, and doors should be self-closing.

14.5 Precautions

14.5.1 Hand washing

14.5.1.1 Transient or resident bacteria

Microorganisms found on the hand surfaces may be transient or resident bacteria. Transient bacteria are picked up accidentally by food handlers and are transient in that they reside on the hands only temporarily (e.g., E. coli). Residual microorganisms permanently reside on the hand surfaces and are the normal or resident microflora of the skin (e.g., Staphylococcus epidermidis). The first line of defense against disease is frequent and effective hand washing by food handlers. Approximately 38% of food contamination is attributable to improper hand washing. Few examples are illustrated below:

1. On a 4-day Caribbean cruise, 72 passengers and 12 crew members has diarrhoea, and 13 people had to be hospitalized. Stool samples of 19 of the passengers and 2 of the crew contained Shigella flexneri bacteria. The illness was traced to German potato salad prepared by a crew member that carried these bacteria. The disease spread easily because the toilet facilities for the galley crew were limited.
2. Over 3,000 women who attended a 5-day outdoor music festival in Michigan became ill with gastroenteritis caused by S. sonnei. The illness began 2 days after the festival ended, and patients were spread all over the United States before the outbreak was recognized. An uncooked tofu salad served on the last day caused the outbreak. Over 2,000 volunteer food handlers prepared the communal meals served during the festival. Before the festival, the staff had a smaller outbreak of shigellosis. Sanitation at the festival was mostly acceptable, but access to soap and running water for hand washing was limited. Appropriate hand washing facilities could have prevented this explosive outbreak of food borne illness.
3. Shigella sonnei caused an outbreak of food borne illness in 240 airline passengers on 219 flights to 24 states, the District of Columbia, and four countries. The outbreak was identified only because it involved 21 of 65 football team players and coaches. Football players and coaches, airline passengers, and flight attendants with the illness all had the same strain of S. sonnei. The illness was caused by cold food items served on the flights that had been prepared by hand at the airline flight kitchen.

14.5.1.2 Procedures for hand washing

Hand washing is conducted to break the transmission route of the microorganisms from the hands to another source and to reduce resident bacteria.

14.5.1.2.1 Manual double hand washing method

Hand washing for 15 seconds (as opposed to the average of 7 seconds) with soap and water, which act as emulsifying agents to solubilise grease and oils on the hands, will remove transient bacteria. Increased friction through rubbing the hands together or by using a scrub brush with soap can reduce the number of transient and resident bacteria than is done by quick hand washing. Hand washing and drying efficacy against resident flora ranges from 35 to 60%. All hand washing agents, including water, are effective when the hands are dried with paper towels. Fig. 14.1 illustrates a manual double hand washing method.

14.5.1.2.2 Mechanized hand washers

Because proper hand washing is essential to attain a sanitary operation, mechanized hand washers are being used. Typical unit is located in the processing area as illustrated in figure 14.2. When workers enter the area, they must use the washing unit. This equipment is responsible for increased hand washing frequency by 300%. The user inserts the hands into two cylinders, passing a photo-optic sensor, which activates the cleansing action. High pressure jet sprays within each cylinder spray a mixture of antimicrobial cleansing solution and water on the hands followed by a portable water rinse. This 10 second cycle is 60 % more effective at removing pathogenic bacteria from the hands than the average manual hand washing and reduced water cost.

Fig. 14.1 Step wise procedure for manual double hand washing

Fig. 14.2 Mechanized hand washers

Disinfection steps after hand washing: Alcohol hand rub, gel, or rinse sanitizers that contain at least 60% alcohol have been incorporated as a disinfection step after washing hands with soap and water. The alcohol present will evaporate in approximately 15 seconds. Alcohol-based instant hand sanitizers used after hand washing, provide an additional 10 - to 100 fold reduction. Instant hand sanitizers (protective creams and lotions) should be considered when washing is not possible but they do not have a lasting effect. Ethanol is more effective at destroying viruses than iso-propanol; however, both alcohols are effective for the destruction of bacteria, fungi, and viruses. The most effective regimen for antimicrobial control is the combination of an antibacterial soap hand wash followed by an alcohol gel application. Caution is necessary when alcohol is applied because it is flammable at the concentration found in hand sanitizers.
Other antiseptic hand washing compounds include iodine and iodophors (complexes of iodine with a carrier such as poly-vinyl-pyrrolidone). Although effective, iodine is irritating and may cause allergic reactions.
Gloves should be put on after the hands are washed and dried. If the hands are not dry, residual moisture forms an incubation environment for bacteria under the gloves.

14.6 Requirements for Hygienic Practices

Management must establish a protocol to ensure hygienic practices by employees. Supervisors and managers should set an example for employees by their own high levels of hygiene and good health while conveying the importance of these practices to the employees. They should provide proper laundry facilities for maintenance of cleanliness through clean dressing rooms, services, and welfare facilities. Management should require employees to have a pre-employment physical examination to verify that they are in good physical, mental, and emotional health. This is an excellent opportunity to impress the importance of good hygienic habits on a new employee and to emphasize how employees “shed” Salmonella and Shigella. Furthermore, those with skin infections may be identified before they handle food. All employees who work with food should be checked regularly for signs of illness, infection, and other unhealthy conditions.

Several countries have a legal requirement for pre-employment health examinations and require that they be repeated at regular intervals. However, this regulation has been challenged because of the expense of routine medical examinations, the difficulty of administering these plans, and because a clear relationship between food handlers and food borne disease has not been established.

14.6.1 These practices should be conducted to ensure personal hygiene

1. Physical health should be maintained and protected through practice of proper nutrition and physical cleanliness.
2. Illness should be reported to the employer before working with food so that work adjustments can be made to protect food from the employee’s illness or disease.
3. Hygienic work habits should be developed to eliminate potential food contamination.
4. During the work shift, hands should be washed after using the toilet; handling garbage or other soiled materials; handling uncooked muscle foods, egg products, or dairy products; handling money; smoking; coughing; or sneezing.
5. Personal cleanliness should be maintained by daily bathing and use of deodorants, washing hair at least twice a week, cleaning fingernails daily, using a hat or hair net while handling food, and wearing clean underclothing and uniforms.
6. Employee hands should not touch food service equipment and utensils. Disposable gloves should be used when contact is necessary.
7. Rules such as “no smoking” should be followed, and other precautions related to potential contamination should be taken.

14.6.2 Employers should emphasize hygienic practices of employees as follows

1. Employees should be provided training in food handling and personal hygiene.
2. A regular inspection of employees and their work habits should be conducted. Violations of practices should be handled as disciplinary violations.
3. Incentives for superior hygiene and sanitary practices should be provided.
4. Food handlers should be responsible for their own health and personal cleanliness. Employers should be responsible for making certain that the public is protected from unsanitary practices that could cause public illness. Personal hygiene is a basic step that should be taken to ensure the production of wholesome food.

14.7 Sanitary Food Handling

A protective sanitation barrier between food and the sources of contamination should be provided during food handling. Barriers include hairnets, disposable gloves, mouth guards, sneeze guards and food packaging and containers.

Role of Employees: Food processing and food service firms should protect their employees and consumers from workers with diseases or other microorganisms of public health concern that can affect the wholesomeness or sanitary quality of food. This precaution is important to maintain a good image and sound operating practices consistent with regulatory organizations. In most communities, local health codes prohibit employees having communicable diseases or those who are carriers of such diseases from handling foods or participating in activities that may result in contamination of food or food contact surfaces. Responsible employers should exercise caution in selecting employees by screening unhealthy individuals. Although some areas no longer require health cards because of the expense involved, many local health departments require all employees who handle food to be examined by a physician who will issue a health card only to healthy individuals. Selection of employees should be predicated upon these facts

1. Absence of communicable diseases should be verified through a county health card or a physician’s report.
2. Applicants should not exhibit evidence of a sanitary hazard, such as open sores or presence of excessive skin infections or acne.
3. Applicants who display evidence of respiratory problems should not be hired to handle food or to work in food processing or food preparation areas.
4. Applicants should be clean and neatly groomed and should wear clothing free of unpleasant odour.
5. Applicants should successfully complete a sanitation course and examination such as that provided by the National Restaurant Association.

14.7.1 Required personal hygiene

Food organizations should establish personal hygiene rules that are clearly defined and uniformly and rigidly enforced. These regulations should be documented, posted, and/ or clearly spelled out in booklets. Policy should address personal cleanliness, working attire, acceptable food handling practices, and the use of tobacco and other prohibited practices.

14.7.2 Facilities

Hygienic food handling requires appropriate equipment and supplies. Food handling and food processing equipment should be constructed according to regulations of the appropriate regulatory agency. Welfare facilities should be clean, neat, well lighted, and conveniently located away from production areas. Restrooms (washrooms, lavatories) should have self-closing doors. It is also preferred that hand washing stations have foot- or knee operated faucets that supply water at 43˚C to 50˚C. Remotely operated liquid soap dispensers are recommended because bars of soap can increase the transfer of microorganisms. Disposable sanitary towels are best for drying hands. The consumption of snacks, beverages, and other foods, as well as smoking, should be confined to a specific area, which should be clean and free of insects and spills.

14.7.3 Employee supervision

Employees who handle food should be subjected to the same health standards used in screening prospective employees. Supervisors should observe employees daily for infected cuts, boils, respiratory complications and other evidence of infection. Many local health authorities require food service and food processing firms to report an employee who is suspected to have a contagious disease or to be a carrier.

14.7.4 Employee responsibilities

Although the employer is responsible for the conduct and practices of employees, responsibilities should be assigned to employees at the time employment begins.

• Employees should maintain a healthy condition to reduce respiratory or gastrointestinal disorders and other physical ailments.
• Injuries, including cuts, burns, boils, and skin eruptions, should be reported to the employer.
• Abnormal conditions, such as respiratory system complications (e.g., head cold, sinus infection, and bronchial and lung disorder), and intestinal disorders, such as diarrhoea, should be reported to the employer.
• Personal cleanliness that should be practiced includes daily bathing, hair washing at least twice a week, daily changing of undergarments and maintenance of clean fingernails.
• Employees should tell a supervisor that items such as soap or towels in washrooms should be replenished.
• Habits such as scratching the head or other body parts should be stopped.
• The mouth and nose should be covered during coughing or sneezing.
• The hands should be washed after visiting the toilet, using a hand kerchief, smoking, handling soiled articles, or handling money.
• Hands should be kept out of food. Food should not be tasted from the hand, nor should it be consumed in food production areas.
• Food should be handled in utensils that are not touched with the mouth.
• Rules related to use of tobacco should be enforced.

14.8 Training

All workers seeking employment in dairy industry must undergo tailor made training programme "health minimum", which should covers foundations of fundamentals of nutrition, microbes, food poisoning and its prevention, personal and production hygiene.

Dairy plants must have an adequate program in place to monitor and control training programs and maintain appropriate documentation. The objective of the personnel training program must be to ensure safe food handling practices. The personnel training program must provide, on an ongoing basis, necessary training for production personnel. A procedure must be developed to verify effectiveness of the training program. Production personnel must be trained to understand critical elements for which they are responsible, what critical limits are, importance of monitoring limits, and actions they must take if limits are not met. Ongoing training in personal hygiene and hygienic handling of food must be provided to every food handler, and training in personal hygiene and hygienic handling of food must be provided to all persons entering food handling areas. Plants must demonstrate that personal hygiene is carried out and controlled. No person known to be suffering from or to be a carrier of a disease likely to be transmitted through food or afflicted with infected wounds, skin infections, sores, or diarrhoea is permitted to work in any food handling area in any capacity in which there is any likelihood of such a person contaminating food with pathogenic microorganisms. All persons having open cuts or wounds may not handle food or food contact surfaces unless the injury is completely protected by a secure, waterproof covering. All persons entering a dairy food production area must wash their hands thoroughly with soap under warm-running potable water. Hands must be washed after handling contaminated materials and after using toilet facilities. Where required, employees must use disinfectant hand dips. All persons working in dairy food handling areas must maintain personal cleanliness while on duty. Protective clothing, hair covering, and footwear functional to the operation in which the employee is engaged must be worn and maintained in a sanitary manner. Gloves, if worn, must be clean and sanitary.

All persons entering dairy food handling areas must remove objects from their person that may fall into or otherwise contaminate food. Tobacco, gum, and food are not permitted in dairy food handling areas. Jewelery must be removed before entering food handling areas. However, jewelery, including Medic Alerts that cannot be removed, must be covered. Personal effects and street clothing must not be kept in food handling areas and must be stored in a manner to prevent contamination of dairy foods. Access of personnel and visitors must be controlled to prevent contamination. All necessary precautions must be taken to prevent contamination, including use of foot baths and hand dips where required.

14.9 Hygiene Monitoring

Targets for hygiene are of little value unless they are monitored. Microbiological methods are available to monitor the total counts on items of plant, most methods require the establishment of a laboratory designed to handle live cultures. The cleanliness can be assessed by objective examination of hand. This is carried out in microbiological laboratory by taking washings from the hands by means of sterile cotton-wool pads and inoculating the washings on to nutrient media. For this the surfaces of palms of both hands and the fingers are rubbed at least five times with each pad and then used to rub the spaces between the fingers, the nails and the space underneath the nails. The results of the examination should be communicated to the workers. The importance of personnel hygiene must be discussed with them (Fig. 14.3).

Fig. 14.3 Hygiene monitoring of personnel

The bacterial cultures growing on Petri dishes should be shown to them. The scale of marks for judging the results of bacterial examination are "excellent" is given to the workers from whose hands washings show < 2000, "good"- 2000 to 5000 bacteria, "fair" - 5000 to10 000 CFU/ ml. and >10,000 is "bad". If gas appears in the fermentation liquid a "bad" mark is given independently of the total number of bacteria.