PART III PROCESS SAFETY
4. Principles of HACCP
4.1. Hazard analysis
verify its implementation and accuracy. The inspection of the manufacturing processes is essential for the validation of how clearly the flow diagram depicts the process. The person responsible for the verification of the flow dia- gram is the quality and safety assurance manager. Moreover, the HACCP team must evaluate all the data concerning the production. Consultations or observa- tions should take place and cases of deviations recorded. The HACCP team should conduct inspections every month without notice, at any time during working hours.
4.1.1. Milk collection
4.1.1a. Microbiological hazards.
Sheep and goat’s milk comprises the major and basic ingredient for the manufac- turing of Feta cheese. Quality and microbiological safety of Feta is primarily dependant on the quality of milk as well as the microbial population as milk con- tains a wide range of nutrients, which provide an excellent culture medium for many pathogens. Only milk from healthy animals should be collected and received by the dairy industry. Unhealthy animals may provide milk with patho- genic organisms such as Listeria monocytogenes or microorganisms responsible for milk spoilage and deterioration of milk or both. The most significant pathogens are shown in Table 1 (Mantis, 1993).
Mycobacterium spp. Both Mycobacterium tuberculosis and Mycobacterium bovis are pathogenic to humans. Although Mycobacterium is killed by low tem- perature milk pasteurization, highly contaminated milk may need more intense thermal treatment. M. paratuberculosis may be associated with Crohn’s disease (ulcerative colitis).
Brucella spp. Strains of Br. melitensis and Br. abortus are pathogenic to humans (causing illness resembling Malta fever in man). The transmission from infected animals to humans takes place through contaminated food and especially dairy products. The pathogen is killed by pasteurization. In the acidic environ- ment of matured Feta cheese, it can survive for as long as a month.
Salmonella spp. As low temperature pasteurization is adequate to kill these pathogens, special care should be taken to avoid post-pasteurization TABLE1. Pathogens transmitted to human via consumption of milka
Mycobacterium spp. (Mycobacterium bovis, M. tuberculosis) Brucella abortus
Salmonella spp.
Listeria monocytogenes Bacillus anthracis Yersinia enterocolitica Shigella spp.
Escherichia coli (enteropathogenic)
E. coli O157:H7 (verotoxigenic, enterohaemorragic) Streptococcus pyogenes
Campylobacter jejuni Staphylococcus aureus Clostridium botulinum Bacillus cereus Clostridium perfringens Coxiella burnetii Pseudomonas aeruginosa Vibrio spp.
Aeromonas hydrophila
aBased on Mantis, 1993; Teuber, 2000
5. HACCP in the Cheese manufacturing process, a case study101 Hazard to be
addressed in
Ingredients & process step Potential hazards Justification plan? Y/N Control measures
Reception of milk (kept cool) M: pathogens (e.g. Listeria Coming from: unhealthy animals, Yes Good Manufacturing Practices monocytogenes, Escherichia farm environment, milk containers, (GMP) during milk collection coli, Staphylococcus aureus, and inadequate refrigeration. and reception,
Salmonella, Mycobacterium, Constitute public health hazard, Low storage temperatures Brucella, Yersinia enterocolitica, responsible for foodborne Adequate thermal treatment
Coxiella burnetii) and viruses illnesses and poisoning (pasteurization)
C: antibiotics, hormones, toxins, Yes Farmer and animal records, raw
heavy metals, sanitizers, additives materials testing, GMPs.
P: metal, pieces of glass, foreign No Centrifugal separation-Filtering
objects
Starter culture M: contamination of starter culture Abnormal fermentation Starter culture analysis and GHPs
Rennet M: recontamination microorganisms Abnormal fermentation Rennet analysis, rennet reception
Foodborne illnesses records
Salt M: microorganisms (pathogens or Affects the microbial cultures, Yes Brine pasteurization spoilage psychrotrophs) enzymes and biochemical reactions Brine reception records C: element residues (copper, iron,
lead)
Pasteurization M: survival of heat-tolerant spores Presence of heat tolerant spores or Yes Farmer and animal records, raw
and toxins (or/and survival of toxins in milk materials testing , GMPs
pathogens – inadequate thermal Temperature control and recording,
treatment) Cheese maturation
Process steps after M: contamination with pathogens Poor hygiene, source: personnel, Yes GMP, prerequisite programs
pasteurization P: foreign objects, dust equipment
Ripening M: contamination, insects Inadequate maturation, finished Yes GMP, temperature control and
C: mycotoxins product spoilage recording, pH
P: foreign objects, dust Key: M: microbiological, C: chemical, P: physical
recontamination of milk. Implementation of prerequisite programmes such as good hygiene practice would eliminate this risk.
Listeria monocytogenes. It has been associated with several outbreaks in humans caused by dairy products. It grows at temperatures as low as 5˚C and is also quite resistant during thermal treatment. It is killed by pasteurization. During maturation of Feta cheese, it appears that the population of Listeria increases for the first 10-14 days but then decreases slowly.
Escherichia coli. Enteropathogenic species of E. coli may be responsible for foodborne infection and poisoning if their population exceeds 107-108cells/g of food. Low temperature pasteurization is capable of destroying this pathogen pop- ulation in milk.
Staphylococcus aureus. Staph. aureus, present in numbers of 105cfu/ml or g of food, is responsible for the production of a heat resistant staphylococcal entero- toxin, which has been implicated in human foodborne illness. Incidents related to consumption of cheese are associated with milk containing enterotoxin prior to its pasteurization. Pasteurization destroys the pathogen but not its toxin.
Yersinia enterocolitica. Is a psychrotroph pathogen able to grow at 4˚C. In Feta cheese, it can survive as long as 5-30 days, depending on the initial population and the acidity of the product.
Coxiella burnetii. High temperature pasteurization (72˚C for 15 sec) destroys the pathogen, whereas low temperature pasteurization (63˚C for 30 min) is not always effective when microbial population is too high.
Furthermore, several potentially pathogenic microorganisms of less impor- tance could be found in milk, but they are killed or destroyed during manufactur- ing of Feta cheese (thermal treatment of milk, ripening, acidity, storage at refrigerator temperatures). Additionally, implementation of the prerequisite pro- grammes such as good manufacturing practices (GMPs) eliminates the possibility of milk contamination with various microbiological hazards.
4.1.1b. Chemical hazards.
The milk collected must be free from chemical contaminants that are able to inhibit microbial activity responsible for cheese production. Potential chemical hazards include antibiotics, pesticides, cleaners and sanitizers, heavy metals and toxins. Since presence of antibiotics is the most common chemical problem for the dairy industry, milk should be tested at the point of collection. Another poten- tial chemical hazard is mycotoxins, which are commonly associated with animal feed of low quality. Mould growth, especially Aspergillus spp., is related with the production of heat resistant aflatoxins, which are transmitted, through the animals, to the milk.
4.1.2. Pasteurization
The aim of performing pasteurization is to kill or inactivate milk pathogens.
Pasteurization is not capable of destroying microbial spores (such as Bacillus cereus or Clostridium perfringens spores) and heat resistant toxins (such as
Staphylococcus aureus enterotoxin). As viruses are sensitive to heat treatment, pasteurization is adequate for their elimination. Among milk pathogens Mycobacterium tuberculosis and Coxiella burnetii are considered the most heat- resistant (Mantis, 1993).
4.1.3. Post pasteurization process
The implementation of good manufacturing practices (GMP) could result in the exclusion of post-pasteurization milk recontamination. Salt, rennet or other sub- stances added may also contain microorganisms. Additionally, microbial hazards may be caused by equipment, as well as by the personnel. Microorganisms usu- ally implicated with post-pasteurization milk recontamination during processing are coliforms, Pseudomonas, Achromobacter, Proteus, moulds and yeasts. Poor hygienic conditions during production could even cause recontamination with pathogens, such as Salmonella, Shigella and Staphylococcus (Mantis, 1993).
Finally, salt quality and hygiene must be taken into consideration. The dry salt used should be free from harmful microorganisms while the brine is usually pas- teurized. The concentration of salt in insoluble matter shall not be exceeded 0.03% and it may not contain contaminants in amounts that may be harmful for the health of the consumer. The maximum limits that shall not be exceeded for copper, iron and lead are 0.002%, 0.01% and 0.0005%, respectively, as they affect biochemical reactions during cheese manufacturing (CAC, 2000; Anifantakis, 2004).