PART III PROCESS SAFETY
4. Principles of HACCP
4.3. Establishment of critical limits
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).
Establishment of critical limits is based on different sources of information and scientific knowledge. The major sources used to establish critical limits are liter- ature, Government and Federal Regulations or specialized scientists (Surak, 2002).
In order to establish the critical limits, critical factors/parameters concerning every CCP should be determined, as well as the boundaries out of which, the product can be characterized as dangerous and unsafe. A factor is critical if loss of its control leads to the loss of food safety control. Food safety assurance may require control of several factors for every CCP. Based on the hazard nature, three categories of critical limits can be distinguished: (i) critical limits of microbio- logical hazards, (ii) critical limits of chemical hazards, and (iii) critical limits of physical hazards.
Safety assurance of microbiological hazards involves the establishment of crit- ical limits, based on microbiological analysis. However, the use of traditional cul- tural techniques is not appropriate for controlling these hazards, because of their time consuming character. Additionally, low level of pathogen population is dif- ficult to identify using traditional techniques, while a more extensive examination increases the cost. Instead of traditional microbiological analysis, measurements of physical or chemical factors indicative of the microbiological safety of the product are used. In this case, the following Critical Limits for every CCP iden- tified in Feta cheese production were established.
Q1 Do preventative control measures exist?
Yes No Modify steps in the process or product Is control at this step necessary for safety? Yes
No Not a CCP Stop*
Q2 Is the step specifically designed to eliminate or reduce the likely occurrence of a hazard to an acceptable level? Yes No
Q3 Could contamination with identified hazard(s) occurs in excess of acceptable level(s) or could this increase to unacceptable levels?**
Yes No Not a CCP Stop*
Q4: Will a subsequent step eliminate identified hazard(s) or reduce likely occurrence to acceptable level(s)?**
Yes No Critical Control Point
(CPC) Not a CPC Stop*
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FIGURE2. Codex Alimentarius decision tree.
CCP in the Cheese manufacturing process, a case study105
Process step Possible Hazards Q1: Q2: Q3: Q4: CCP
Reception of milk M: pathogens, viruses
C: Antibiotics, hormones, toxins, heavy metals, Yes No Yes No CCP 1
sanitizers, additives
P: metal, pieces of glass, foreign objects Yes No Yes Yes / centrifugal
separation -filtering -
Pasteurization M: survival of heat-tolerant spores and toxins Yes Yes - - CCP 2
(or/and survival of pathogens – inadequate thermal treatment
Addition of LAB, rennet, CaCl2 M: growth of contamination microorganisms Yes No Yes Yes / ripening -
Curd handling M: growth of contamination microorganisms Yes No Yes Yes / ripening -
Salting M: growth of contamination microorganisms Yes No Yes Yes / ripening -
Ripening M: growth of contamination microorganisms Yes Yes - - CCP 3
Q1. Do control measures exist for the identified hazard? (no: not a CCP, yes: Q2).
Q2. Is this process step specifically designed to eliminate or reduce the likely occurrence of this identified hazard to an acceptable level? (No: Q3, Yes: CCP).
Q3. Could contamination with the identified hazard(s) occurs in excess of acceptable level(s) or increase to unacceptable level(s)? (No: not a CCP, Yes: Q4).
Q4. Will a subsequent step eliminate the identified hazard(s) or reduce its likely occurrence to an acceptable level(s)? (No: CCP, Yes: Not a CCP).
Key: M: microbiological, C: chemical, P: physical
4.3.1. Milk reception (CCP 1)
Milk supplied to the dairy must be tested for: i) milk acidity (pH) should be 6.65- 6.45, ii) presence of antibiotics (absence), iii) temperature (<4˚C), iv) periodi- cally, bacterial count (at 30˚C Total Viable Count (TVC) should be ≤106cells/ml of milk).
4.3.2. Pasteurization (CCP 2)
Thermal treatment at 68˚C for 10 min, periodical bacterial counts of milk sam- ples after pasteurization should be determined (at 30˚C TVC should be ≤105 cells/ml of milk).
4.3.3. Ripening (CCP 3)
Pre-ripening: takes place at 17-18˚C for 5-15 days. After this time, the pH of the product must be 4.6-4.7. ii) Ripening during storage occurs at refrigeration tem- perature (4˚C). It is legally defined that this period must be at least 2 months. The microbiological standards of the final product, as established by national and European legislation, are illustrated in Table 2.