Session A1 Food Safety
Using a Biological Testing Laboratory Water and surface testing Validating the quality of water used to wash produce or incorporate into food Monitoring of food surface cleaning Food Testing Validation of the Food Safety Plan Shelf life testing Routine quality control of products Yeast and Mould, Standard Plate Counts, and E. coli Measurement of uncertainty
Water Testing The water quality is important, either as an ingredient, a spray or rinse during processing. Water used for food manufacturing should meet the Australian Drinking Water Guidelines (ADWG). Plate count and Coliforms appeared in the 2004 version of the ADWG but both these analyses were removed in the 2011 edition. There are no acceptable limits now for these analyses and they do not need to be performed.
Water Testing The only microbiological analyses now required are Faecal Coliforms and/or E. coli. The acceptable limit for both analyses is <1 cfu/100ml. There are some DA requirements that specify other analyses. Occasionally specific producers may be required to test for pathogens by local health authorities.
Food Surface Testing Performing bacterial testing of cleaned surfaces is the only decisive way to monitor this control point. Only test properly cleaned and disinfected surfaces that come in contact with food. Do not test door handles, walls, floors or any surface presently in use. A Standard Plate Count is all that is required. Be careful of the size of area you test. A small swab tip cannot pick up all the bacteria in a 100 cm 2 area. An acceptable Plate Count result for a properly cleaned and disinfected food contact surface is < 6 CFU/cm 2.
Validation of your Food Safety Program All food businesses are required to have a food safety program. Once this has been completed it has to be validated to prove it is effective in ensuring the provision of safe food. Laboratory testing is required to validate the established food safety program.
Validation of your Food Safety Program To validate a food safety program a set of analyses needs to be performed on the final product. These are primarily microbiological analyses as specified in the Food Standards Australia and New Zealand (FSANZ) documents "Food Standards Code 1.6.1 - Schedule 27 Microbiological limits in food" and, where applicable, the "Compendium of Microbiological Criteria for Food (October 2016)". Foods with a Use By or Best Before date require validation.
Validation of your Food Safety Program The validation of the food safety program will need to be repeated every 6 months to two years depending on the risk of the product and the target consumer. It should also be noted that if a significant change to a product recipe then revalidation the food safety program and the shelf life is required. Examples: possibly a change of an ingredient supplier addition of a risk ingredient a change in the target consumer to a high risk category infants, elderly or a health care facility
Food Standards Code - Standard 1.6.1 Standard 1.6.1 Schedule 27 Microbiological limits in food specifies microbiological standards for nominated foods or classes of foods. Foods listed in the standard must meet the prescribed microbiological limits at any stage of their manufacture or sale. Not all foods are specified in the standard e.g. processed fruit and vegetables, herbs and many spices, yoghurt, dairy desserts, pasteurised milk, beverages, cooked foods other than meat, sandwiches & rolls and mixed foods such as coleslaw and ready to eat meals.
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Bivalve molluscs that have undergone processing other than depuration Food Microorganism Samples c m M Listeria monocytogenes/25 g 5 0 0 Cereal based foods for infants Coliforms/g 5 2 <3 20 Salmonella/25 g 10 0 0 Powdered infant formula products Bacillus cereus/g 5 0 100 Coagulase-positive staphylococci/g 5 1 0 10 Powdered infant formula products with added lactic acid producing cultures Coliforms/g 5 2 <3 10 Salmonella/25 g 10 0 0 SPC/g 5 2 10 3 10 4 Bacillus cereus/g 5 0 100 Coagulase-positive staphylococci/g 5 1 0 10 Coliforms/g 5 2 <3 10 Salmonella/25 g 10 0 0 SPC/g 5 2 10 3 10 4 Pepper, paprika and cinnamon Salmonella/25g 5 0 0 Dried, chipped, dessicated coconut Salmonella/25 g 10 0 0 Cocoa powder Salmonella/25 g 5 0 0 Cultured seeds and grains (bean sprouts, alfalfa etc) Salmonella/25 g 5 0 0 Processed egg product Salmonella/25 g 5 0 0 Mineral water Escherichia coli/100 ml 5 0 0 Packaged water Escherichia coli/100 ml 5 0 0 Packaged ice Escherichia coli/100 ml 5 0 0
Validation of your Food Safety Program With regard to the Compendium of Microbiological Criteria for Food - there are three categories of analyses: spoilage organisms, indicator organisms and pathogens. Spoilage organisms are evaluated by the Mesophilic Aerobic Bacteria Count, which is also known as a Heterotrophic Plate Count, Standard Plate Count or Plate Count. Indicator organisms include Escherichia coli (E. coli) and Enterobacteriacae. Remember: Microorganisms are not evenly distributed throughout a food matrix.
All Bacteria Yeast & Mould Aerobic Non fastidious (SPC) Bacillus cereus Vibrio parahaemolyticus Listeria monocytogenes Staphylococcus Enterobacteriacae Coliforms Faecal Coliforms E. coli Campylobacter Clostridium perfringens Salmonella
<1,000 1,000 - <100,000 >100,000 <10,000 10,000 - <1,000,000 >1,000,000 <1,000,000 1,000,000 - <10,000,000 >10,000,000
>10,000 100 - <10,000 <100 >100 3 - <100 <3
Validation of your Food Safety Program With regard to the Compendium of Microbiological Criteria for Food - there are three categories of analyses: spoilage organisms, indicator organisms and pathogens. Spoilage organisms are evaluated by the Mesophilic Aerobic Bacteria, which is also known as a Heterotrophic Plate Count, Standard Plate Count or Plate Count. Indicator organisms include Escherichia coli (E. coli) and Enterobacteriacae. The list of food pathogens include Coagulase positive staphylococci, Clostridium perfringens, Bacillus cereus, Campylobacter, Salmonella, Listeria monocytogenes and Vibrio parahaemolyticus (applicable for seafood only).
Test Satisfactory CFU/gram Marginal CFU/gram Unsatisfactory CFU/gram Potentially Hazardous Pathogens Staphylococcus (coag +ve) <100 >100 to <1,000 >1,000 to <=10,000 >10,000 Clostridium perfringens <100 >100 to <1,000 Bacillus cereus <100 >100 to <1,000 Vibrio parahaemolyticus Campylobacter Salmonella Listeria monocytogenes (Can t grow in product) Listeria monocytogenes (Can grow in product) >1,000 to <=100,000 >1,000 to <=100,000 >100,000 >100,000 <3 >3 to <100 >100 to < 10,000 >=10,000 Not detected in 25 grams Not detected in 25 grams Not detected in 25 grams (* Detected & <100) Not detected in 25 grams Detected in 25 grams (* <100) Detected Detected (>= 100) Detected in 25 grams * Satisfactory if a Listericidal process has not been applied. * Marginal if a Listericidal process has been applied.
Shelf Life Validation The frequency for testing and the specific analyses performed at each testing episode should be determined by the food producer, not the laboratory. Solely using laboratory advice may lead to over testing and therefore increased expenses. It is important that food producers get advice from regulatory bodies and a number of different laboratories before they decide on an validation protocol.
Shelf Life Validation In our experience it is not necessary to test for spoilage, indicator and pathogenic microorganisms at every testing episode. This may vary depending on the shelf life period, storage conditions and food matrix. However, testing for all three groups is necessary at the start of any shelf life evaluation for two reasons. it validates the food safety program if there is a fail at the initial round of testing then the shelf life evaluation can be cancelled.
Shelf Life Validation The next issue is how long to run the shelf life laboratory testing? The last round of testing must not be the last day of the shelf life period. Rather, it should be approximately 10% - 25% past the expected end. At this final testing it is not necessary for spoilage microorganisms to be at acceptable levels but it is essential that indicator and pathogens are within acceptable limits.
Shelf Life Validation By proving that the food is still safe at 10% to 25% past the stated shelf life you can: allow for a degree of temperature abuse of products that may accelerate microbial growth. allow for the fact that the general public will often consume a product after its stated shelf life.
Shelf Life Validation The final and often contentious issue is how many times during the shelf life period it is necessary to test the product and what microorganisms should be evaluated at each testing episode. The number of times the product requires testing will vary depending on the shelf life period. In general, for shelf life periods under 10 days it would only be necessary to test three times: Day 0 and Final date plus 10% -25% for the full list of microorganisms; and at the Expected shelf life end date for spoilage and indicator organisms only. For longer periods you may need additional testing rounds, but again these would generally only be for spoilage and possibly indicator organisms.
Yeast and Mould Counts Yeast and Mould (fungal) are generally regarded as members of the spoilage organism group. However, there are no guidelines for result interpretation in any FSANZ document. Some customers of food producers may require this analysis to be performed. But the results are uninterpretable (except WQA or other specified non-fsanz guidelines).
Standard Plate Count Testing Some laboratories perform a Standard Plate Count (SPC) analysis using a Petrifilm or other method where the culture plates are incubated at 35/37 C for 2 days. This form of testing is in direct conflict to the FSANZ Food Standards Code and the Compendium of Microbiological Criteria for Food and therefore cannot be used to evaluate a SPC. The FSANZ documents specifically state that the SPC must be performed where the culture plates are incubated at 30 C for 3 days. Rarely do laboratory reports specify the SPC incubation conditions.
Standard Plate Count Testing These two methods are not equivalent and the 2 day @ 35/37 C version cannot be validated against the 3 day @ 30 C version. It is imperative that when you are testing a product against microbiological criteria according to FSANZ requirements that the Standard Plate Count be performed at 30 C for 3 days as this is a mandatory requirement. I have been advised by NATA that it is the food producers responsibility to advise the laboratory that they are using results to validate acceptance to the FSANZ guidelines and/or the Food Standards Code. Food producers have a right to hold a copy of all methods used by their laboratory and it is highly recommend that they do so unless it is clearly stated on the report that the SPC method meets the FSANZ requirements.
E. coli Testing There are numerous methods available for E. coli testing in foods. These include: presence/absence methods for detection in 0.1 gram or 1 gram. count methods with a LOD of <1, <2, <3 or <10 CFU/gram. A result of <10 CFU/gram is useless for ready to eat foods and most foods listed in the FSC where an acceptable result is <3 CFU/gram. Some commodities such as cheese, oysters, uncooked fermented meat have different limits for E. coli in Schedule 27 of the Food Standards Code. It is important that you know what limits of detection are required and communicate this to your laboratory service provider.
Directions to food processors to perform microbiological testing In some cases, food inspectors or health officers have directed producers to test foods which are not listed or covered in any FSANZ document. However, if there are no guidelines for acceptable limits for the analyses, what meaning has the results?. Any recommendation must provide: A list of the analyses required The acceptable limits for each analysis The reference for these criteria so it can be listed in the Food Safety Program manual This also applies to process water samples and compressed air samples.
Routine Quality Control of Products How frequently does laboratory testing need to be performed? There is no requirement to perform routine batch testing once the food safety program and shelf life have been validated. Some customers require laboratory reports to be supplied with each purchase. However, minimal routine testing (usually spoilage and possibly indicator bacteria) may alert producers to a developing problem.
Measurement of Uncertainty Every measurement is subject to some degree of uncertainty. Measurement uncertainties can come from a variety of sources and usually a combination of more than one. Such uncertainties can be estimated using statistical analysis of a set of measurements. All NATA accredited laboratories are required to determine the measurement of uncertainty (MU) for quantitative analyses. At this time qualitative analyses such as presence/absence testing (e.g. Salmonella/Listeria in 25 grams and E. coli/faecal coliforms in swabs) are not required to have MU estimates.
Measurement of Uncertainty ISO/IEC 17025, the standard to which every laboratory is NATA accredited requires procedures to estimate the uncertainty of their measurements. Furthermore, Section 5.10.3.1 c of the standard states test reports shall include information regarding MU when a customer instructs the laboratory to provide the information, when it is relevant to the validity or application of test results, or when it affects compliance to a specification limit. Measurement uncertainty reflects the range within which the true result lies at a stated level of probability (often 95%). It is different for each laboratory and within the laboratory it is a different value for each type of analysis. However, MU should not differ significantly between laboratories using the same technique for the same analysis.
Measurement of Uncertainty Let s presume for a specific test and sample we got a result of 50 and that this result had a MU range of 39 to 64. Basically this means that if we tested the same sample by the same test method 100 times, 95 times the result would be somewhere between 39 and the 64. Actual Result Lower MU Result Upper MU Result 50 39 64
Measurement of Uncertainty How do you interpret the measurement of uncertainty range results? Regulatory guidelines such as AS3666, Australian Drinking Water Guidelines, Food Standards Code and other documents either make no mention of MU or do not specifically state how a measurement of uncertainty result it should be interpreted. We, and NATA, recommend you use the diagram from Eurochem CITAC Guide (https://www.eurachem.org/images/stories/guides/pdf/quam2012_p1.pdf) describing how MU affects considerations of pass/fail.
Measurement of Uncertainty The diagram below, from page 32 of the Eurochem CITAC Guide, describes the relationship between MU and pass/fail to a specification. It should be noted that the true value can occur anywhere in the MU range estimated is not the mid value of the range ( ). 210 110 90 50 100 cfu/gram
Measurement of Uncertainty Until the applicable regulations and guidelines are reissued with clear statements on how the MU range is to be interpreted, the interpretation of the report should be based on the reported analysis results, not on the MU range if it is reported. However, it is up to each company to determine how they will evaluate MU results based on risk analysis.
Measurement of Uncertainty Would you call counts of 110 and 90 a fail if this was a food for a health care facility? Fail Pass 270 210 140 120 160 110 90 64 86 70 50 39 100 cfu/gram
Measurement of Uncertainty It must also be remembered that the interpretive comments on laboratory reports i.e. ticks or crosses, or statements of acceptability are generally based on the reported result and do not include consideration of MU estimates regardless of proximity of the reported result to specifications or compliance limits.
Measurement of Uncertainty It is a NATA requirement that MU be reported when results are to be compared to the a known guideline or standard. Make sure your laboratory is providing these results on the report and in an manner that is easily interpreted.
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