Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products FSQ-588003-0104 Table of contents Preface Procedural Flow Chart Evaluation of customer requirements .3 Evaluation of customer requirements .4 Plant pre-requisites Commissioning Filling test with product .5 Test procedure Microbiological evaluation of end product (trial) Introduction Sampling procedure for the long term storage test .7 Rapid screening test for detection of severe failure .8 Pre-incubation of packages Incubation conditions Plating Microbiological evaluation 10 Long term storage test for ESL products .11 Pre-incubation of packages 11 Plating 11 Test evaluation 11 Documentation 12 Microbiological evaluation of end product (commercial production) 12 Sampling procedure 12 Microbiological evaluation .12 Filing of results 12 Acknowledgement 13 FSQ – 588003-0104 i Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Preface This document is intended to support the supply and installation of processing and filling equipment The document is supplied as a guideline only and is not intended to be prescriptive It presumes that all operating manuals as well as generally accepted good manufacturing practices are followed It shall not imply or constitute any kind of guarantee of the result of the testing nor shall it replace legally required methods concerning product safety and quality The scope of the document is concerned with the verification of microbiological performance only The result does not necessarily reflect the long term performance of the equipment, which is the cumulative result of many variable factors Prior to the verification of the microbiological performance the following events are a suggested sequence to be followed: FSQ – 588003-0104 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Procedural Flow Chart Evaluation of customer requirements Verification of plant pre-requisites Commissioning of equipment Filling tests with product – trial runs Sampling & product incubation Rapid screening test 100 samples minimum Long term storage test Sample size determined by pre-agreed target failure rate Pre-incubate samples 24-28 h @ 23°C- 25°C Incubation of samples at reference temperature for duration of shelf life Incubation of plates 24-28 h @ 23°C- 25°C Plating of samples, Incubation as at left, Evaluation of results of plating Evaluation of microbiological results Abort long-term storage test Continue Evaluation of test by comparison of actual failure rate with pre-agreed target rate Troubleshooting & root cause analysis FSQ – 588003-0104 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Evaluation of customer requirements It is the responsibility of the local Tetra Pak Market Company to fully evaluate the customer requirements, including appropriate legal requirements, for supply and performance of equipment and services This will form the basis for determining the scope of supply Plant pre-requisites Verification of the listed plant pre-requisites is recommended when: • Equipment is installed in an existing plant • A new product is developed • Key components are changed The following pre-requisites should be verified according to the generally accepted Good Manufacturing Practice for liquid food production/manufacturers specifications: • raw material quality • thermal process • CIP • utilities • environmental hygiene Commissioning Commissioning is the demonstration that the equipment, production line or plant performs as specified or agreed upon Commissioning should be carried out after equipment installation according to specifications and methods supplied by the respective Tetra Pak Business Unit The following tests are applicable: • “Water Test”(verifies the technical parameters of equipment performance) • Package Integrity Test The procedure for testing package integrity supplied by the relevant Tetra Pak Business Unit should be followed FSQ – 588003-0104 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Filling test with product The goal of the test is to evaluate the performance of the complete production line The expected target shelf life, storage temperature, detectable defect rate and method of evaluation should be the subject of the agreement between customer and Tetra Pak Market Company The requirements shall be in accordance with applicable local legislation Test procedure A filling test should consist of at least three separate runs with a CIP and disinfection between each run The duration of each run shall be agreed between the customer and Tetra Pak with a suggested minimum of at least hour Note that contamination related to run duration such as condensation and environmental effects may not be detected with a short run time Note: All test protocol shall be well documented for record purposes Raw material quality shall be verified prior to the test commencing to determine whether the raw material is suitable for processing FSQ – 588003-0104 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Microbiological evaluation of end product (trial) Introduction The following methods are recommended as Tetra Pak standard procedures, unless local legal requirements provide differently Statistical evaluation will be according to the defect rate initially agreed upon with reference to the table above The long term storage test is the reference test to determine the failure rate of the production line during the defined shelf-life of the product In addition it is recommended to conduct a rapid screening test in order to detect any severe recontamination by substandard cleaning or operational problems during production The following methods are applicable to all categories of chilled low-acid dairy products including: - Bactofugated milk - Micro-filtrated milk - High heat-treated milk (135 °C / 7% defect level) in a sample size of 100 packages, it is recommended that the long-term storage test be discontinued immediately Note: If a volume of 10 µl is used the dilution factor will be 100 in order to express the result in ml After adequate pre incubation usually the count will be > log to log7 / ml this corresponds to > log 3(1,000) to log (100,000) colonies per streak Less than 10 colonies in the streak should be regarded as negative FSQ – 588003-0104 10 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Long term storage test for ESL products Pre-incubation of packages The packages should be stored until the expiry date that has been defined as the target shelf life The storage temperature is the reference temperature that has been defined by legislation or by agreement The difference in temperature between layers of packages should not be more than +/-1 °C Packages should be stacked in a way that allows free circulation of air between packages Means to check and record the temperature during the storage must be used The decision to continue further depends on the result of the rapid screening test Plating The recommended method for evaluation of the target shelf life is streaking a volume of 10 µl on Standard Plate Count agar The method of application is a straight-line inoculation, beginning approximately mm from the edge of the plate and ending about mm from the opposite edge of the plate (see diagram below) Streak line 10 µl loop This is not a strict quantitative method but will show whether the sample is within the legal demands or not (e.g > 100 colonies on streak corresponds to > log cfu / ml which is normally the range of legal requirements (PMO, EC directive, Milk Hygiene Ordinance) If, however there is a strict demand on a quantitative result by the customer, either pour plating or the spiral plating technique is options The plates should be incubated at 23 °C - 25 °C for 72 hours for checking slow growing micro-organisms (coryneform, moulds etc.) It is recommended to check plates for growth also after 24 and 48 hours Microbiological evaluation of plates is carried out as previously described Test evaluation A defect in terms of a microbial failure must be defined, e.g.: • A total plate count greater than 20.000 to 50.000 cfu /ml depending on applicable legislation • A positive streak showing > 10 cfu’s is regarded as a failure • Where no legislation exists, a target failure rate should be the subject of agreement between customer and Tetra Pak The number of packages to be tested in total depends upon the pre-agreed acceptable percentage failure rate and should be statistically determined Refer to the table above Note: In case of failure, the test should only be repeated when troubleshooting has been performed, and the problem root cause identified and rectified Preferably the result from the rapid screening test from the first test run should be available before the second test run starts FSQ – 588003-0104 11 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Documentation All testing procedures need to be carefully documented for reference purposes The results need to be filed and interpreted by a microbiological specialist and the "commissioning team"(pre-agreed combination of joint group customer/TP) will decide if the production line is acceptable for commercial production Microbiological production) evaluation of end product (commercial This procedure could be applied in addition to the regular microbiological quality control carried out by the customer Sampling procedure When the results from the line performance test are acceptable and the commercial production starts, the sampling procedure will be switched to regular quality control The following sampling scheme could be implemented: Samples are taken every 30 to 60 minutes from each filler and the minimum number of samples to be drawn per hour as follows: Minimum samples / hour sample for rapid detection for severe failures sample for long term storage at reference temperature Microbiological evaluation The samples should be analysed according to the appropriate methodology described as described earlier Filing of results It is recommended that the results obtained in regular quality control be filed in a computer based data system, e.g spreadsheet software such as Microsoft Excel or compatible Should the failure rate deviate from the applicable internal standard level, a troubleshooting programme shall be considered including production step control until the failure rate is on the standard level again FSQ – 588003-0104 12 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Acknowledgement This document is has been created as a joint effort between the former Tetra Pak ESLAC group, Tetra Pak Research & Development and the Tetra Pak FiSQA-Group Grateful thanks are due to: Lennart Olbjer for his invaluable assistance with the statistics in this document The inclusion of relevant and user-friendly statistics plays a major role in the sampling and evaluation procedures FSQ – 588003-0104 13 (13) [...]... be available before the second test run starts FSQ – 588003-0104 11 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Documentation All testing procedures need to be carefully documented for reference purposes The results need to be filed and interpreted by a microbiological specialist and the "commissioning team"(pre-agreed combination of joint group customer/TP).. .Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Microbiological evaluation The plates are evaluated by growth / no growth where less than 10 colonies on the streaks or plate are considered as negative If there are 3 or more defective packages (> 7% defect level) in a sample size of 100 packages, it is recommended that... e.g spreadsheet software such as Microsoft Excel or compatible Should the failure rate deviate from the applicable internal standard level, a troubleshooting programme shall be considered including production step control until the failure rate is on the standard level again FSQ – 588003-0104 12 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled Dairy Products Acknowledgement... volume of 10 µl is used the dilution factor will be 100 in order to express the result in ml After adequate pre incubation usually the count will be > log 5 to log7 / ml this corresponds to > log 3(1,000) to log 5 (100,000) colonies per streak Less than 10 colonies in the streak should be regarded as negative FSQ – 588003-0104 10 (13) Procedures & Guidelines Guideline for Microbiological Evaluation of Chilled. .. technique is options The plates should be incubated at 23 °C - 25 °C for 72 hours for checking slow growing micro-organisms (coryneform, moulds etc.) It is recommended to check plates for growth also after 24 and 48 hours Microbiological evaluation of plates is carried out as previously described Test evaluation A defect in terms of a microbial failure must be defined, e.g.: • A total plate count greater... minutes from each filler and the minimum number of samples to be drawn per hour as follows: Minimum 2 samples / hour 1 sample for rapid detection for severe failures 1 sample for long term storage at reference temperature Microbiological evaluation The samples should be analysed according to the appropriate methodology described as described earlier Filing of results It is recommended that the results... stacked in a way that allows free circulation of air between packages Means to check and record the temperature during the storage must be used The decision to continue further depends on the result of the rapid screening test Plating The recommended method for evaluation of the target shelf life is streaking a volume of 10 µl on Standard Plate Count agar The method of application is a straight-line inoculation,... Microbiological Evaluation of Chilled Dairy Products Long term storage test for ESL products Pre-incubation of packages The packages should be stored until the expiry date that has been defined as the target shelf life The storage temperature is the reference temperature that has been defined by legislation or by agreement The difference in temperature between layers of packages should not be more than... group customer/TP) will decide if the production line is acceptable for commercial production Microbiological production) evaluation of end product (commercial This procedure could be applied in addition to the regular microbiological quality control carried out by the customer Sampling procedure When the results from the line performance test are acceptable and the commercial production starts, the... document is has been created as a joint effort between the former Tetra Pak ESLAC group, Tetra Pak Research & Development and the Tetra Pak FiSQA-Group Grateful thanks are due to: Lennart Olbjer for his invaluable assistance with the statistics in this document The inclusion of relevant and user-friendly statistics plays a major role in the sampling and evaluation procedures FSQ – 588003-0104 13 (13)