Conversations in Microbiology

by Tracey Botes

Based on the five principles of Good Laboratory Selecting Practice (GLSP), you have confidently selected one of the forty-six registered SANAS laboratories to perform your microbiological analyses:

Principle 1: Select an accredited laboratory (SANS 17025)
Principle 2: Visit/inspect your selected laboratory
Principle 3: Laboratory methods accredited
Principle 4: Budget testing in accordance with a testing programme
Principle 5: Good service

But you are asking:
“What do I do NOW?”
“What do I test?”
“When do I test?”
“What do I test for?”

The small steps you are about to take will empower you to interact with your selected laboratory knowledgeably. This will enable you to understand the laboratory’s requirements and ensure the laboratory meets your requirements. Many customers, that require microbiological testing, feel they are quite ignorant when it comes interacting with the laboratory manager with respect to microbiological testing. Furthermore, it does not put the customer at ease that some laboratory managers do not have the expertise to assist with their requirements, are not willing to assist with the potential client without them committing to some kind of contract, nor will they offer this assistance without a cost.

Unless you are a microbiologist or have experience in the micro field, it can be quite daunting to ask “What samples do I test?”, “What do I test for?”, “How much sample to you need?”, “How often should I test”, ”How must I prepare my samples”, to just give you a few examples. Can you imagine how daunting it must be if you do not know what questions to ask? So let me recommend a few questions that you must ask the laboratory manager when you call your selected laboratory for the first time. In addition, let me recommend some answers you should receive from the laboratory manager (who knows what they are doing). Let the conversation begin....

[Setting the scene]

Potential retail supplier in Gauteng that manufactures 30 varieties of ready-to-eat pasta meals, which are fixed portions, in pre-packed containers that can be heated conventionally in an oven or in the microwave....

RING RING....ring ring (Telephone call made by above customer to a leading microbiological laboratory in SA)

Knowledgeable, experienced, friendly laboratory manager: Good day sir, how may I assist you?

Ignorant customer: I manufacture ready-to-eat pasta meals and am busy negotiating supplying one of SA’s leading retailers and I need to test the products microbiologically. Please can guide me on the procedure to prepare, deliver and test the samples?

Lab Manager: Thank you for enquiry! Firstly, do you have a testing schedule, which includes the tests required and the testing intervals?

Customer: I was asked the same question by the retailer, and I do not. What is this testing schedule? The
retailer has supplied me with their microbiological testing requirements, but this is Greek to me!

Lab Manager: No problem, let me give you a bit of information and then we can assist you with this schedule. I need to know the following from you in order to guide you further:

1. Your product is a high-risk product? And according to legislation guidelines and minimal requirements of the supplier, you would be required to test the product according to your predetermined testing schedule that should meet the following requirements:
a. All products variants should be tested over a specified time cycle e.g. 3 month interval and then the cycle will repeat over the year in order to trend repeated test results. For example, if you have 30 variants you shall be required to test all of those variants over the time period specified. Such trending enables one to evaluate the influence of seasons, staff, busy periods of the year, raw materials and any other changes that may occur during the year and that could influence the microbiological populations.

b. Raw materials, line samples and finished product testing need to be incorporated into this schedule. And one must not forget environmental testing, but that we can discussed at a later stage.

c. Whether all batches of the products manufactured need to be tested may be a requirement of your customer and should be discussed with them. Remember this schedule also needs to meet your budget for microbiological testing.

d. The schedule shall have to depict daily, weekly and/or monthly testing as per point a-c.

2. Do you have variants of the meals? How many? The answer to this question shall enable you to determine the number of samples you should able test per day/week/month as per your budget.

Customer: Thank you, and no, I do not have a testing schedule, but from the information you have just given me I can easily draw one up. There are 30 variants of the meals consisting of pasta with either bechamel, plain cream, tomato or tomato and chilli base. To these base meals we add varieties of chicken, bacon, beef or vegetarian sauces and cheese. Depending on the cost of your analyses, I will either send in all 30 samples per week, fortnightly or monthly. Thus I will ensure that all samples are tested at least monthly.

Lab Manager: Based on those quantities of samples I will provide a quotation and a discount structure....


Customer: Yes that would be great, the cost of microbiological testing is not costed into our manufacturing costs nor the retail pricing. I do believe this testing to be an important part of my food safety programme, however, it cannot bankrupt me!

Lab Manager: Sir, I shall provide the best pricing I can based on the quantities you have given me. Just remember we offer a support service in the form of technical expertise should you have queries regarding your results, free of charge as part of your service to you.

Customer: Fantastic! So what samples should I send to you? How much of each sample, and tell me more about the environmental testing?

Lab Manager: Let me answer each question separately:

1. What samples should you send me?
You need to work into your testing schedule both raw material and finished product samples. Namely, any ingredients you buy-in to prepare and which forms part of the finished product needs to be tested. These samples can be done less frequently over the schedule as you should not accept any of these materials without completed laboratory reports from your suppliers. You are just randomly testing your supplier’s products to ensure that they are testing and that the results you obtain concur with those of the laboratory reports already supplied. Finished products are the final packed products as they would be found in the retailers’ refrigerators.

2. How much of each sample should I send?
Raw materials are generally delivered in bulk, and the lab should generally only require about 100g to perform extensive testing. Raw materials need to sampled aseptically into sterile containers, such as whirlpack bags or specimen containers. Finished products, however, should be submitted as the total product as they would be found in the retailers refrigerators for resale.

3. Environmental testing?
This testing includes analysing samples from the environment namely swabs of surfaces and hand, air in various parts of the factory by means of air plates and water samples. Environmental samples can either be taken by yourself, after one of our staff members has trained you in the technique or we can send one of our staff out to you to perform the analyses for you. Both options will provide you with the tools (swabs, buffers, airplates and water sample containers), however, an additional cost will be incurred when we send our hygiene auditors to perform the task for you.

Customer: How often do I need to do the environmental testing?

Lab Manager: It is recommended to do this analyses at least monthly according to a predetermined schedule. Swabs should be taken after cleaning as this analyses attempts to assess the efficacy of your cleaning regimes. It takes into account both the effectiveness of your cleaning team and the chemicals being used to clean your facility. Air plates and water samples can be taken at the same time. The number of airplates and water samples taken will depend on the size of your factory and the number of taps in your facility. You should concentrate on food contact surfaces as well as your high care area when performing the environmental analyses. Other areas of concern may be drains and cooling units, however, this can be discussed further once one of our hygiene auditors have assessed your facility.

Customer: Brilliant! It seems you have the solutions to most of my testing queries. So how do I get these samples to you?

Lab Manager: If you decide to sample the food samples yourself, you must remember that you need to take them aseptically, and store them in the refrigerator until submission. Transportation of the samples must ensure that this cold chain is not broken, so transport in refrigerated vehicles or in cooler boxes with ice bricks would be essential. The samples should also reach the laboratory and be tested within 24 hours of the samples be taken.
Thus you have two options: either our driver can collect your samples or you can deliver the samples to our laboratory in the above manner. Either way, by informing us 24 hours in advance we shall ensure that either the drivers are sent to collect your samples or that your driver is delivering the samples – nevertheless the laboratory shall be ready to analyse you samples.

Customer: I may make use of both options, as I have drivers you can deliver the food samples weekly and then when your hygiene auditors perform the environmental analyses on my facility, they can collect samples for analyses too.

Laboratory Manager: I shall inform the hygiene auditors of your requirements and get one of them to call you and set up a meeting within the next day or two so that you can get your schedule going. I will send you a quotation this afternoon then? What....


Customer: Great, that will give me time to finalise my schedule within the next few days so that when your auditor meets with me I can provide him with the plan and discuss the way forward. I look forward to hearing from you later and forward to meeting with your hygiene auditor, thanks and cheers...


Laboratory Manager: Sir, Sir...what analyses (tests) should be performed on your samples?

...Click...silence from receiving handset (phone put down by customer)

This conversation is what typically should take place when you are conversing with a “Knowledgeable, experienced, friendly laboratory manager”. Telephonically most of your questions can be answered and if they cannot, you should consider calling another laboratory. Regarding the pertinent question of “What to test for?”, you shall just have to wait for the next article in this series....

Remember small steps and you will MAKE SENSE OUT OF MICRO....


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