How does pistachio validation work at Steripure?
Validation makes it possible to verify the effectiveness of our process in eliminating pathogenic bacteria such as Salmonella and to assess the logarithmic reduction.
What are the different steps in the validation process for pistachios?
1. Product inoculation with Salmonella in the laboratory
The validation process is conducted on a single batch of whole pistachios. We begin by taking a sample which we sterilize. This step ensures the process is carried out on a sterile basis. The sterilized sample is then sent to AQMC laboratory, where it is inoculated with Salmonella and then returned to us.
2 . Sample preparation
On the scheduled day, the Quality and R&D team at Steripure divides the contaminated sample into several portions and prepares them. Each portion is then placed into the individual chambers of the machine.
For each chamber:
- 3 samples are prepared, each contaminated with Salmonella.
- A data logger is attached to each sample to record temperature and time data.
👉 In total: 6 chambers, 18 identically prepared samples.
3. Loading the chambers before treatment
We begin filling the chambers with untreated/non-inoculated pistachios and place the contaminated samples inside. At the end of the loading process, each chamber contains 500 kg of pistachios and 3 contaminated samples.
4. Strategic placement
The test samples are placed at three levels within the chamber:
- Bottom
- Middle
- Top
This setup allows us to evaluate the effectiveness of the treatment throughout the entire chamber, including the coldest zones.
5. Start of the pasteurization cycle
Each chamber is then processed in the machine – the “Grande Statique” (GS) – for a 2-hour cycle.
6. Recovery and analysis
At the end of the cycle:
- The test samples are retrieved from the chambers, identified by their chamber number and position, and placed in sterile bags.
- The data loggers are handed over to the quality assistant to verify that the samples reached the targeted temperature and duration during the cycle.
The Quality teams then measure:
- Moisture content (Hu)
- Water activity (AW)
- These measurements are used to verify stability before and after treatment.
- The test samples are then sent back to AQMC laboratory for thorough microbiological analysis of each of the 18 samples.
- The comparison of contamination levels before and after treatment is used to calculate the logarithmic reduction.
- To finalize the study, Steripure and AQMC laboratory compile the data: on one side, the processing data for each cycle, and on the other, the microbiological results. This information becomes the final validation report, signed by both parties.
- AQMC then issues us a validation certificate, certifying that our process consistently achieves a 4.9-log reduction in Salmonella in pistachios.
