Purpose: In order to reduce time to result to as short as 3 h, we developed a new qPCR-based method using the GeneDisc® PCR based technology from Pall Corporation for relative quantification of TAB contamination in filterable samples.
Methods: Briefly, 105 sugar samples including superfine sugar, cane sugar and glucose syrup, were spiked with the four major TAB spoilers (A. acidoterrestris, A. acidophilus, A. cycloheptanicus, A. herbarius). The sample sizes were comprised between 10 and 200 g. Artificially contaminated samples were diluted with distilled water and filtered through polycarbonate 0.4 µm. After direct lysis on the filter, qPCR analyses were performed using the GeneDisc Plate TAB Spoilage on DNA extract which could be optionally concentrated with the Nanosep® centrifugal device 30K. This method was also tested on naturally contaminated maltodextrine samples collected before and after micro-filtration from a sugar industry.
Results: Whatever the sample size and the spiking dose, Ct values obtained with the DNA ranges and the cells ranges from pure culture and spiked sugar samples were very close, demonstrating that the method was reproducible and linear between 100 and 10,000 bacteria/sample. Applied to naturally contaminated maltodextrin samples, this method enabled to monitor the micro-filtration efficiency by showing a 4-log reduction in Alicyclobacillus spp. between filtrate and inlet while none of the four TAB major spoilers was detected.
Significance: With this GeneDisc method, fruit juice and ingredients producers can now increase their profitability by implementing early and rapid in-process controls and checking efficacy of their TAB contamination reduction countermeasures.