Sterility testing of a dispensing valve for aseptic function in food service applications

Manual dispensing equipment for aseptically packaged beverages or foods requires refrigeration of the product package following breakage of the hermetic seal. The food service industry would benefit greatly by implementing dispensing equipment that maintains the sterility of products after continued use without the need for refrigeration. The purpose of this study was to evaluate the ability of a valve, designed to operate aseptically and dispense products with or without refrigeration, to maintain the sterility of products following breakage of the hermetic seal and continued use simulating that of food service. Plastic packages equipped with the "aseptic" dispensing valve in a bag-in-box (BIB) format were aseptically filled with enrichment media with and without the addition of 1% cornstarch to simulate high- and low-viscosity products, respectively. BIBs filled with media were left uninoculated or inoculated (10(4) CFU/ml) with Staphylococcus aureus or Aspergillus niger on the interior of the spout 1 cm from the opening to simulate consumer misuse. Uninoculated and inoculated BIBs were stored at 25 degrees C, and media were dispensed once to twice per day, every day for up to 30 days to simulate food service use. Dispensates were observed for turbidity (compared with controls) indicating growth in BIBs and, thus, breach of sterility. Growth of samples taken aseptically through the package wall was checked microbiologically every 5 days by standard plating techniques. There was no breach in sterility until day 25. At day 25, uninoculated BIB (1 of 45 samples positive for growth) containing high-viscosity media and BIB inoculated with S. aureus (1 of 45 samples positive for growth) containing low-viscosity media became turbid. Viscosity and type of organism did not appear to influence the ability of the valve to maintain the sterility for > or =20 days. The results of this study provide evidence that the dispensing valve tested can maintain the sterility of aseptically filled products following initial dispensation and continued use under unrefrigerated conditions.