A technical guidance, published by GMA, identifies the seven main control measures for the control of Salmonella in low moisture foods.  One key control measure includes minimization of cross-contamination, which can occur during processing or post-processing.  Proper cleaning and sanitation is vital to ensure uncontaminated low moisture foods do not become contaminated post-lethality.  When dealing with this category of foods the introduction of moisture can enhance the growth of pathogens, exponentially increasing the issue.  This limits the use of conventional wet clean and sanitation and only permits the use of controlled wet clean or dry cleaning in these processing areas.  It is important to understand how we can implement these Salmonella control measures effectively on low moisture food processing equipment and in facilities.

This is especially true in the case of products such as peanut butter and other nut butters, where we have seen numerous outbreaks and recalls.  In both the 2006-2007 and 2012 outbreaks, lack of sanitary control was documented, which likely propagated the issue.  An inspection conducted in September and October of 2012 noted the absence of records documenting the cleaning of production equipment.  Under FSMA regulations, if documentation does not exist, there is no proof that it was actually completed.

The difficulty that arose for these companies is the lack of validated and published dry cleaning and sanitation methods that can be used on processing equipment.  To help fill this knowledge gap, scientists at the Institute for Food Safety and Health undertook a study to investigate the efficacy of a cleaning (hot oil) and sanitation (isopropanol-based sanitizer) procedure to decontaminate pilot-scale processing lines contaminated with Salmonella.

Researchers inoculated peanut butter with a 4 serovar Salmonella cocktail and circulated it throughout the lines to fully contaminate the system.  The peanut butter was removed and lines were circulated with hot oil for up to 2 h.  Following the hot oil clean, 60% isopropanol (with and without added quaternary ammonium compounds) was circulated for 1 h.  Product samples were taken of the peanut butter and hot oil as well as environmental swabs from various food-contact locations within the processing lines.  Samples were enumerated for Salmonella.

Non-significant reductions were found using the hot oil circulation alone, although it did aid in the removal of residual peanut butter from within the processing lines.  This is important as you cannot sanitize a dirty surface.  Both of the isopropanol based sanitizers investigated were able to provide significant reductions in Salmonella as there were no detected Salmonella in environmental samples (<0.16 log CFU/cm2). These data suggest that a two-step hot oil clean followed by an alcohol-based sanitizer may eliminate pathogens from contaminated processing equipment.

Pictured: E. Grasso-Kelley conducting an isopropanol-based sanitizer trial on the nut butter processing lines in the Institute for Food Safety and Health’s BSL-3 BioContainment Pilot Plant.

Pictured: L. Halik collecting peanut butter samples to determine initial contamination levels of Salmonella within the nut butter processing lines in the Institute for Food Safety and Health’s BSL-3 BioContainment Pilot Plant.