Chocolate, peanut butter and tahini have been recalled due to the presence of Salmonella in New Zealand and globally in recent times. Many of the affected products have resulted in widespread hospitalisation of consumers, predominantly in children who are generally more susceptible to salmonella infection.
Salmonella Risk in High Lipid, Low Water Activity Foods
These three products share characteristics including high fat and very low moisture content / water activity: aw. Although Salmonella is unable to grow in these conditions, some strains appear to be protected, allowing them to survive for long periods of storage. Most significantly these high fat low moisture products provide conditions for salmonella to survive in routine cooking conditions which effectively kills salmonella in other types of food:
Typically salmonella is killed instantaneously by cooking at 70°C
In high fat, low aw foods: chocolate, tahini and peanut butter; temperatures of 80°C for 220 minutes and 90°C for 50 minutes are not wholly effective at eliminating salmonella
Raw materials for these foods generally includes a roasting step which should eliminate salmonella.
However, finished products infected by salmonella are generally contaminated after the roasting process. No typical heat treatment thereafter will disinfect such products. These products are also often ready to eat, so no treatments are provided prior to consumption.
Controls to Manage Salmonella in Chocolate, Peanut Butter and Tahini
To manage salmonella risk, very good hygienic practices are required to prevent contamination of these foods after the roasting step. Managing salmonella in these products requires:
Validated heat treatment to prevent survival of salmonella in the roasting step
Good hygiene management after heat treatment until the product is packed. This includes:
Hygienic design & maintenance of the facilities and equipment
Controls on the movement and hygienic practices of staff moving into the high hygiene zone
Controls and disinfection procedures for the movement of materials and equipment into the high hygiene zone (including machinery & packaging)
Robust sanitation procedures for processing equipment and facilities
Cleaning verification activities, including monitoring the product and environment for salmonella
Where such products are sold as ingredients to other food processors, all products made using contaminated materials are also likely to be implicated in food recalls.
For businesses using tahini, chocolate or peanut butter products as ingredients, development of robust procurement procedures and relationships with your suppliers is recommended. Requesting Certificates of Analysis for each batch that include relevant parameters such as Salmonella may be appropriate.
The attached report Salmonella in High Lipid Foods produced by ESR for NZ Food Safety in 2010 provides more detail on this subject.
The MPI website details controls for “Imported Foods that Require Food Safety Clearance”. However of the three product types discussed here, only Crushed Sesame / Tahini has an import control for Salmonella.
The attached Food Notice: Requirements for Registered Food Importers and Imported Food for Sale specifies the controls for different food types in the Schedules.
