In 1998, the presence of Salmonella spp. in dry cereals led to one company initiating a large and costly product recall.


Ten years later, the same company had to repeat the process when the same strain of Salmonella spp. was again identified in a product. In 2001, the almond industry experienced a major setback when a heat resistant strain of Salmonella Enteritidis Phage Type 30 was found in its product. In these cases, the foodstuffs had previously been thought to have insufficient water activity (aw) for there to be any concern about microorganism contamination.

Subsequent research has shown that Salmonella can not only survive for long periods in dry foods but also that living in dryer environments increases the bacteria’s resistance to heat inactivation, the process typically used to make foods safe during processing. This discovery meant manufacturers needed to focus on ways to not only prevent contamination but also find ways to validate the steps that they take to ensure safety during production. These must include a step to greatly reduce the presence of Salmonella, should contamination occur.


Trade body, the Almond Board of California (ABC), quickly enlisted research groups to develop protocols for the validation of process control steps aimed at the reduction of pathogenic microorganisms on almonds. Understandably, companies were not keen to allow pathogenic organisms into their production facilities and so a surrogate organism had to be found for the studies. The surrogate had to replicate the characteristics of Salmonella Enteriditis PT30, especially resistance to low water activity and heat, but without being harmful to humans. It was determined Enterococcus faecium NRRL B-2354 could act as a suitable replacement.

The protocol developed by these studies is now widely accepted as the standard protocol for the validation of dry-heat processes (dry roast, brine and pre-wet dry roast, dry roast flavoring, and dry plasticizing) and moist air or steam processes for the pasteurization of almonds. The protocol is publicly available on the ABC’s website.

Food Safety Modernization Act (FSMA)

With the implementation of the FSMA, there is an increased focus on the validation of preventive controls for all products regulated by the US Food and Drug Administration (FDA). This includes food production environments where traditionally concern about pathogenic organisms has been minimal because of the low aw of the products. The recalls caused by Salmonella have clearly shown businesses they cannot afford to be complacent and should now look to validate their control processes for products including nuts, spices, cereals, milling, and dairy powder.

Global Supply Chains

The increased need for process validation relating to low aw products is not restricted to the US. Global supply chains means that many companies source their ingredients from countries all over the world and they must be certain the foodstuffs they import are safe before adding them to their products. This is especially true with spices where the majority are grown and processed internationally. Paprika, cumin, cardamom, basil, red pepper and black pepper, as well as other spices, have all been implicated in market recalls, with some being identified as the origin of illnesses caused by finished products. Because spices are agricultural products, they can be contaminated by environmental factors like soil, water and animals. In addition, they can be contaminated during handling or transportation and, in some instances, while drying, if allowed to dry naturally in the open air. At the same time, it is often preferable to not heat-treat these ingredients because this can cause a deterioration in their flavor.

When processing ingredients such as these, it is therefore important to have a validated kill step in the process because the raw spice will not undergo another process designed to reduce the level of microorganism activity.

Low Water Activity Services

SGS’s experts and laboratories in North Sioux City, South Dakota, USA, have considerable expertise in the field of process validation for low aw products. The company works with numerous clients in the confectionary, snack, milling, and nut sectors to design and perform robust process validation studies to confirm the critical times and temperatures needed for ovens, dry-roasters, and/or oil roasters to reduce the level of Salmonella spp., or a surrogate mimicking Salmonella, in their ingredients and finished products by at least 5 log CFU/g.

Our R&D team begins the development of a process validation study by looking at the clients’ production techniques and products. This will often involve a site visit and/or comprehensive information gathering undertaken with the client. Once our experts fully understand the individual factors involved in the client’s processes, they can identify the challenges involved in the process and product, allowing them to execute a successful validation.

Our North Sioux City facility works alongside other SGS laboratories around the world to expand our global capabilities and meet the needs of the spice industry and other low aw product processors. For example, laboratories in China and India are currently working with clients to provide the expertise to validate the effectiveness of their suppliers’ manufacturing processes at reducing the level of microorganisms in a product and ensuring only safe products reach consumers.

For the complete range of SGS services and support visit SGS Food Safety.

For further information, please contact:

Leslie Thompson-Strehlow, Ph.D.
SGS Agriculture, Food and Life
Senior Director, Research and Development
t: +1 605 232 7084