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Food Quality and Safety 
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Standard Operating Procedures for PPO
Propylene Oxide Facts about Dietary Safety

Pasteurization Technology

The Technical Expert Review Panel (TERP) comprised of almond scientific experts, is responsible for evaluating and approving the treatment processes that demonstrate effectiveness in achieving a reduction of possible contamination in almonds while not affecting their quality and sensory attributes.

Alternatively, the Food and Drug Administration (FDA) can evaluate treatment processes and make a determination on whether they deliver a process sufficient for use of the term pasteurization. FDA has approved oil roasting, blanching, steam processing and propylene oxide (PPO) processes as acceptable forms of pasteurization for almonds.

While the Action Plan standard for treated almonds is a minimum 4-log reduction, a number of technologies have already been identified which results in a 5-log reduction, and can be labeled as pasteurized – these include steam pasteurization, fumigation with propylene oxide (PPO), blanching and oil roasting.

Approved pasteurization methods:

  • Oil roasting and blanching: These traditional processes provide the necessary reduction in harmful bacteria while providing consumers with the same product they have come to know.
  • Steam processing: These treatments are surface treatments only. The steam treatments utilized by the industry meet USDA Organic Program standards, and protect the raw characteristics of the almonds. The short bursts of steam do not impact the nutritional integrity of the almond. These treatments do not “cook” proteins or destroy vitamins and minerals. The nutritional and sensory characteristics of the almonds remain unchanged when treated with steam.
  • Propylene oxide (PPO) treatment: PPO is also a surface treatment and has been approved for use on foods since 1958. It is widely used for a variety of foods such as other nuts, cocoa powder and spices. PPO is very effective at reducing harmful bacteria on almonds and poses no risk to consumers. In fact, PPO residue dissipates after treatment. The effectiveness and safety of this process was revalidated in July 2006, when PPO underwent a stringent re-registration process with the Environmental Protection Agency (EPA). The EPA confirmed that PPO poses no health risk. The treatment does not affect the nutritional and sensory characteristics of almonds.

All pasteurization technologies are first evaluated by the Almond Board of California's (ABC) Technical Expert Review Panel (TERP) for their ability to provide the appropriate pathogen log reduction. Then, almonds treated using accepted technologies are submitted to third party experts for sensory and quality evaluations.

Research is ongoing to identify new options for pasteurization such as steam, moist heat, other thermal processes and non-thermal treatments that will not adversely affect the characteristics of a “raw” almond. The development of additional pasteurization technologies that achieve a minimum 4-log reduction will also provide the almond industry with more tools to respond to individual and customer needs.

To access a summary of the current technology research, as well as the operating parameters for TERP accepted treatment processes, please contact the Almond Board of California at


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