Agricultural commodities are exposed to microbiological contamination in the field from wildlife that harbor pathogens. Despite the fact that low moisture foods do not support the growth of microorganisms, a small number of surviving bacteria is sufficient to cause a food born illness outbreak. This poses a risk in all products that are consumed raw most notably nuts, edible seeds, and spices.
Because the pathogen is present in low numbers and is not homogenously distributed, sample analysis is insufficient to guarantee the safety of a product. The decontamination of low moisture foods is challenging because dry heat is relatively inefficient and can cause scorching. Moist heat treatments on the other hand are more effective but can result in moisture pick up requiring a subsequent drying phase. The Napasol process exposes the product to saturated steam in a partial vacuum thus moisture pick up is minimal and no drying is necessary.
Improved surveillance and new regulatory measures have lead to the identification of recurring outbreaks. The subsequent product recalls have had far reaching consequences on the companies and brands associated with them as well as shaking consumer confidence in entire product sectors.
Food safety must be a top concern in the food industry and a substantial investment in pasteurization equipment is more than justified. Food operators are looking for new technologies to tackle this challenge and NAPASOL is offering solutions to insure the microbiological safety of their products.
Spices, seeds, herbs, teas, botanicals, dehydrated vegetables, and dry fruit are all exposed to environmental contaminants and often carry high microbiological loads. The food industry measures the quality of their ingredients against specifications which are becoming more and more stringent. Natural levels of contamination are usually too high to meet the required standards and a microbiological reduction step is necessary.
The NAPASOL process is very effective in reducing the microbiological load in all low moisture foods. Data collected from industrial runs show that in a significant number of lots microbial counts where above the maximum level defined in the specifications. Following pasteurization all microbiological loads were below target values across all products tested.
High total plate count and high levels of yeast and mould are indicative of poor hygiene and spoilage, but the greatest risk resides in the presence of pathogens such as Salmonella or E. coli which have been involved in multiple food born illness outbreaks. Guidance documents have been issued by GMA (Grocery Manufacturers Association) and ASTA (American Spice Trade Association) which recommend applying a validated thermal process or gas treatment that insures the elimination of Salmonella.
The pasteurization of almonds has been mandated since 2007 and has been very effective; since then almonds are the only nut that has not been subject to a product recall.
In order to validate a pasteurization process the product is first artificially inoculated with high levels of a target microorganism. After pasteurization, enumeration of the surviving organisms must show a 10’000 (4log) to 100’000 (5log) fold reduction. Based on the results of the validation conducted on the Napasol unit in 2006 the Technical expert review panel of the Almond Board of California confirmed that proof of principle was achieved for a 5log reduction for pasteurized almonds.
Over the last few years Napasol installations have been validated for other nuts and several varieties of seeds.
The control of insects in low moisture foods mobilizes a great deal of resources. Most commonly chemical fumigants are used, but heat treatments are an effective natural alternative. A trial was conducted with the Centre de Recherches Phoenicicoles Degueche in Tunisia who provided test the materials: dates infested with the Date Moth (Ectomyelois ceratoniae) at all stages of development. Dates cannot be pasteurized at elevated temperatures because of their high sugar content. The Napasol process killed all life form without affecting the quality of the product
Efficacy trials were also performed with spice mixes infested with the Cigarette Beetle (Lasioderma serricorne) and the Indian Mealmoth (Plodia interpunctella)
Sunflower seeds: very frequently high Coliform levels
Pumpkin seeds: very frequently high Total Bacterial Count, Enterobacteria and Coliform levels and occasionally high Mould levels.
Sesame seeds: very frequently high Total Bacterial Count, Enterobacteria and Coliform levels.
Walnuts: very frequently high Total Bacterial Count, Enterobacteria and Coliform levels and occasionally high Mould levels.
Pine nuts: very frequently high Total Bacterial Count, Enterobacteria and Coliform levels and occasionally high Mould and Yeast levels
Macadamia: very frequently high Mould and Enterobacteria levels and occasionally high Total Bacterial Count and Coliform levels.
Almonds: occasionally high Total Bacterial Count, Yeast, Enterobacteria and Coliform levels.
Dried apricots (organic): very frequently high Total Bacterial Count, occasionally high Yeast, Enterobacteria and Coliform levels.
Raisins: occasionally high Mould count