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High Pressure Processing of Natural, Organic, and Minimally Processed Peanut Butter


High pressure processing (HPP), a viable method for increasing food safety and shelf life of certain food products that experience no or minimal processing, should be considered as a potential technology for peanut butter and minimally processed organic foods. This proposed research will demonstrate for peanut butter the efficacy of HPP on eliminating Salmonella and improving shelf life without decreasing quality. Reductions in Salmonella in inoculated, HPP treated peanut butter samples will be measured by enumeration on both selective and recovery media. HPP is an acceptable process under current organic guidelines, and therefore is suitable for this investigation. Pyrosequencing technology will also be utilized on samples spiked with fecal organisms to simulate real-world conditions and to investigate the survival of species of ecological significance in peanut butter. Industrial scale units, using process optima identified at the pilot scale, will be used to prepare samples for sensory and shelf life studies.

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NON-TECHNICAL SUMMARY: Two recent peanut butter recalls that caused economic hardship on peanut processors and growers resulted from post-processing contamination by Salmonella. Minimally processed peanut butters, often organic products, have an even greater risk of microbial contamination in the finished product. The proposed research will demonstrate for peanut butter the efficacy of HPP, an acceptable process per current organic guidelines, on Salmonella elimination and impact on product quality and shelf life. This research will facilitate the continued development of a processing technology that will benefit organic agriculture, as well as peanut processing and HPP technology stakeholders, and can be applied to other organic products. The expected outcome is the determination of the parameters needed for the elimination of Salmonella in peanut butter using high pressure processing. The benefit is increased food safety and prevention of future outbreaks in peanut butter and related products.


APPROACH: A Stansted ISO Food Lab System will be used for conducting lethality studies on minimally processed peanut butter. The vessel pressure and temperature will be monitored during each run using the data acquisition system that reads the pressure transducer and thermocouples in the pressure vessel while tracking the time during the HPP cycle (compression, dwell and decompression). The processing fluid (liquid in contact with sample packaging) will be maintained at 25 C using the temperature control equipment consisting of a chiller, heat exchangers and thermocouples. A 5-strain cocktail of Salmonella strains will be inoculated into peanut butter samples. The samples will be subjected to different pressures and the D values (decimal reduction time)will be determined for each pressure selected. A shelf life study of organic peanut butter using pyrosequencing technology will be conducted to determine the significant populations of microorganisms surviving over time. Sensory and organoleptic properties of HPP treated minimally processed peanut butter will also be determined during the shelf life study.

Smith, David; Stratton, Jayne
University of Nebraska - Lincoln
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