High pressure processing during drying of fermented sausages can enhance safety and reduce time required to produce a dry fermented product

Citation

Balamurugan, S., Gemmell, C., Lau, A.T.Y., Arvaj, L., Strange, P., Gao, A., Barbut, S. (2020). High pressure processing during drying of fermented sausages can enhance safety and reduce time required to produce a dry fermented product. Food Control, [online] 113 http://dx.doi.org/10.1016/j.foodcont.2020.107224

Plain language summary

Dry fermented sausages (DFS) rely on a combination of ingredients, fermentation, and drying for pathogen control. However, this might not always provide the mandated 5 log reduction of Escherichia coli O157:H7, and would require a 25 day extended period of drying to achieve the required pathogen inactivation. This extended drying in most cases results in a product that is extremely dry and unacceptable for consumption. Therefore, a non-thermal intervention that can achieve the 5-log pathogen inactivation without the need for extended drying, meanwhile preserve the product quality would be very useful. A study was designed to examine the effectiveness of using high-pressure processing (HPP) during the drying of the fermented sausages to achieve the highest inactivation of E. coli O157:H7. Sausages containing a five-strain cocktail of E. coli O157:H7 at 107 CFU/g, manufactured using industry standard production processes, were subjected to HPP at 600 MPa for 3 min after fermentation and at different times during drying. Changes in inoculated E. coli O157:H7 and physicochemical properties of HPP treated sausages were monitored. Results indicate that meat processors can incorporate HPP without undertaking any significant modification to their fermentation and dry curing process to produce a shelf-stable product and achieve the mandated 5-log E. coli O157:H7 reduction within 10 to 12 days, which is a significant reduction in the DFS production time.

Abstract

Dry fermented sausages (DFS) rely on a combination of ingredients, fermentation, and drying for pathogen control. However, this might not always provide the mandated 5-log Escherichia coli O157:H7 reduction. High-pressure processing (HPP) has been successfully used to inactivate pathogens in ready-to-eat (RTE) foods, however, different food ingredients and physicochemical properties of foods protect pathogens against high-pressure (HP) inactivation. The present study examined the effectiveness of using HPP during the drying of fermented sausages to achieve the highest inactivation of E. coli O157:H7 and its recovery during storage at 4 °C. Sausages containing a five-strain cocktail of E. coli O157:H7 at 107 CFU/g were manufactured and subjected to HPP at 600 MPa for 3 min after fermentation and at different times during drying. Changes in inoculated E. coli O157:H7 and added starter culture bacteria counts and physicochemical properties of the sausages at differing time points in drying subjected to HPP were compared to their respective controls. A 1.6-log CFU/g inactivation of E. coli O157:H7 was observed in sausages that had a aw and MPr of 0.95 and 2.22, respectively, following fermentation and maturation and prior to drying (day 5). However, pressure treatment of these sausages enhanced E. coli O157:H7 inactivation by 4.8-log CFU/g, resulting in an overall 6.4-log inactivation. After 7 days of drying, when the aw and MPr of the sausages fell to 0.85 and 1.35, respectively, E. coli O157:H7 inactivation due to HPP was only 2.2 logs. E. coli O157:H7 inactivation due to HPP was further reduced as the sausages continued to dry. High-pressure treatment did not significantly affect the starter culture bacterial population. Examination of HP treated sausages stored at 4 °C revealed that E. coli O157:H7 could be recovered a week into storage, but the numbers were not significantly (P = 0.0742) different from those in sausages right after HP treatment. E. coli O157:H7 was not recovered from any pressure-treated sausage thereafter in weeks 2, 3, and 4 of storage at 4 °C. These results suggest that HPP could be successfully used in conjunction with fermentation and drying to reduce the time required to achieve a 5-log E. coli O157:H7 inactivation and is most effective when HP treatments are applied prior to the fermented sausages reaching a aw of ≤0.90 or MPr in the range of 1.9–2.3.

Publication date

2020-07-01

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