title: Evaluation of fermentation, drying, and/or high pressure processing on viability of Listeria monocytogenes, Escherichia coli O157:H7, Salmonella spp., and Trichinella spiralis in raw pork and Genoa salami.
abstract: We evaluated the effectiveness of fermentation, drying, and high pressure processing (HPP) to inactivate Listeria monocytogenes, Escherichia coli O157:H7, Salmonella spp., and Trichinella spiralis in Genoa salami produced with trichinae-infected pork. In addition, we evaluated the effectiveness of using HPP to inactivate T. spiralis larvae in pig masseter tissue. In part A, Genoa salami batter (about 2.3 log larvae/g) prepared with trichinae-infected pork was separately spiked with a five-strain cocktail of each microbial pathogen (about 7.0 log CFU/g) and subsequently fermented at 20 degrees C and about 90 to 95% RH for 6h and then at 27 degrees C and about 90 to 95% RH for 26 h before being dried at 20 degrees C and about 65 to 75% RH for 40 h and then at 17 degrees C and about 65 to 75% RH to/for: A) 25 d (65 mm casing), B) a target a(w) of 0.92 (65 mm casing), C) 35 d (105 mm casing), or D) a target a(w) of 0.94 (105 mm casing). Inactivation of L. monocytogenes, E. coli O157:H7, and Salmonella spp. after fermentation and drying ranged from about 1.1 to 1.3, about 1.1 to 2.2, and about 4.2 to 4.8 log CFU/g, respectively. After drying, three replicate salami samples in each of two trials for each treatment were subjected to HPP. Pressurization at 600 MPa or at 483 MPa for 1 to 12 min reduced pathogen numbers by an additional 1.6 to >or=5.0 (L. monocytogenes), 4.7 to >or=5.8 (E. coli O157:H7), and 1.9 to 2.4 (Salmonella)log CFU/g. After storage for 28 d at 4 degrees C, L. monocytogenes levels decreased by up to an additional 3.0 log CFU/g, whereas an additional decrease of up to about 1.1 and 1.7 log CFU/g was observed for E. coli O157:H7 and Salmonella, respectively. In contrast, in each of three trials, T. spiralis was inactivated (about 2.3 log larvae/g) in Genoa salami by all treatments of fermentation and drying as confirmed by both microscopy and mouse bioassays. In part B, in each of two trials, a 10-g portion (2 replicates per treatment) of infected pig masseter muscle (about 3.4 log larvae/g) were pressurized at 483 and 600 MPa for 0.5 to 5 min. T. spiralis was inactivated in pig masseter by all treatments of HPP as confirmed by both microscopy and mouse bioassays. Thus, fermentation and drying and/or HPP of contaminated Genoa salami or pork are effective for inactivating L. monocytogenes, E. coli O157:H7, Salmonella spp., and/or T. spiralis larvae. These data validate that HPP can be used as an alternate to curing for trichinae control and as a post-process intervention to meet performance standards and/or compliance guidelines for the three microbial pathogens evaluated herein.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Microbial Food Safety Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Anna C S
authors.initials: AC
authors.lastname: Porto-Fett
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Call
authors.forename: Bradley E
authors.initials: BE
authors.lastname: Shoyer
authors.forename: Dolores E
authors.initials: DE
authors.lastname: Hill
authors.forename: Claudette
authors.initials: C
authors.lastname: Pshebniski
authors.forename: George J
authors.initials: GJ
authors.lastname: Cocoma
authors.forename: John B
authors.initials: JB
authors.lastname: Luchansky
mesh_terms: D000818:Animals; D018407:Bacterial Physiological Phenomena; D003890:Desiccation; D019453:Escherichia coli O157 / Q000502:physiology; D005285:Fermentation; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D016266:Food Parasitology; D008089:Listeria monocytogenes / Q000502:physiology; D008460:Meat / Q000382:microbiology; D008461:Meat Products / Q000382:microbiology; D050296:Microbial Viability; D011312:Pressure; D012475:Salmonella / Q000502:physiology; D013552:Swine; D017160:Trichinella spiralis / Q000502:physiology*