Inactivation of Shiga Toxin-Producing Escherichia coli and Listeria monocytogenes within Plant versus Beef Burgers in Response to High Pressure Processing

Growth and survival of common spoilage and pathogenic bacteria in ground beef and plant-based meat analogues

To better understand the microbial quality and safety of plant-based meat analogues, this study investigated the changes of native microflora present in soy- and pea-based meat analogues (SBM and PBM) and compared them with ground beef (GB). SBM, PBM, and GB were also artificially inoculated with meat spoilage microorganisms, Pseudomonas fluorescens and Brochothrix thermosphacta, and pathogenic microorganisms, Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes; the fitness of these bacteria was evaluated during storage at refrigerated and/or abused temperatures. Results showed that the initial total aerobic plate count (APC), coliform, lactic acid bacteria (LAB), and mold/yeast (M/Y) counts for GB could be as high as 5.44, 2.90, 4.61, and 3.45 log CFU/g, while the highest initial APC, coliform, LAB, and M/Y counts found in SBM were 3.10, 2.00, 2.04, and 1.95 log CFU/g, and were 3.82, 2.51, 3.61, and 1.44 log CFU/g for PBM. The batch-to-batch differences in microbial counts were more significant in GB than in SBM and PBM. Despite the different initial concentrations, there was no difference among APC and LAB counts between the three meat types by the end of the 10-day 4 °C storage period, all approaching ca. 7.00 log CFU/g. Artificially-inoculated B. thermosphacta increased by 0.76, 1.58, and 0.96 log CFU/g in GB, PBM, and SBM respectively by the end of the refrigeration storage; P. fluorescens increased by 4.92, 3.00, and 0.40 log CFU/g in GB, PBM, and SBM respectively. Under refrigerated storage conditions, pathogenic bacteria did not change in GB and SBM. L. monocytogenes increased by 0.74 log in PBM during the 7-day storage at 4 °C. All three pathogens grew at abused storage temperatures, regardless of the meat type. Results indicated that plant-based meat could support the survival and even growth of spoilage and pathogenic microorganisms. Preventive controls are needed for ensuring the microbial quality and safety of plant-based meat analogues.

A systematic review of clean-label alternatives to synthetic additives in raw and processed meat with a special emphasis on high-pressure processing (2018-2021)

The meat industry is continuously facing challenges with food safety, and quality losses caused by thermal processing. This systematic review reports recent clean label approaches in high-pressure production of meat. A literature search was performed using Scopus, Web of Science, PubMed, and Springer databases for studies published in 2018-2021. In this regard, 69 articles were assessed out of 386 explored research articles in the identified stage. The findings indicate that most of the earlier work on high-pressure processing (HPP) focused on physicochemical and sensorial meat quality rather than providing nutritional aspects and clean-label solutions. However, few advanced studies report effective and innovative solutions to develop low salt/fat, and reduced nitrite for raw and cured meat products. HPP could help on increasing the shell life by five times in meat products; however, it depends on the formulation and packaging, etc. HPP can also preserve nutrients by using this non-thermal technology and reduce food waste as once the shelf life of products is known, it easily reduces the shrinkage in the marketplace. This review explores the latest trend of experimental research in high-pressure processing alone, or multi-hurdle techniques employed to increase the effect of clean-label ingredients for enhanced meat safety/quality.

Sensitivity of wild-type and rifampicin-resistant O157 and non-O157 Shiga toxin-producing Escherichia coli to elevated hydrostatic pressure and lactic acid in ground meat and meat homogenate

Various serogroups of Shiga toxin-producing Escherichia coli have been epidemiologically associated with foodborne disease episodes in the United States and around the globe, with E. coli O157: H7 as the dominant serogroup of public health concern. Serogroups other than O157 are currently associated with about 60% of Shiga toxin-producing E. coli related foodborne illness episodes. Current study evaluated sensitivity of the O157 and epidemiologically important non-O157 serogroups of the pathogen to elevated hydrostatic pressure and 1% lactic acid. Pressure intensity of 250 to 650 MPa were applied for 0 to 7 min for inactivation of strain mixtures of wild-type and rifampicin-resistant E. coli O157, as well as O26, O45, O103, O111, O121, and O145 serogroups and ATCC® 43895™ strain in ground meat and 10% meat homogenate. E. coli O157 were reduced (p < 0.05) from 6.86 ± 0.2 to 4.56 ± 0.1 log CFU/g when exposed to pressure of 650 MPa for 7 min. Corresponding reductions (p < 0.05) for non-O157 E. coli were from 6.98 ± 0.3 to 4.72 ± 0.1. The D-values at 650 MPa were 3.71 and 3.47 min for O157 and non-O157 serogroups, respectively. Presence of 1% lactic acid to a great extent augmented (p < 0.05) decontamination efficacy of the treatment in meat homogenate resulting in up to 5.6 and 6.0 log CFU/mL reductions for O157 and non-O157 serogroups, respectively. Among the tested serogroups, the wild-type and rifampicin-resistant phenotypes exhibited (p ≥ 0.05) comparable pressure sensitivity. Thus, these two phenotypes could be used interchangeably in validation studies. Our results also illustrate that, application of elevated hydrostatic pressure could be utilized for assuring safety of ground and non-intact meat products against various serogroups of Shiga toxin-producing E. coli. Addition of 1% lactic acid additionally provided industrially appreciable augmentation in efficacy of the pressure-based treatments.