Blown pack spoilage (BPS) is a major issue for the beef industry. Etiological agents of BPS involve members of a group of Clostridium species, including Clostridium estertheticum which has the ability to produce gas, mostly carbon dioxide, under anaerobic psychotrophic growth conditions. This spore-forming bacterium grows slowly under laboratory conditions, and it can take up to 3 months to produce a workable culture. These characteristics have limited the study of this commercially challenging bacterium. Consequently information on this bacterium is limited and no effective controls are currently available to confidently detect and manage this production risk. In this study the complete genome of C. estertheticum DSM 8809 was determined by SMRT® sequencing. The genome consists of a circular chromosome of 4.7 Mbp along with a single plasmid carrying a potential tellurite resistance gene tehB and a Tn3-like resolvase-encoding gene tnpR. The genome sequence was searched for central metabolic pathways that would support its biochemical profile and several enzymes contributing to this phenotype were identified. Several putative antibiotic/biocide/metal resistance-encoding genes and virulence factors were also identified in the genome, a feature that requires further research. The availability of the genome sequence will provide a basic blueprint from which to develop valuable biomarkers that could support and improve the detection and control of this bacterium along the beef production chain.
A set of real-time PCR methods for the detection of C. estertheticum, C. gasigenes and C. ruminantium, the causative agents of blown pack spoilage (BPS) in vacuum packaged beef, was developed. Robust validation of the sensitivity and specificity was carried out in the three matrices (beef meat drip, wet environmental swabs and dry environmental swabs) as encountered in our testing laboratory and against Clostridium strains (n=76) and non-Clostridium strains (n=36). It was possible to detect 4-5 spores per ml for C. estertheticum, 2 spores per ml for C. gasigenes and 8 spores per ml for C. ruminantium, without the need for enrichment of the samples. This high sensitivity is particularly important for the beef sector, not just for testing spoiled product but also in the early detection of contaminated beef and in validation of sporicidal cleaning procedures for critical pieces of equipment such as the vacuum packaging machine, which have the potential to contaminate large volumes of product.
Active (anti-microbial) packaging was prepared using three different formulations; Auranta FV; Inbac-MDA and sodium octanoate at two concentrations (2.5 and 3.5 times their minimum inhibitory concentration (MIC, the lowest concentration that will inhibit the visible growth of the organisms) against Clostridium estertheticum, DSMZ 8809). Inoculated beef samples were packaged using the active packaging and monitored for 100 days storage at 2 °C for blown pack spoilage. The time to the onset of blown pack spoilage was significantly (p < 0.01) increased using Auranta FV and sodium octanoate (caprylic acid sodium salt) at both concentrations. Moreover, sodium octanoate packs had significantly (p < 0.01) delayed blown pack spoilage as compared to Auranta FV. It was therefore concluded that Auranta FV or sodium octanoate, incorporated into the packaging materials used for vacuum packaged beef, would inhibit blown pack spoilage and in the case of the latter, well beyond the 42 days storage period currently required for beef primals.
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Accepted ArticleThis article is protected by copyright. All rights reserved.Significance and Impact of the study: This study adds to our growing understanding of blown pack spoilage of vacuum packaged beef primals and suggests that rapid chilling of vacuum packaged beef primals is not a control option for the beef industry. The results suggest that neither eliminating the heat shrinkage step or rapid chilling of vacuum packaged beef, retard the time to blown pack spoilage.
AbstractThe aim of this study was to investigate if rapid slurry chilling would retard or prevent blown pack spoilage (BPS) of vacuum packaged beef primals. Beef primals were inoculated with Clostridium estertheticum subspp. estertheticum (DSMZ 8809), C. estertheticum subspp.laramenise (DSMZ 14864) and C. gasigenes (DSMZ 12272) and vacuum packaged with and without heat shrinkage (90°C for 3 seconds). These packs were then subject to immediate chilling in an ice slurry or using conventional blast chilling systems and stored at 2°C for up to 100 days. The onset and progress of BPS was monitored using the following scale; 0 -no gas bubbles in drip; 1 -gas bubbles in drip; 2 -loss of vacuum; 3 -"blown"; 4 -presence of sufficient gas inside the packs to produce pack distension and 5 -tightly stretched, "overblown" packs/ packs leaking. Rapid slurry chilling (as compared to conventional chilling) did not significantly affect (P > 0.05) the time to the onset or progress of BPS. It was therefore concluded that rapid chilling of vacuum packaged beef primals, using an ice slurry system, may not be used as a control intervention to prevent or retard blown pack spoilage.
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