Microbial growth, communities and sensory characteristics of vacuum and modified atmosphere packaged lamb shoulders

Antilisterial and Antimicrobial Effect of Salvia officinalis Essential Oil in Beef Sous-Vide Meat during Storage

If food is contaminated with pathogens such as Listeria monocytogenes, improper cooking during sous-vide preparation can lead to foodborne illnesses. In this study, it was found that L. monocytogenes were inactivated with both heat and the essential oil of Salvia officinalis (sage EO) in beef tenderloin of the musculus psoas major that had undergone sous-vide processing. To determine whether the enhancement of the efficacy of heat treatment is prospective, L. monocytogenes and sage EO were mixed. Groups with L. monocytogenes alone and sage essential oil combined with L. monocytogenes and test groups without EO were established. The samples were vacuum-packed, inoculated with L. monocytogenes, and then cooked sous-vide for the predetermined duration at 50, 55, 60, or 65 °C. In both groups with sous-vide beef tenderloin, the total bacterial count, the coliforms bacterial count, and the amount of L. monocytogenes were assessed on days 0, 3, 6, 9, and 12. Over these days, the amounts of L. monocytogenes, coliform bacteria, and overall bacteria increased. The identification of bacterial strains in various days and categories was performed by MALDI-TOF mass spectrometry. The test group that was exposed to a temperature of 50 °C for 5 min had a higher overall bacterial count for each day that was assessed. Pseudomonas fragi and L. monocytogenes were the most isolated organisms from the test group and the treated group. To ensure the safety for the consumption of sous-vide beef tenderloin, it was found that the addition of natural antimicrobials could produce effective outcomes.

Molecular insights into quality and authentication of sheep meat from proteomics and metabolomics

Sheep meat (encompassing lamb, hogget and mutton) is an important source of animal protein in many countries, with a unique flavour and sensory profile compared to other red meats. Flavour, colour and texture are the key quality attributes contributing to consumer liking of sheep meat. Over the last decades, various factors from 'farm to fork', including production system (e.g., age, breed, feeding regimes, sex, pre-slaughter stress, and carcass suspension), post-mortem manipulation and processing (e.g., electrical stimulation, ageing, packaging types, and chilled and frozen storage) have been identified as influencing different aspects of sheep meat quality. However conventional meat-quality assessment tools are not able to elucidate the underlying mechanisms and pathways for quality variations. Advances in broad-based analytical techniques have offered opportunities to obtain deeper insights into the molecular changes of sheep meat which may become biomarkers for specific variations in quality traits and meat authenticity. This review provides an overview on how omics techniques, especially proteomics (including peptidomics) and metabolomics (including lipidomics and volatilomics) are applied to elucidate the variations in sheep meat quality, mainly in loin muscles, focusing on colour, texture and flavour, and as tools for authentication. SIGNIFICANCE: From this review, we observed that attempts have been made to utilise proteomics and metabolomics techniques on sheep meat products for elucidating pathways of quality variations due to various factors. For instance, the improvement of colour stability and tenderness could be associated with the changes to glycolysis, energy metabolism and endogenous antioxidant capacity. Several studies identify proteolysis as being important, but potentially conflicting for quality as the enhanced proteolysis improves tenderness and flavour, while reducing colour stability. The use of multiple analytical methods e.g., lipidomics, metabolomics, and volatilomics, detects a wider range of flavour precursors (including both water and lipid soluble compounds) that underlie the possible pathways for sheep meat flavour evolution. The technological advancement in omics (e.g., direct analysis-mass spectrometry) could make analysis of the proteins, lipids and metabolites in sheep meat routine, as well as enhance the confidence in quality determination and molecular-based assurance of meat authenticity.

Microbial spoilage mechanisms of vacuum-packed lamb meat: A review

Lamb meat is an important export commodity, however chilled vacuum-packed (VP) lamb has approximately half the shelf-life of beef under the same storage conditions. This makes the industry more vulnerable to financial losses due to long shipping times and unexpected spoilage. Understanding the spoilage mechanisms of chilled VP lamb in relation to VP beef is important for developing effective strategies to extend the shelf-life of lamb. This review has discussed various key factors (i.e., pH, fat, and presence of bone) that have effects on microbial spoilage of VP lamb contributing to its shorter shelf-life relative to VP beef. A range of bacterial organisms and their metabolisms in relevance to lamb spoilage are also discussed. The data gap in the literature regarding the potential mechanisms of spoilage in VP red meat is highlighted. This review has provided the current understanding of key factors affecting the shelf-life of VP lamb relative to VP beef. It has also identified key areas of research to further understand the spoilage mechanisms of VP lamb. These include investigating the potential influence of fat and bone (including bone marrow) on the shelf-life, as well as assessing changes in the meat metabolome as the spoilage microbial community is developing using an integrated approach. Such new knowledge would aid the development of effective approaches to extend the shelf-life of VP lamb.

Impact of Industrial Practices on the Microbial and Quality Attributes of Fresh Vacuum-Packed Lamb Joints

The impact of different industrial practices at lamb export abattoirs in Ireland on the microbial and quality attributes of fresh vacuum-packed (VP) lamb leg joints, including Clean Livestock Policy (CLP), fleece clipping, carcass chilling times and vacuum pack storage, at typical chill and retail display temperatures was investigated. Five separate slaughter batches of lamb (ranging in size from 38 to 60 lambs) were followed at two lamb export plants over a two-year period, accounting for seasonal variation. In general, fleece clipping resulted in significantly lower microbial contamination on the fleece than the use of CLP alone. Lamb from carcasses chilled for 24 h had significantly lower psychrophilic total viable counts and Brochothrix thermosphacta and pseudomonad counts than carcasses chilled for 72 h. Following vacuum-packed (VP) storage of meat from these carcasses at 1.7 ± 1.6 °C for 23 days in the meat plant followed by retail display at 3.9 ± 1.7 °C (up to day 50), the dominant microorganisms were lactic acid bacteria, Br. thermosphacta, Enterobacteriaceae and pseudomonads, and all had reached maximum population density by storage day 34. Aligned with this, after day 34, the quality of the raw meat samples also continued to deteriorate, with off-odours and colour changes developing. While the mean values for cooked meat eating quality attributes did not change significantly over the VP storage period, high variability in many attributes, including off-flavours and off-odours, were noted for lamb meat from all storage times, highlighting inconsistences in lamb quality within and between slaughter batches.

Effect of Pre-Slaughter Practises and Early Post-Mortem Interventions on Sheep Meat Tenderness and Its Impact on Microbial Status

Tenderness, together with flavour, is the main quality trait that defines consumer acceptance of sheep meat. The factors affecting tenderness can be grouped as those influenced before slaughter, in the early post-mortem intervention and, finally, during the aging period. These factors have been extensively studied with respect to tenderness, but the impact of early post-mortem interventions and subsequent aging on the microbial quality of the final products has not been broadly reviewed to date. In this review, the authors summarize the most recent knowledge on lamb meat tenderness management and how such practices may impact the final meat quality, especially its microbial status. The impacts of pre-slaughter factors (age, sex, diet, genotype and transport) and post-mortem interventions (chilling regime, electrical stimulation, or hanging method), are described and comprehensively discussed.

The pathogenic and spoilage bacteria associated with red meat and application of different approaches of high CO2 packaging to extend product shelf-life

With the fast-global development of packaging techniques, the potential antimicrobial effect of CO₂, as a safe, cheap and readily available gas, makes it the integral component for packaging of meat products. The associated spoilage and/or pathogenic bacteria on raw meat may respond in different ways to elevated CO₂ concentrations. The growth of some aerobic Gram-negative bacteria such as Pseudomonas spp. is significantly inhibited but some LAB bacteria may be allowed to grow faster and dominate the product. The antimicrobial efficacy of enriched CO₂ packaging is attributed to the rate of CO₂ solubility in the product which is itself affected by the level of headspace CO₂, product pH, temperature and the ratio of headspace gas to product (G:P). This review, first, explores the varied range of beef and sheep meat spoilage and pathogenic bacteria and the intrinsic and extrinsic parameters that may influence the pattern of microbial growth and meat spoilage rate during storage. Then, the antimicrobial mechanism of elevated CO₂ packaging will be discussed and the different approaches of achieving enriched CO₂ packaging i.e. the traditional technique of flushing a desired gas mixture and/or using the new commercially developed CO₂ emitters will then be compared in terms of their strengths, limitations and technical mode of action.

Effects of Peroxyacetic Acid Spray and Storage Temperature on the Microbiota and Sensory Properties of Vacuum-Packed Subprimal Cuts of Meat

We investigated the impact of peroxyacetic acid (PAA; 200 ppm) spray on the microbiota and shelf life of commercial, vacuum-packed beef stored at chiller temperatures. Ribeye cuts (n = 147) were collected from a local beef plant on the day of production for two consecutive days, with one set collected at the start of work with the PAA spray nozzles turned off (control) and during routine production with the PAA spray nozzles turned on (PAA) each day. Packs were stored at 4, 2, and -1°C for up to 34, 104, and 180 days and sampled at appropriate intervals for sensory assessment, microbial enumeration, and microbial profiling by 16S rRNA gene amplicon analysis. Treatment with PAA did not affect the initial meat pH, the initial numbers of total aerobes, lactic acid bacteria, or Enterobacteriaceae (P > 0.05) before storage; however, it delayed the onset of spoilage by 7, 21, and 54 days at 4, 2, and -1°C, respectively. Square-root models of the variation of growth rate with temperature indicated lactic acid bacteria grew faster and Enterobacteriaceae grew slower on PAA-treated than on untreated meat. Negative associations between pH and deterioration of meat during storage were observed for PAA-treated meat. During storage, the microbiota were primarily dominated by Carnobacterium and Lactobacillus/Lactococcus on control meat but by Leuconostoc on PAA-treated meat. Serratia, Yersinia, and Clostridium were identified by linear discriminant effect size analysis as biomarkers for control meat; Clostridium was found in high abundance in samples that had the highest spoilage scores.IMPORTANCE The findings of this study show that PAA solutions applied at low concentrations under commercial settings positively modulated the meat microbiota. It did not have bactericidal effects for beef subprimals with very low microbial loads. However, it differentially impacted the members of the microbiota, which resulted in delayed onset of spoilage of vacuum-packed beef subprimal stored at all three temperatures (4, 2, and -1°C). This differential impact could be through one or a combination of the following factors: favoring the growth of lactic acid bacteria, which may in turn exert a competitive exclusion that might be due to production of antimicrobial compounds such as organic acids and bacteriocins; exerting synergistic antimicrobial effects with low temperatures against members of Enterobacteriaceae; and direct or indirect inhibitory effects against members of the clostridia. These findings not only advance our understanding of the microbial ecology of vacuum-packed meat stored at chiller temperatures but also suggest that bacteriostatic concentrations of antimicrobial interventions can be explored for shelf-life extension.

Effects of spraying lactic acid and peroxyacetic acid on the quality and microbial community dynamics of vacuum skin-packaged chilled beef during storage

A long shelf life for fresh meat products is very important both to processors, retailers and consumers. In this work, the effect of repeat acid spraying on the shelf life of vacuum skin-packaged (VSP) chilled beef, as well as the quality and microbial community dynamics was evaluated. Carcasses were sprayed with 300 ppm peroxyacetic acid (PA) or 3% lactic acid (LA) three times during the chilling process, or one more time of LA spray before packaging (LLA). Quality, sensory attributes and microbial load of VSP beef during 32 days of storage at 4 °C were evaluated. The results showed that quality and sensory scores decreased over time for all treatments, but LLA treated samples were still above the rejection threshold at the end of the storage period. Moreover, the total volatile basic nitrogen value and the total viable counts were 15.0 mg/100 g and 7.2 log CFU/g for the control group, while acid treated groups remained below these two values until the end of the storage period. In particular LLA treated beef steaks exhibited the best preservation potential even at the end of storage. This is attributed to the reduction of Proteobacteria in LLA beef steaks shown by the bacterial diversity analysis via high-throughput sequencing, as well as the lower counts of B. thermosphacta and Enterobacteriaceae during storage. This indicates that LLA treatment has the potential to achieve a shelf life extension of VSP steaks without impacting on quality.

Risk Mitigation in a Meat Supply Chain with Options of Redirection

The aim of this paper is to present how a higher income can be achieved by developing a broader and more accurate planning framework and control perishability from stable to fork if it is possible to redirect the shipments in the case of increasing perishability dynamics or longer time delays on the roads. It also gives the answer to the question of how such a Supply Chain (SC) can be evaluated using Net Present Value (NPV) approach. The procedures include a real-time calculation and communication about the remaining shelf life (RSL) during transportation and other logistic manipulations from one chain node to another if the time to exceed the contractually stipulated Customer Remaining Shelf Life (CRSL) is distributed by known distribution. Planning and control on the skeleton of the extended material requirements planning (MRP) model are advised, where time delays and their impact on the CRSL can be easily calculated. The changes in the NPV at contractually stipulated CRSL are calculated dynamically in real-time. Smart devices, tracking temperature, humidity, and gas concentration enable such reports immediately after detecting a high probability that CRSL, as stipulated in a contract, will not be achieved, based on the known parameters of the exponential distribution of the remaining shelf life as a time to failure at each node of the graph. The model includes possibilities to deliver the meat to the local market or to the reverse logistics plants in the nodes of the remaining route, if the expected contractually stipulated CRSL becomes too high. On this way, shortening unnecessary routes further contributes to less pollution.

Effect of abattoir, livestock species and storage temperature on bacterial community dynamics and sensory properties of vacuum packaged red meat

Shelf life of red meat is influenced by a number of intrinsic and extrinsic factors making its prediction challenging. Here we investigated the influence of geographically distant abattoir facilities and storage temperature relevant to commercial supply chain on the shelf lives of vacuum packaged (VP) beef and lamb meat. Samples of VP beef and lamb were analysed for surface pH, total viable counts, lactic acid bacterial counts, sensory properties, and associated bacterial community using Illumina MiSeq based 16S rRNA gene amplicon sequencing over a period of >200 days. The consistent 0.41 pH unit difference between beef and lamb was found to have a profound effect on bacterial community diversity and composition, bacterial growth rates and the rate of loss of sensory quality. Though different community structures were derived from different abattoir source, bacterial growth rate and rate of sensory quality deterioration were found to be comparable for individual meat type. The greatest variation in rates was found resulting from storage temperature and livestock species themselves. Our findings indicate that bacterial growth and sensory quality loss are essentially predictable when considering their temperature dependency, however for successful meat export validation of shelf life predictive models is required due to stochastic variation in abattoir seeded bacterial populations.

Spoilage of Chilled Fresh Meat Products during Storage: A Quantitative Analysis of Literature Data

A literature search was performed on spoilage of fresh meat products by combining keyword query, text mining and expert elicitation. From the 258 collected studies, a quantitative analysis was first performed to identify the methods which are the most used to evaluate spoilage beside the preservation strategies suggested. In a second step focusing on a subset of 24 publications providing quantitative data on spoilage occurrence time, associations between spoilage occurrence time of meat products and specific spoilage indicators were investigated. The analysis especially focused on factors well represented in the 24 publications, i.e., gas packaging (O2 and CO2) and storage temperature. Relationships between spoilage occurrence and several microbiological indicators were also sought. The results point out possible advantages of removing dioxygen in packaging to delay spoilage occurrence, whereas, in the presence of dioxygen, the carbon dioxide proportion in the gas mixtures was shown to influence spoilage occurrence. The collected data clearly reveal a potentially protective role of lactic acid bacteria. Besides, while a spoilage role could be attributed to Pseudomonas spp., the growth of mesophilic aerobic microbes, Brochothrix spp. and Enterobacteriaceae seemed independent of spoilage occurrence time.

Volatile and non-volatile metabolite changes in 140-day stored vacuum packaged chilled beef and potential shelf life markers

During storage of vacuum packaged chilled beef (VPCB), lactic acid bacteria become the dominant microflora, facilitating an extended shelf life. However, at some point, (bio)chemical and organoleptic changes render the meat unacceptable. In this investigation we evaluated volatile and non-volatile metabolite changes in VPCB after 84-, 98-, 120- and 140-days storage at ~ - 1 °C. After 140-days storage, the sensory, volatile and non-volatile data did not indicate spoilage. Minimal changes in volatile signatures of collected weep and on raw and grilled steaks were measured. Changes in selected non-volatile components indicated increased proteolysis (free amino acids, carnosine) and changes in organic acids (lactic, succinic) and nucleotide metabolism. Rapid volatile profiling using proton transfer reaction mass spectrometry showed a clear progression of changes in selected compounds over the storage period. An increased concentration of ethanol and other compounds between 120 and 140 days, suggested that volatile changes may be a useful objective indicator of extended storage VPCB quality.

Effect of Carcass Chilling on the Palatability Traits and Safety of Fresh Red Meat

Chilling procedures have been widely used in livestock abattoirs since the development of refrigeration systems. The major criteria when applying chilling regimes is not only complying with regulations, but economic concerns, and also meat safety and quality assurance requirements. Given recent developments, an updated review is required to guide the industry to choose the best chilling method and to inspire the development of new approaches to chilling. Thus in this paper, the quality and microbial safety of beef, lamb, pork, venison, and bison resulting from different chilling treatments has been reviewed, as well as the underlying mechanism(s) for the different impacts on meat quality traits as a result of different chilling regimes. The effect of fast chilling on the tenderness of beef and lamb is a focus, as some new findings, have recently been reported, while multistep chilling is highlighted as it incorporates the advantages of fast chilling to reduce carcass weight loss, resulting in similar quality improvements as found with slow chilling. It is, suggested, that if spray chilling can be combined with the second phase of multi-step chilling, it will benefit the meat industry in terms of both meat quality and safety. Future studies should focus on combinations of chilling methods with new technologies, such as medium voltage electrical stimulation, muscle stretching, or ultrasound and so on, to move meat quality and safety to a new level.

Dynamics of Bacterial Communities of Lamb Meat Packaged in Air and Vacuum Pouch during Chilled Storage

In this study, the changes in microbial communities of lamb meat packaged in the air (plastic tray, PT) and in a vacuum pouch (VAC) were assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) during the storage at 4°C. For the PT lamb, the total viable count (TVC) was 10⁷ CFU/g on Day 5, and the dominated bacteria were Pseudomonas fragi, P. fluorescens, and Acinetobacter spp. For the VAC lamb, the TVC was 10⁷ CFU/g on Day 9, and the dominated bacteria were lactic acid bacteria, including Carnobacterium divergens, C. maltaromaticum, and Lactococcus piscium. One strain of Pseudomonas spp. also appeared in VAC lamb. The relative abundance of Enterobacteriaceae in VAC lamb was higher than that PT lamb, indicating a more important role of Enterobacteriaceae in spoilage for VAC lamb than that of PT lamb. The microbial compositions changed faster in the lamb stored in a PT than that stored in a VAC, and microbial community compositions of the late storage period were largely different from those of the early storage period for both the conditions. The findings of this study may guide improve the lamb hygiene and prolong the shelf life of the lamb.

Shelf life extension of vacuum packaged chilled beef in the Chinese supply chain. A feasibility study

Arbitrary microbiological limits or noticeable organoleptic decline are mainly used to define the shelf life of vacuum packaged chilled beef (VPCB). Excellent temperature control is critical to enable a long shelf life. The robustness of export supply chains was tested by sending Australian VPCB (striploins) to three Chinese destinations and a CONTROL (Brisbane, Australia) treatment (~-1 °C). Data loggers monitored temperature during storage and meat biochemistry (pH, color, weep), aerobic plate counts, lactic acid bacteria, total volatile basic nitrogen (TVB-N) and sensory changes were measured 84, 98, 120 and 140 days postslaughter. Temperature was generally well maintained and sensory scores were not indicative of spoilage. Microbial counts did not increase from 84 to 140 days, however TVB-N increased with time and was a better predictor of sensory attributes. TVB-N was below the limit of 15 mg/100 g in all CONTROL samples but most Chinese samples exceeded this value. This study demonstrated that extended shelf life is feasible with excellent temperature control.

Strain-Level Diversity Analysis of Pseudomonas fragi after In Situ Pangenome Reconstruction Shows Distinctive Spoilage-Associated Metabolic Traits Clearly Selected by Different Storage Conditions

Microbial spoilage of raw meat causes huge economic losses every year. An understanding of the microbial ecology associated with the spoilage and its dynamics during the refrigerated storage of meat can help in preventing and delaying the spoilage-related activities. The raw meat microbiota is usually complex, but only a few members will develop during storage and cause spoilage upon the pressure from several external factors, such as temperature and oxygen availability. We characterized the metagenome of beef packed aerobically or under vacuum during refrigerated storage to explore how different packaging conditions may influence the microbial composition and potential spoilage-associated activities. Different population dynamics and spoilage-associated genomic repertoires occurred in beef stored aerobically or in vacuum packaging. Moreover, the pangenomes of Pseudomonas fragi strains were extracted from metagenomes. We demonstrated the presence of specific, storage-driven strain-level profiles of Pseudomonas fragi, characterized by different gene repertoires and thus potentially able to act differently during meat spoilage. The results provide new knowledge on strain-level microbial ecology associated with meat spoilage and may be of value for future strategies of spoilage prevention and food waste reduction.IMPORTANCE This work provides insights on the mechanisms involved in raw beef spoilage during refrigerated storage and on the selective pressure exerted by the packaging conditions. We highlighted the presence of different microbial metagenomes during the spoilage of beef packaged aerobically or under vacuum. The packaging condition was able to select specific Pseudomonas fragi strains with distinctive genomic repertoires. This study may help in deciphering the behavior of different biomes directly in situ in food and in understanding the specific contribution of different strains to food spoilage.

Effect of abattoir and cut on variations in microbial communities of vacuum-packaged beef

This report builds on the earlier studies of the shelf-life of chilled Australian vacuum packaged (VP) beef primals (striploin and cube roll), products distinguished in the global marketplace for unusually long shelf-life. Notable findings in those studies were a shelf-life of at least 26weeks at -0.5°C, low microbial counts, and relatively high sensory scores. However, growth rates for total viable counts (TVC) and lactic acid bacteria (LAB) varied among the different abattoirs. The present study adds to these findings, by providing greater definition about temporal changes in bacterial communities using terminal restriction fragment length polymorphism (TRFLP) and clone library analyses of 16S ribosomal RNA (16S rRNA) gene, and measuring statistical associations among abattoir, beef cut, storage time and sensory attributes. Bacterial communities changed over time, with Carnobacterium spp. typically predominating (29-97%) at the end of storage. Variation in TRFLP profiles showed that different Carnobacterium strains predominated in different abattoirs, and that additional variation was due to the presence of other taxa typical of VP meat microbiomes. TRFLP-based community structure correlated significantly (P≤0.01) with sensorial characteristics, such as vacuum integrity, confinement odour, and intact pack appearance of beef. This study shows that Carnobacterium spp. predominate on extended shelf-life VP beef primals, while other taxa may produce subtle effects on shelf-life duration.

Exploring lot-to-lot variation in spoilage bacterial communities on commercial modified atmosphere packaged beef

Understanding the factors influencing meat bacterial communities is important as these communities are largely responsible for meat spoilage. The composition and structure of a bacterial community on a high-O₂ modified-atmosphere packaged beef product were examined after packaging, on the use-by date and two days after, to determine whether the communities at each stage were similar to those in samples taken from different production lots. Furthermore, we examined whether the taxa associated with product spoilage were distributed across production lots. Results from 16S rRNA amplicon sequencing showed that while the early samples harbored distinct bacterial communities, after 8-12 days storage at 6 °C the communities were similar to those in samples from different lots, comprising mainly of common meat spoilage bacteria Carnobacterium spp., Brochothrix spp., Leuconostoc spp. and Lactococcus spp. Interestingly, abundant operational taxonomic units associated with product spoilage were shared between the production lots, suggesting that the bacteria enable to spoil the product were constant contaminants in the production chain. A characteristic succession pattern and the distribution of common spoilage bacteria between lots suggest that both the packaging type and the initial community structure influenced the development of the spoilage bacterial community.

Characterization of volatile metabolites associated with confinement odour during the shelf-life of vacuum packed lamb meat under different storage conditions

Confinement odour was investigated. Volatiles were extracted directly from the pack, using solid phase microextraction and analysed by gas chromatography-mass spectrometry. Sensory evaluation and microbiological analysis of the meat surface were also performed. Commercial samples of vacuum packed lamb legs (n=85), from two meat processing plants, were kept for 7weeks at -1.5°C then at different regimes of temperature (-1.5 to +4°C) until 11, 12 or 13weeks. Persistent odour was observed in 66% of samples, confinement odour in 24% and no odour in 11%. Volatiles associated with confinement odour (3-methyl-butanal, 3-hydroxy-2-butanone and sulphur dioxide) corresponded with end/sub products of glucose fermentation and catabolism of amino acids by bacteria (all bacteria naturally found in meat and do not represent a risk to health). Confinement odour could indicate a stage at which the environment for bacteria growth is becoming favourable for the production of volatiles with strong odours that are noticed by the consumer.

Interstrain interactions between bacteria isolated from vacuum-packaged refrigerated beef

The formation of bacterial spoilage communities in food is influenced by both extrinsic and intrinsic environmental factors. Although many reports describe how these factors affect bacterial growth, much less is known about interactions among bacteria, which may influence community structure. This study investigated interactions among representative species of bacteria isolated from vacuum-packaged (VP) beef. Thirty-nine effectors and 20 target isolates were selected, representing 10 bacterial genera: Carnobacterium, Pseudomonas, Hafnia, Serratia, Yersinia, Rahnella, Brochothrix, Bacillus, Leuconostoc, and Staphylococcus. The influence of live effectors on growth of target isolates was measured by spot-lawn agar assay and also in liquid culture medium broth using live targets and effector cell-free supernatants. Inhibition on agar was quantified by diameter of inhibition zone and in broth by measuring detection time, growth rate, and maximum population density. A number of interactions were observed, with 28.6% of isolates inhibiting and 4.2% promoting growth. The majority of Pseudomonas isolates antagonized growth of approximately one-half of target isolates. Two Bacillus spp. each inhibited 16 targets. Among lactic acid bacteria (LAB), Carnobacterium maltaromaticum inhibited a wider range of isolates compared to other LAB. The majority of effector isolates enhancing target isolate growth were Gram-negative, including Pseudomonas spp. and Enterobacteriaceae. These findings markedly improve the understanding of potential interactions among spoilage bacteria, possibly leading to more mechanistic descriptions of bacterial community formation in VP beef and other foods.

Quality tracing in meat supply chains

The aim of this study was the development of a quality tracing model for vacuum-packed lamb that is applicable in different meat supply chains. Based on the development of relevant sensory parameters, the predictive model was developed by combining a linear primary model and the Arrhenius model as the secondary model. Then a process analysis was conducted to define general requirements for the implementation of the temperature-based model into a meat supply chain. The required hardware and software for continuous temperature monitoring were developed in order to use the model under practical conditions. Further on a decision support tool was elaborated in order to use the model as an effective tool in combination with the temperature monitoring equipment for the improvement of quality and storage management within the meat logistics network. Over the long term, this overall procedure will support the reduction of food waste and will improve the resources efficiency of food production.