Meat Surface Research Articles

Oil-in-water emulsions of geraniol and carvacrol improve the antibacterial activity of these compounds on raw goat meat surface during extended storage at 4 °C

Application of plant-based essential oils as antimicrobial agents has received considerable attention. However, these antimicrobial compounds undergo quick depletion due to various factors such as volatile nature, low-water solubility, and interactions with lipophilic food components. Therefore, to retain the antimicrobial efficacy of such compounds, the combination with an oil-in-water based emulsion system as a carrier can be a viable option. The current work focuses on the development of geraniol and carvacrol loaded oil-in-water emulsion-based coating solutions through ultrasonication approach. Medium chain triglyceride was used as the carrier oil, whereas Tween 80 and gum arabic were used as emulsifiers. The essential oils, geraniol, and carvacrol at ratios of 1:0, 2:1, 1:1, 1:2, and 0:1 (2.5% v/v) were used for the preparation of oil only, non-emulsion formulations and emulsion-based coating solutions, respectively. The emulsion-based coating solutions were characterized for mean particle diameter, polydispersity index, and ζ-potential. These coating solutions were also characterized for microstructural features using confocal laser scanning microscopy and transmission electron microscopy. Finally, the impact of the delivery system on antimicrobial evaporation of oil-only, non-emulsion formulation and emulsion-based coating solutions were assessed against Bacillus cereus MTCC 430 and Escherichia coli MTCC 443. The study showed that the emulsion-entrapped formulations could prolong the antimicrobial efficacy of geraniol and carvacrol till 9 day as compared to treatments performed with oil only, non-emulsion formulations on a goat meat model. Tween-80 and gum arabic stabilized emulsions could be used to extend antimicrobial efficacy of essential oils on solid food matrices.

Evaluation of an WPC edible film added with a cocktail of six lytic phages against foodborne pathogens such as enteropathogenic and Shigatoxigenic Escherichia coli

Active packaging materials with antimicrobial properties have gained significant interest over the last decade. Furthermore, phages are potentially useful as antimicrobial agents in food. Phage stability assays were conducted in the whey protein concentrate (WPC) matrix over 5 weeks of storage. In addition, the phages incorporated in the WPC matrix were characterized by their release from films into an aqueous system and solid food, as well as by their antimicrobial activity against pathogenic E. coli in a liquid medium and in meat at refrigerated, room and abusive temperatures. The results demonstrate that phages are highly stable in WPC films within 5 weeks of storage. Moreover, WPC films can release a significant number of phages into an aqueous system and onto a meat surface at similar concentrations. Phage-added films produced a significant reduction in E. coli cells to non-detectable levels in antimicrobial assays. Similar results, such as a complete inactivation achieved for DH5α and O157:H7 STEC strains, were obtained when antimicrobial assays were performed on meat. As a conclusion, the six-phage cocktail added into WPC films was highly stable, effectively released from films and proved highly effective as a biocontrol tool, though not under all the conditions evaluated.

Estimation of pathogenic exposure levels and associated baseline bio-risks in edible terrestrial snails (Achachatina marginata) sold in Nigerian markets

This research estimated the pathogenic exposure levels and associated baseline bio-risks in edible terrestrial snails ( Achachatina marginata ) sold in the Nigerian markets in an attempt to ascertain the probable contribution of contaminated snails to the burden of foodborne illnesses in Nigeria. Identification of bacterial pathogens in the edible snails was performed with phenotypic methods. Baseline probability (risk) of a case of illness caused by the identified pathogens was quantified with the United States FDA-iRisk version 4.0 stochastic software. Findings from this research revealed that there were gross contaminations of the meat surfaces of fresh snails (exposed foot of a snail) with bacterial indicators of hygiene [median viable (TAVC) and enterobacteria (TEC) counts = 7.23 log 10 CFU/g and 5.07 log 10 CFU/g respectively] and food safety [median presumptive Staphylococci (TSC) count = 4.71 log 10 CFU/g]. The unsafe profile of the meat surface was further confirmed by the presence of high concentration (exposure level) of coagulase-positive Staphylococci pathogen [median concentration = 4.17 log 10 CFU]. Unlike the meat surface, concentrations of haemolytic (group B) Enterococci pathogen isolated from the viscera of snails were insignificant [median concentration of pathogen = 0 log 10 CFU]. Therefore, snail meat surfaces were the main sources of significant risks to potential consumers. This probable significant health consequence was further corroborated by a predicted significant baseline risk which indicated that in the absence of adequate microbial mitigation protocols, 1750 potential human consumers above the age of 3 years were most likely to fall ill per 10000 potential consumers. Thus, there is a need for increased advocacy to ameliorate the baseline risks associated with edible fresh snails sold in Nigerian markets or exported to other markets around the world. Keywords: Bio-risk, Coagulase-positive Staphylococci , Group B Enterococci , FDA-iRisk software

Dietary essential oil mix improves oxidative stability and hygienic characteristic of lamb meat

Lamb meat hygiene and oxidation were considered in two groups of animals fed a diet with and without a mix of dill (Aneto graveolens L.), cinnamon bark (Cinnamomum Zeylanicum Blume) and eucalyptus (Eucalyptus globulus Labill.) essential oils. After 7 days of storage, a significant difference was observed on the Total Viable Count (TVC) of the meat surface (6.58 and 7.03 Log CFU/g for the meat from treated and untreated group, respectively), but not on the Enterobacteriaceae count (2.54 and 2.84 Log CFU/g). The effect on red meat color was evident after 7 days (redness values, 11.51 and 12.96 in untreated and treated group, respectively). The antioxidant effect of the essential oil mix was shown by the DPPH and ABTS assays, which revealed a higher antioxidant activity of the meat, and by the TBARs values, with lower levels observed in the meat of the supplemented group.

Nanoemulsion-loaded hydrogel coatings for inhibition of bacterial virulence and biofilm formation on solid surfaces

The indiscriminate use of antibiotics has led to the emergence of drug-resistant bacteria which has become one of the biggest challenges of the twenty-first century for the researchers to combat and in turn search for novel targets which could lead to the development of effective and sustainable therapies. Inhibition of biofilm formation and virulence of bacterial pathogens is an emerging approach to address the challenges related to bacterial infections. To suppress the virulence and biofilm formation by Escherichia coli O157:H7 (ECOH), we developed stable nanoemulsion (NE) of Gaultheria fragrantissima Wall. essential oil’s (EO) bioactive compounds, viz., eugenol (E-NE) and methyl salicylate (MS-NE) that showed significantly higher anti-biofilm and anti-virulence activities as compared to eugenol and methyl salicylate without affecting ECOH planktonic cell growth. Transcriptional analysis showed that E-NE and MS-NE reduced the expression of genes, including curli, type I fimbriae, Shiga-like toxins, quorum sensing, and ler-controlled toxins, which are needed for biofilm formation, pathogenicity, and attachment. E-NE and MS-NE loaded hydrogel coatings showed superior anti-biofilm activity against ECOH on glass, plastic and meat surfaces as compared to eugenol and methyl salicylate loaded coatings. Conclusively, NE-loaded hydrogel coatings could be used in combating ECOH infection on solid surfaces through anti-biofilm and anti-virulence strategies.

Carvacrol loaded halloysite coatings for antimicrobial food packaging applications

Abstract Antimicrobial thin film coatings that can be utilized in food packaging provide an effective approach to enhance food quality and safety. Here, the coating of polyethylene films with an antimicrobial thin film through a Layer-by-Layer (LbL) assembly is demonstrated. Halloysite nanotubes (HNTs) which are tubular clay nanoparticles were utilized for the encapsulation and sustained release of carvacrol, the active component of essential thyme oil. Antimicrobial thin film coatings of 225 nm thickness were prepared by the deposition of ten bilayers of chitosan (CHI) and carvacrol loaded HNTs onto the polyethylene surface by spray LbL. Coated films reduced the viability of a food pathogen, Aeromonas hydrophila by 85% and the aerobic count on chicken meat surfaces by 48%. Furthermore, coated film surfaces demonstrated lower bacterial attachment compared to control polyethylene films indicating their antibiofilm character. Composed of natural and safe components, antimicrobial coatings developed in this study provide a novel and effective approach to obtain antimicrobial food packaging materials that can greatly contribute to food safety.

FTIR spectroscopy studies of high pressure-induced changes in pork macromolecular structure

High pressure processing (HPP) allows to extend the shelf life of meat and meat products by pressurization of microorganisms. At the same time, HPP can induce changes of the protein structure. Vacuum-packed pork chops were HPP-treated at 300, 600 MPa for 1 or 15 min. Samples of raw, cooked and HPP-treated meat muscles and juice were analysed to evaluate the structure of macromolecules. HPP caused visible discolouration of pork chops; hence, the colour of pork meat surface was tested. The lightness (colour component L*) was directly proportional to the applied pressure, probably due to the increased protein denaturation by high pressure. Pork meat muscle and juice samples were analysed with FTIR high-throughput screening (FTIR HTS-XT, Bruker, Germany). FTIR spectra of meat muscle showed pressure and time dependent decrease of numbers of α-structures and β-sheet conformations of proteins. In spectra of cooked meat muscle, the number of α-helix structures and β-sheets, identified at 1682 cm−1, was the lowest. The decrease of intensities of absorption bands at 1655 cm−1 and 1454 cm−1, assigned to the collagen type I, was directly proportional to the pressure and treatment time, thus, suggesting the release of denatured collagen into meat juice. In spectra of meat released juice, changes of Amide band shapes, frequencies and the minimum between the Amide I and II bands, compared to those of control, indicated changes in the protein secondary structure and the ratio of α-helix to β-sheet. In spectra of all juice samples an absorption band at 1394 cm−1 assigned to CH3 groups in proteins Amide I and lipids was detected. The intensities of bands at 1394 and 1124 cm−1 increased proportionally to the increase of pressure and treatment time. It was shown that the absorption band at 1394 cm−1 can be used as a marker for assessment of the HPP induced changes in proteins. This study showed that HPP-induced changes in protein structure can be evaluated by FTIR high-throughput screening of pork meat muscles as well as released juice. FTIR analyses of the meat released juice is significantly faster and simpler method than analyses of muscle. This approach is especially effective for quick assessment of large sample sets and search of the most effective meat HPP treatment mode.

Diffusion of mycotoxins and secondary metabolites in dry-cured meat products

The aim of this study was to analyse the pattern and diffusion capacity of secondary metabolites produced by ochratoxin A (OTA)- and cyclopiazonic acid (CPA)-producing mould species commonly growing in dry-cured meat products. Dry-fermented sausage and dry-cured ham pieces were inoculated with Penicillium nordicum, Penicillium verrucosum and Penillium griseofulvum, and incubated at 20 °C for 15 days at 94% relative humidity. After incubation, the samples were divided into 3 subsamples: A (0–1 cm; including the fungal colony), B (1–2 cm) and C (2–3 cm). The subsamples were analysed with a UHPLC-Q trap-MS method capable of detecting and quantifying 33 mycotoxins at values around 1 μg/kg. Mould strains produced from 5 to 12 secondary metabolites on the surface of the meat products. Besides, a higher number of metabolites was encountered in dry-fermented sausage than in dry-cured ham. Some of the fungal secondary metabolites diffused from the surface (layer A) into the inner core of meat products (layers B and C) contaminating the products up to 3 cm depth. In general, the concentration of fungal metabolites able to diffuse generally decreased as they diffused inward; while other compounds remained on the surface. This supposes a problem for the industry given that the removal of mouldy surface of dry-cured meats seems not to protect consumers’ health.

Совершенствование технологии посола ферментированных продуктов из мяса маралов

The research features the effect of salting methods on the physical, chemical, and biochemical properties of maral (Siberian red deer) meat in the manufacture of fermented products. Meat salting is considered to be the most significant process in the formation of organoleptic and qualitative properties of whole muscle meat products. The authors measured the changes in the mass fraction of moisture in the products. After that they studied the effect of dry, wet, and mixed salting on mass transfer processes in the maral meat according to the fermentation period. The study revealed the dynamic pattern in pH and water-binding capacity of meat during salting, as well as the differences in the colloidal-chemical state of protein substances. The best results were achieved in mixed salting samples after short-term massaging. This method changed the degree of hydration and the solubility of proteins, which improved the structural and mechanical properties. The experiment showed that fermented products require preliminary mechanical processing of meat in massagers, which makes it possible to soften raw materials, accelerate the redistribution of saline substances in meat, and intensify biochemical processes. According to the present research, the best results were achieved by mixed salting when the salting mixture was applied to the meat surface. The mixture contained the starting cultures of microorganisms “Bitec LC-30”. The meat was aged under dry salting at 0–4 °C for 24 hours and then in the pickle. This changed the rheological properties of the meat and resulted in a gentler consistency of the fermented products. The proposed technology of maral meat salting increases the efficiency of meat fermentation processes while improving the quality of manufactured products and their organoleptic properties.

Effect of the MS Bacteriophage on STEC O157:H7 Populations in Beef

ObjectivesThis research was conducted to evaluate the killing efficiency of the Mello-Shebs (MS) O157:H7 bacteriophage against three strains of STEC O157:H7 in vitro and on beef surface under aerobic conditions.Materials and MethodsKilling efficiency of bacteriophage MS O157:H7 (University of Nevada, Reno– Meat Science library) was tested against three strains including ATCC® 43895 (stx1 and stx2 positive), ATCC® 43894 (stx1 and stx2 positive), and Micreos 128. To determine the efficiency of the phage in vitro, each strain of STEC O157:H7 was incubated at 37°C overnight and then diluted to achieve 1500 CFU/mL. Subsequently, 0.1 mL of this dilution for each strain was plated onto 1.6% LB agar plates. The experimental plates received 0.1 mL of phage solution at 108 PFU/ml, in quadruplicate. The plates were incubated at 37°C for 24 h and the resulting colonies were counted and compared to controls to determine killing efficiency of the phage against each STEC strain. To evaluate the effect of bacteriophage application on beef, m. cutaneous trunci (rose meat, IMPS 194) were sourced from a USDA inspected facility, fabricated into 100 cm2 and randomly assigned to either control or treatment groups. Samples acclimated to 7°C were inoculated with a STEC cocktail to result in a contamination level of approximately 3 log CFU/cm2 on meat surfaces after swabbing. After bacterial attachment for 30 min at 7°C, control samples were treated with sterile buffered peptone water (BPW) and experimental samples were treated with the phage solution at 108 PFU/ml. After dwelling for 1 h at 7°C, samples were swabbed and the resulting 1 mL was thoroughly vortexed, serial diluted, and plated onto LB plates. The plates were incubated at 37°C for 24 h and the resulting colonies were counted. Data was analyzed as a completely randomized design in SAS. Means were separated by LSMEANS and differences were indicated by using DIFF functions.ResultsIn vitro killing efficiency of bacteriophage MS O157:H7 was determined to be 85%, 98.89%, and 97.16% for ATCC® 43894, ATCC® 43895, and Micreos 128 strains, respectively. On beef, bacteriophage application significantly decreased STEC loads by 0.626 log CFU/cm2 (P = 0.0184, SEM = 0.21).ConclusionBacteriophage MS-O157:H7 applications as an antimicrobial on beef reduces STEC O157:H7 populations on contaminated beef. Commercial applications of this bacteriophage may improve STEC control in meat products, however, having this treatment combined with other interventions such as organic acids or UV light treatment may increase the killing efficiency of STEC populations, warranting further research to determine industry applicability.

Relationship Between Relative Humidity and Moisture Loss in Dry Aged Beef

ObjectivesThe objective of this research was to assess the impact of low relative humidity (RH) during dry aging on moisture and trim loss, tenderness, and flavor. The working hypothesis was that rapid drying would create a hard crust on the meat surface that could reduce moisture release over time, thereby reducing weight loss, enhancing tenderness (by retaining more water), and altering flavor when compared to dry aging at higher RH.Materials and MethodsSixteen USDA low Choice boneless strip loins were assigned to one of the four aging treatments: vacuum (Wet), dry-aging at 50% RH (RH50), dry-aging at 70% RH (RH70), or dry-aging at 85% RH (RH85). Loins were placed in individual dry aging chambers and aged for 42 d at 1°C and 2200 RPM fan speed. A computerized dry aging system was designed and built that is capable of measuring and precisely controlling RH (± 1%), temperature (± 0.5°C), and air velocity (± 0.1m/s). The chambers have built-in weighing scales that can continuously monitor weight loss (± 5 g). All measured data can be saved on the connected computer in intervals of 1 s. After aging, loins were trimmed of dehydrated fat/lean and evaluated for trim loss. Loins were fabricated anterior to posterior, cut into steaks and evaluated for water activity (aw), Warner-Bratzler shear force (WBSF), and by sensory analysis to detect flavor differences via triangle test (n = 32). Rate of moisture loss was analyzed as a split plot design with treatment as the main plot and days of aging as the repeated measures. All the other data were analyzed as a completely randomized design. Chamber (loin) was considered the experimental unit. Data were analyzed using the PROC GLIMMIX procedure of SAS with α = 0.05.ResultsThere was a treatment by day interaction for rate of moisture loss (P 0.05). Wet-aged samples had lower moisture loss (P 0.05), trim loss (P > 0.05) and yield (P > 0.05). Steaks from dry-aging treatments had lower aw values (P 0.05). There was a location effect for aw values. Samples from the ventral region of the steak had lower aw values than samples from the central and dorsal region (P 0.05). Results from the triangle test indicated that there was a detectable difference between Wet and RH70 (P 0.05).ConclusionResults suggest that no such case hardening effect occurs when dry aging beef, even when the RH was kept very low (50%) and the total weight loss was 23%. Instead, the lower RH results in more rapid moisture loss at the beginning of the aging process without significantly affecting the total amount of moisture loss. Trim loss, yield, tenderness and flavor were not affected by relative humidity during dry aging.

Efficieny of Phage Intervention Against Salmonella in Meat and Poultry Processing

ObjectivesPathogen Reduction, Hazard Analysis, and Critical Control Point systems final rule mandates establishments to seek and adopt antimicrobial interventions that can help in reducing the prevalence and most probable number of Salmonella in their meat and poultry products. Bacteriophages can aid in this challenge, as they can invade and kill specific target pathogenic bacteria on food products. Effective kill by phages relies on the appropriate phage application technique. Correct dose, good distribution on the food surface area, and adequate dwell time are key factors which influence phage-bacteria contact and thereby phage efficacy. This study determined the efficacy of a commercially available phage product, PhageGuard S consisting of 2 phages, FO1a, and S16. Different pick up levels, blend and hold times (chosen based on regulatory restriction and process limitations), as well as spray versus dip treatment methods were tested.Materials and MethodsOvernight culture streptomycin resistant Salmonella enterica enterica Enteritidis C (Se13) was diluted and inoculated at a concentration of 2×104 CFU/cm2 or CFU/g on parts of chicken fillet and held for 10 min for bacterial attachment (duplicate samples per time point). Subsequently, contaminated parts were spray treated with one phage concentration (108 Plaque Forming Units/g) at 0.5%, 1% or 3% pick up (v/w) or water (control) and blended for 5, 10, and 20 min before immediate grinding and retrieval of bacteria (latter blend time sample was held for 24 h before grind). Another set of contaminated fillet parts were treated by dipping in 5% phage solution (at 1% pick up, 108 PFU/g) and held for 1, 5, 10, and 20 min, and 1 and 24 h at 40°F (4°C) before retrieval of bacteria. Enumeration of bacteria was done on selective agar plates and reductions were calculated relative to water treated control.ResultsThe application of phages 108 PFU/g via spray on chicken parts at 3% pick up and 20 min blend time resulted in 0.9 log10 CFU/g log reduction of Salmonella. Additional hold time of 24 h before grind resulted in 1.1- 1.2 log10 CFU/g kill at lower and higher pick up of 0.5% and 3%. Dip treatment resulted higher Salmonella reduction of 1.2 log10 CFU/cm2 within 5 min of 108 PFU/cm2 phage application and up to 2.3 log10 CFU/cm2 log10 reduction when held for 24 h. Overall, the spray technique, showed a dose response effect where increasing pick up and blend time resulted in an increasing Salmonella kill in ground product. However, the dip technique resulted in more effective Salmonella kill in shorter dwell time. All values are mean value of two individual experiments.ConclusionThe above results indicate that the commercially available phage solution, PhageGuard S, either via spray or dip method reduces Salmonella contamination on meat and poultry parts by 1.2 to 2.3 log10, respectively. Thereby is an effective intervention in reducing risks and allowing for increase in consumer safety. Dip technique works better than spray due to better distribution on meat surface. Longer hold and/or blend time after phage treatment results in more kill.

Hệ thống gọt vỏ nâu cơm dừa tự động

Among products made from the coconut tree, products made from coconut meat generally have a large proportion of product value. In the preliminary processing phase of any products made from coconut meat, it is necessary to remove its brown skin, which is often performed manually. Semi-automatic machines for removing the brown skin of coconut meat have been developed but their price is relatively high while their productivity is not high enough. This paper proposed a novel mechanism to remove coconut brown skin on a spiral trajectory by moving the blade in tangent contact with the outer surface of the coconut meat while the cocunut meat is rotating around its vertical axis. The brown skin removing mechanism has been successfully developed for half-nut-size coconut meat with removal rate of about 94.5 kg/hour (which is almost 4 times of the manual removal rate) and coconut meat loss of less than 15%, removal percentage of more than 95%. Preliminary results showed the applicability of the system for removing the brown skin of half-nut-size coconut meat which is the traditional product of manual removal of coconut meat from the coconut husk. In addition, the developed system could be integrated with preceding automatic sort-and-flip system to form a complete automatic system for sorting coconut meat and removing its brown skin.

Anti-Salmonella Effects of Pyruvic and Succinic Acid in Combination with Oregano Essential Oil

ObjectivesEffective decontamination approaches will aid in improving safety of poultry products and help processors comply with pathogen performance standards. Increasing consumer demand for clean label and more natural ingredients presents a scope to explore alternative decontamination approaches for meat and food contact surfaces. This study aimed to evaluate the antimicrobial efficacy of combinations of pyruvic acid (PA), succinic acid (SA), and oregano essential oil (EO) against Salmonella Typhimurium in suspensions, cells inoculated on raw chicken, and cells attached to steel.Materials and MethodsMinimum bactericidal concentration (MBC) assays were conducted in Mueller-Hinton broth (5 mL). Bacterial cells were added to broth suspensions of antimicrobial agents or their combinations. A contact time not exceeding 10 s was provided. Surviving bacteria were recovered on tryptic soy agar (TSA). Bacterial inactivation was confirmed by enrichment in D/E broth. Experiment involved completely randomized design with each concentration of organic acid and essential oil being considered as one level. Data were analyzed using 1-way ANOVA. Aqueous solutions of PA, SA, EO, and the mixtures of PA+EO and SA+EO were prepared using 0.05% agar to suspend the essential oil. Skin-on raw chicken breast meat pieces (2.5 cu cm) were used as a substrate to inoculate nalidixic acid (NA) adapted Salmonella cells. Pieces were treated with antimicrobial agents for 30 s by dipping, and surviving Salmonella were recovered using D/E broth on XLT-4 agar with 50 ppm NA. Four different experiments with variable acid and essential oil concentrations were performed and data were analyzed using 1-way ANOVA. Each experiment included an inoculated untreated control. Stainless steel coupons (2 × 5 cm) were used as a substrate for Salmonella attachment. Cells were allowed to grow and attach on coupons submerged in tryptic soy broth for 24 h. Coupons were rinsed to remove planktonic cells. Attached cells remaining on the coupon were dip treated with antimicrobial agents for 5 min. Surviving cells were recovered on TSA. For antimicrobial treatments leading to no cell recovery, additional experiments were performed. The recovery broth was enriched in tryptic soy broth and streaked on TSA to confirm inactivation. Three different experiments were conducted while including their respective inoculated and untreated controls and analyzed using 1-way ANOVA. All experiments were conducted in three replicates.ResultsMBC for was found to be PA (0.5%), SA(3%), EO (0.04%), PA+EO (0.25 + 0.02%), SA+EO (0.25 + 0.02%), respectively. 1% PA + 0.08% EO combination produced the maximum reduction (1.42 ± 0.11 log CFU/cm2) followed by 6% SA + 0.08% EO (1.02 ± 0.08 log CFU/cm2) in Salmonella populations on raw chicken. More than 6 log CFU/coupon of attached Salmonella were inactivated by mixtures of 0.25% PA + 0.02% EO and 1.5% SA + 0.02% EO.ConclusionThe combinations of PA+EO and SA+EO both exhibited strong anti-Salmonella activity in cell suspensions, on cells attached to stainless steel, and were effective in reducing Salmonella populations on raw chicken. Therefore, these antimicrobial combinations merit further research for raw poultry, meat, and other sanitation applications.

СТАФИЛОКОККОВЫЕ БИОПЛЕНКИ: НОВЫЙ ВЫЗОВ ДЛЯ САНИТАРИИ МОЛОЧНОЙ И МЯСНОЙ ПЕРЕРАБАТЫВАЮЩЕЙ ПРОМЫШЛЕННОСТИ

The article presents data on studies of the stability of staphylococcal biofilms. Staphylococcus grows predominantly as biofilm on virtually any type of industrial surface, causing contamination of food and water, corrosion of the metal surface and obstruction of the equipment. In particular, in the processing meat and dairy industry, biofilm formation can contribute to food spoilage and the transfer of pathogenic microorganisms, increasing the possibility of cross-contamination, which can be associated with a serious risk to consumer health. Staphylococci are often isolated from products of animal origin, but it turned out that in the state of biofilm they are more stable and viable than planktonic cells, especially after insufficiently effective disinfection. In this regard, commonly used means and modes of rehabilitation of technological surfaces of meat and dairy processing enterprises must be improved.

A rapid and sensitive method to determine potassium permanganate in meat

In some countries, potassium permanganate is illegally added to meat to improve the colour and mask the smell of spoiled meat. In this study, we developed a method for rapidly detecting and quantifying potassium permanganate in beef, horse, lamb and pork meats. First, the surface of meat was treated with 0.2% ethanolic benzidine. In meat containing potassium permanganate, the spots treated with ethanolic benzidine developed a dark green colour within 1–2 s, turning rapidly to black. The changes in colour were similar in potassium permanganate-containing meat of different types (beef, horse, lamb, pork), suggesting that the proposed method can be applied to determine the presence of potassium permanganate irrespective of animal species. We also prepared filter paper strips impregnated with 0.2% ethanolic benzidine, which developed a dark blue-green colour when applied to meat treated with potassium permanganate. The intensity of colour developed was directly related to the concentration of potassium permanganate used in the meat. Analysis of the same samples by spectrophotometer at 450 nm confirmed the results. Using the paper strip method, we were able to non-invasively analyse 37,000 retail meat samples from cattle, horses, lambs and pigs for their content of potassium permanganate. We believe that this method has considerable potential for use by food safety regulatory bodies and consumers at the point of sale.

Fluorescent method of bacterial contamination control on meat surface

This work presents the fluorescent method of meat bacterial contamination control based on the influence of E. coli metabolites on the fluorescence spectrum of meat surface. The experiment revealed that proposed method allows detecting bacterial contamination with concentrations above 106 CFU/cm2 on a beef surface.

Predictable and unpredictable survival of foodborne pathogens during non-isothermal heating

In previous work, extreme survival of various bacterial species during cooking was reported when attached to chicken meat. In this paper the effects of an extremely high challenge temperature on survival of Salmonella Typhimurium and Campylobacter jejuni, attached to chicken breast fillets or pork to test for matrix effects are reported. Survival was predicted, using standard D- and z-values from the literature, and compared to experimentally obtained data. Attached to meat, both S. Typhimurium and C. jejuni survived longer than predicted, longer when attached to chicken meat than when attached to pork.Additionally, the effect of non-isothermal heating on survival of almonella in buffer is described. In buffer, when slowly heated, Salmonella died off as predicted. When Salmonella was heated in buffer according to a heating profile mimicking that of the surface of meat in boiling water, it appeared that cells died off much slower than predicted. It is shown that the thermal characteristics of Salmonella surviving the first 35 s of fast heating had changed. After these 35 s, remaining Salmonella survived for minutes, even at a challenge temperature of 90 °C.During heating, cell size decline was observed. A loss of intracellular water during cooking might have resulted in smaller, dehydrated cells, in cells with altered thermal resistance characteristics. This could explain why the use of standard D-and z-values did not allow the correct prediction of survival of Salmonella during fast heating in buffer, or during cooking, being attached to the surface of meat.Many factors affect the level of heat resistance of bacteria. The results of this and a former study show that attachment to meat contributes to an increased level of heat resistance of bacteria. A fast heating process further contributes to the increased level of heat resistance possibly as the result of changed thermal characteristics due to a loss of water.

Effect of ionized calcium on bacteria contamination in chicken carcass under slaughter process.

The purpose of this study was to determine the effect of ionized calcium on bacteria cross contamination on chicken carcass and meat during the slaughter process. Compared to the control group, colony of E. coli was not observed on medium containing 0.5% ionized calcium. Cross contamination of bacteria on carcass surface of fresh chicken was increased as the number of scalding was increased. Cross contamination of bacteria on carcass surface of fresh chicken was lower in the 0.5% ionized calcium scalding treatment group than that in the control group. Bacteria colony count on chicken meat surface after cooling water treatment was increased as the storage period was increased. Bacteria colony count was lower in the 0.5% ionized calcium treatment group than that in the control group.

Identification and metagenetic characterisation of Listeria monocytogenes-harbouring communities present in food-related industrial environments

The main aim of this study was to localise, identify and characterise the Listeria monocytogenes-harbouring bacterial communities present in food related premises via 16S rRNA gene metagenetic analysis. With this scope, 319 environmental samples coming from a wide variety of surfaces of fish (n = 120), meat (n = 80) and dairy industries (n = 119), were firstly analysed following ISO 11290–1 and ISO 11290–2 norms. Direct L. monocytogenes quantification was possible in 9 samples (2.8%) with values between 2.00 and 3.97 log CFU/cm2. After enrichment, an overall L. monocytogenes incidence of 12.54% (n = 40) was obtained, being samples from meat industry the most contaminated. Molecular serotyping assays showed that most of the isolates belonged to 1/2b-3b-7 subgroup, followed by 1/2a-3a and 1/2c-3c. These results combined with AscI and ApaI PFGE macrorestriction patterns, yielded 7 different L. monocytogenes clusters. Nevertheless, no clear ecological relationships could be stablished. High amounts of L. monocytogenes-associated psychrotrophic microbiota were obtained in all cases with values above 9 log CFU/cm2 in some cases. Metagenetic analysis of one representative sample per each food industry type (fish, meat, dairy) demonstrated that Actinobacteria (53.16%) was mostly present in the meat sample whereas Proteobacteria was the most representative phylum in dairy (69.58%) and fish (97.11%) samples. Subsequent operational taxonomic units (OTUs) analysis, showed a wide variety of taxa associated with L. monocytogenes such as spoilage-associated genera (e.g. Psyschromonas or Shewanella), lactic acid bacteria genera (e.g. Lactococcus or Lactobacillus) or pathogenic species such as Yersinia enterocolitica. It was thus demonstrated, that L. monocytogenes is capable to both survive with different bacteria in different ecological niches, highlighting once more the need for proper surveillance schedules so as to guarantee the safety of the food products.