Meat Suspension Research Articles

PREVALENCE AND MOLECULAR CHARACTERIZATION OF ROTAVIRUS IN MEAT CUTS, AND MEAT HANDLERS IN SELECTED ABATTOIRS IN NAIROBI, KENYA

In Kenya, food screening exercises mostly applies to bacterial and parasitic agents, with enteric viral detection neglected. This study aimed to determine the prevalence and molecular characterization of rotavirus in beef/pork cuts and beef/pork handlers in 4 selected abattoirs in Nairobi. Rotavirus was preferred because of its high prevalence rates and its ability to cause pathophysiologic infective gastroenteritis in humans. It has diverse strains characterized as P and G genotypes based on the VP7 and VP4 proteins, respectively. This cross-section study involved the collection of a total of 467, (165) beef/pork cuts and (302) handlers fecal samples. Collected samples wereprepared before rotavirus identification. Prepared meat and stool suspensions were subjected to direct RNA extraction and EIA detection respectively. All the stool suspensionsand RNA extracted meat suspensions subjected to EIA and Two step RT-PCR were all non-reactive respectively. Therefore, there was no VP4 and VP7 genotyping for characterizationpurposes on confirmed primary PCR products. Eppicollect5 was also used to collect and store the descriptive data of study participants, and the analysis conducted using Power BI statistical software application. The studys findings, indicating no human rotaviral infections in meat cuts, enhance public health by reassuring consumers, guiding regulatory policies, emphasizing the need for ongoing surveillance, directing resources to pressing concerns, supporting safe food handling campaigns, establishing baseline data for future assessments, and encouraging best practices in both formal and informal markets.

Continuous separation of bacterial cells from large debris using a spiral microfluidic device.

With the global increase in food exchange, rapid identification and enumeration of bacteria has become crucial for protecting consumers from bacterial contamination. Efficient analysis requires the separation of target particles (e.g., bacterial cells) from food and/or sampling matrices to prevent matrix interference with the detection and analysis of target cells. However, studies on the separation of bacteria-sized particles and defined particles, such as bacterial cells, from heterogeneous debris, such as meat swab suspensions, are limited. In this study, we explore the use of passive-based inertial microfluidics to separate bacterial cells from debris, such as fascia, muscle tissues, and cotton fibers, extracted from ground meat and meat swabs-a novel approach demonstrated for the first time. Our objective is to evaluate the recovery efficiency of bacterial cells from large debris obtained from ground meat and meat swab suspensions using a spiral microfluidic device. In this study, we establish the optimal flow rates and Dean number for continuous bacterial cell and debris separation and a methodology to determine the percentage of debris removed from the sample suspension. Our findings demonstrate an average recovery efficiency of 80% for bacterial cells separated from debris in meat swab suspensions, while the average recovery efficiency from ground beef suspensions was 70%. Furthermore, approximately 50% of the debris in the ground meat suspension were separated from bacterial cells.

Differentiation of live and dead Mycobacterium tuberculosis complex in meat samples using PMA qPCR

The causative agents of zoonotic bovine tuberculosis (bTB), Mycobacterium bovis and M. caprae, are members of the M. tuberculosis complex (MTC). Wildlife such as red deer infected with bTB are often without pathological findings, thus meat thereof may be classified as safe for human consumption. The culturing of MTC is time consuming and inappropriate to be applied with fresh meat and food. Therefore, a rapid method “PMA qPCR” to differentiate living and dead cells of MTC was developed in this study. By treating with 50 μM PMA™ dye, dead M. bovis BCG (≤104 cells/ml meat suspension) could be completely discriminated and was not detected by specific MTC PCR. The limit of detection of MTC without treatment with PMA™ dye was 10 cells/ml. All 50 venison samples obtained for field study purposes were negative for MTC. However, 40% were slightly PCR positive for non-TBC mycobacteria. By culturing using selective enrichment, one single colony of M. avium was isolated. This is the first report on the isolation of M. avium from venison. Considering the difficulties of diagnosing mycobacteria in various matrices, the developed PMA qPCR is applicable for the differentiation of dead and living cells of MTC in meat samples.

Rheological design of stabilized meat sauces for industrial uses

In the present work a rheological analysis was carried out on sauces produced with a spreadable spicy sausage, typical of the Italian dietary culture, and modified by organogelator addition in order to change their mechanical properties and to solve potential stability issues. From a microstructural point of view, the investigated sauces are suspensions of hard fat/meat phase in a liquid oil solvent based on a mixture of sunflower and olive oil. The stabilization of these heterogeneous systems was carried out by an organogelation technique, thanks to which the solvent was stabilized by a network linking the solid particles. Monoglycerides of fatty acids and policosanol, a fatty alcohol mixture, were used as organogelators at two different fractions (0.1 and 0.5% w/w). Small amplitude oscillation tests and flow tests were carried out, both on fresh samples and on samples destabilized by centrifugation; policosanol was found to be more efficient, even at low concentration, in stabilizing the system, guaranteeing rheological properties similar to those of a benchmark unstable sample, and, in the meantime, giving a good stability to the system subjected to shear stresses (like those arising during mechanical manipulations).Practical applications: Oil suspension stabilization is a relevant challenge in food industry owing to the difficulties in structuring an oil phase. Organogelation is a potential solution to these stability issues because organogelators can structure the oil phase entrapping the dispersed particle in a semi‐solid gel network that prevents or delays the separation phenomena.In the present work two different edible organogelators were adopted to stabilize meat suspensions in a vegetable oil mixture, and their effects on both quiescent stability and resistance to mechanical stresses were investigated by using rheological tests. It was shown that organogelation can significantly reduce the separation phenomena between two phases, and it can increase the capacity of materials to bear mechanical loads without affecting the desired consistency. The proposed rheological approach and the adopted organogelators can be used to stabilize also different food suspensions based on liquid oils.The ratio between zero shear viscosity of the destabilized samples and fresh samples as function of the weight loss for: raw material fresh and ground (samples S1 and S2), ground with unstabilized oil phase (sample S3), stabilized with Myverol (sample S4, S5) and with Policosanol (samples S6 and S7).

Stabilization of meat suspensions by organogelation: A rheological approach

AbstractThe stabilization of suspensions is a relevant issue in several industrial applications and particularly in the food area. Water‐based systems are widely studied and they are commonly stabilized by the addition of hydrocolloids (such as polysaccharides or proteins) whereas for oil‐based products less information is available. In this paper, oil‐based meat suspensions are investigated, and the addition of organogelators is proposed as a potential solution to the stability problems currently observed in some practical applications. Investigated suspensions are obtained by grinding a meat phase with vegetable oil blends, thus yielding products typically used in the traditional southern Italian diet as spreadable spicy sauces or as oil‐based dressings for pizzas. The effects of proposed additives were investigated by destabilizing the modified suspensions (by centrifugation) and comparing their rheological characteristics and oil loss to those of the unmodified systems (i.e., without addition of stabilizers). It was observed that both additives exert a stabilizing action, even if one of them (monoglycerides of fatty acids) is more effective than the other, even at a very low concentration. The adopted rheological approach has proved very useful to determine the type and amount of the proper organogelator to be used as an oil suspension stabilizer.

Growth inhibition of heat-injured Enterococcus faecium by oligophosphates in a cured meat model

Cells of two heat-resistant strains of Enterococcus faecium were heated and incubated in meat suspensions containing curing ingredients. The concentrations of the curing ingredients were those frequently used for pasteurized ham-type products, except that the concentrations of the oligophosphates (triphosphate and diphosphate) varied. Heating tests at 69 °C were performed with inoculated meat suspensions in heat-sealed plastic pouches. Numbers of bacteria were counted immediately after heating and in parallel series of heated pouches incubated at 37 °C. Plating was performed in Tryptone Dextrose Yeast Meat Peptonised Milk Agar (TDYMP); in TDYMP Agar to which the curing ingredients were added; and in TDYMP Agar to which the curing ingredients except oligophosphates were added. The inclusion of oligophosphates in the heating medium increased the heat-injury sustained by the E. faecium cells, and in combination with rather severe heat treatment even completely blocked the growth of surviving organisms in the meat suspension incubated at 37 °C. The presence of oligophosphates in the culture medium TDYMP Agar severely reduced the counts of freshly heated cells; however, this effect disappeared after repair and growth of the surviving organisms in the meat suspension.

The potential of vancomycin-resistant enterococci to persist in fermented and pasteurised meat products

Experiments with 148 isolates of vancomycin-resistant enterococci (VRE) were performed to assess their potential to persist and grow in fermented sausages and pasteurised meat products. All strains were meat isolates and Van-type A, except a single VanC1 strain. In total, 143 strains of Enterococcus faecium were involved. Eight selected strains were examined for their potential to grow at high salt and nitrite levels and at reduced pH. The same isolates were used in experiments with fermented sausages. All available strains were subjected to heating tests in meat suspensions with added curing ingredients. All but one of the eight tested isolates grew at pH 4.0 in tryptone soya broth (TSB). With the combination of 8% w/w NaCl, 400 ppm NaNO 2 and 0.5% w/w glucose in the meat suspension, all isolates grew at 37 °C, whereas none grew at 7 °C even after 56 days. With the addition of 10% w/w NaCl, 200 ppm NaNO 2 and 0.5% w/w glucose, still one E. faecium isolate grew at 37 °C, although very slowly. Overall, the strains tolerated high salt and nitrite concentrations and reduced pH very well, even beyond levels applied in the regular production of fermented and/or pasteurised meat products. The tested strains could be isolated after the fermentation and further ripening of “boerenmetworst” and “snijworst”. Overall, their colony counts decreased on average about 1 log-unit over a period of 60 days after batter manufacture. All 148 isolates demonstrated a relatively weak thermal resistance compared to results for selected vancomycin-sensitive enterococci strains reported in the literature and to results collected under identical experimental conditions in this laboratory. None of the strains (log inoculation level about 5–6 ml −1 for each isolate) could be cultured after heating at 70 °C for 10 min.

Comparison of effects of Wasabia japonica and allyl isothiocyanate on the growth of four strains of Vibrio parahaemolyticus in lean and fatty tuna meat suspensions

Lean tuna meat suspensions (LEAN), with a fat content of 0.006%, and fatty tuna meat suspension (FATTY), with a fat content of 3.0% were inoculated with four strains of Vibrio parahaemolyticus and wasabi ( Wasabia japonica Matsumura) or allyl isothiocyanate (AIT) was added before incubation at 37°C. During the incubation, viable Vibrio counts were determined on TCBS agar plates. Both LEAN and FATTY suspensions were inoculated with V. parahaemolyticus AOTO-81, (1.28±0.20)×10 2 CFU/ml, followed by addition of 20 mg wasabi/ml, and incubation for 8 h. The viable Vibrio counts were (7.76±5.93)×10 5 CFU/ml in LEAN and (3.50±2.65)×10 1 CFU/ml in FATTY. When the same strain, at (1.18±0.22)×10 2 CFU/ml, was incubated for 8 h with 50.9 μg AIT/ml, viable Vibrio counts were (4.79±1.78)×10 4 CFU/ml in LEAN and (1.80±1.30)×10 1 CFU/ml in FATTY. Growth of the other three strains with wasabi or AIT was shown to be less in FATTY than in LEAN. These results indicate that growth of V. parahaemolyticus is inhibited more in FATTY than in LEAN by wasabi and allyl isothiocyanate.

Solubilization of fish proteins using immobilized microbial cells

Cells of Bacillus megaterium, Aeromonas hydrophila, and Pseudomonas marinoglutinosa were immobilized in calcium alginate. The immobilized cells secreted protease when held in fish meat suspension in water. The enzyme synthesis by the entrapped cells was supported by small amounts of soluble nutrients present in the meat. The secreted protease solubilized the fish meat, solubilization being optimum at pH range of 7.5 to 9.5 and at 50 degrees C. Under these conditions immobilized B. megaterium was most efficient giving 30% solubilization of the meat, followed by A. hydrophila (18%), while immobilized P. marinoglutinosa was less effective. The optimum ratio of fish meat to beads was about 4:3 for B. megaterium and A. hydrophila. The beads had a storage life of 30 days at 4 degrees C. The results suggested potential for use of immobilized microbial cells having extracellular protease activity to enhance solubility of waste proteins. A prototype reactor with beads holding assembly was fabricated which could recover the beads from the meat slurry after the treatment.

Microcalorimetry as a Rapid Method for Estimation of Bacterial Levels in Ground Meat

The potential of microcalorimetry as a rapid method for the estimation of bacterial levels in ground meat was studied. The exothermic heat production rates (HPRs) of Escherichia coli and meat suspensions were measured in a BioActivity Monitor and correlated to log10 CFU/ml or g. Comparative experiments using 0.1% peptone saline (PS) or nutrient broth (NB) as the suspending medium showed that maximum HPRs (peak times) were obtained faster with NB than with PS, and that HPR peaks were more distinct when using NB. Two series of 11 meat samples suspended 1:10 in NB were examined at instrument operating temperatures of 21 and 30°C, respectively, and HPRs were compared to mesophilic colony counts (30°C/3 d) and to psychrotrophic counts (17°C/17 h then 7°C/72 h). Peak times at 30°C were considerably shorter than those at 21°C. The correlation between both plate count methods and the peak times were better when measuring at 21°C than at 30°C. Significant correlations between HPRs and colony counts were obtained with all experimental conditions. Results indicate that micro-calorimetric measurements of 10−1 NB suspensions of ground meat provide a promising analytical tool for estimation of the bacterial levels in less than 24 h in the range of 105 to 108 CFU/g.

Effects of reaction variables on the hydrolysis of lean beef tissue by alcalase

The effects of the reaction variables, pH, time, temperature, enzyme: meat ratio and meat concentration, on the hydrolysis and solubilisation of lean meat protein by Alcalase have been determined. Experiments were performed with both dilute meat suspensions and undiluted ground meat. Reaction progress curves were similar to those for the enzymic hydrolysis of other proteins, with rapid initial reaction rates followed by a gradual decline in rate. The optimum reaction pH was 8·5. Optimum temperatures were found to be 55°C for the hydrolysis reaction and 60°C for meat solubilisation. Both solubilisation and degree of hydrolysis increased with increasing enzyme concentration. At an enzyme: meat ratio of 80 mg Alcalase 0·6L per gram of dry meat, a solubilisation of 94% and a degree of hydrolysis of 18% were achieved after a 3-h reaction period. As meat concentration was increased, degree of hydrolysis decreased slightly and solubilisation decreased markedly.

Two modified selenite media for the recovery of Yersinia enterocolitica from meats.

Yersinia enterocolitica is one of the few human pathogens that grows at the proper food refrigeration temperatures of 0 to 5 degrees C. Although the isolation of environmental biotypes of Y. enterocolitica from many types of food and water has been reported in the literature, the recovery of the sensitive strains inoculated into foods has been slow and uncertain. Rapid recovery of several clinical strains inoculated into meats was accomplished by using two modified selenite broths without added nutrients. It was critical to restrict the sample size of the blended meat suspension at the 0.2-g/100 ml level, thereby restricting the growth of the total bacterial population in the selenite enrichment media. Otherwise, the slower growing Y. enterocolitica would be overwhelmed by the faster growing normal bacterial flora from the meat. Both the resistant serotype O:3 and the sensitive O:8 clinical isolates of Y. enterocolitica were recovered from the modified selenite enrichment media after 2 and 3 days of incubation at 22 degrees C.

Inhibition of Clostridium Botulinum by Sodium Nitrite as Affected by Bacteriological Media and Meat Suspensions

The inhibitory effect of sodium nitrite on the outgrowth of spores of Clostridium botulinum 13983B was studied in various bacteriological media and meat suspensions. The media and meat suspensions were adjusted to pH 6.2 and heated in the presence of nitrite at 110°C for 20min. Perigo factor was produced in Perigo-type medium (PT) and Reinforced Clostridial Medium (RCM) when heated with 20ppm of nitrite, but not in Liver Veal Medium (LVM) and Wynne Fluid Medium (WFM) even when heated with 100ppm of nitrite. Suspensions of 50% meat in water, prepared from under-process, normal-process and over-process meats, required 500ppm, 150ppm and 50ppm of nitrite, respectively, for inhibition of outgrowth.Dialysis removed the inhibitory activity from two of the bacteriological media (LVM and WFM) and from all meat suspensions, but not from PT and RCM media. The residual nitrite concentrations were approximately the same in all seven heated preparation (100ppm added before heating), but the redox potential varied considerably among them. The addition of reducing agents to meat suspensions decreased the redox potential and increased the inhibitory activity but did not induce the formation of the Ferigo factor.

Inhibition of Clostridium Botulinum by Sodium Nitrite in a Bacteriological Medium and in Meat

The inhibitory effect of sodium nitrite on the growth of Clostridium botulinum was studied in a bacteriological medium and in meat suspension. We found that a bacteriological medium heated at 110°C for 20 min with as little as 20ppm of sodium nitrite became inhibitory to C. botulinum and the inhibitor was non-dialyzable. Meat suspension heated with 150ppm of nitrite was inhibitory to C. botulinum, but the inhibitory activity was probably due to a residuum of greater than 100ppm of nitrite: dialysis removed the inhibitory activity. Inhibitor formed in medium could be inactivated by non-fat meat solids but not by fat or water soluble meat extracts. It appears that the inhibitor produced in media is of little or no consequence in explaining the role of nitrite in the safety of commercially-produced canned cured meat.