A. S. Barreto

The effect on turkey meat shelf life of modified-atmosphere packaging with an argon mixture

There is a lack of knowledge related to the action of Ar on microbial development and prevention of oxidation when applied to raw meat under modified-atmosphere package (MAP). The aim of this study was to evaluate the effect of an anaerobic gas mixture with Ar on spoilage flora growth, color, and lipid oxidation stability of turkey meat under MAP stored at 0 degrees C. Breast muscles samples were collected on different working days from turkey carcasses (BUT9 and BIG6), fast-cooled in a tunnel (-2 degrees C, 2 m.s(-1), 90% RH) for 2 h and selected to be deboned according current practices in industrial slaughterhouses. The breasts were cut into slices that were individually packaged under aerobiosis (P0) and in 4 different modified atmospheres containing different gas mixtures as (P1) 100% N2, (P2) 50% Ar-50% N2, (P3) 50% Ar-50% CO2, and (P4) 50% N2-50% CO2. All samples were stored at 0+/-1 degrees C in the dark for between 12 and 25 d. Meat samples packaged in P0 were analyzed for their microbial and physicochemical characteristics on d 0, 5, and 12 of storage and then extended to 19 and 25 d when samples were under MAP. The microbial shelf life period extension of MAP sliced turkey meat compared with aerobic packaging (5-d shelf life) is 1 wk more for P1 and P2 mixtures, 2 wk for P4, and 3 wk for P3. The Ar-CO2 mixture was more efficient in delaying flora development than CO2-N2 with 1 log difference on the 25th day of storage, for total psychrotrophic counts, total anaerobic counts, and Brochothrix thermosphacta. The presence of Ar on gas mixtures did not seem to have any additional protective effect on lipid turkey meat oxidation.

Spoilage of light (PSE-like) and dark turkey meat under aerobic or modified atmosphere package: microbial indicators and their relationship with total volatile basic nitrogen

1. The aim of this work was to evaluate the shelf life of turkey meat from different colour categories (Pale, Soft and Exudative (PSE)-like), intermediate and dark), packaged under aerobic or modified atmosphere (MAP) conditions; also to establish a relationship between microbial quality and total volatile basic nitrogen (TVB-N), evaluating its capacity for shelf life determination. 2. Breasts were selected according to luminance (L*) and pH24: L ≥ 51 and pH < 5·8 for light colour, 43 < L < 51 for intermediate colour, L ≤ 43 and pH > 5·8 for dark colour. Sliced meat was packaged under aerobic or MAP conditions with 50% N2 and 50% CO2, then stored in the dark at 0 ± 1°C for periods of 12 or 25 d. Meat under aerobic conditions was evaluated for microbiological characteristics and TVB-N on d 0, 5 and 12. This evaluation was extended to include d 19 and 25 when samples were under MAP conditions. 3. The dark meat group after 12 d of storage in aerobiosis presented significantly higher plate counts of aerobic mesophilic, psychrotrophic micro-organisms and higher TVB-N than other meat colour categories. The shelf life of turkey meat under MAP was one week longer for intermediate and light colour meat (20 d) than for dark meat. TVB-N values of 20 to 30 mg NH3/100 g turkey meat correspond to advanced spoilage stages. We proposed 14 mg NH3/100 g as the limit of freshness acceptability for turkey meat. 4. TVB-N was an indicator of turkey meat microbial spoilage but was not a suitable early predictor for microbial spoilage and in particular for turkey meat stored under MAP conditions because counts of micro-organisms were moderately correlated (Pseudomonas spp. and Enterobacteriaceae) with this index, as they were inhibited by MAP gas mixture and storage temperature used in the present study.

Nutritional evaluation of the lipid fraction of feral wild boar (Sus scrofa scrofa) meat.

Consumer increasing demand for wild boar meat and scarceness of data on its lipid fraction justified this study. The psoas major muscle collected from 25 feral wild boars was used to quantify the total lipid, total cholesterol, fatty acid (FA) profile, and vitamin E homologues. Intramuscular fat and total cholesterol contents averaged 4.64 g/100g of meat and 56.9 mg/100g of meat, respectively. No differences were found in FA composition between groups, except for 20:5n-3 that was higher in youngsters. All groups presented small concentrations of rumenic acid in meat (CLA; 0.24% of total FA). FA profile showed considerable resemblance with pork, while the vitamin E profile is marked by high concentrations of both alpha- (17.4 ± 3.3 μg/g meat) and gamma-tocopherols (2.6 ± 1.3 μg/g meat) and by the presence of other vitamin E homologues not previously reported in wild boar meat.

Antimicrobial resistance among Campylobacter spp. strains isolated from different poultry production systems at slaughterhouse level

The aim of the current work was to evaluate the prevalence and antimicrobial susceptibility of Campylobacter spp. isolated from different chicken production systems at the slaughterhouse level. Chicken sampling at slaughterhouse was performed for cecum, carcass, and breast meat from flocks of organic (n = 6), extensive indoor (n = 14), and intensive production (n = 14), totaling 34 ceca pools, 64 neck skin pools, and 132 breasts, representing 96,386 chickens. A collection of 167 strains were identified as Campylobacter coli (n = 85) and Campylobacter jejuni (n = 82) and were tested for susceptibility to 11 antimicrobial agents by the disk diffusion method. The frequency of Campylobacter in chicken samples from different production systems was between 79 and 100%. Campylobacter isolated from all origins were resistant to the fluoroquinolones studied (80-98%). However, for ciprofloxacin and ofloxacin, the Campylobacter isolates from extensive indoor chicken were significantly (P < 0.05) less resistant (77 and 58%) than that from organic (97 and 91%) and intensive production (96 and 95%). A high probability of tetracycline resistance occurrence was also found for the Campylobacter spp. tested (58% for C. jejuni and 76% for C. coli). A more frequent profile of multidrug resistance was noticed for isolates from intensive and organic production than for extensive indoor production. These results reinforce the need of efficient strategy implementation to control and reduce Campylobacter in chickens at production and slaughter levels, and the necessity to reduce the use of antimicrobials in poultry sector.

Biogenic amine formation in turkey meat under modified atmosphere packaging with extended shelf life: Index of freshness

The aim of this study was to evaluate the effect of modified atmosphere packaging (MAP) on biogenic amine production in turkey meat according to its shelf life period, determining an index of freshness. Sliced meat samples of different meat quality categories (according to color and pH₂₄) were individually packaged under aerobiosis (aerobic package) and in 6 different modified atmospheres containing different gas mixtures: MAP1, 50% N₂/50% CO₂; MAP2, 0.5% CO/50% CO₂/49.5% N₂; MAP3, 50% Ar/50% N₂; MAP4, 0.5% CO/80% CO₂/19.5% N₂; MAP5, 100% N₂; and MAP6, 50% Ar/50% CO₂. All samples were stored at 0 ± 1°C in the dark for between 12 and 25 d. Meat samples packaged in aerobic packaging were analyzed for their microbial and physicochemical characteristics on d 0, 5, and 12 of storage, and then extended to 19 and 25 d when samples were under MAP. The production of biogenic amines analyzed in turkey meat increased over time. The values of putrescine, cadaverine, and tyramine increased significantly (P < 0.05) during storage time in samples packaged under aerobiosis, MAP3, and MAP5. Histamine was not detected in turkey meat packaged under study conditions, or when present, the levels were below the limit of quantification (1.03 mg/kg). Tyramine in turkey meat under MAP was not the best amine indicator of meat deterioration, with cadaverine being suggested instead, or the sum of the amines putrescine, cadaverine, and tyramine, to characterize and quantify meat freshness. After 25 d of storage, the meat packaged under MAP with a mixture containing a higher concentration of CO₂ and with CO was the one with a lower index value (11.36 mg/kg), although not significantly different from the indices provided by the meat packaged with MAP1, 2, and 6.

Gas mixtures approach to improve turkey meat shelf life under modified atmosphere packaging: The effect of carbon monoxide

Gas mixtures with CO have been applied to beef and pork meat, but no data have been reported regarding their application to poultry meat. The aim of this study was to evaluate the effect of an anaerobic gas mixture with CO on the growth of spoilage flora, color, and lipid oxidation stability of turkey meat under modified atmosphere packaging (MAP) stored at 0°C. Sliced meat samples were individually packaged under aerobiosis (aerobic packaging) and in 4 different modified atmospheres containing different gas mixtures: MAP 1, 50% N(2) and 50% CO(2); MAP 2, 0.5% CO, 50% CO(2), and 49.5% N(2); MAP 3, 0.5% CO, 80% CO(2), and 19.5% N(2); and MAP 4, 100% N(2). All the samples were stored at 0 ± 1°C in the dark for 12 to 25 d. Meat samples packaged in aerobic packaging were analyzed for their microbial and physicochemical characteristics on d 0, 5, and 12 of storage, which was extended to 19 and 25 d when samples were under MAP. For meat packaged with MAP 3, the total mesophilic and psychrotrophic counts were significantly lower (P < 0.001) than those observed in condition MAP 1. The introduction of CO, added to a higher concentration of CO(2), inhibited microbial flora in general, with particular action on Brochothrix thermosphacta. In terms of microbial quality, the shelf life of turkey meat under the MAP study conditions was longer than that of meat in aerobic packaging (5 d): 12 d for mixture MAP 4, 19 d for MAP 1 and MAP 2, and 25 d for MAP 3. Only MAP 4 without CO(2) or CO prevented lipid oxidation of the meat. The presence of CO in anoxic gas mixtures with CO(2) for turkey meat under MAP was useful, giving the bright pink color preferred by consumers without leading to the appearance of undercooked meat.

Nutritional evaluation of the lipid fraction of Iberian red deer (Cervus elaphus hispanicus) tenderloin.

The meat lipid fraction of psoas major muscle from 20 adult (10 males and 10 females) feral Iberian red deer (Cervus elaphus hispanicus) was characterized by quantification of total fat, total cholesterol, vitamin E and fatty acid (FA) composition, including detailed trans octadecenoate isomers and conjugated linoleic acid (CLA) isomeric profile. The total lipid content revealed a very lean meat (0.99 g/100g of meat), with total cholesterol content averaging 55.6 mg/100g of muscle. The FA profile displayed a very high PUFA level for ruminant meat (30.2g/100g FA). The 18:2 cis-9,trans-11 content was fairly low (0.26% of total FA) compared with other ruminant meats. The comparison of stags and hinds showed more similarities than differences. Nevertheless, hinds displayed superior contents of α-tocopherol and trans MUFA and a better n-6/n-3 ratio than stags.

Characterization of Enterococci from Food and Food-Related Settings

Enterococcus species are ubiquitous in nature, exist at high levels in food, and can cause severe diseases in humans. Thus, surveillance of enterococci harboring antibiotic resistance and virulence factors in food and food-related environments is needed. In the present study, 89 samples from food and food processing surfaces were collected in a cheese factory, a swine slaughterhouse, and a supermarket, and 132 Enterococcus isolates were recovered. Most isolates were identified as E. faecalis, which is considered the most pathogenic member of this genus. Safety analysis covering antibiotic resistance revealed that all isolates were resistant to sulfamethoxazole-trimethoprim and sensitive to amoxicillin-clavulanate, ampicillin, ciprofloxacin, gentamicin, levofloxacin, linezolid, nitrofurantoin, or teicoplanin. More than half of the isolates were resistant to quinupristin-dalfopristin, tetracycline, and bacitracin, and less than half were resistant to the other antibiotics evaluated. Regarding virulence factors, 52% the isolates were beta-hemolytic, 39% were gelatinase producers, and 45% contained the gelE gene. For the remaining genes evaluated, efaAfs was detected in more than half of the isolates, and agg, esp, and efaAfm were found in less than half of the isolates. The present investigation revealed that food-related enterococci obtained from very different settings have multidrug resistance and virulence factors, highlighting the importance of effective surveillance networks to avoid the spread of putative pathogenic enterococci.

Assessment of Coagulase-Negative Staphylococci and Lactic Acid Bacteria Isolated from Portuguese Dry Fermented Sausages as Potential Starters Based on Their Biogenic Amine Profile: Biogenic amines on staphylococci…

The aim of this study was to evaluate the decarboxylase activity of coagulase-negative staphylococci (CNS) and lactic acid bacteria (LAB) involved in meat products fermentation, in order to characterize and select the strains most suitable to be used as safe starter cultures. Isolates were obtained from traditional Portuguese dry fermented meat sausages, identified by PCR and characterized according to their technological properties. Lactobacilli and enterococci were assessed for their bacteriocinogenic potential. Biogenic amines (BA) were screened by culture method and analyzed by RP-HPLC/UV. The screening method, compared with chromatographic analysis, was not reliable for CNS and LAB strains selection. Tyramine decarboxylase activity was present in CNS strains, with a slight production of amines. No other hazardous BA were produced. Among lactobacilli, moderate production of tyramine was related only to Lactobacillus curvatus, with some strains producing putrescine or 2-phenylethylamine. Enterococci were high and moderate producers of tyramine and 2-phenylethylamine, respectively. Staphylococcus xylosus, Staphylococcus equorum, and Staphylococcus carnosus, independent of their genetic and technological profiles and BA production, were adequate for use in meat products, according to the data. Lactobacillus plantarum and Lactobacillus sakei strains could also be selected for starters. PRACTICAL APPLICATION The selection of coagulase-negative staphylococci and lactic acid bacteria (LAB) isolates were based on their production of biogenic amines in order to avoid this potential hazard production in meat products. The most suitable isolates could be used as safe starter cultures in meat products industry. The staphylococci and LAB selected will achieve particular organoleptic characteristics in meat products and bioprotection from pathogens.

Antimicrobial activity of essential oils against foodborne multidrug-resistant enterococci and aeromonads in planktonic and biofilm state

The selection and use of natural compounds with antimicrobial activity against foodborne pathogens is of major importance. The present study evaluated the antimicrobial activity of commercial essential oils against multidrug-resistant Enterococcus spp. and Aeromonas spp. Cymbopogon flexuosus and Thymus vulgaris essential oils presented the highest inhibitory zones against both bacterial groups (p < 0.05). Subsequent determination of the minimum inhibitory concentrations showed values between 0.47 and 1.9 mg/ml for Aeromonas spp. and from 1.9 to 15 mg/ml for Enterococcus spp. The antimicrobial effect of C. flexuosus and T. vulgaris essential oils was also assessed against biofilms. Bacteria in biofilm state were subjected to 30 min or 1 h of exposure to each essential oil and eradication ability estimated by colony counting. Both essential oils exhibited antimicrobial activity against preformed Aeromonas biofilms, but were unable to successfully eradicate biofilms produced by enterococci, in the conditions under investigation. Nonetheless, the presumptive use of essential oils in the food industry should be considered in further investigations.