scholarly journals Specific microflora of packed meet – a review

2000 ◽  
Vol 18 (No. 4) ◽  
pp. 159-163
Author(s):  
I. Steinhauserová

Meat is an attractive medium for microorganism multiplication due to its composition. The microflora of unpacked meat or of meat packed in wrapping plastic foil is significantly different from the microflora of vacuum-packed or controlled-atmosphere packed meat. Dominant microorganisms of unpacked meat are some species of the genus Pseudomonas sp., namely Pseudomonas fragi, Shewanella putrefaciens, Psychrobacter and Acinetobacter, which largely contribute to meat spoilage. From vacuum-packed or controlled-atmosphere packed meat were isolated mainly Brochotrix thermosphacta, heterofermentative lactobacilli (L. cellobiosus), Carnobacterium sp. and Leuconostoc sp. Characteristic microorganisms of vacuum-packed meat were Leuconostoc carnosum, Leuconostoc gelidum and Carnobacterium divergens. Quantitative proportions of the groups of microorganisms in packed meat are related to meat pH value, plastic foil permeability for oxygen and type of packed product.

Author(s):  
Anna Nikolaevna Gneush ◽  
Albina Vladimirovna Luneva ◽  
Nadezhda Leonidovna Machneva ◽  
Yury Andreevich Lysenko ◽  
Maria Vladimirova Aniskina ◽  
...  

The purpose of the research work was to select the optimal conditions for the cultivation of microorganisms. As a result of the conducted research work, the modes of growing a nitrogen-fixing culture and a microorganism with high enzymatic activity were selected and worked out. At the same time, the optimal conditions for the cultivation of Azotobacter sp were determined – the temperature optimum for cell accumulation was 30°C, for increased polysaccharide production 20 °C, aeration within 5-10 l/l/min, agitator speed-150 rpm, pH value within 6.0±0.2 units, which allowed to achieve a cell titer of at least 1.0×109 CFU/ml. A cost-effective nutrient medium was selected for growing Pseudomonas sp. molasses-autolysate medium and optimal conditions for growing the culture: cultivation temperature 30-32 °C, aeration 1.0-1.5 l/l/ min, agitator speed 150-200 rpm, pH 6.8-7.2 units, sub-titration 5.0 % KOH, defoaming with adecanol, cultivation time-72 hours, which allowed to achieve a cell titer of at least 1.0×109 CFU/ml.


2009 ◽  
Vol 72 (12) ◽  
pp. 2597-2601 ◽  
Author(s):  
ILARIO FERROCINO ◽  
DANILO ERCOLINI ◽  
FRANCESCO VILLANI ◽  
SANDRA M. MOORHEAD ◽  
MANSEL W. GRIFFITHS

Quorum sensing (QS) is a signalling mechanism through which bacteria cellular functions are modified to promote access to nutrients and more favorable environmental niches. The frequent occurrence of Pseudomonas spp. in fresh and spoiled meat may involve enhanced gene expression regulated by QS. Several Pseudomonas spp. produce different N-acyl homoserine lactone (AHL) signal molecules. Meat spoilage during aerobic, refrigerated storage is often associated with the presence of Pseudomonas fragi. As with other Pseudomonas species in natural habitats, the dominance and activities of P. fragi in meat may be regulated by QS. In this study, five biosensor strains were used to detect AHL production on three different media by 72 different P. fragi strains isolated from fresh and spoiled meat. Positive and negative AHL-producing strains were used to verify the assays. None of the strains produced detectable quantities of AHLs, even when concentrated cell-free culture supernatants were assayed, nor did exogenous lactones increase biofilm formation in P. fragi strains. However, all isolates produced furanosyl borate diesters (type II autoinducers; AI-2) when tested using the bioluminescent biosensor strain of Vibrio harveyi (BB170). The production of AI-2 was presumed to be of metabolic origin even though Pseudomonas spp. have not been shown to harbor the luxS gene. Thus, the efficient development of P. fragi in fresh meat is not regulated by an AHL-mediated QS system. The mechanism of AI-2 production and its possible role in spoilage dynamics needs further study.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shanying He ◽  
Yaoqi Ni ◽  
Li Lu ◽  
Qiwei Chai ◽  
Haiyang Liu ◽  
...  

Abstract Pseudomonas sp. strain NEE2 isolated from oil-polluted soils could biodegrade n-hexane effectively. In this study, the secretory product of n-hexane biodegradation by NEE2 was extracted, characterized, and investigated on the secretory product’s enhanced effect on n-hexane removal. The effects of various biodegradation conditions on n-hexane removal by NEE2, including nitrogen source, pH value, and temperature were also investigated. Results showed that the secretory product lowered surface tension of water from 72 to 40 mN/m, with a critical micelle concentration of 340 mg/L, demonstrating that there existed biosurfactants in the secretory product. The secretory product at 50 mg/L enhanced n-hexane removal by 144.4% within 48 h than the control group. The optimum conditions for n-hexane removal by NEE2 were at temperature of 25–30 °C, pH value of 7–8, and (NH4)2SO4 as nitrogen source. Besides n-hexane, NEE2 could also utilize a variety of carbon sources. These results proved that NEE2 can consume hydrophobic volatile organic compounds (VOCs) to produce biosurfactants which can further enhance hydrophobic VOCs degradation.


Foods ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 74
Author(s):  
John Samelis ◽  
Athanasia Kakouri

This study evaluated microbial growth in commercial frankfurters formulated with 1.8% sodium lactate (SL) singly or combined with 0.25% sodium diacetate (SDA), vacuum-packaged (VP) and stored at 4 °C and 12 °C. Standard frankfurters without SDA, containing 0.15% SL, served as controls (CN). Lactic acid bacteria (LAB) were the exclusive spoilers in all treatments at both storage temperatures. However, compared to the CN and SL treatments, SL + SDA delayed growth of LAB by an average of 5.1 and 3.1 log units, and 3.0 and 2.0 log units, respectively, after 30 and 60 days at 4 °C. On day 90, the SL + SDA frankfurters were unspoiled whereas the SL and CN frankfurters had spoiled on day 60 and day 30 to 60, respectively. At 12 °C, LAB growth was similar in all treatments after day 15, but strong defects developed in the CN and SL frankfurters only. Differential spoilage patterns were associated with a major reversal of the LAB biota from gas- and slime-producing Leuconostoc mesenteroides and Leuconostoc carnosum in the CN and SL frankfurters to Lactobacillus sakei/curvatus in the SL + SDA frankfurters. Thus, SL + SDA extends the retail shelf life of VP frankfurters by delaying total LAB growth and selecting for lactobacilli with a milder cured meat spoilage potential than leuconostocs, particularly under refrigeration.


2007 ◽  
Vol 23 (5-6-2) ◽  
pp. 49-58
Author(s):  
B. Miscevic ◽  
S. Aleksic ◽  
Lj. Sretenovic ◽  
V. Pantelic ◽  
S. Trivunovic ◽  
...  

Investigations were carried out on four muscles (M. longissimus dorsi, M. semimembranosus, M. semitendinosus, M. biceps femoris) taken from five young cattle (crosses Domestic Spotted x Limousine) of average body mass prior to slaughtering of 587 kg. On all muscles, 24 h after slaughtering, sensory evaluation was carried out and the following parameters determined: pH value, colour, water binding ability, cooking loss and tenderness (initial values). The remaining part of each muscle was divided into 6 parts, 3 were packaged in plastic foil (control samples), and other 3 were soaked in solution containing 0,4% CaCl2 and 0,4% NaCl and packaged in plastic foil. Pieces of meat prepared in this way were left on temperature of + 40C 7, 14 and 21 days to mature. After this period, all mentioned analyses were carried out on meat samples. It was established that pH value during maturation increased, that meat packaged in plastic foil after 14 days of maturation becomes unusable, whereas the increase of pH values of meat whose maturation occurred in solution CaCl2 and NaCl was slower and therefore meat was still usable after 21 days. Color of meat in control samples was slightly lighter compared to initial condition, whereas the color of meat whose maturation occurred in solutions of salt was statistically considerably lighter (P<0,05 after 7 days, a P<0,001 after 14 and 21 days). Water binding ability in control samples was slightly better (P>0,05) after 7 days and after 14 days it was statistically significantly better (P<0,05) compared to initial state, whereas in meat whose maturation occurred in salt solution this ability was at initial level even after 21 days. Cooking loss in control samples was lower compared to initial values whereas in meat soaked in salt solution cooking loss was higher. Meat tenderness in control samples was statistically considerably better after 14 days of maturation (when meat was not fit for use) and in meat soaked in salt solution it was statistically highly significantly better after 14 and 21 days. According to sensory evaluation, control samples of meat, after 14 days of maturation are not fit for use, whereas meat whose maturation occurred in solution of CaCl2 and NaCl even after 21 days is acceptable from the sensory aspect.


2020 ◽  
Vol 7 (2) ◽  
pp. 55-60
Author(s):  
I. Muižniece ◽  
D. Kairiša

Aim. The aim of the study was to explain the difference of pH values in heifer and bull meat and to carry out an analysis of the effect of age in groups of both sexes. Methods. The study contains data on 2,469 beef breed and their crossbreed cattle fattened on farms in Latvia and Lithuania, slaughtered in a certifi ed Lithuanian slaughterhouse ʻAgaras’ in 2018. For the assessment of the effect of sex, the beef cattle were divided into 2 study groups: 1,266 bulls and 1,203 heifers. 3 study groups were created for analysis of the effect of age: 12 – 17 months; 18 – 23 months; 24 and more months. Analysis of the data acquired was based on the indicators of descriptive statistics. T–test and Pearson correlation analysis were used. Results. The average pH in the meat of bulls was 5.87 ± 0.011, but in the meat obtained from heifers – 5.66 ± 0.005 (p ≤ 0.05). Within the desired pH value from 5.4 to 5.8, the group of bulls comprised 65 % of carcasses and the group of heifers – 86 % of carcasses. In the group of bulls, 35 % of carcasses had an increased pH in the meat (pH –≥ 5.9), while in the heifers’group – 13%. For a small part of the carcasses in both study groups, too low pH was found in meat (pH ≤ 5.3), with 1% in the group of bulls and 0.4% in the group of heifers. An analysis of the effect of age found no signifi cant differences in pH values between bulls of different ages. In the heifers’study group, the highest pH in meat was found in the group above 24 months of age, pH–5.69. Correlation analysis between the meat pH and the slaughter results showed a weak or non–existent relationship. In the overall study group, stronger correlation was observed between pH and fat score (r = –0.21, p < 0.05). Conclusions. The results indicate that meat from heifers is better quality in terms of desired pH. Meat with the desired pH can be used in the production of high-quality products that provide higher profi ts.


2009 ◽  
Vol 78 (3) ◽  
pp. 497-504 ◽  
Author(s):  
Alena Saláková ◽  
Eva Straková ◽  
Veronika Válková ◽  
Hana Buchtová ◽  
Iva Steinhauserová

The objective of this study was to compare the quality indicators of chicken breast meat depending on sex, to evaluate individual quality indicators and to find relationships between them. Three groups (A, B and C) of commercial meat-type hybrid broilers ROSS 308 (10 males and 10 females from each group) were used for colour measurement (CIE L*a*b*), pH, chemical analysis (amount of dry matter, fat and collagen) and texture (shear force, hardness, cohesiveness). Cooked meat indicators (texture, colour, pH and chemical indicators) were measured after heat treatment (80 °C, 30 min). In all groups we were able to prove raw meat differences between sexes only in the following indicators: carcass weight (A group P < 0.01, B and C group P < 0.001), breast weight (A group P < 0.01, B and C group P < 0.001) and pH value (A group P < 0.05, B group P < 0.001, C group P < 0.01). Differences were found (P < 0.05) between sexes in texture indicators (hardness or cohesiveness), breast meat of males was more tender. The cooked breast meat was significantly (P < 0.05) lighter, redder and more yellow than the raw meat. Raw meat pH had a significant negative correlation (r = -0.41, P < 0.001) with raw meat lightness. Cooked meat pH had a significant correlation with cooked colour indicators. The amount of collagen had significant correlations with shear force (P < 0.001), hardness (P < 0.001) and cooking loss (P < 0.01).


Author(s):  
Xiao Liu ◽  
Mingli Zhang ◽  
Xi Meng ◽  
Yanhong Bai ◽  
Xiuping Dong

Plasma-activated water (PAW) is a new sanitizer, which has received great attention for application in food industries. This research aimed to evaluate the effect of PAW on the inactivation of Shewanella putrefaciens and quality attributes of Yellow River carp ( Cyprinus carpio ) fillets. The carp fillet samples were immersed in sterile deionized water (SDW) or PAW120 (plasma discharge on the deionized water surface for 120 s) for 1.5, 3.0, 4.5, and 6.0 min, respectively. After being treated by PAW120 for 6 min, the population of Shewanella putrefaciens on carp fillets was significantly decreased by 1.03 log 10 CFU/g ( p &lt; 0.05). Compared with SDW-treated samples, the L * value of carp fillets increased, whereas the a * value was decreased following PAW120 treatment, while there was no significant difference in the b * value ( p &gt; 0.05). Compared with SDW, PAW120 caused no significant changes in sensory properties and texture attributes of carp fillets including hardness, springiness, gumminess, and cohesiveness ( p &gt; 0.05). However, for 6-min treatment of PAW120 caused a significant increase in the lipid oxidation level and a decrease in the pH value of the carp fillets. This work provides a basis for the potential application of PAW in the preservation of aquatic products.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nirmani N. Wickramasinghe ◽  
Mya M. Hlaing ◽  
Joshua T. Ravensdale ◽  
Ranil Coorey ◽  
P. Scott Chandry ◽  
...  

Abstract Psychrotrophic Pseudomonas species are the key spoilage bacteria of aerobically stored chilled meat. These organisms readily form biofilms on meat under refrigerated conditions leading to consumer rejection and associated economic losses. Limited information is available on the matrix composition of the biofilms formed by these bacteria. We quantified and characterized the main components of the matrix of mono-species biofilms of selected Pseudomonas fragi and Pseudomonas lundensis strains using chemical analysis and Raman spectroscopy. The biofilms were grown at 10 °C and 25 °C on nitro-cellulose membranes placed on surface sterilized beef cuts. Extra-cellular polymeric substances of the matrix were extracted in soluble and bound forms and were chemically assessed for total carbohydrates, proteins and extra-cellular DNA. Both Pseudomonas species showed a significant increase in total carbohydrates and total proteins when grown at 10 °C as compared to 25 °C. Extra-cellular DNA did not show a strong correlation with growth temperature. Raman spectra were obtained from planktonic bacteria and membrane grown biofilms at 10 °C and 25 °C. Higher levels of guanine were detected in planktonic cells as compared to biofilm cells. This study suggests that psychrotrophic Pseudomonas species may respond to cold stress by increasing extra-cellular polymer secretions.


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