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1.
This paper analyses changes in the quality of meat (M. longissimus dorsi) of roe deer bucks during 21 days of cold storage (2 degrees C) under vacuum and modified atmosphere (MA) conditions (40% CO2/60% N2 and 60% CO2/40% N2). After 21 days of storage, meat packaged in a MA with 40% CO2 had higher (P < or = 0.05) L*, a*, b* and C* values in comparison with meat stored under vacuum and MA with 60% CO2. The mean pH and TBARS values of meat packaged under vacuum and a MA with 40% CO2 were increasing for the first 7 days of storage, and then they decreased (P < or = 0.05). Following storage, the colour of meat became lighter (L*) and more yellow (b*). The meat stored under vacuum was characterised by increased (P < or = 0.05) cooking loss. During meat storage, a significant increase (P < or = 0.05) in total microbial counts and psychrotrophic bacteria was observed.  相似文献   

2.
Proteolytic and lipolytic enzymatic activities of microorganisms are the most important cause for food spoilage and a limited shelf life. Until now the determination of the total aerobic count is the base of shelf life evaluations. Our investigations show the proportion of proteolytes and lipolytes to the total germ count in different kinds of food (milk and milk products, meat products and fish) which is in part surprisingly high. Results were observed on different media--proteolytic germs were counted on protein containing agar (casein, meat protein, fish protein) and lipolytic organisms on fat containing agar (tributyrin, olive oil, butterfat). Using the predictive microbiology and the knowledge about the activity of microbial enzymes under different milieu conditions in food the results give an important tool for a better shelf life evaluation.  相似文献   

3.
研究不同气调包装方法对保存期间的牛肉品质的影响,探索适宜新疆地区生鲜冷却牛肉保鲜的包装方法.将宰后的牛肉采用5种不同的气调包装放在4℃条件保存,对牛肉保鲜效果进行研究,测定分析理化、菌落总数、色泽等主要指标.结果表明,在不同气调包装条件下,贮藏过程中牛肉样品的理化指标变化和微生物繁殖情况不同,气调包装C组的牛肉在保持较...  相似文献   

4.
Fresh meat color is a major factor influencing the purchase of meat products by consumers, whereas tenderness is the primary trait determining overall eating satisfaction of consumers. The objectives of this research were to determine the effects of packaging atmosphere on fresh beef color stability, cooked color, and tenderness. Longissimus lumborum muscles (n = 14 pairs) from USDA Select, A-maturity carcasses were assigned to either 14-d tenderness measurement or to display and then to 18-d [80% O(2), 20% CO(2) (HiO(2)) modified atmosphere packaging (MAP)] or 28-d [vacuum package (VP) and ultra low (ULO(2)) plus CO MAP blends] tenderness measurement. Loins were then fabricated on d 7 postmortem into 2.54-cm-thick steaks. Steaks 8 to 10 caudal to the first 7 steaks were bisected, assigned to a packaging treatment, and used for internal cooked color. One full steak was used for initial tenderness. Packaging treatments were as follows: vacuum-packaging (VP); 80% O(2), 20% CO(2) (HiO(2)); 0.4% CO, 35% CO(2), 64.6%N(2) (ULO(2)CO); 0.4% CO, 99.6% CO(2) (ULO(2)COCO(2)); 0.4% CO, 99.6% N(2) (ULO(2)CON(2)); or 0.4% CO, 99.6% Ar (ULO(2)COAr). Steaks packaged in HiO(2) MAP were in dark storage (2 degrees C) for 4 d, and all other steaks were in dark storage for 14 d. Steaks were displayed under fluorescent lighting (2,153 lx; 3,000 K) for 7 d, with instrumental color measured on d 0 and 7 of display. Trained color panelists (n = 10) assigned color scores. Steaks for Warner-Bratzler shear force and cooked color were cooked to 70 degrees C. Steaks packaged in the 4 ULO(2) MAP blends with CO had no change (P > 0.05) or increased (P < 0.05) a* values for fresh color. Steaks packaged in VP or the 4 ULO(2) MAP blends with CO had little or no surface discoloration. Steaks packaged in HiO(2) MAP discolored faster (P < 0.05) and 56% more (P < 0.05) than those in any other packaging treatment. There were no differences (P > 0.05) in Warner-Bratzler shear force on d 14 postmortem. Steaks packaged in HiO(2) MAP were less tender (P < 0.05) than the other treatments at the end of display but had 10 d less aging due to a shorter dark storage period. Steaks packaged in HiO(2) had the lowest (P < 0.05) a* values for internal cooked color of all packaging treatments. Steaks packaged in ULO(2)COCO(2) and VP had intermediate a* values, whereas those packaged in ULO(2)COAr, ULO(2)CO, and ULO(2)CON(2) had the greatest (P < 0.05) a* values for internal cooked color. Ultra-low oxygen packaging treatments had longer fresh color stability than steaks packaged in HiO(2) MAP and equal or better tenderness. Packaging atmospheres altered the internal cooked color, with steaks packaged in HiO(2) MAP exhibiting premature browning.  相似文献   

5.
1. The combined effect of sage (S), sodium erythorbate (SE), a mixture of sage and sodium erythorbate (MIX) and vacuum packaging (VP) and modified atmosphere packaging (MAP) on the quality of cooked turkey meatballs stored at 4°C was investigated. The physicochemical properties (colour, MDA, AV, pH, water activity), microbiological quality characteristics (counts of mesophilic and psychrotrophic bacteria, fungi, coliforms and Clostridium sp.) and flavour attributes of meatballs were determined. 2. The values of the colour parameters L*, a* and b* were affected by the additives and packaging method. The colour of meatballs was better protected by sodium erythorbate than by sage or a mixture of sage and sodium erythorbate. The additives effectively stabilised lipids against oxidation and slowed down hydrolytic changes in turkey meatballs. Sage and a mixture of sage and sodium erythorbate showed stronger antioxidant properties than sodium erythorbate added alone. Products with additives were characterised by better sensory quality than control samples. Sage and MIX prevented the growth of mesophilic and psychrotrophic bacteria. All additives inhibited the growth of coliforms. 3. MAP was more effective than VP in maintaining the microbial and sensory quality stability of cooked turkey meatballs. However, VP appears to be a better method as regards the maintaining of lipid stability in turkey meatballs.  相似文献   

6.
The objective of this study was to determine the retail shelf stability of beef chuck and round muscles enhanced with ammonium hydroxide, salt, and carbon monoxide. A split plot design was used for each of 3 muscles [triceps brachii (TB), biceps femoris (BF), and rectus femoris (RF)] with 2 treatments (0 and 20% pump), 3 dark storage periods (1, 2, and 3 wk), and 3 replications in the whole plot and retail display period as the split plot. There were a total of 12 subprimals per treatment per dark storage period (n = 72 each). Individual steaks were cut to a thickness of 2.54 cm and packaged in a modified-atmosphere package (MAP). The TB was packaged in a high-oxygen MAP (80% oxygen, 20% carbon dioxide). The BF and RF were packaged in a low-oxygen MAP (100% carbon dioxide). At the completion of each dark storage period, steaks were subjected to 7 d of simulated retail display. Steaks were used for objective and subjective color measurements, total plate counts, and determination of retail purge and oxidation. For all muscles, total plate counts were always numerically greater in injected steaks. Triceps brachii steaks held in dark storage for 3 wk and displayed at retail for 4 or more days all exceeded 10(7) log of cfu/cm(2) for aerobic plate count. Biceps femoris and RF steaks packaged in a low-oxygen MAP had much lower bacterial counts, with levels below 4.2 log of cfu/cm(2), even after 7 d of retail display. Oxidation values for the TB were extremely high (ranging from 12.3 to 26.6), whereas the BF and RF had values that were much lower (< or =1.0 mg of malonaldehyde/kg of muscle), likely due to the oxidation occurring in a high-oxygen MAP for the TB. Enhanced TB steaks proved to have greater color stability (less discoloration) than nonenhanced TB steaks. In addition, the BF and RF (low-oxygen MAP) steaks had better color stability (more stable redness values) than TB (high-oxygen MAP) steaks, although TB steaks initially exhibited a brighter red color. Retail display life was enhanced by packaging in 100% carbon dioxide, and enhanced steaks exhibited greater color stability in retail display than control steaks.  相似文献   

7.
This paper reviews the microbiological aspects of forage preserved by ensilage. The main principles of preservation by ensilage are a rapid achievement of a low pH by lactic acid fermentation and the maintenance of anaerobic conditions. The silage microflora consists of beneficial micro-organisms, i.e. the lactic acid bacteria responsible for the silage fermentation process, and a number of harmful micro-organisms that are involved in anaerobic or aerobic spoilage processes. Micro-organisms that can cause anaerobic spoilage are enterobacteria and clostridia. Clostridium tyrobutyricum is of particular importance because of its ability to use lactic acid as a substrate. Silage-derived spores of C. tyrobutyricum can cause problems in cheese making. Aerobic spoilage of silage is associated with penetration of oxygen into the silage during storage or feeding. Lactate-oxidizing yeasts are generally responsible for the initiation of aerobic spoilage. The secondary aerobic spoilage flora consists of moulds, bacilli, listeria, and enterobacteria. Mycotoxin-producing moulds, Bacillus cereus, and Listeria monocytogenes in aerobically deteriorated silage form a serious risk to the quality and safety of milk and to animal health.  相似文献   

8.
1. Early post-mortem pH was used to identify PSE-like turkey meat, characterised by a low water-holding capacity and pale colour. In a commercial turkey processing facility, the pH value of turkey breast muscle was measured at 0, 9, 10, 14, 154, 231, and 246 min post mortem. 2. At 14 min post mortem, the carcases were separated into 3 pH classes: low (<5.70), medium (5.70 to 6.18), and high (>6.18). Low pH carcasses (<5.70) had higher drip loss(1.75%) than medium (0.81%) and high pH carcases (0.75%). Furthermore, high pH carcases (>6.18) had a lower L* value (darker) than low and medium pH carcases. 3. The effects of using CO2 'snow' on turkey breast muscle quality were also investigated. Light CO2 'snow' treatment (57 g snow/kg breast) and heavy CO2 treatment (113 g snow/kg breast) resulted in higher drip losses than the control no CO2 snow) group.  相似文献   

9.
1. The objective of this study was to evaluate the effect of sex and gas stunning on quality attributes of turkey breast meat.

2. One hundred B.U.T. Premium turkeys (50 males and 50 females) were divided into four groups of 25 animals and subjected to one of two CO2 stunning procedures: G1 stepwise (step 1: 30% CO2, 15 s; step 2: 55% CO2, 40 s; step 3: 70% CO2, 45 s) or G2 fixed concentration (80% CO2, 100 s). The pH and meat colour at 20 min post-mortem, and pH, colour (L*, a*, b*), water holding capacity (WHC), drip loss (DL), cooking loss (CL) and Warner–Bratzler shear force (WBSF) in breast samples at 24 h and 7 d post-mortem were assessed.

3. There were significant differences between stunning groups for pH, meat colour and CL, whereas no significant differences were found for DL and WBSF. Sex had a significant effect on pH and b* and ageing of meat affected pH, colour coordinates, DL and WBSF.

4. It was concluded that the G2 treatment affected negatively the pH value and colour coordinates. However, G2 stunning affected positively the WHC parameters. Female turkeys had better results than males for pH, and the colour of female turkey breast meat was less yellow than male breast meat.  相似文献   


10.
1. This experiment evaluated the influence of the rate of post mortem pH fall on the processing ability of turkey meat. 2. Four hundred and twenty male turkeys from a selected pure line (grand-parental female line, BUT Ltd) were slaughtered at 16 weeks of age in a commercial plant and pH was measured in the Pectoralis superficialis (PS) and Ilio tibialis (IT) muscles, at 20 min post mortem. Three groups of PS muscle differing in pH20 and two groups of IT muscle differing in pH20 were constituted and processed as cured-cooked white meat and turkey ham, respectively. 3. The technological yield was lower in the groups showing the lowest pH20 (97.4% at pH20 5.90 vs 98.6 and 98.3% at pH20 6.24 and 6.55, respectively, for white meat and 97.2% (pH20 6.28) vs 98.3% (pH20 6.56) for turkey hams). The groups showing the lowest pH20 also showed higher drip loss in commercially packed products. 4. Acceptability tests of processed products were carried out in the commercial plant. Texture and taste of white meat were better in the highest pH group but the overall impression was similar in the lowest and the highest pH groups (mean scores of 4.2 and 4.1, respectively), due to better colour in the former (mean scores of 4.4 for the lowest pH20 group vs 4.0 and 3.9 for the medium and highest pH20 groups, respectively). 5. For turkey hams, the meat processed from the highest pH group got the best score for all items.  相似文献   

11.
Lactic acid bacteria (LAB) can reduce Escherichia coli O157:H7 and Salmonella spp. in ground beef during storage. Furthermore, the addition of rosemary oleoresin (RO), a natural antioxidant, to ground beef has been shown to increase shelf life and is commonly used in modified-atmosphere packaged (MAP) ground beef. This study evaluated the effects of LAB and RO treatment on the shelf life and stability of MAP ground beef displayed at abusive (10°C) temperatures for 36 h. Subjective and objective sensory analyses were conducted to determine spoilage endpoints. Trained and consumer panel responses and Hunter lightness (L*), redness (a*), and yellowness (b*) values were not affected (P = 0.62, 0.66, 0.45) by LAB addition, although RO inclusion improved (P < 0.05) lean color. Ground beef with LAB and RO had significantly less (P < 0.0001) thiobarbituric acid reactive substance values than control ground beef, indicating decreased lipid oxidation. Additionally, RO inclusion reduced (P < 0.0001) off odors, as determined by trained and consumer odor panelists. Overall, the addition of LAB did not negatively affect beef color, odor, or oxidative rancidity, suggesting that LAB can be added to ground beef in MAP packaging as a processing intervention without detrimentally affecting shelf life or stability.  相似文献   

12.
Lactic acid as a decontaminant in slaughter and processing procedures   总被引:1,自引:0,他引:1  
An attempt was made to interrelate the data obtained in experiments conducted by our Department along beef, veal and pig slaughter lines, using lactic acid (LA) for the decontamination of carcasses, cold and hot boned primal cuts, slaughter byproducts, and butcher's knives. First and foremost it was observed, that provided Good Manufacturing Practices are strictly followed, the microbial load of carcass surfaces will be substantially reduced. LA-decontamination may result in an additional reduction. Since in the early post-mortem period bacteria are not yet attached to the meat surface, LA-decontamination should preferably be applied to the hot carcass. It was demonstrated that, dependent on mode and duration of application, LA sprays not exceeding 1% v/v (beef), 1.25% v/v (veal) and 1.5% v/v (pork) resulted in acceptable carcass colour scores. Blood spots, which are particularly prone to discolouration by lactic acid application, should be removed at an early post-mortem stage e.g. by strong showering. The difference in surface pH between LA-treated and control carcasses disappeared within 72 hours post-mortem. Veal longissimus chops treated with LA solutions up to 2% v/v were not identified by a consumer taste panel as significantly different from controls. The 'immediate' bactericidal effect of LA-decontamination for beef, veal and pig carcasses, as well as for pig liver and veal brain, amounted to approximately 1.5 log cycles for the aerobic colony counts, strongly dependent on substrate and conditions of decontamination. In addition, a 'delayed' bacteriostatic effect was observed during storage, which is probably the result of a prolonged lag phase of acid-injured micro-organisms surviving lactic acid decontamination.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
The aim of the present study was to evaluate the bacterial quality of chicken (n = 96) and turkey (n = 96) marketed in Casablanca, Morocco. Poultry samples (n = 192) were collected randomly from traditional shops and supermarkets during 2 sampling periods (hot and cold seasons). The samples were analyzed for the presence and counts of various bacteria. Results indicated that aerobic plate counts and fecal coliforms were particularly high in all the samples analyzed. Escherichia coli, coagulase-positive Staphylococcus, Clostridium perfringens, Salmonella, and Listeria monocytogenes were detected, respectively, in 48.4, 10.4, 7.2, 1.6, and 0.5% of the poultry meat samples. The chicken and turkey samples contained, respectively, 25 and 33.3% of bacteria above the maximum limits established by the Moroccan regulatory standards. The highest bacterial counts in poultry meat product samples were recorded with the traditional slaughtering process during the hot season (P < 0.05). These high levels of microbial contamination and occurrence of pathogenic bacteria reflect the poor hygienic quality of poultry meat under these conditions.  相似文献   

14.
Extract

The contamination of refrigerated and chilled meats with microbial growths has been of concern ever since the 1880s when micro-organisms possessing the ability to survive and grow at low temperatures were first incriminated as causative agents of the contamination. The first microbial organisms described on meat at low temperatures were bacterial and it would seem that at present bacteria are still the most important agents of meat spoilage. Spoilage by fungi is less well known, but occasional consignments are still encountered that show visible mould growth.  相似文献   

15.
1. The effects of rearing chickens using standard, maize-fed, free-range or organic production systems on meat quality and sensory characteristics were evaluated. The standard system used either Ross or Cobb birds with a slaughter age of approximately 40 d, the other systems in the trial used Hubbard birds with considerably older slaughter ages, up to 72 d in the case of organic systems. 2. Paired breast fillets from 120 birds, 30 from each rearing system, were used. The meat quality variables, ultimate pH, colour coordinates L*, a*, b* and water-holding capacity were measured and taste panel assessments were made using 8-point category scales of texture, juiciness, abnormal flavour, flavour liking and overall flavour. 3. There were significant differences between rearing systems, with fillet muscles from birds grown under the standard system having a higher ultimate pH. Differences were also seen in colour with fillets from birds reared under a standard system having a smaller hue angle than those grown using the maize-fed system which had the highest. 4. Fillets from birds reared in the standard system were rated by the taste panel as more tender and juicy. There were no significant differences in chicken flavour. Based on hedonic assessments of flavour liking and overall liking, by a small panel of assessors, meat from birds produced in the standard system was most preferred and that from organic systems the least preferred. Meat from free-range and maize-fed systems was intermediate in preference. This result reveals a trend, but does not infer consumer acceptance.  相似文献   

16.
17.
The effects of freeze-thaw conditions on the fermentation quality and aerobic stability of oat silage were investigated. Four strains of freeze-thaw-resistant lactic acid bacteria(LAB)with rapid growth and efficient acid production were screened from 437 strains,which had been isolated from the Qinghai-Tibetan Plateau. Based on physiological and biochemical characteristics and 16S rRNA gene sequence alignment,the four strains were identified as Lactobacillus plantarum 157(LP157),L. plantarum 160(LP160),Lactobacillus brevis 248(LB248),and Lactobacillus pentosus 260(LPE260). In order to investigate their effects on the fermentation quality,nutrient composition,microbial counts and aerobic stability of oat silage under freeze-thaw conditions,seven treatments were tested as follows:1)LP157;2)LP160;3)LB248;4)LPE260;5)LP160+Lactobacillus rhamnosus 753 mixture (MIX);6)A commercial bacterial silage additive(COM);7)The same amount of sterilized distilled water(CK). All treatments were ensiled for 60 days at a constant temperature of 20 ℃ and under a 20 ℃/-5 ℃ regime alternating every 12 h(freeze-thaw). LP inoculation improved silage quality:The pH and dry matter loss in silages inoculated with LP157,LP160,LB248 and LPE260 were significantly lower than CK(P<0. 05)and lactic acid and acetic acid contents were significantly higher than CK(P<0. 05),and the growth of spoilage micro-organisms such as coliform bacteria,yeast and mold were inhibited,both with fermentation at constant 20 ℃ and under freeze-thaw conditions. After aerobic exposure for 5 days,the pH and NH3-N of silages treated with LP157,LP160,LB248 and LPE260 were significantly(P<0. 05) lower than CK,MIX and COM. The aerobic stability of oat silage was improved,especially when inoculated with LP160(70 h vs. CK 11 h). The results show that the four screened strains can be used as effective LAB inoculants for silage preparation in the freeze-thaw environment of the Qinghai-Tibetan Plateau. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.  相似文献   

18.
The objective of this study was to determine the effect of feeding zilpaterol hydrochloride (ZH) on the shelf life and stability of ground beef. Beef knuckles and plates were obtained from USDA Select beef heifer carcasses from control (CON) animals or those supplemented with ZH (8.33 mg/kg of dietary DM basis) for the last 20 d of the finishing period. Subprimals were coarsely ground and blended to produce an 80% lean product. The mixture was vacuum-stuffed into chubs and placed in dark storage at 2 to 4°C for 7, 14, or 21 d before fine grinding. Each week, the finely ground samples were packaged on expanded polystyrene trays overwrapped with polyvinyl chloride film and placed in refrigerated retail cases (0 to 2°C) under continuous fluorescent lighting to simulate retail display. Samples were subjected to a variety of analyses at different time intervals (h) during simulated display, including composition analysis, thiobarbituric acid-reacting substance analysis (TBA), sensory color, instrumental color, and aerobic plate count. Data analysis revealed trained sensory color and discoloration scores were similar between CON and ZH-treated samples. Instrumental L* and b* values for CON and ZH-treated samples did not differ (P = 0.13 and 0.19, respectively). Instrumental a* values declined (P < 0.05) over the display period for CON and ZH ground beef. However, a* values for ZH ground beef stored for 7 d were greater (P < 0.05) than CON values at 18 through 72 h of display. There was a treatment × storage day interaction (P < 0.001) for TBA values with ZH having smaller TBA values than CON after 7 d of dark storage. There was no difference (P = 0.21) in aerobic plate count between ZH and CON ground beef samples. Overall, ground beef from cattle supplemented with ZH was equal to or better than CON for sensory color and discoloration, instrumental color, and stability variables, including TBA reactive substances and aerobic plate counts.  相似文献   

19.
1. The effect of increasing the pH (4.5 to 7.5) of white and dark comminuted turkey meat on the microstructure of cooked batters was studied.

2. Both scanning and transmission electron micrographs revealed that low pH caused the formation of a dense aggregated gel matrix while increasing the pH resulted in more open structures.

3. At pH 7.5 both the white and dark meat exhibited superior water holding capacity (both raw and cooked) compared to the low pH treatments; all adjusted to 14% protein.

4. The high pH also resulted in a higher gel strength, while the low pH (4.5) produced a soft and crumbly texture. As pH was raised, gel strength gradually increased reaching a maximum at pH 7.5. Decreasing the pH resulted in lighter meat batters in both the white and dark turkey meat.

5. Muscle fibre microstructure appeared to be better preserved at the low pH treatments.  相似文献   


20.
1. Conventional cultivation and immunomagnetic separation (IMS) cultivation methods were compared for the isolation specificity and sensitivity of L. monocytogenes from turkey meat samples. PCR was used to confirm the isolates. Disc diffusion was performed to determine the antibiotic susceptibility profiles. A total of 180 turkey meat samples collected from markets in Turkey were tested. 2. L. monocytogenes was detected in 23 samples (12.7%) by IMS and conventional cultivation. It was isolated from 16.6% (10/60), 11.6% (7/60) and 10.0% (6/60) of the meat cut, breast and leg samples, respectively. PCR assay was performed based on hlyA (LLO-listeriolysin O) gene specific primers. In all 23 (100.0%) isolates of the hlyA gene were determined. The disc diffusion test showed that 19 (82.6%) isolates were resistant to penicillin G and 17 (73.9%) to ampicillin. In addition, 8 isolates were partially resistant to erythromycin and 8 to streptomycin. 3. In conclusion, to safeguard public health turkey meat must be produced under hygienic and suitable technological conditions. Furthermore antimicrobials, as prophylactic or growth promoter agents, must be firmly controlled by governmental agencies.  相似文献   

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