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Muscle glycogen stores and meat quality as affected by strategic finishing feeding of slaughter pigs.

The aim of the present study was to investigate whether muscle glycogen stores in slaughter pigs could be decreased through strategic finishing feeding before slaughter. Moreover, preliminary meat quality traits were measured to see whether such a regulation of muscle glycogen stores affected ultimate pH, color, and tenderness in the meat. The strategic finishing feeding was carried out the last 3 wk prior to slaughter. Seven experimental groups with eight animals per group were fed diets low in digestible carbohydrates. A control group with four animals was fed a traditional grower-finishing diet. The muscle glycogen stores were reduced in longissimus muscle (LM) 11 to 26% at the time of slaughter in pigs that were fed the experimental diets compared with the control group. Meat quality measured as ultimate pH and color on LM muscle in half the pigs 24 h postmortem showed that ultimate pH in LM was not affected by the reduction in glycogen stores in the muscles from pigs fed any of the experimental diets. However, the meat from pigs fed the experimental diets was darker than the meat from pigs that were fed the control diet with two of the experimental diets, resulting in significantly lower L* values. Activities of key enzymes in the glycolytic pathway, glycogen phoshorylase a and b, phosphofructokinase, and the fatty acid oxidative pathway, beta-hydrozyacyl-CoA-dehydrogenase, were not affected by the strategic feeding. In contrast, the activity of the proteolytic enzyme calpain as well as its inhibitor calpastatin was influenced by the strategic feeding. Lower activity of mu-calpain and greater activity of calpastatin in the muscle samples from the strategically fed pigs indicate a lesser muscle protein degradation in the muscles compared with muscles of control animals. The present study showed that the muscle glycogen stores in slaughter pigs can be reduced at the time of slaughter through strategic finishing feeding with diets low in digestible carbohydrate without compromising growth rate.

3-Hydroxyacyl CoA Dehydrogenases↗

The influence of farmers' behavior on calves' reactions to transport and quality of veal meat.

The relationships between farmers' behavior toward veal calves, calves' responses to handling and transport, and veal meat quality were assessed. Two groups of 10 veal units were selected based on previous observed farmers' behavior toward the calves: one group consisted of farmers who had shown predominantly "positive" behavior toward the calves, and the other group of farmers had shown predominantly "negative" behavior. Calves were observed for their reactions to people at the unit, and 20 calves per veal unit were transported either directly to the slaughterhouse or subjected to additional transport consisting of a supplementary 20-min transport with additional unloading and loading. The effort needed to load the calves onto the truck and their behavior during loading was observed. During loading and unloading, and during lairage at the slaughterhouse, potentially traumatic incidents (falling down, hits against structures, slips) were recorded, and heart rate and cortisol measurements were taken. Carcasses were evaluated on their weight, color, conformation, pH, and bruise level. A meat sample was taken from the longissimus thoracis muscle for physical, chemical, and sensory analysis. Calves originating from "positive behavior" units showed fewer fear responses to people at the veal unit, needed less effort to be loaded to the truck, had lower heart rates during loading and unloading, and had fewer incidents at the slaughterhouse than calves from "negative behavior" units (P < 0.05). Carcasses from calves from "positive behavior" units were paler, and analyses of the meat sample revealed lower pH, moisture level, and redness compared to carcasses from calves from "negative behavior" units (P < 0.05). Additional transport led to a lower cortisol level after transport and to higher carcass pH values at slaughter compared to direct transport (P < 0.05) but did not affect meat quality. We concluded that farmers' positive behavior toward veal calves during rearing is likely to reduce the emotional responses of calves to handling and transport and to lead to fewer incidents, compared to negative behavior. This reduction of calves' emotional responses seems to be the reason for improved veal meat color.

Animals↗

The provision of solid feeds to veal calves: I. Growth performance, forestomach development, and carcass and meat quality.

Growth performance, forestomach development, and carcass and meat quality of veal calves fed a milk replacer diet (Control) were compared to those obtained from calves fed the same liquid diet plus 250 g x calf(-1) x d(-1) of dried beet pulp or wheat straw. Three groups of 46 Polish Friesian calves, balanced according to initial BW, were assigned to the three dietary treatments in a fattening trial, which lasted 160 d. The provision of either solid feed did not affect the milk replacer intake. However, calves' ADG was increased (P < 0.01) only by feeding the beet pulp diet. The administration of both solid feeds improved calves' health status; calves fed solid feeds required fewer iron treatments for low hemoglobin and needed less medical treatments for respiratory or gastrointestinal diseases. In comparison to the Control calves, the provision of wheat straw and beet pulp increased iron intake throughout the fattening period by 41 and 130%, respectively. However, only calves fed beet pulp showed higher levels of hemoglobin and plasma iron concentrations (P < 0.05), whereas the same blood parameters were similar between Control calves and those fed wheat straw. At slaughter, both solid feeds led to empty forestomach weights heavier than those of Controls without reducing dressing percentage. The reticulorumen was heaviest in calves fed beet pulp, whereas wheat straw promoted omasal development. The administration of beet pulp resulted in a better carcass conformation than did the Control diet or wheat straw, but it had a detrimental effect on carcass color, which was graded as the darkest (P < 0.001). Consistent with this result, meat color of calves fed beet pulp was darker than that of Control calves and those fed wheat straw, because of the higher hematin concentration measured at the muscle level. No differences in carcass and meat color were observed between Control calves and calves fed wheat straw. The administration of solid feeds for welfare purposes does not always prevent the production of veal meat fulfilling the color standards required by the market. There is not a straight-forward relationship between a solid feed's iron content and the "redness" of veal meat, which should be related to the capability of the calves to use the iron provided by the roughage.

Animal Feed↗

The effect of selection for growth rate and slaughter age on carcass composition and meat quality traits in rabbits.

The effect of selection for growth rate on carcass and meat quality was assessed by comparing selected and control populations of rabbits measured at the same stage of maturity and slaughtered at 9 and 13 wk of age. Embryos belonging to Generation 7 were frozen, thawed, and implanted in does to produce the control group. The control group was formed from the offspring of the embryos belonging to the Generation 7. Selected animals belonging to Generation 18 (S) were compared with contemporary animals of the control group (C). Carcasses were dissected and measured according to World Rabbit Science Association recommended practices. When animals were compared at similar degrees of maturity, selection for growth rate did not produce a negative effect on carcass and meat quality. There was no increase in fat content of the carcass, and there was an improvement of the meat:bone ratio with selection, with a difference between C and S groups of -0.42. However, the carcasses of S animals have 1.45% lower water-holding capacity. Carcass quality changed markedly with animal age. Heavy rabbit carcasses had lower organ percents and a higher loin percent. Dissectible and i.m. fat content were higher in older rabbits, with older animals having 0.97 and 0.79% more dissectible and i.m. fat content, respectively. Meat quality traits improved with age of slaughter, although there was an increase in glycolytic metabolism. Results from this study indicate that selection for growth rate has little effect in carcass and meat quality when rabbits are measured at the same stage of maturity.

Age Factors↗

Meat quality traits were unaffected by a quantitative trait locus affecting leg composition traits in Texel sheep.

A QTL affecting leg muscle and fat traits has been identified within the New Zealand Texel population. The QTL maps to a region on OAR 2 with a two-marker haplotype test established at markers BULGE20 and BM81124. These markers encompass the likely position of Growth Differentiation Factor 8 (GDF8). The pleiotropic effects of this QTL on meat quality traits are tested. Objective measures of meat quality including pH, color (L*, a*, and b*), and tenderness (as assessed by Warner-Bratzler shear force measurements) were assessed on longissimus and semi-membranosus muscles of 540 progeny from six Texel sires. Four of these sires were subsequently identified as segregating for leg muscle and fat traits. For these segregating sires, comparison of progeny that had inherited the favorable haplotype from their sire with those that had received the alternate haplotype revealed no significant differences in the meat quality traits assessed. This finding suggests that the muscling QTL does not have pleiotropic effects on meat quality. A general scan for meat quality QTL was carried out using genotype data for eight markers from FCB128 to RM356 flanking 122cM of OAR 2 using Haley-Knott regression. This analysis revealed two QTL for a single sire. A QTL detected in the region of Marker INRA40 for color L* mapped to a site close to the muscling QTL, but there was evidence to suggest it is at a distinct locus. The QTL in the region of Marker RM356 might map distal to Marker RM356, as no peak was observed. This QTL, which seems to affect pH, color a*, color b*, and Warner-Bratzler shear measurements, requires further characterization.

Animals↗

Low birth weight is associated with enlarged muscle fiber area and impaired meat tenderness of the longissimus muscle in pigs.

The objective of this study was to determine the relationships between birth-weight-associated modifications in histological or chemical muscle characteristics and meat quality traits in pigs. At 68 d of age, Pietrain x (Large White x Landrace) female littermates were allocated into 2 groups on the basis of low birth weight (LW = 1.05 +/- 0.04 kg; n = 15) or high birth weight (HW = 1.89 +/- 0.02 kg; n = 15). Pigs were reared in individual pens with free access to a standard diet up to slaughter at approximately 112 kg of BW. During the growing-finishing period, LW and HW pigs had a similar daily feed consumption, whereas G:F was lower (P = 0.009) for LW pigs than for HW littermates. At final BW, LW pigs were 12 d older (P < 0.001) than HW littermates. Estimated lean meat content, relative proportions of loin and ham in the carcass, and weights of LM and semitendinosus muscle (SM) were decreased (P < 0.05) in LW pigs compared with HW pigs. Conversely, the LW pigs exhibited a fatter carcass, greater activity levels of fatty acid synthase and malic enzyme in backfat (n = 15 per group), and enlarged subcutaneous adipocytes (n = 8 per group) compared with the HW pigs. Similarly, lipid content was increased by 25% (P = 0.009), and mean adipocyte diameter was 12% greater (P = 0.008) in the SM from LW pigs compared with that from HW pigs, whereas lipid content did not vary in the LM of either group. Mean myofiber cross-sectional areas were 14% greater in the LM (P = 0.045) and the SM (P = 0.062) of LW pigs than of HW pigs. Conversely, the total number of myofibers was less (P = 0.003) in the SM of LW vs. HW pigs. There were no differences between groups for glycolytic potential at slaughter and rate and extent of postmortem pH decline in both muscles, as well as for LM drip losses. A trained sensory test panel judged the roast loin meat to be less tender (P = 0.002) in LW pigs relative to HW pigs. Scores for juiciness, flavor, flouriness, and fibrousness of meat did not differ between groups. Overall, negative but somewhat low correlation coefficients were found between LM tenderness score and ultimate pH (r = -0.36; P = 0.06) and between LM tenderness and mean cross-sectional area of myofibers (r = -0.34; P = 0.07). This study demonstrates a lower tenderness of meat from pigs that had a LW, partly as a result of their enlarged myofibers at market weight.

Animals↗

Variations in meat pH of beef bulls in relation to conditions of transfer to slaughter and previous history of the animals.

Animals are subjected to various events that cause physical exhaustion and psychological stress during transfer to slaughter. This can lead to defective meat quality. Some animals may be better able to withstand the stress of transfer, depending on their previous experience of transport and on their finishing conditions (mixing, farmers' attitudes). The objective of this study was to assess the impact of 1) the conditions of transfer to slaughter (including duration of the journey, waiting time at lairage, etc.); and 2) the bulls' previous history (including experience in transport, mixing during finishing, and the farmers' attitudes) on the reactions of bulls to transfer and on their meat quality. We conducted a survey in commercial conditions. The history of the bulls and the facilities on the farms were noted; farmers were questioned on their attitudes; the bulls' reactions to loading into and unloading from the truck were observed; journey-related data were collected; and cortisol concentration at slaughter and the pH of the LM and the rectus abdominis were measured. Our study confirmed that certain physical factors associated with transport can increase stress and limit the decline of meat pH. These factors include the absence of loading facilities on the farm, transport on a warm day, or a short waiting time at lairage. Social aspects also played a role; the presence of bulls from the same finishing group limited stress and improved the pH decline. Events and management before transfer were also of importance; the farmer awareness of the sensitivity of bulls to humans or to feeding schedules but the absence of a positive attitude toward close contacts with bulls were all likely to limit stress or its consequences on meat pH. Although these results need to be confirmed in controlled experiments, they suggest that good management of beef bulls before and during transfer is essential to meat quality.

Abattoirs↗

Effects of two beta-adrenergic agonists on finishing performance, carcass characteristics, and meat quality of feedlot steers.

The impact of using 2 beta-adrenergic agonists in feedlot cattle fed finishing diets was evaluated using 54 steers (45 crossbred Charolais and 9 Brangus) initially weighing 424 +/- 26.6 kg in a randomized complete block design with 3 treatments and 6 blocks (i.e., 18 pens with 3 steers per pen). Response variables were feedlot performance, carcass characteristics, and meat quality. Treatments were 1) control (no supplement added); 2) zilpaterol hydrochloride (ZH; 60 mg.steer(-1).d(-1)); and 3) ractopamine hydrochloride (RH; 300 mg.steer(-1).d(-1)). The beta-agonists were added to the diets during the final 33 d of the experiment. The groups of steers fed ZH or RH improved (P < 0.01) ADG by 26 or 24%, respectively, compared with control steers. Steers supplemented with RH consumed less (P = 0.03) DM (8.37 kg) than control steers (8.51 kg), whereas intake was similar (P = 0.37) for ZH and control steers. Addition of either beta-agonist to the diet considerably improved (P < 0.01) the G:F (ZH, 0.253 and RH, 0.248 vs. control, 0.185). Hot carcass weight and carcass yield were enhanced (P < 0.05) with both beta-agonists. The LM area was increased (P = 0.026) by ZH (75.2 cm(2)), but that of RH (72.2 cm(2)) was similar (P = 0.132) to the control steers (66.8 cm(2)). Meat from the ZH- (P = 0.0007) and RH- (P = 0.0267) supplemented steers had greater shear force values than control steers (ZH = 5.11; RH = 4.83; control = 4.39 kg/cm(2)). Variables related to meat color indicated that both beta-agonists led to a similar redness of the LM area related to the control group. In general, feedlot performance was greatly enhanced by beta-adrenergic agonists, and meat tenderness from treated animals was classified as intermediate. Furthermore, meat color was not altered by beta-agonist supplementation.

Adrenergic beta-Agonists↗

Supercritical carbon dioxide extraction of lipids and cholesterol from dehydrated chicken meat.

Supercritical carbon dioxide (SC-CO2) extraction was studied for removal of lipids and cholesterol from dried chicken meat powder and chunks. Two combinations of pressure and temperature were used: 299 atm and 45 C, and 381 atm and 55 C, both providing a fluid density of .90 g/cm3. For a given quantity of CO2, at the higher temperature and pressure, significantly (P < .05) more lipids and cholesterol were extracted from the powder. At 381 atm and 55 C, approximately 89% of the lipids and 90% of the cholesterol were removed from the dehydrated chicken meat powder. With respect to the chunk chicken meat, about 93% of the lipids and 82% of the cholesterol were extracted at 299 atm and 45 C. It seemed that the SC-CO2 extraction process was more efficient when chunks were used. Protein was concentrated as cholesterol and lipids were removed by SC-CO2 extraction of both chicken meat types, and Hunterlab L values increased but aL values decreased, indicating a lighter color with less redness. This research indicated that SC-CO2 extraction holds promise for substantially reducing lipids and cholesterol in chicken meat.

Animals↗

Film oxygen transmission rate effects on ground chicken meat quality.

Effects of the packaging film oxygen transmission rate (OTR) on the odor, color, aerobic plate count, and cooked volatile compounds in ground chicken leg meat were evaluated over a 14-d refrigerated storage (4 C) period. Freshly desinewed and ground chicken leg meat was packaged under minimal vacuum in five films of different OTR. Films ranged from 30 to 12,000 mL oxygen/m2 per 24 h. Odor scores of meat in packages opened after 10 d were lower for the lowest OTR film than films with higher OTR. Aerobic plate counts increased at a faster rate in the higher OTR films, and cooked meat volatile profiles showed little variation due to OTR film type. Specific products will require different packaging to optimize shelf-life quality. For ground chicken leg meat, an intermediate OTR film is best to maintain a majority of the quality attributes during refrigerated storage.

Analysis of Variance↗

Effect of stunning amperage on broiler breast muscle rigor development and meat quality.

Two experiments were conducted to determine the effects of constant amperage (as opposed to constant voltage) electrical stunning on broiler blood loss, post-mortem breast muscle (Pectoralis major) rigor development, and breast meat quality. Broilers were individually stunned for 5 s at 0 (unstunned control group), 50, 100, 150, and 200 mA in Experiment 1 and at 0, 50, and 125 mA in Experiment 2. Breast muscle pH and R-value (ratio of adenosine to inosine nucleotides) were determined at 15 min and 24 h post-mortem; breast meat shear value and color were determined at 48 h post-mortem. Stunning amperage had no effect on percentage blood loss in either experiment. The most rapid post-mortem reactions were observed for the unstunned control group as determined by pH and R-value at 15 min post-mortem. Birds stunned with 50 mA were intermediate with regard to rate of rigor development. The slowest post-mortem reactions occurred in broilers stunned from 100 to 200 mA. There were no differences in pH, R-value, or color between stunning treatments after carcasses were aged for 24 h. Stunning amperage did not affect Allo-Kramer shear value for breast muscles deboned at 15 min post-mortem. In Experiment 2, 24 h aged breast meat from broilers stunned with 125 mA required significantly higher shear value (4.5 kg/g) than breast meat from broilers stunned at 0 or 50 mA (3.8 and 3.6 kg/g, respectively). Results indicate that stunning amperages between 0 and 200 mA had effects on the rate of early rigor development but there were no consistent effects on final breast meat quality.

Animals↗

Effect of stunning time and polyphosphates on quality of cooked chicken breast meat.

The objective of this research was to determine effects of stunning duration and polyphosphates on color, pH, and texture of chicken breast meat. Sixty broiler chickens were electrically stunned for 2 to 10 s in 2-s intervals and then slaughtered. Left and right Pectoralis major muscles were excised 1 h post-mortem. The left muscles (treated) were treated with a sodium tripolyphosphate salt solution, and the right muscles (controls) were treated with a salt solution alone. All muscles were cooked to an endpoint temperature of 72 C in a 95 C water bath. Measurements of muscle pH were taken on the meat 1 h post-mortem, after treating, and after cooking. Color values and Warner-Bratzler shear values were evaluated on each cooked meat sample. As stunning time increased, pH increased at 1 h post-mortem but treating with either of the solutions eliminated this trend. Muscle pH also increased upon cooking except in the polyphosphate-treated muscles, because the latter muscles achieved maximum pH prior to cooking. Stunning had no apparent effect on color values of the cooked meat; however, polyphosphate treatment resulted in meat that was darker and less red than controls. Longer stunning times resulted in greater shear values but polyphosphates did not affect Warner-Bratzler results. Taken together, these data suggest that processing variables that affect muscle pH also affect quality attributes.

Animals↗

A modification of a method to determine expressible moisture in ground, dark poultry meat.

Research was conducted to develop a more accurate and less time-consuming method of determining expressible moisture in poultry meat. Two modifications of wrapping meat in netting (fold wrap or basket wrap) were compared to a conventional method that did not include wrapping meat. Ground, dark poultry meat, with and without 2.0% added NaCl, was wrapped in netting and analyzed for expressible moisture. The fold wrap method was determined to be more accurate and easier to use, as less expressed meat adhered to the surrounding filter papers. Thus, actual expressed moisture absorbed by filter papers was measured.

Animals↗

Effect of diacetyl on controlling Escherichia coli O157:H7 and Salmonella Typhimurium in the presence of starter culture in a laboratory medium and during meat fermentation.

Diacetyl is a flavor compound that possesses antimicrobial activity and is found in several dairy products. The effect of diacetyl on controlling the growth of two foodborne pathogens, Escherichia coli O157:H7 and Salmonella Typhimurium, when grown with Pediococcus acidilactici as a meat starter culture was evaluated in a laboratory medium and during salami fermentation. Diacetyl (50 ppm) added to each mixed culture system strongly inhibited the growth of E. coli O157:H7 and Salmonella Typhimurium in the laboratory medium (brain heart infusion, 2.3% of NaCl, 0.75% of dextrose) (P < 0.05). During meat fermentation, the growth of E. coli O157:H7 and Salmonella Typhimurium was inhibited significantly by addition of diacetyl (300 ppm) (P < 0.05) after 24 h fermentation. However, the acid production and growth of P. acidilactici were not affected by the addition of diacetyl (P > 0.05). After 24 h meat fermentation, about a 1.0-log CFU/g difference occurred in numbers of each foodborne pathogen mixed with P. acidilactici (P < 0.05) with and without 300 ppm diacetyl. Diacetyl and the acid produced by the meat starter culture reduced the growth of the two foodborne pathogens during salami fermentation. These results suggest that diacetyl can be used as a food ingredient during meat fermentation to control E. coli O157:H7 and Salmonella Typhimurium without harmful effects on the growth and acid production of P. acidilactici.

Animals↗

Interventions to reduce microbiological contamination of beef variety meats.

Hot water and solutions of acetic acid, lactic acid, or trisodium phosphate applied by immersion or spraying, chlorine solution applied by immersion, and exposure to steam in a pasteurization system, in a cabinet, or in combination with vacuum were evaluated for their effectiveness in reducing levels of bacterial contamination on samples of beef cheek meat, large intestine, lips, liver, oxtail, and tongue. Treated samples (five per treatment) and controls were analyzed for aerobic plate counts (APCs) on tryptic soy agar and for total coliform counts (TCCs) and Escherichia coli counts (ECCs) on Petrifilm. Acetic acid (2%) immersion and trisodium phosphate (12%) spraying and immersion for 10 s were among the most effective treatments in 16, 15, and 14, respectively, of 18 comparisons for reducing APCs, TCCs, and ECCs on four or more of the six variety meats tested. Acetic acid (2%) spraying, lactic acid (2%) immersion, and hot water (78 to 80 degrees C) spraying for 10 s were among the most effective treatments for reducing APCs, TCCs, and ECCs on four or more of the six variety meats. Chlorine (0.005%) immersion and steam were among the least effective treatments for reducing APCs, TCCs, and ECCs on variety meats. The results indicated that interventions applied to decontaminate beef carcasses can also be considered for decontamination of variety meats.

Animals↗

Microbial evaluation of Spanish potato omelette and cooked meat samples in University restaurants.

The focus of this study was to evaluate the microbial quality of Spanish potato omelette and cooked meat samples including pork loin, chicken croquettes, long pork sausage, chicken breast, and meatballs from University restaurants. Microbiological analyses of Spanish potato omelette and cooked meat samples resulted in aerobic plate counts from <1.00 to 2.90 and from <1.00 to 6.04 log10 CFU g(-1), respectively. Total coliforms ranged from <3 to 43 most probable number (MPN) g(-1) and from <3 to >2,400 MPN g(-1) for Spanish potato omelette and meat products, respectively. Escherichia coli, coagulase-positive staphylococci, and Lancefield group-D streptococci were detected in 1.7%, 3.5%, and 12.9% of Spanish potato omelette samples, respectively. For cooked meat samples, 8.8%, 7.6%, and 24.6% contained E. coli, coagulase-positive staphylococci, and Lancefield group-D streptococci, respectively. E. coli O157:H7, Salmonella spp., and Shigella spp. were not detected. Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter freundii, Enterobacter cloacae, and Serratia spp. were isolated from Spanish potato omelette samples. For cooked meat samples, C. freundii, E. cloacae, and Aeromonas hydrophila were detected. The results suggest that some handling practices should require more attention, and as a consequence, a hazard analysis and critical control point program should be developed and implemented.

Animals↗

Pathogen testing of ready-to-eat meat and poultry products collected at federally inspected establishments in the United States, 1990 to 1999.

The Food Safety and Inspection Service (FSIS) conducted microbiological testing programs for ready-to-eat (RTE) meat and poultry products produced at approximately 1,800 federally inspected establishments. All samples were collected at production facilities and not at retail. We report results here for the years 1990 through 1999. Prevalence data for Salmonella, Listeria monocytogenes, Escherichia coli O157:H7, or staphylococcal enterotoxins in nine different categories of RTE meat and poultry products are presented and discussed. The prevalence data have certain limitations that restrict statistical inferences, because these RTE product-testing programs are strictly regulatory in nature and not statistically designed. The cumulative 10-year Salmonella prevalences were as follows: jerky, 0.31%; cooked, uncured poultry products, 0.10%; large-diameter cooked sausages, 0.07%; small-diameter cooked sausages, 0.20%; cooked beef, roast beef, and cooked corned beef, 0.22%; salads, spreads, and pâtés, 0.05%; and sliced ham and luncheon meat, 0.22%. The cumulative 3-year Salmonella prevalence for dry and semidry fermented sausages was 1.43%. The cumulative 10-year L. monocytogenes prevalences were as follows: jerky, 0.52%; cooked, uncured poultry products, 2.12%; large-diameter cooked sausages, 1.31%; small-diameter cooked sausages, 3.56%; cooked beef, roast beef, and cooked corned beef, 3.09%; salads, spreads, and pâtés, 3.03%; and sliced ham and luncheon meat, 5.16%. The cumulative 3-year L. monocytogenes prevalence for dry and semidry fermented sausages was 3.25%. None of the RTE products tested for E. coli O157:H7 or staphylococcal enterotoxins was positive. Although FSIS and the industry have made progress in reducing pathogens in these products, additional efforts are ongoing to continually improve the safety of all RTE meat and poultry products manufactured in federally inspected establishments in the United States.

Animals↗

Postpackage pasteurization of ready-to-eat deli meats by submersion heating for reduction of Listeria monocytogenes.

A mixed cocktail of four strains of Listeria monocytogenes was resuspended in product purge and added to a variety of ready-to-eat (RTE) meat products, including turkey, ham, and roast beef. All products were vacuum sealed in shrink-wrap packaging bags, massaged to ensure inoculum distribution, and processed by submersion heating in a precision-controlled steam-injected water bath. Products were run in pairs at various time-temperature combinations in either duplicate or triplicate replications. On various L. monocytogenes-inoculated RTE deli meats, we were able to achieve 2- to 4-log cycle reductions when processed at 195 degrees F (90.6 degrees C), 200 degrees F (93.3 degrees C), or 205 degrees F (96.1 degrees C) when heated from 2 to 10 min. High-level inoculation with L. monocytogenes (approximately 10(7) CFU/ml) ensured that cells infiltrated the least processed surface areas, such as surface cuts, folds, grooves, and skin. D- and z-value determinations were made for the Listeria cocktail resuspended in product purge of each of the three meat categories. However, reduction of L. monocytogenes in product challenge studies showed much less reduction than was observed during the decimal reduction assays and was attributed to a combination of surface phenomena, including surface imperfections, that may shield bacteria from the heat and the migration of chilled purge to the product surface. The current data indicate that minimal heating regimens of 2 min at 195 to 205 degrees F can readily provide 2-log reductions in most RTE deli meats we processed and suggest that this process may be an effective microbial intervention against L. monocytogenes on RTE deli-style meats.

Animals↗