J A Scanga

Colorado State University, Fort Collins, Colorado, United States

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Publications (138)172 Total impact

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    ABSTRACT: British × Continental steers (initial BW = 484.6 kg) were fed at a commercial feed yard to evaluate the effects of β-agonists on live performance, carcass characteristics, and carcass subprimal yield. Weights and ultrasonic measurements were used to allocate steers to pens (n = 40) divided equally into 4 blocks, with 2 treatment replicates per block. Pens were randomly assigned to 1 of 5 treatments: control; ractopamine-HCl (RH) fed at 200 or 300 mg • steer(-1) • d(-1), or 400 mg • steer(-1) • d(-1) top dress for the final 30 d of feeding; or zilpaterol-HCl (ZH) fed at 7.5 mg/kg beginning 23 d before slaughter with a 3-d withdrawal period. Steers were harvested by block at a commercial facility over 4 wk. Carcass based performance measures were calculated using initial pen weights and actual DMI. From each pen, eight carcasses that were within ± 13.6 kg of the mean pen HCW were selected such that two carcasses were within each of the following four Yield Grade (YG) ranges: YG ≤ 2.8; 2.9-3.2; 3.3-3.5; YG > 3.5. Carcasses were fabricated by plant personnel to determine subprimal yield. Steers fed ZH had higher carcass-based ADG and carcass-based G:F compared with all other treatments (P < 0.05). Carcass-based ADG and carcass-based G:F were higher in RH treatments compared with controls (P < 0.05). Steers fed ZH had higher dressing percentages (1.0 to 1.6%) and larger LM area (4.3 to 6.7 cm(2)) than all other treatments (P < 0.05). Use of RH 400 and ZH increased HCW 6.3 and 11.1 kg, respectively compared with controls (P < 0.05). Compared with controls, RH 300 and ZH decreased marbling score and the frequency of carcasses qualifying for upper 2/3 Choice premiums (P < 0.05). Beta-agonists increased subprimal yield from the round and loin; however, blade meat was the only cut from the rib or chuck affected by β-agonists. Results from this study indicated improvements in performance and carcass traits as a result of β-agonist use; however, differences between ZH, RH 400, and RH 300 treatments were minimal for carcass traits and cutability. Increases in saleable yield following β-agonist use were not uniformly distributed across the four major primals and the majority of weight gain occurred in the lower priced cuts of the round and chuck. Increased response of the lower priced cuts to β-agonists could have economic implications to packers.
    Journal of Animal Science 02/2014; 92(2):836-43. · 1.92 Impact Factor
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    ABSTRACT: The effect of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on slice shear force (SSF) and sensory characteristics of beef from calf-fed Holstein steers was evaluated. All steers were implanted with a progesterone (100 mg) plus estradiol benzoate (10 mg) implant followed by a terminal trenbolone acetate (200 mg) plus estradiol (40 mg) implant. Steers were blocked by weight into pens (n = 32) randomly assigned to one of four treatments: control, RH fed at 300 mg/steer(-1)/d(-1) (RH 300) or RH fed at 400 mg/steer(-1)/d(-1)(RH 400) for the final 31 d of finishing, or, ZH fed at 6.8 g/ton for 21 d with a 5 d withdrawal prior to harvest. Fourteen carcasses were randomly selected from each pen and two LM samples (1/side) were excised and aged either 14 or 21 d before SSF testing. For trained panel evaluation, two steaks were collected from each of 60 low Choice strip loins (20 each from control, RH 300 and ZH treatments) and aged either 14 or 21 d. Steers fed RH and ZH produced steaks with SSF values that were 9% to 25% higher than controls. No difference in SSF was detected between the two levels of RH (P > 0.05). Compared to controls, the probability of steaks aged 14 d failing to meet SSF requirements to be certified tender (SSF < 20 kg) was increased 0.15, 0.17 and 0.26 in steers fed RH 300, RH 400 and ZH, respectively. Compared to controls, probability of steaks aged 21 d having SSF values > 20 kg was increased 0.03, 0.08 and 0.16 in steers fed RH 300, RH 400 and ZH, respectively. Steaks from Select carcasses of steers fed ZH aged 21 d postmortem had double the probability (0.39 vs. 0.17) of having SSF values > 20 kg compared to steaks from steers fed either level of RH (P < 0.05). This difference tended to be identical in steaks from Select carcasses 14 d postmortem (0.50 vs. 0.33; P = 0.11); however, no difference was found in low Choice samples at 14 or 21 d postmortem. Trained panelists rated steaks aged 14 d from steers fed ZH lower for overall tenderness and flavor compared to controls (P < 0.05); however, no difference was found between controls and those fed RH 300. Steaks from steers fed ZH aged 21 d were rated lower for overall tenderness and juiciness compared to controls and those from steers fed RH 300 (P < 0.05). This study suggests RH and ZH negatively impact sensory attributes of beef from calf-fed Holstein steers.
    Journal of Animal Science 11/2013; · 1.92 Impact Factor
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    ABSTRACT: Effects of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on saleable yield of carcass sides from calf-fed Holstein steers were evaluated using steers implanted with a progesterone (100 mg) plus estradiol benzoate (10 mg) implant followed by a terminal trenbolone acetate (200 mg) plus estradiol (40 mg) implant, and blocked by weight into pens (N = 32) randomly assigned to one of four treatments: control, RH fed at 300 mg/steer(-1)/d(-1) (RH 300) or RH fed at 400 mg/steer(-1)/d(-1) (RH 400) the final 31 d of finishing, and ZH fed at 60 to 90 mg/steer(-1)/d(-1) for 21 d with a 5 d withdrawal prior to harvest. Eight to nine carcass sides were randomly selected from each pen; carcasses with excessive hide pulls, fat pulls or bruises were avoided. Cutout data were collected within a commercial facility using plant personnel to fabricate sides at a rate of one every 3 to 4 minutes into items typically merchandised by the facility. All lean, fat and bone were weighed and summed back to total subprimal weight with a sensitivity of ± 2% to be included in the data set. Compared to controls, beta-agonists increased saleable yield of whole-muscle cuts by 0.61%, 0.86% and 1.95% for RH 300, RH 400 and ZH, respectively (P < 0.05). Percent fat was less in carcasses from the ZH treatment compared to controls (P < 0.05); however, this difference was not observed between RH treatments and controls (P > 0.05). Percent bone was less in the ZH treatment due to increased muscle (P < 0.05). The percent of chilled side weight comprised of trimmings was unchanged between treatments, but on a 100% lean basis, RH 400 and ZH increased trim yields (P < 0.05). Analysis of saleable yield by primal showed a fundamental shift in growth and development. Beta-agonists caused a shift in proportion of saleable yield within individual primals, with a greater portion produced from the hindquarter relative to the forequarter, specifically in those muscles of the round (P < 0.05). Beta-agonists increased saleable yield, but these effects were not constant between all major primals. The cutout value gained by packers as a result of beta-agonist use may be influenced more by reduced fatness if musculature is primarily increased in the lower priced cuts of the carcass.
    Journal of Animal Science 11/2013; · 1.92 Impact Factor
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    ABSTRACT: Effect of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on LM tenderness and sensory attributes was determined using pens (N = 40) of approximately eighty British x Continental crossbred steers randomly allocated to one of the following treatments: control; RH fed at 200 (RH 200) or 300 mg/steer(-1)/d(-1) (RH 300), or 400 mg/steer(-1)/d(-1) (RH 400) for the final 30 d of feeding; and ZH fed at 7.5 mg/kg beginning 23 d before slaughter with a 3 d withdrawal. Two replicates (pens) per treatment were represented in 4 feeding blocks. Eighteen carcasses per pen were randomly selected (720 total) and one 5 cm LM sample was removed from both carcass sides to be used for tenderness and sensory evaluation. Samples were aged for 14 d, frozen at -28.8° C, and cut into 2.5 cm steaks. All steaks were cooked to an internal temperature of 71.1°C before being evaluated for Warner-Bratzler shear force (WBSF), slice shear force (SSF), or being fed to trained sensory panelists. Increasing dose and potency of beta-agonist increased WBSF by 4 to 17% and SSF by 5 to 24% (P < 0.05). Steaks from steers fed ZH had higher WBSF and SSF values compared to all other treatments (P < 0.05), whereas steaks from controls and steers fed RH 200 were not different (P > 0.05). Probability of steaks failing to meet shear force standards to be certified tender (WBSF < 4.4 kg, SSF < 20 kg; ASTM, 2011) was increased from an initial incidence of less than 0.06 in steaks from steers in the control treatment to 0.10 to 0.20 in steers fed RH 400 and ZH (P < 0.05). No difference was detected in panel ratings for overall tenderness of steaks from steers fed RH 200 compared to controls (P > 0.05). Steaks from steers fed RH 300 and RH 400 were comparable for all sensory attributes; however, both RH 300 and RH 400 were rated lower for overall tenderness than controls (P < 0.05). Steers fed ZH produced steaks with the lowest sensory panel tenderness ratings; however, panelists failed to detect a differences in overall tenderness of steaks from steers fed RH 400 and ZH. Panelists detected no difference in flavor profile or juiciness between treatments (P < 0.05). Results from this study indicated beta-agonists negatively affected beef tenderness and that these effects may be more noticeable in steers supplemented with ZH and higher doses of RH.
    Journal of Animal Science 10/2013; · 1.92 Impact Factor
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    ABSTRACT: Fifty-four stores in thirty U.S. cities were sampled from June 2011 through May 2012 to benchmark beef tenderness at retail as assessed by Warner-Bratzler shear force (WBSF). Top loin (Longissimus dorsi; N=980) and sirloin (Gluteus medius and Biceps femoris; N=860) steaks were collected at random (random Quality Grade and brand) and shipped via overnight delivery to Colorado State University. From June 2011 through November 2011 [North American Beef Tenderness Survey (NABTS) - Period 1] samples were shipped fresh and then frozen. Mean WBSF values during Period 1 were 2.9 and 3.9 kg for top loin and sirloin steaks, respectively. Frequencies of steaks classified as tough (WBSF ≥ 4.4 kg) were 8.6% and 17.7% for top loin and sirloin steaks, respectively. When shipped fresh, a disproportionately high frequency (16.9%) of top loin steaks had WBSF ≤ 2.0 kg, representing a deviation from previous works. Two trials were conducted to assess the effect of freezing, retail display and shipping on WBSF and slice shear force (SSF) of beef top loin steaks. Freezing, retail display and shipment reduced WBSF by 0.4, 0.3 and 0.0 kg during Trial 1; and by 0.4, 0.3 and 0.1 kg during Trial 2. Slice shear force was lower (P < 0.05) in steaks exposed to shipping conditions during Trial 1; however, this difference was not observed in Trial 2. Shipping decreased the frequency of steaks categorized as tough (SSF ≥ 20.0 kg) from 11.1% to 5.7% and from 30.5% to 28.6% during Trial 1 and 2, respectively. During Trial 1, WBSF indicated that shipping increased incidence of tough samples from 0.0% to 3.8%, but this trend was reversed during Trial 2 when shipping reduced incidence of tough samples from 13.0% to 5.6%. Coefficients of variation for treatment effects suggested variance remained unchanged (±2.0%) with respect to shear force values, however mean values were reduced as a result of shipping conditions. These findings dictated a change in NABTS protocol from December 2011 through May 2012 (Period 2), during which time samples were shipped frozen. Mean WBSF values were 3.4 and 4.0 kg for top loin and sirloin samples, respectively. Frequencies of steaks classified as tough were 14% and 23.5% for top loin and sirloin steaks, respectively. These findings suggest freezing samples prior to shipment may influence shear force of steaks collected at the retail level. These data should be considered when evaluating beef tenderness surveys and in the design of future works.
    Journal of Animal Science 10/2013; 91(12). · 1.92 Impact Factor
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    ABSTRACT: This study evaluated chemical tenderizers and cooking methods to inactivate Escherichia coli O157:H7 in ground beef patties (model system for non-intact beef). Ground beef was inoculated with E. coli O157:H7 and mixed with (i) nothing (control), (ii) calcium chloride (CC) and flavoring agents (FA), (iii) CC, FA, and acetic acid (AA), (iv) sodium chloride (SC), sodium tripolyphosphate (ST), and potassium lactate (PL), and (v) the combination of SC, ST, PL, and AA. Patties were stored in aerobic or vacuum bags at -20, 4, and 12°C. Samples were grilled, broiled, or pan-fried to 60 or 65°C. Total bacterial and E. coli O157:H7 populations remained unchanged during storage. Broiling was more effective in reducing E. coli O157:H7 than grilling and pan-frying, and acidified tenderizers reduced E. coli O157:H7 more than non-acidified tenderizers in broiling. Higher reductions were observed at 65°C than 60°C in broiled and grilled samples. These results indicate that acidified tenderizers and broiling may be useful in non-intact beef safety.
    Meat Science 04/2013; 95(2):317-322. · 2.23 Impact Factor
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    ABSTRACT: The objective of this study was to determine the source(s) of Salmonella contamination in ground beef. One hundred dairy cows were harvested in a U.S. commercial beef processing plant. Samples of hides, carcasses after hide removal and before exposure to antimicrobial intervention, carcasses after all antimicrobial interventions, superficial cervical lymph nodes from the chuck, trim, ground beef, and air were obtained. Ninety-six percent of the hide samples, 47% of the carcasses before intervention, 18% of the lymph nodes, 7.14% of the trim, and 1.67% of the ground beef samples were positive for Salmonella. None of the samples obtained from the carcasses after the full complement of interventions and none of the air samples were positive for Salmonella. All Salmonella-positive samples were subjected to pulsed-field gel electrophoresis, and eight DNA Xba I restriction patterns were identified. The majority of isolates had one of two restriction digest patterns. The strain isolated from ground beef had the same pattern as the strains isolated from hides and from carcasses immediately after hide removal. The Salmonella isolates from trim samples and lymph nodes also had the same restriction digest pattern. These results indicate that hide and lymph nodes are the most likely sources of Salmonella in ground beef. Dressing practices that effectively reduce or eliminate the transfer of bacteria from hide to carcass and elimination of lymph nodes as a component of raw ground beef should be considered as measures to reduce Salmonella contamination of ground beef. Because total elimination of lymph nodes from ground beef is not possible, other approaches should be explored. Easily accessible lymph nodes could be screened for Salmonella very early in the slaughter process. When the results are positive for Salmonella, the corresponding carcasses should be fabricated separately at the end of the production run, and the trim from these carcasses should be subjected to a treatment that destroys Salmonella.
    Journal of food protection 08/2012; 75(8):1464-8. · 1.80 Impact Factor
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    ABSTRACT: Study objectives were to evaluate ractopamine hydrochloride's (RAC) effect on performance, carcass characteristics, and tenderness of early weaned beef steers. Steers were assigned to a control diet (0 mg RAC·steer(-1)·d(-1)), 200 mg RAC mg·steer(-1)·d(-1), or 300 mg RAC·steer(-1)·d(-1). Steers fed 200 and 300 mg RAC·steer(-1)·d(-1) gained 14.84 kg and 14.57 kg more live weight and produced 13.22 and 14.90 kg more hot carcass weight, respectively, than controls. Feed conversions for steers fed 200 or 300 mg RAC·steer(-1)·d(-1) of RAC increased 45.2% and 47.3% and average daily gain increased 55.5% and 54.5% compared to controls, respectively. Feeding either dose of RAC increased (P<0.05) loin muscle area and increased (P<0.05) Warner-Bratzler shear force (WBSF) values compared to controls, however the magnitude of WBSF difference diminished (P>0.05) over 14 days of postmortem aging. Results of this study confirm that RAC increases weight gain and feed efficiency, minimally impacts carcass quality and has manageable impacts on tenderness when fed at either 200 or 300 mg steer(-1)·d(-1).
    Meat Science 06/2012; 92(4):458-63. · 2.23 Impact Factor
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    ABSTRACT: Studies examined the effects of meat-contact material types, inoculation substrate, presence of air at the liquid-solid surface interface during incubation, and incubation substrate on the attachment/transfer and subsequent biofilm formation by Escherichia coli O157:H7 on beef carcass fabrication surface materials. Materials studied as 2 × 5 cm coupons included stainless steel, acetal, polypropylene, and high-density polyethylene. A 6-strain rifampicin-resistant E. coli O157:H7 composite was used to inoculate (6 log CFU/mL, g, or cm²) tryptic soy broth (TSB), beef fat/lean tissue homogenate (FLH), conveyor belt-runoff fluids, ground beef, or beef fat. Coupons of each material were submerged (4 °C, 30 min) in the inoculated fluids or ground beef, or placed between 2 pieces of inoculated beef fat with pressure (20 kg) applied. Attachment/transfer of the pathogen was surface material and substrate dependent, although beef fat appeared to negate differences among surface materials. Beef fat was the most effective (P < 0.05) inoculation substrate, followed by ground beef, FLH, and TSB. Incubation (15 °C, 16 d) of beef fat-inoculated coupons in a beef fat homogenate (pH 4.21) allowed the pathogen to survive and grow on coupon surfaces, with maximal biofilm formation observed between 2 and 8 d of storage and when air was present at the liquid-solid interface. The results indicated that the process of fabricating beef carcasses may be conducive to the attachment of E. coli O157:H7 onto meat-contact surfaces and subsequent biofilm formation. Furthermore, it is recommended that substrates found in beef fabrication settings, rather than laboratory culture media, be used in studies designed to investigate E. coli O157:H7 biofilm development and control in these environments. PRACTICAL APPLICATION: Findings of this study provide knowledge on the effect of type of beef carcass fabrication surface material, fabrication-floor fluids and residues, and incubation conditions on attachment/transfer and subsequent biofilm formation by E. coli O157:H7. The results highlight the importance of thoroughly cleaning soiled surfaces to remove all remnants of beef fat or other organic material that may harbor or protect microbial contaminants during otherwise lethal antimicrobial interventions.
    Journal of Food Science 05/2012; 77(6):M343-7. · 1.78 Impact Factor
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    ABSTRACT: This study evaluated the efficacy of various sanitizers against Escherichia coli O157:H7 cells in biofilms formed on surface materials used in beef fabrication facilities. Coupons (2 × 5 cm) of stainless steel, acetal, and high-density polyethylene were inoculated (3–4 log CFU/cm2) with rifampicin-resistant E. coli O157:H7 (6-strain mixture) and incubated at 15°C in an unsterilized beef fat-lean tissue homogenate (pH 5.66). After 3 days of incubation, attached cells were challenged (for 1 or 10 min) by submerging coupons in minimum and maximum recommended concentrations of each of seven sanitizing solutions or distilled water (control). Sanitizer treatments reduced E. coli O157:H7 on coupons by 0.0 to 2.2 log CFU/cm2, and treatment efficacy decreased in the order acidified sodium chlorite > peroxyacetic acid > potassium peroxymonosulfate/sodium chloride = peroxyacetic acid/octanoic acid mixture (PA/OA) > cetylpyridinium chloride > quaternary ammonium chloride compound mixture (QACC) = sodium hypochlorite (SH) = water control. Pathogen reductions generally increased as sanitizer concentration and exposure time increased. The influence of biofilm age (0, 3 and 7 days incubation at 15°C) on sanitizer (SH, QACC and PA/OA) efficacy was evaluated in a separate experiment; results showed that E. coli O157:H7 biofilm cells became less sensitive to most sanitizer treatments as biofilm age increased. Surface material did not (P ≥ 0.05) influence the fate of biofilm cells during sanitizing treatments. While no sanitizer consistently reduced pathogen populations by more than 2.2 log cycles on soiled surfaces, approved concentrations of acidified sodium chlorite and peroxyacetic acid-based sanitizers may be more effective than other sanitizers against E. coli O157:H7 on inadequately cleaned surfaces.
    Food Protection Trends. 01/2012; 32(4):173-182.
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    ABSTRACT: This study examined the effect of tenderizing/marinating and flavoring ingredients on thermal inactivation of Escherichia coli O157:H7 in a lean ground beef model system, simulating non-intact products. Ground beef (3% fat) was inoculated with E. coli O157:H7 (5 strains; 6–7 log CFU/g), followed by mixing with nothing (control) or solutions of water, a mixture of flavoring agents (FA), 0.23% calcium chloride (CC) + FA, CC + FA + 0.3% acetic acid (AA), 0.5% sodium chloride (NaCl) + 0.25% sodium tripolyphosphate (STP), NaCl + STP + FA, NaCl + STP + 1.8% potassium lactate (PL), NaCl + STP + PL + FA, NaCl + STP + PL + AA, and NaCl + STP + PL + AA + FA. Samples (30 g) were extruded into tubes, stored (4 °C) overnight, and cooked to 60 °C (rare) or 65 °C (medium-rare) in a water bath. Cooking weight losses, and fat and moisture contents, water activity, pH, and total bacterial and E. coli O157:H7 populations were determined after inoculation, after storage, and after heating. Reductions of the pathogen at 60 °C in acid (AA)-treated samples were higher than reductions obtained in samples not treated with acid. Surviving pathogen counts at 65 °C in NaCl and STP-treated samples with no acid were higher (P < 0.05) than those of samples of all other tested treatments; however, the counts decreased to 0.7–1.6 log CFU/g when AA was added. Overall, the results of the study indicate that tenderizing/flavoring ingredient formulations combined with 0.3% AA (i.e., CC + FA + AA, NaCl + STP + PL + AA, and NaCl + STP + PL + AA + FA) enhanced destruction of E. coli O157:H7 during cooking of a non-intact beef product.Highlights► Thermal inactivation of Escherichia coli O157:H7 internalized in non-intact beef evaluated. ► Lean ground beef model system used to simulate non-intact products. ► Effect of beef tenderizing/marinating/flavoring ingredients on pathogen heat destruction determined. ► Pathogen reductions at 60 °C enhanced in acetic acid (AA)-treated beef. ► Addition of AA to salt + phosphate formulations enhanced pathogen destruction at 65 °C.
    Food Control 12/2011; 22(12):1859-1864. · 2.82 Impact Factor
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    ABSTRACT: This study developed growth/no growth models for predicting growth boundaries of Listeria monocytogenes on ready-to-eat cured ham and uncured turkey breast slices as a function of lactic acid concentration (0% to 4%), dipping time (0 to 4 min), and storage temperature (4 to 10 °C). A 10-strain composite of L. monocytogenes was inoculated (2 to 3 log CFU/cm²) on slices, followed by dipping into lactic acid and storage in vacuum packages for up to 30 d. Total bacterial (tryptic soy agar plus 0.6% yeast extract) and L. monocytogenes (PALCAM agar) populations were determined on day 0 and at the endpoint of storage. The combinations of parameters that allowed increases in cell counts of L. monocytogenes of at least l log CFU/cm² were assigned the value of 1, while those limiting growth to <1 log CFU/cm² were given the value of 0. The binary data were used in logistic regression analysis for development of models to predict boundaries between growth and no growth of the pathogen at desired probabilities. Indices of model performance and validation with limited available data indicated that the models developed had acceptable goodness of fit. Thus, the described procedures using bacterial growth data from studies with food products may be appropriate in developing growth/no growth models to predict growth and to select lactic acid concentrations and dipping times for control of L. monocytogenes. PRACTICAL APPLICATION: The models developed in this study may be useful in selecting lactic acid concentrations and dipping times to control growth of Listeria monocytogenes on cured ham and uncured turkey breast during product storage, and in determining probabilities of growth under selected conditions. The modeling procedures followed may also be used for application in model development for other products, conditions, or pathogens.
    Journal of Food Science 08/2011; 76(6):M450-5. · 1.78 Impact Factor
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    ABSTRACT: United States regulations require ready-to-eat meat and poultry processors to control Listeria monocytogenes using interventions which may include antimicrobials that reduce post-processing contamination by at least 1 log-cycle; if the treatment achieves > or = 2 log reductions, the plant is subject to less frequent microbial testing. Lactic acid (LA) may be useful as a post-lethality intervention and its antimicrobial properties may increase with temperature of application. The aim of this study was to evaluate the effect of LA solution concentration and temperature on L. monocytogenes counts of inoculated frankfurters and to identify parameters (concentration, temperature, and time) that achieve 1 and 2 log-unit immediate reductions. Frankfurters were surface-inoculated with a 10-strain mixture of L. monocytogenes (4.4 +/- 0.1 log CFU/cm(2)) and then immersed in distilled water or LA solutions (0-3%) of 4, 25, 40, or 55 degrees C for 0-120 s. A regression equation for L. monocytogenes reduction included significant (P < 0.05) effects by the terms of concentration, time, temperature, and the interaction of concentration and temperature; other tested parameters (other interactions, quadratic and cubic terms), within the experimental range examined, did not affect (P > or = 0.05) the extent of reduction. Results indicated that the effectiveness of LA against L. monocytogenes, in addition to concentration, increased with solution temperature (in the range of 0.6-2.8 log CFU/cm(2)). The developed equation may allow processors to vary conditions of treatment with LA to achieve a 1 or 2 log-unit reduction of the pathogen and comply with United States regulations.
    Food Microbiology 09/2010; 27(6):783-90. · 3.37 Impact Factor
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    ABSTRACT: A beef carcass instrument grading system that improves accuracy and consistency of marbling score (MS) evaluation would have the potential to advance value-based marketing efforts and reduce disparity in quality grading among USDA graders, shifts, and plants. The objectives of this study were to use output data from the Video Image Analysis-Computer Vision System (VIA-CVS, Research Management Systems Inc., Fort Collins, CO) to develop an appropriate method by which performance of video image analysis MS output could be evaluated for accuracy, precision, and repeatability for purposes of seeking official USDA approval for using an instrument in commerce to augment assessment of quality grade, and to use the developed standards to gain approval for VIA-CVS to assist USDA personnel in assigning official beef carcass MS. An initial MS output algorithm was developed (phase I) for the VIA-CVS before 2 separate preliminary instrument evaluation trials (phases II and III) were conducted. During phases II and III, a 3-member panel of USDA expert graders independently assigned MS to 1,068 and 1,242 stationary carcasses, respectively. Mean expert MS was calculated for each carcass. Additionally, a separate 3-member USDA expert panel developed a consensus MS for each carcass in phase III. In phase II, VIA-CVS stationary triple-placement and triple-trigger instrument repeatability values (n = 262 and 260, respectively), measured as the percentage of total variance explained by carcasses, were 99.9 and 99.8%, respectively. In phases II and III, 95% of carcasses were assigned expert MS for which differences between individual expert MS, and for which the consensus MS in phase III only, was < or = 96 MS units. Two differing approaches to simple regression analysis, as well as a separate method-comparability analysis that accommodates error in both dependent and independent variables, were used to assess accuracy and precision of instrument MS predictions vs. mean expert MS. Method-comparability analysis was more appropriate in assessing the bias and precision of instrument MS predictions. Ether-extractable fat percentages (n = 257; phase II) differed among MS (P < 0.05) but were not suitable to predict or validate assigned MS. The performance and reproducibility of expert MS assignment in future evaluations was considered, and an official USDA performance standard was established, to which an instrument must conform to be approved for official on-line MS assessment. The VIA-CVS subsequently was approved to assign MS to carcasses on-line after completion of a 2006 USDA instrument approval trial conducted according to methods developed during completion of this study.
    Journal of Animal Science 03/2010; 88(7):2464-75. · 1.92 Impact Factor
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    ABSTRACT: Little information is available regarding the fate of Listeria monocytogenes during freezing, thawing and home storage of frankfurters even though recent surveys show that consumers regularly store unopened packages in home freezers. This study examined the effects of antimicrobials, refrigerated storage, freezing, thawing method, and post-thawing storage (7 degrees C) on L. monocytogenes on frankfurters. Inoculated (2.1 log CFU/cm(2)) frankfurters formulated without (control) or with antimicrobials (1.5% potassium lactate plus 0.1% sodium diacetate) were vacuum-packaged, stored at 4 degrees C for 6 or 30 d and then frozen (-15 degrees C) for 10, 30, or 50 d. Packages were thawed under refrigeration (7 degrees C, 24 h), on a countertop (23 +/- 2 degrees C, 8 h), or in a microwave oven (2450 MHz, 1100 watts, 220 s followed by 120 s holding), and then stored aerobically (7 degrees C) for 14 d. Bacterial populations were enumerated on PALCAM agar and tryptic soy agar plus 0.6% yeast extract. Antimicrobials completely inhibited (p < 0.05) growth of L. monocytogenes at 4 degrees C for 30 d under vacuum-packaged conditions, and during post-thawing aerobic storage at 7 degrees C for 14 d. Different intervals between inoculation and freezing (6 or 30 d) resulted in different pathogen levels on control frankfurters (2.1 or 3.9 log CFU/cm(2), respectively), while freezing reduced counts by <1.0 log CFU/cm(2). Thawing treatments had little effect on L. monocytogenes populations (<0.5 log CFU/cm(2)), and post-thawing fate of L. monocytogenes was not influenced by freezing or by thawing method. Pathogen counts on control samples increased by 1.5 log CFU/cm(2) at d-7 of aerobic storage, and reached 5.6 log CFU/cm(2) at d-14. As indicated by these results, consumers should freeze frankfurters immediately after purchase, and discard frankfurters formulated without antimicrobials within 3 d of thawing and/or opening.
    Food Microbiology 02/2010; 27(1):144-9. · 3.37 Impact Factor
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    ABSTRACT: Microwave oven heating was evaluated for inactivation of Listeria monocytogenes on inoculated and stored frankfurters. Frankfurters formulated without/with 1.5% potassium lactate and 0.1% sodium diacetate were inoculated with L. monocytogenes (1.9 +/- 0.2 log CFU/cm(2)), vacuum-packaged, and stored (4 degrees C) to simulate conditions prior to purchase by consumers. At storage days 18, 36, and 54, packages were opened and placed at 7 degrees C, simulating aerobic storage in a household refrigerator. At 0, 3, and 7 d of aerobic storage, 2 frankfurters were placed in a bowl with water (250 mL) and treated in a household microwave oven at high (1100 W) power for 30, 45, 60, or 75 s, or medium (550 W) power for 60 or 75 s. Frankfurters and the heating water were analyzed for total microbial counts and L. monocytogenes populations. Exposure to high power for 75 s reduced pathogen levels (0.7 +/- 0.0 to 1.0 +/- 0.1 log CFU/cm(2)) to below the detection limit (<-0.4 log CFU/cm(2)) on frankfurters with lactate/diacetate, even after 54 d of vacuum-packaged storage followed by 7 d of aerobic storage. For frankfurters without lactate/diacetate, high power for 75 s caused reductions between > 1.5 and 5.9 log CFU/cm(2) from control levels of 1.5 +/- 0.1 to 7.2 +/- 0.5 log CFU/cm(2). Depending on treatment and storage time, the water used to reheat the frankfurters had viable L. monocytogenes counts of <-2.4 to 5.5 +/- 0.5 log CFU/mL. The results indicated that frankfurters should be reheated in a microwave oven at high power for 75 s to inactivate up to 3.7 log CFU/cm(2) of L. monocytogenes contamination.
    Journal of Food Science 10/2009; 74(8):M453-60. · 1.78 Impact Factor
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    ABSTRACT: Carcasses that do not conform to mainstream specifications (i.e., those with nonconforming ribeye area) may not achieve their full potential value. Research was conducted to evaluate the relationship between beef carcass LM area at the 12th and 13th rib interface (LMA) and portion size acceptability of other muscles in the carcass. Sixty beef carcass sides of varying LMA sizes (between 67.74 and 116.13 cm(2)) were fabricated to generate 14 individual muscle cuts (triceps brachii long head, infraspinatus, chuckeye complexus, pectoralis profundus, longissimus thoracis, latissimus dorsi, gluteus medius, longissimus lumborum, tensor fasciae latae, psoas major, semimembranosus, biceps femoris, semitendinosus, and vastus lateralis). Retail portion size (g/1.27-cm-thick steak) as well as face surface area and dimensions were recorded for each steak cut perpendicular at the midpoint of the longitudinal axis of each muscle. Subsequently, a nationwide survey was conducted with foodservice chefs and retail meat merchandisers to evaluate acceptability of portion sizes and dimensions of individual muscle cuts. Simple linear regression and nonparametric regression analyses were used to evaluate results of the carcass muscle evaluation and survey, respectively. Results demonstrated that LMA did not affect (P < 0.05) retail portion size of 7 of the 14 muscles (chuckeye complexus, pectoralis profundus, psoas major, semimembranosus, tensor fasciae latae, triceps brachii, and vastus lateralis). Similarly, LMA did not affect (P < 0.05) surface area of steak cross-sectional face areas from 7 of the 14 muscles (chuckeye complexus, psoas major, semimembranosus, tensor fasciae latae, infraspinatus, vastus lateralis, and latissimus dorsi). Muscles for which carcass LMA (P < 0.05) was related to portion size or surface area of portion steaks, or both, were included in the survey. Results of the survey demonstrated that portion size for many muscles were still acceptable to retail merchandisers and foodservice chefs, even though carcass LMA was outside the range of commercially acceptable sizes. Results of this study demonstrated that carcass LMA is not an accurate determinant of the size, and subsequent acceptability, of many other muscles of beef in the carcasses, and may not be a good determinant of value of the beef carcass.
    Journal of Animal Science 06/2009; 87(9):2935-42. · 1.92 Impact Factor
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    ABSTRACT: Non-intact beef products include beef cuts that have been ground, mechanically tenderized, restructured, or have been injected with solutions to enhance tenderness and/or flavor. This study examined the effects of tenderizing salts and organic acids on thermal inactivation of Escherichia coli O157:H7 in a ground beef model system simulating non-intact beef products. Ground beef (95% lean; 700 g batches) was mixed (2 min) with nothing (C) or solutions (22 ml) of water (WA), calcium ascorbate (CaA, 0.86%; wt/wt), calcium chloride (CaC, 0.23%; wt/wt), acetic acid (AA, 0.3%; v/wt), citric acid (CA, 0.2%; wt/wt), NaCl (NA, 0.5%; wt/wt), and mixtures of CaA/NA, CaC/NA, AA/NA, CA/NA, CaA/CaC/NA, CaA/AA/NA, CaA/CA/NA, CaC/AA/NA and CaC/CA/NA. Samples (30 g) were extruded into test tubes, inoculated (7 log CFU/g) with E. coli O157:H7 (5-strain mixture), and stored (4 degrees C) overnight. Samples were then cooked to 60 degrees C or 65 degrees C, in a water bath, to simulate rare or medium-rare doneness of beef, respectively. Weight, fat and moisture losses, total bacterial (tryptic soy agar) and E. coli O157:H7 (modified eosin methylene blue agar, and modified sorbitol MacConkey agar) populations were determined after inoculation, storage, and cooking. Fat and moisture losses were not affected by treatment and temperature, while weight losses increased at 65 degrees C and in acid treated samples (60 degrees C). E. coli O157:H7 survivors were generally lower (P<0.05) in acid treated than non-acid treated samples. Pathogen counts in samples treated with tenderizers (CaA, CaC) and NA were not different (P> or =0.05) than those of control samples. Thus, inclusion of organic acids in beef tenderizing recipes may help in thermal inactivation of E. coli O157:H7 that may been transferred to the interior of non-intact products during their production.
    International journal of food microbiology 05/2009; 133(1-2):78-85. · 3.01 Impact Factor
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    ABSTRACT: This study evaluated the effects of meat binding or restructuring formulations, including salt/phosphate, algin/calcium, ActivaRM, and Fibrimex, with or without 0.27% (wt/wt) lactic acid, on thermal inactivation of internalized Escherichia coli O157:H7 in ground beef, serving as a model system for restructured products. Ground beef batches (700 g; approximately 5% fat) were mechanically mixed with a 5-strain composite of E. coli O157:H7 (7 log CFU/g) and then with the restructuring formulations. Product portions (30 g) were extruded into plastic test tubes (2.5 x 10 cm) and stored at 4 degrees C (18 h), before heating to 60 or 65 degrees C in a circulating water bath to simulate rare or medium-rare doneness of beef, respectively. Cooking to 60 or 65 degrees C reduced (P < 0.05) bacterial counts of control samples by 1.8 and 3.2 log CFU/g, respectively. Thermal destruction at 60 degrees C was not different (P > 0.05) among all treatments and the control. At 65 degrees C, greater (P < 0.05) thermal inactivation of E. coli O157:H7, as compared to the control, was obtained in samples treated with lactic acid alone (reductions of 4.9 log CFU/g), whereas for all other treatments, microbial destruction (reductions of 2.2 to 4.5 log CFU/g) was comparable (P > 0.05) to that of the control. Cooking weight losses were lower (P < 0.05) in salt/phosphate samples (<1%) compared to other formulations and the control (7.4% to 15.9%). Findings indicated that, under the conditions examined, restructuring of beef with salt/phosphate, algin/calcium, ActivaRM, or Fibrimex did not affect inactivation of internalized E. coli O157:H7 in undercooked (60 or 65 degrees C) samples, whereas inclusion of lactic acid (0.27%) in nonintact beef products enhanced pathogen destruction at 65 degrees C.
    Journal of Food Science 04/2009; 74(2):M94-9. · 1.78 Impact Factor
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    ABSTRACT: If present, Listeria monocytogenes may not be eliminated during processing of pepperoni or may be introduced during peeling, slicing, or packaging. We evaluated the fate of the pathogen on sliced inoculated pepperoni during vacuum-packaged storage, and potential differences in survival among three types of inocula, including nonacid-adapted, acid-adapted and pepperoni extract-habituated cultures. Commercial pepperoni (two replicates, three samples per treatment) was sliced and inoculated (3 to 4 log CFU/cm(2)), before vacuum-packaging and storage for up to 180 days at 4, 12 or 25 degrees C. Samples were periodically analyzed for pathogen counts (PALCAM agar) and total bacterial counts (tryptic soy agar with 0.6% yeast extract). The pH of the product was relatively stable (4.50-4.81) throughout storage. Overall, levels of the pathogen (all inocula) and total counts decreased continuously during storage at all temperatures. The pathogen died slower at 4 degrees C than at 12 and 25 degrees C, while at 12 and 25 degrees C the death rates were similar. Death rates depended on type of inoculum and generally decreased in the order: acid-adapted, extract-habituated and nonacid-adapted inoculum. At day 60, pathogen levels were below the detection limit and remained undetectable throughout the rest of the 180-day storage period, regardless of inoculum type and storage temperature. Therefore, storage of sliced vacuum-packaged pepperoni, especially at ambient temperature, prior to consumption may reduce the potential risk of listeriosis.
    Food Microbiology 03/2009; 26(1):77-81. · 3.37 Impact Factor

Publication Stats

1k Citations
172.00 Total Impact Points


  • 1998–2013
    • Colorado State University
      • • Department of Animal Sciences
      • • Center for Red Meat Safety and Quality
      Fort Collins, Colorado, United States
  • 2009–2012
    • IEH Laboratories and Consulting Group
      Lake Forest Park, Washington, United States
  • 2008
    • Texas A&M University
      • Department of Animal Science
      College Station, TX, United States
  • 2007
    • United States Department of Agriculture
      • Agricultural Research Service (ARS)
      Washington, D. C., DC, United States
  • 2006
    • University of Wisconsin - Green Bay
      Green Bay, Wisconsin, United States