How Meat Science Academic Programming Can Facilitate Undergraduate and Graduate Student International Exposure

As the world population increases and the trajectory of meat trade continues to expand across the borders of sovereign nations, it is important for university educators to increase the opportunities that undergraduate and graduate students have for engaging with other cultures. In the future, it is unlikely that students can be successful in a meat-based career without knowledge of the global markets. The Meat Science Group at Colorado State University have tried to offer such opportunities to students by engaging them in research; providing forums for exchange, internships, capacity building, and participating in international scientific meetings; and offering courses that assist students in their understanding of the global marketplace. As the world becomes a smaller place, all such student international activities are becoming a compulsory need to accommodate the Land Grant Mission

Intramuscular fat and sensory properties of pork loin

Pork loins (n= 53) were selected from a commercial packing plant to determine the influence of subjective visual marbling score on sensory attributes and quality properties. The loins were obtained from commercial hybrid castrated male pigs originating from different herds fed similar commercial diets. Increasing subjective marbling score corresponded with decreased protein content, less percent drip loss, increased pH, and more desirable sensory tenderness and juiciness scores. Greater visual marbling scores resulted in more desirable sensory scores and may be used or included as one of the variables to evaluate fresh pork quality

Photohydroionization Reduces Shiga Toxin-Producing Escherichia coli and Salmonella on Fresh Beef with Minimal Effects on Meat Quality

The photohydroionization (PHI) technology utilizes a combination of UV light and low-level oxidizers to produce antimicrobial action, and thus, is a potential intervention to control pathogen contamination on surface of fresh beef. The objectives of the study were 1) to evaluate the effect of PHI on reduction of selected Escherichia coli (E. coli) O157:H7, non-O157 Shiga toxin-producing E. coli (STEC; O26, O45, O103, O111, O121, O145), antimicrobial resistant (AMR) and non-AMR Salmonella strains inoculated on beef flanks, and 2) to evaluate the effect of PHI treatment on the lean color and lipid oxidation of beef during refrigerated storage. Inoculated beef flanks were exposed to PHI treatment for 0 (control), 15, 30, or 60 s at 4°C. Exposure to PHI for 15 s reduced (P ≤ 0.05) pathogens on the surface of fresh beef ranging from 0.3 to 0.9 log CFU/cm2. Increasing the exposure time to 60 s did not improve (P > 0.05) reductions over 15 s for the majority of the selected pathogens, but yielded pathogen reductions ranging from 0.5 to 1.1 log CFU/cm2. Over all storage times when beef samples were exposed to PHI for 75 s, no difference (P > 0.05) was detected on lean a* value (24.67 versus 24.95), of treated and control fresh beef tissues, respectively. The highest TBARS values after storage for 14 d at 4°C was 0.33 mg MDA/kg of meat indicating that no oxidative rancidity occurred for treated beef samples. The PHI technology with 15 to 75 s exposure time was effective in controlling STEC and Salmonella contaminated on surface of fresh beef without causing adverse effects on fresh beef quality while reducing water and energy use. Further study of PHI treatment parameters under commercial plant conditions and ultimate validation of those parameters will be necessary for commercial implementation

Comparison of rose meat from the U.S. and Mexico with and without marination

El objetivo de este estudio fue evaluar las características sensoriales, la suavidad y la pérdida durante el cocinado del suadero marinado (MR) y sin marinar (NM) procedente de México y EE.UU. El suadero se comparó con la arrachera, ya que ésta es un corte muy demandado en forma marinada por el consumidor mexicano. Se usaron dos métodos de cocinado, uno a la parrilla (en seco) y otro al horno (con humedad). El marinado del suadero y la arrachera disminuyó la WBSF (P 0.05). El panel de consumidores calificó al suadero marinado mejor en aroma, jugosidad, sabor, textura y aceptación general que el no marinado (P 0.05). Consumers rated marinated rose meat higher than non-marinated rose meat for aroma, juiciness, flavor, texture, and overall acceptance (P <0.05). Marinated rose meat was more tender when cooked using moist heat (wetoven) than when grilled (P <0.05). Results of this study indicate that marinade improved the tenderness of rose meat and oven cooking of marinated rose meat produces lower WBSF values than grilling

Whole-Genome Sequencing and Concordance Between Antimicrobial Susceptibility Genotypes and Phenotypes of Bacterial Isolates Associated with Bovine Respiratory Disease.

Extended laboratory culture and antimicrobial susceptibility testing timelines hinder rapid species identification and susceptibility profiling of bacterial pathogens associated with bovine respiratory disease, the most prevalent cause of cattle mortality in the United States. Whole-genome sequencing offers a culture-independent alternative to current bacterial identification methods, but requires a library of bacterial reference genomes for comparison. To contribute new bacterial genome assemblies and evaluate genetic diversity and variation in antimicrobial resistance genotypes, whole-genome sequencing was performed on bovine respiratory disease-associated bacterial isolates (Histophilus somni, Mycoplasma bovis, Mannheimia haemolytica, and Pasteurella multocida) from dairy and beef cattle. One hundred genomically distinct assemblies were added to the NCBI database, doubling the available genomic sequences for these four species. Computer-based methods identified 11 predicted antimicrobial resistance genes in three species, with none being detected in M. bovis While computer-based analysis can identify antibiotic resistance genes within whole-genome sequences (genotype), it may not predict the actual antimicrobial resistance observed in a living organism (phenotype). Antimicrobial susceptibility testing on 64 H. somni, M. haemolytica, and P. multocida isolates had an overall concordance rate between genotype and phenotypic resistance to the associated class of antimicrobials of 72.7% (P &lt; 0.001), showing substantial discordance. Concordance rates varied greatly among different antimicrobial, antibiotic resistance gene, and bacterial species combinations. This suggests that antimicrobial susceptibility phenotypes are needed to complement genomically predicted antibiotic resistance gene genotypes to better understand how the presence of antibiotic resistance genes within a given bacterial species could potentially impact optimal bovine respiratory disease treatment and morbidity/mortality outcomes

Preliminary Exploration of the Accuracy of Visual Evaluation in Estimating Actual Bruise-Trim Weight of Beef Carcasses

Carcass bruising results in economic loss to the beef industry and is an indicator of a potential animal-welfare concern. The industry relies on visual assessment to determine the prevalence of bruising and to estimate bruise size (weight). This study examines the accuracy of using visual assessment to estimate bruise-trim weight from beef carcasses in a commercial slaughter facility. The removed bruise trim from 105 beef carcasses (84 cow and 21 steer carcasses; hot carcass weight for a subsample [mean ± standard deviation] = 768 ± 157 lb) was visually assessed by one trained observer using a protocol adapted from the National Beef Quality Audit Bruise Key visual assessment tool, and a second observer weighed the bruise trim. These data were used to assess the accuracy of the visual assessment of trim off of a carcass. A total of 68.6% (95% confidence interval: 58.7%, 77.1%) of collected bruise-trim weights were assessed correctly using the modi- fied National Beef Quality Audit Bruise Size Key visual assessment. Because of a limited number of samples in several of the bruise-trim categories, there is not a clear trend in how accuracy of estimation changed with increased bruise weight. These findings suggest that visual assessment of bruise trim may not be providing an accurate estimate of bruise-trim weight. The development of training materials to aid in visual bruise weight/size assessment would be helpful for improving bruise estimates within the cattle industry

Effect of Extended Postmortem Aging on Beef Muscles of Differing Quality Grade during Retail Display

Aging of beef subprimals is a common industry practice to improve tenderness. However, the effect of extended aging (up to 63 d) on retail shelf life, tenderness, and eating quality of beef strip loin and sirloin of differing quality grades is not clearly understood. Therefore, in the current study, longissimus dorsi (strip loin) and gluteus medius muscles (sirloin) were collected from USDA Choice or Select carcasses and fabricated into 6 portions. Each of these portions was designated to an assigned time of wet aging (14, 21, 28, 35, 45, or 63 d) in vacuum bags. After aging, samples were fabricated into steaks and placed into a multideck retail display case for 72 h. Steaks were evaluated for color (instrumental and color panelists) every 8 h during retail display, and Warner-Bratzler shear force and sensory analysis were conducted after retail display. The results were analyzed using the PROC MIXED procedure of SAS with repeated measures for the color data. Among the effects evaluated (aging, quality grade, and aging×quality grade), quality grade was not significant (P&gt;0.05) for either strip loin or sirloin steaks. An aging×display hour interaction was identified (P&lt;0.05) for the color measurements. In general, as aging time increased over the display period, color was negatively impacted. Although tenderness improved (P&lt;0.05) with aging, the incidence of off-flavors also increased, especially in sirloin steaks, suggesting that beef processors need to consider flavor changes during extended aging

Investigating the Etiology of Sour Knuckles in Postchilled Beef Carcasses

Development of sourness in beef round muscle cuts, such as knuckles, has been a long-standing issue in the beef industry with little characterization. Therefore, the objective of this study was to investigate and characterize the sour odor associated with beef knuckles using sensory, analytical (gas chromatography-mass spectrometry [GC-MS]), and microbiological approaches. Knuckles (n = 10) with no sour odor (control), a slight sour odor, or severe sour odor were collected during fabrication from a commercial beef processing plant. In addition, the synovial fluid from the femur joint, and the femur surface associated with the collected knuckles, were sponge-sampled. Knuckles were separated into 2 halves, with one half subjected to an odor panel, GC-MS, and microbial analyses on the day of collection (day 0). The remaining half was analyzed for odor and microbial populations following 35 d of vacuum-packaged storage at 0°C ± 2°C (day 35). Odor panelists identified differences (P &lt; 0.05) between control and sour knuckles (slight sour odor and severe sour odor) for all attributes tested (off-odor, oxidation, putrid, and sour notes) regardless of storage day. GC-MS analysis found no statistical difference (P &gt; 0.05) in volatiles between control and severe-sour-odor samples. Microbial analysis (aerobic plate counts and lactic acid bacteria counts) of muscle tissue on day 0 and day 35 of storage revealed no (P &gt; 0.05) differences between the 3 treatment groups. Similarly, no (P &gt; 0.05) differences between the treatment groups were obtained following analysis of synovial fluid and femur surface sponge samples for psychrotrophic anaerobic sporeformer counts. The findings of the study indicated that the souring condition in knuckles exists at identifiable intensities with no volatile acid or microbial population differences; therefore, further investigation is needed to determine the etiology

The Impact of Carcass Size, Chilling Conditions, and Electrical Stimulation on Beef Postmortem Temperature and pH Decline

Variability in carcass size can influence carcass chilling rates, which could result in issues associated with beef tenderness and color. Moreover, the usage of electrical stimulation can affect postmortem metabolism and meat quality. However, few studies have looked at the combined impact of chilling and electrical stimulation on temperature decline, postmortem biochemistry, and color among the current population of US beef. Beef carcasses (N = 162, &lt; 30 mo) were randomly selected from 2 beef processing plants. One side of each carcass was electrically stimulated, while the opposing side was not electrically stimulated. Matched sides were subjected to either conventional spray chilling (CONV) or delayed spray chilling (DELAY). Deep tissue (10.5 cm under the pelvic bone) and surface temperature (1.5 cm under the loin fat) were continuously monitored during chilling in addition to temperature and pH measurements from the semimembranosus (SM), longissimus lumborum (LL), and psoas major (PM) muscles at an initial time (45 to 60 min), 6 h, 12 h, and after chilling (28 to 36 h) postmortem. Further, the instrumental (L*, a*, and b*) and visual color were evaluated on 14-d aged PM steaks. For data analysis, carcasses with hot carcass weights above or below the plant average were considered heavy or light, respectively. A nonlinear regression model was fitted to the continuous deep and surface temperatures, whereas other parameters were evaluated using a mixed model. Electrical stimulation improved L* (lightness; P &lt; 0.05) of PM in light- weight carcasses but not (P &gt; 0.05) in heavyweight carcasses. Temperature decline was faster (P &lt; 0.05) and pH decline slower (P &lt; 0.05) in the SM and LL of lightweight carcasses under CONV compared to lightweight carcasses under DELAY and heavyweight carcasses under CONV and DELAY. Exponential decay models for deep and surface temperatures indicated the rate of cooling differed (P &lt; 0.05) due to the combination of treatment factors. Heavyweight carcasses in DELAY had slower rates of temperature decline (P &lt; 0.05). Overall, the variability in carcass size affected temperature decline and postmortem metabolism. Therefore, postmortem management practices should consider carcass weights to optimize meat quality

Antimicrobial Efficacy of Acidified Peroxyacetic Acid Treatments Against Surrogates for Enteric Pathogens on Prerigor Beef

Two studies were conducted to evaluate the antimicrobial effects of pH-adjusted solutions of peroxyacetic acid (PAA) against nonpathogenic Escherichia coli surrogates for Shiga toxin–producing E. coli and Salmonella, inoculated on beef. In both studies, prerigor beef carcass surface tissue (10 × 10 cm pieces) was inoculated (6–7 log colony-forming units [CFU]/cm2) on the adipose side with a 5-strain mixture of E. coli biotype I. In the first study, samples were left untreated (control) or were immersed (10 s) in solutions of PAA (300 parts per million [ppm]) acidified with a sulfuric acid and sodium sulfate blend (SSS) (pH 1.2) or PAA (400 ppm) acidified with acetic acid (2%), citric acid (1%), lactic acid (3.5%), or SSS (pH 1.2 or pH 1.8). In the second study, samples were left untreated or were spray treated (10 s) using a spray cabinet, with water, PAA (350 ppm or 400 ppm), PAA (350 ppm or 400 ppm) acidified with SSS (pH 1.2), or PAA (400 ppm) acidified with acetic acid (2%). All immersion treatments effectively (P &lt; 0.05) reduced inoculated E. coli populations (6.2 log CFU/cm2) by 2.3 to 2.8 log CFU/cm2. When the test solutions were applied by spraying, the water and all PAA-containing treatments lowered inoculated populations (6.4 log CFU/cm2) by 0.4 (P ≥ 0.05) and 1.7–1.9 (P &lt; 0.05) log CFU/cm2, respectively. No (P ≥ 0.05) differences in decontamination efficacy were observed between the 5 PAA-containing spray treatments. Overall, the results showed that PAA and the pH-adjusted PAA treatments were effective in reducing levels of the surrogates for Shiga toxin–producing E. coli and Salmonella. Although no differences in antimicrobial efficacy were noted between the nonacidified and acidified PAA treatments immediately after treatment application, further studies are needed to evaluate how the acidified PAA treatments perform as part of a sequential multi-hurdle decontamination strategy to reduce pathogen contamination on beef carcasses