Mountain Scholar :: Browsing by Author "Belk, Keith E., advisor"

Browsing by Author "Belk, Keith E., advisor"

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Open Access
A proof of concept to differentiate among differences in flavor of American lamb using volatile flavor compound analysis
(Colorado State University. Libraries, 2023) Isaacs, Karissa Ann, author; Woerner, Dale R., advisor; Belk, Keith E., advisor; Tatum, J. Daryl, committee member; LeValley, Stephen B., committee member; Heuberger, Adam L, committee member; Meiman, Paul, committee member
Experiments were conducted on lamb legs (n=25 per treatment) from 3 dentition groups [ young lambs (0 permanent incisors), yearlings (2 permanent incisors) and mature sheep or mutton (>2 permanent incisors)] to establish a proof of concept for differentiating the inherent differences in flavor that exist in meat from ovine animals of various age classes using volatile flavor compound analysis. The legs were selected from commercial processing facilities. Differences among age group, breed type, sex and production background were evaluated for sensory analysis and volatile compound analysis. Trained panelists evaluated ground meat patties from each leg for lamb flavor intensity and off flavor intensity. In addition, samples were analyzed to determine percentages of lipid, moisture, protein, and ash as well as to identify volatiles produced during cooking of a raw composite of lean and fat from the external surface of the leg. Analysis of variance was conducted for sensory flavor attributes relative to animal age and production background (grain vs grass) helped to describe the experimental samples. Ratings for lamb flavor intensity were higher (P < 0.05) for lamb carcass samples than for yearling carcass samples, and lamb flavor intensity scores were similar for lamb and mature age classes. Off-flavor intensity ratings were highest (P < 0.05) for samples from mature lamb carcasses, while lamb and yearling samples produced the lowest (P < 0.05) off-flavor intensity ratings. Lamb flavor intensity and off-flavor intensity ratings were higher (P < 0.05) for grass-fed lamb samples compared to grain-fed lamb samples. Mature samples had the greatest (P < 0.05) off-flavor intensity, while lamb and yearling samples had the least (P < 0.05) off-flavor intensity. Grass-fed lamb samples had the higher (P < 0.05) lamb flavor intensity scores and higher (P < 0.05) off-flavor intensity scores. Correlations between sensory attributes and metabolites helped to narrow the 500+ to 50 of significance. Findings indicated that metabolites (volatile compounds) were related to flavor of sheep meat. Finally, regression techniques helped to predict lamb flavor intensity, off flavor intensity and proof-of-concept for classifying lamb flavor.
Open Access
An evaluation of the effectiveness of FreshCase® technology to extend the shelf life of beef and pork
(Colorado State University. Libraries, 2012) Yang, Xiang, author; Belk, Keith E., advisor; Woerner, Dale R., advisor; Chapman, Phillip L., committee member; Tatum, J. Daryl, committee member
This research evaluated the effect of FreshCase®, a novel packaging technology that has been shown to extend the shelf life of whole muscle beef and ground beef, whole muscle pork and ground pork sausages by stabilizing fresh meat color. FreshCase® utilizes a high-barrier nitrite containing film in conjunction with vacuum packaging technology. Storage life was defined by the number of days required to reach an aerobic psychrotrophic plate count of 107 log CFU/g, and all treatmes were stored and evaluated until storage life expired. The storage life for beef steaks stored in FreshCase® packages at 4°C was 36 days; and the shelf life for ground beef stored in FreshCase® packages at 4°C was 12 days. The shelf life for pork chops stored in FreshCase® packages at 1°C was 46 days; and the shelf life for ground pork sausages stored in FreshCase® packages at 1°C was 19 days. Values for CIE a* (redness) were greater (P < 0.05) for FreshCase®-packaged samples for both beef steaks and ground beef with the increase of storage time. Both pork chops and sausages stored in FreshCase® packages retained more acceptable redder color (P < 0.05) than those stored in Control packages throughout storage. By the point at which spoilage was detected, off-odors of putrid, acid, sour and rancidity for FreshCase®-packaged samples were detected, but were present at very low level. Likewise, by the point of spoilage, no significant differences (P > 0.05) were found between samples in control and FreshCase® packages in all off-odors detection for both pork chops and sausages and the intensities of these off-odors were very low. Also, beef and pork samples resulted in very low (1.19 mg malonaldehyde/kg and 0.55 mg malonaldehyde/kg, respectively) TBA values throughout storage. Therefore, utilization of FreshCase® Technology in whole muscle beef and ground beef, whole muscle pork and ground pork sausages results in a more stable fresh red meat color with a low level of off-odors, and lipid oxidation. FreshCase® did not influence microbial growth in vacuum packaged samples.
Open Access
Beef tenderness and management of calf-fed Holstein steers to meet market standards
(Colorado State University. Libraries, 2013) Howard, Scott Thomas, author; Belk, Keith E., advisor; Woerner, Dale R., committee member; Tatum, J. Daryl, committee member; Scanga, John A., committee member; Salman, M. D., committee member
Tenderness is one of the most influential sensory attributes determining consumer acceptance of beef products. Beef at retail represents production of a diverse cattle population, including both beef breeds and cattle bred for milk production. Objectives of this work were to first benchmark tenderness at the retail level and then determine appropriate management strategies to maximize quality and yield of calf-fed Holstein steers. Fifty-four stores in thirty U.S. cities were sampled from June 2011 through May 2012 to benchmark tenderness of beef steaks at retail as assessed by Warner-Bratzler shear force (WBSF).Top loin (N = 980) and sirloin (N = 860) steaks were purchased and shipped via overnight delivery to Colorado State University, Fort Collins, CO. The survey was divided into two periods based on samples shipped fresh and frozen on arrival (Period 1) or samples shipped frozen and stored frozen (Period 2). 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. Examination of coefficients of variation associated with means reflecting the influence of freezing, retail display and shipping suggested that variance remained unchanged (± 2.0%) with respect to shear force values; however, mean shear force values were reduced as a result of shipping conditions. Mean WBSF values during Period 2 were 3.4 and 4.0 kg for top loin and sirloin samples, respectively. Frequencies of steaks classified as tough were 14.3% and 24.8% for top loin and sirloin steaks, respectively. Calf-fed dairy steers comprise approximately 10% of fed-beef harvested in the United States, annually (Moore et al., 2012).This population of cattle is much different genetically and requires use of growth promotants to meet comparable feedlot performance to that of beef breeds. The effect of beta-agonist supplementation on live performance, carcass characteristics, fabrication yields and beef quality of calf-fed Holstein steers was investigated using steers implanted with a combination trenbolone acetate/estradiol based implant and blocked by initial weight into pens (N = 32). Pens consisted of 90 steers each and were randomly assigned to one of four management strategies including: implant only, ractopamine hydrochloride (RH) fed at 300 mg/hd/d for the final 30 d of finishing or RH fed at 400 mg/hd/d for the final 30 d of finishing, and zilpaterol hydrochloride fed at 6.8 g/ton for 23 d with a 3 d withdrawal prior to harvest. Feed efficiency was improved in beta-agonist fed steers 18 to 25% and hot carcass weight was increased by 1.8 to 3.7% (P < 0.05). Beta-agonists increased saleable yield by 0.6 to 1.9%, decreased fat by 0.6 to 1.3% and shifted tissue distribution such that a greater percentage of side weight was comprised of the muscles of the round (P < 0.05). Changes in development were observed as a result of beta-agonist use, specifically as an increased proportion of weight comprised of muscles of the hindquarter (P < 0.05). Use of beta-agonists negatively impacted shear force and sensory attributes. Beta-agonists had no effect on marbling; however, supplementation using any treatment increased shear force by 9 to 26%. Zilpaterol hydrochloride reduced trained panel ratings for tenderness, juiciness and flavor, but this was not observed in beef from steers treated with RH at 300 mg/hd/d. These effects were nearly linear as dose and potency of beta-agonists increased. The most aggressive beta-agonist treatments increased incidence of samples failing to be certified as tender from just over 10% in controls to approximately 20 to 25% at 21 d postmortem (P < 0.05). To produce beef comparable to current tenderness levels at retail, producers must appropriately manage use of beta-agonists and implants in populations of calf-fed Holstein steers.
Open Access
Benchmark of lamb quality in U.S. retail and foodservice markets
(Colorado State University. Libraries, 2015) Hoffman, Travis William, author; Belk, Keith E., advisor; Woerner, Dale R., committee member; Ahola, Jason K., committee member; Pendell, Dustin L., committee member; Holt, Timothy N., committee member
Quality is an accumulation of attributes that satisfy customer preferences and expectations. Lamb quality is a moving target that means different things to the supply chain and sheep/lamb industry stakeholders. The objectives of this research were to determine the rank, definition, relative preference, and willingness to pay (WTP) for seven quality attributes and quantify product attributes of lamb at U.S. retail markets. Structured interviews of retail and foodservice respondents were conducted from May 2014 to March 2015 via face-to-face or telephone with lamb/protein purchaser representatives of retail (n = 60), foodservice (n = 45), and purveyor (n = 15) marketing sectors. Shares of preference (relative percentage of preference) in best/worst evaluation for all interviews indicated that eating satisfaction (38.9%) was the most important attribute. Shares of preference for all seven specified quality attributes were statistically different from each other (P < 0.05). Credence attributes of origin (17.2%) and sheep raising practices (13.6%) ranked second and third overall, respectively. Physical product characteristic traits of product appearance/composition (10.5%) and weight/size (8.5%) were ranked fourth and fifth in shares of preference, respectively. Nutrition/wholesomeness (7.1%) ranked sixth and product convenience/form (4.2%) ranked seventh in the overall ranking across all sectors of retailer, foodservice, and purveyor interview respondents. In WTP analyses, origin (25.8%) and sheep raising practices (20.0%) had the greatest likelihood of being a non-negotiable requirement for lamb purchasers. Eating satisfaction was the trait most likely to receive a premium (71.7%) from buyers, and product assurance of eating satisfaction generated the greatest average WTP premium (18.6%). This research indicated, across all sectors, eating satisfaction, defined as lamb flavor/taste, was the most important quality trait to those who purchase lamb. In-store evaluations of retail lamb labels showed that lamb shoulder and loin chops originating from the U.S. garnered the greatest price premiums compared to either New Zealand or Australian lamb (P < 0.05). Lamb was merchandised to American consumers at specialty type stores at an increased price per kg premium than either locally owned or national grocery chains (P < 0.05). Lamb shoulder prices at retail were merchandised with the greatest premium for product of U.S. origin from a specialty store packaged in modified atmosphere packaging and labeled with local (+ $5.42/kg) and natural (+ $5.40/kg) claims (P < 0.05). Lamb loin prices at retail were merchandised with the greatest premium for product of U.S. origin from a specialty store merchandised in a full service case or modified atmosphere packaged and labeled with a source verified and branded (+ $7.21/kg) label claim (P < 0.05). Shoulder and loin chop prices analyzed via hedonic modeling were not different for store location (East, Central, and West) nor USDA process verified Never-Ever 3 claim (P > 0.05). Additionally, this research indicated that lamb loin and rib chops purchased at U.S. retail markets originating from U.S. lamb were the most muscular. Loin eye area of loin chops from U.S. origin were greater (19.55 cm2) than Australian chops (16.77 cm2), and chops from New Zealand (14.52 cm2) were the least muscular (P < 0.05). Also, Australian lamb (0.64 cm) had a trimness advantage of external fat of loin chops compared to lamb originating from either the U.S (0.84 cm) or New Zealand (0.86 cm; P < 0.05). Lamb producers should strive to place a strategic emphasis on quality attributes identified in this research to ensure eating satisfaction and lamb flavor are optimized for American Lamb, and to produce lamb with product authenticity attributes requested by retail and foodservice sectors, and inevitably American lamb consumers. An important application of the research included the development of an American lamb quality mission to: improve the consistency of quality, cutability, and marketability of American lamb with a consumer driven focus. The final phase of this project was a sheep/lamb industry strategy workshop that identified goals to: 1) Address factors contributing to lamb flavor, their impact on consumer satisfaction, and align flavor characteristics with target markets; 2) Improve lamb management to hit market-ready targets for product size, composition, and eating satisfaction while reducing production costs; and 3) Identify and capitalize on market opportunities for American lamb. A continuous improvement mentality is essential to lamb quality management throughout the supply chain in order to maintain (and increase) market share and demand for American lamb.
Open Access
Consumer preferences for beef flavor
(Colorado State University. Libraries, 2014) Webb, Megan Jean, author; Woerner, Dale R., advisor; Belk, Keith E., advisor; Pendell, Dustin L., committee member; Engle, Terry E., committee member
For consumer satisfaction to occur, beef retailers and producers must continuously provide beef that contributes to desirable beef flavor. The objectives of this research was: 1) determine the consist of preference for beef flavors resulting from various production practices among beef consumers, 2) develop a true ranking of preference via best-worst (B/W) scaling, and 3) identify the proportion of preference for beef product categories resulting from various production practices. Nine consumer panels were conducted in three different geographical locations (eastern, central and western US). Consumer beef flavor preference was determined using B/W scaling, multinomial logit, and random parameter logit models in SAS® MDC. Proximate analysis and consumer ranking of attributes when making beef purchases was analyzed using an ANOVA, then means were separated using least squares means in SAS® and consumer demographic information was analyzed using PROC GLIMMIX. Overall, the four samples with the greatest percentage of lipid, F-1 Wagyu x Angus (20.2%), wet-aged upper two-thirds USDA Choice (15.6%), USDA Prime (14.7%), and dry-aged upper two-thirds USDA Choice (13.7%) resulted in a greater percentage of preference for flavor than product categories with a lower percent lipid, low USDA Choice (12.5%), USDA Select (11.9%), beef derived from domestic grass-fed cattle (6.8%); and beef derived from Uruguayan grass-fed cattle (4.5%). Results suggest the incorporation of Wagyu genetics, breeding cattle for a greater propensity of lipid, and grain finishing market beef cattle should result in a more preferred beef flavor characteristic. Results from demographic preference show females, Millennials (18 - 34 years of age), and respondents with an average or higher household income are more likely to consider beef derived from Uruguayan grass-fed cattle as their least preferred sample. Results from consumers making beef purchasing decisions show marbling level (3.8) and USDA grade of product (4.2) are moderately important and if the product was grass-fed vs. grain-fed (7.5) is the least important beef characteristic. Demographic information shows Baby Boomers (over 50 years of age) prefer beef derived from domestic grass-fed cattle (10.3%) more than both Generation X (6.0%; 35 - 50 years of age) and Millennials (7.1%; P < 0.05). Baby Boomers (18.6%) also prefer dry-aged upper two-thirds USDA Choice more than Millennials (13.6%; P < 0.05).
Open Access
Ecology and persistence of Escherichia coli O157:H7 in feedlot cattle and characterization of molecular mechanisms responsible for attachment
(Colorado State University. Libraries, 2009) Carlson, Brandon Adolph, author; Belk, Keith E., advisor
Studies were conducted to elucidate the shedding dynamics and ecology of Escherichia coli O157:H7 in feedlot cattle. Feedlot cattle (N=788) were evaluated for E. coli O157:H7 shedding six times during the final 120 d of finishing. Fecal samples were analyzed for E. coli O157:H7 with IMS and confirmed with multiplex PCR. During the first two collections, where all 788 steers were samples, 39.8 and 33.6% of steers were shedding an E. coli O157:H7 isolate possessing eae, stxI, and stxII. Through subsequent sampling, 1% of steers were characterized as persistent E. coli O157:H7 shedders (PS) where as 1.4% of steers were never shedding a detectable amount of the organism. Molecular characterization of E. coli O157:H7 isolates obtained from PS (n=80) and transient E. coli O157:H7 shedders (n=52) revealed a diverse but closely related population of isolates and identified a predominant subtype that accounted for 53% of the isolates characterized that was not dependent (P > 0.05) on animal shedding status. Pathogenic potential of E. coli O157:H7 isolates representing different subtypes was delineated with a Caco-2 cell (intestinal epithelial cell line) attachment assay. There was an inverse relationship (P < 0.05) between genetic diversity and attachment efficacy; as diversity from the dominant subtype increased, ability to attach to Caco-2 cells diminished. Additional attachment assays were initiated to evaluate the influence of virulence genes upon E. coli O157's ability to attach to Caco-2 cells. E. coli O157 isolates without either stx, no stxI, and no stxII genes resulted in attachment abilities of 76.7, 65.5 and 57.7%, respectively; all of which were greater (P < 0.05) than an E. coli O157:H7 that was isolated from a food implicated in human disease and possessed both stx genes. Cytotoxicity assays were utilized to verify that differences in attachment efficacy, exhibited by E. coli O157 isolates of various virulence genotypes, were independent of cellular destruction.
Open Access
Effect of packaging during storage time on retail display shelf-life of beef strip loins from two different production systems
(Colorado State University. Libraries, 2016) Luzardo, Santiago, author; Belk, Keith E., advisor; Woerner, Dale R., committee member; Tatum, J. Daryl, committee member; Hess, Ann M., committee member
The objective of this study was to evaluate the influence of packaging during storage of strip loins (to simulate export shipment) from steers fattened on intensive grazing systems (Uruguay; UR) or on high concentrate diet (United States; US) on retail display life color, microbial growth, fatty acids profile, lipid peroxidation and vitamin E content. Four different packaging treatments were applied to UR and US strip loins or steaks during 35 d storage; treatments were applied 7 d following slaughter. After 35 d storage, the samples were evaluated during simulated retail display for 6 d. In block 1, the treatments were: vacuum packaging (VP); low-oxygen modified atmosphere packaging (MAP) with nitrogen (N2) and CO2 (MAP/CO2); low oxygen MAP with N2 plus CO2 and carbon monoxide (CO); VP plus an application of peroxyacetic acid (VP/PAA). In block 2, the treatments were: VP, MAP/CO and VP with ethyl-N-lauroyl-L arginate HCl (LAE) incorporated into the film as an antimicrobial agent (VP/AM). In block 3, the treatments were: VP, MAP/CO2, MAP/CO and VP/AM. Regardless of production system and packaging treatment, mesophilic and psychrotrophic counts of 6.9 to 7.8 log10 CFU/cm2, and 6.7 to 7.7 log10 CFU/cm2, respectively, were obtained at the end of retail display, except for US samples in blocks 2 and 3 (5.5 to 6.3 log10 CFU/cm2). The UR strip loins packaged with MAP/CO had greater (P < 0.05) a* values than product packaged in VP/PA and MAP/CO2 following 6 d of display. For US beef, the MAP/CO treatment resulted in the reddest lean color (P < 0.05) compared to the other three packaging treatments in block 1. In blocks 2 and 3, the UR strip loin steaks packaged in MAP/CO also had the greatest a* values compared to the other three treatments, but no differences (P > 0.05) were detected among the VP treatments and the MAP/CO in the US steaks at the end of retail display. Only system (in block 1, and blocks 2 and 3), and time (in block 1) affected (P < 0.005) lightness (L*). In all blocks, US samples had greater L* values than UR samples (32.6 vs. 28.5; P = 0.0015, for block 1; and 33.4 vs. 31.1; P < 0.0001 for blocks 2 and 3). Vitamin E content in UR steaks, regardless of packaging treatment, was greater (P < 0.05) than US steaks. No effect of packaging treatment (P > 0.05) was observed by country of origin at the different display times in block 1, but UR beef displayed for 0 d from the MAP/CO2 treatment had greater (P < 0.05) vitamin E content than beef from the other three packaging treatments in blocks 2 and 3. Packaging x system, system x time and packaging x system x time interactions were not significant for any of the fatty acids analyzed on this study. Beef from UR had lower (P < 0.05) SFA and MUFA concentrations and greater (P < 0.05) PUFA, n-6 and n-3 concentrations than US beef when evaluated during retail display. Beef from UR developed more detectable (P < 0.05) oxidized odor than US samples while the latter exhibited a greater (P < 0.05) sour odor than UR grass-fed samples. Values from TBARS were influenced by significant packaging x system x time interaction in block 1 (P = 0.0027) and in blocks 2 and 3 (P = 0.0104). In block 1, UR beef had a greater (P < 0.001) TBARS values than US samples on d 0 of display, but TBARS values tended to decrease during retail display and differences almost disappear by the end of the display period. For blocks 2 and 3, TBARS value tended to increase between d 0 to d 6 of retail display in the UR and US samples. Complexity of fresh meat post-mortem chemistry warrants a more comprehensive and systemic approach to maximize shelf-life.
Open Access
Effects of antimicrobial interventions on food safety and an assessment of the Colorado pork supply
(Colorado State University. Libraries, 2018) Britton, Brianna C., author; Woerner, Dale R., advisor; Belk, Keith E., advisor; Geornaras, Ifigenia, committee member; Prenni, Jessica E., committee member
To view the abstract, please see the full text of the document.
Open Access
Effects of antimicrobial treatments on food safety, quality and shelf-life of beef
(Colorado State University. Libraries, 2019) Swenson, Joanna Kristine, author; Belk, Keith E., advisor; Woerner, Dale R., advisor; Geornaras, Ifigenia, committee member; Narayanan Nair, Mahesh, committee member; Prenni, Jessica E., committee member
To view the abstract, please see the full text of the document.
Open Access
Effects of various processing techniques and interventions on beef safety and shelf-life
(Colorado State University. Libraries, 2017) Woerner, Christy M., author; Belk, Keith E., advisor; Martin, Jennifer N., advisor; Delmore, Robert J., committee member; Weir, Tiffany L., committee member
Two experiments were conducted; the first evaluated decrease in log survival of pathogenic bacterial populations using three antimicrobial interventions (Peroxyacetic acid – PAA; Lactic Acid – LA; lactic/citric acid blend – LCA) applied at a spray cabinet used just before carcass chilling. Efficacy was evaluated using a Shiga-toxin producing Eschericia coli (STEC) inoculation cocktail that incorporated two strains of E. coli O157:H7 and 12 non-O157 STEC strains. In addition, this study was intended to validate the use of non pathogenic E. coli to serve as surrogates for the aforementioned STEC cocktail in plant operations. Influence of the carcass interventions on color stability of beef subprimals over a 30-day storage period was included to simulate effects on storage and display life. Each day, for three sampling days, 90 hot tissue samples from the plate subprimal were obtained immediately following slaughter. The tissue samples were evenly split into two inoculation groups (n = 45 samples/group): 1) STEC, or 2) surrogate. Within each inoculation group, samples were assigned randomly to one of nine treatments: i) 200 ppm PAA; ii) 1% LCA; iii) 1.5% LCA; iv) 2.5% LCA; v) 5% LA; vi) 8% LA; vii) 10% LA; viii) potable water; or ix) untreated control. Samples assigned to the surrogate inoculation group were further portioned into two equal sections for evaluation of the treatment influence on microbiological decrease in log survival and color. Samples were subjected to treatment using a custom-built, laboratory-scale spray cabinet to apply the intervention. Lightness (L*), redness (a*), and yellowness (b*) was evaluated before and immediately following spray application using a portable spectrophotometer. Following assessment of color immediately post-treatment application, the sample was further divided into three subsections that were vacuum packaged and stored for color evaluation at 10, 20, and 30 d. Among samples inoculated with STEC, log survival means with potable water and control were greater (P < 0.05) when compared to all other spray treatment groups. Likewise, the lower (P < 0.05) log survival means were observed for 8 and 10% LA treatment groups. No differences (P > 0.05) were observed among PAA, 1.5 and 2.5% LCA. Pairwise comparisons of surviving populations of STEC and surrogates revealed that the non-pathogenic strains could be effectively used as surrogates for the STEC cocktail. Color measures of L* values for samples spray treated with 8 or 10% LA were lower (P < 0.05) than for all other treatments, and declined over the 30 d storage period—indicating that the product darkened due to LA exposure and dark storage. Following 10 d dark storage, a* values were greater (P < 0.05) for untreated control samples than for samples sprayed with 1.5 or 2.5% LCA or for samples treated with any level of LA. Spectrophotometric b* values increased during dark storage (P < 0.05) suggesting product discoloration; however, no noticeable trends were observed among or between treatments. The second experiment monitored spoilage microorganisms, panelist and instrument color, and lipid oxidation changes during retail case display for three ground beef batches individually. After 7, 14, 18 or 21 d of vacuum-sealed, dark refrigerated storage (4C), three 73/27 ground beef batches (conventional - control; 25% inclusion of advanced meat recovery (AMR) product from plant one – BBFT 1; 25% inclusion of AMR product from plant two – BBFT 2) were separately fine ground, portioned into 454g loaves, and overwrapped with polyvinyl chloride (PVC) film for retail case display (4C) for 72 h. Sampling for aerobic plate count (APC), lactic acid bacteria (LAB) and 2-thiobarbituric acid reactive substances (TBAR) assay occurred every 24 h during retail case storage. Trained panelist-determined lean color, discoloration and redness intensity values, along with instrument L* (lightness), a* (redness) and b*(yellowness) measurements occurred every 12 h during retail case display. For each of the three products, neither least squares means for APC nor LAB exceeded 7 log CFU/g until after 21 d dark storage. Throughout retail case display, for all products, following all dark storage times, tan/brown discoloration means remained below 3%. With some exceptions, least squares means for panelist-determined lean color and redness intensity declined (P < 0.05) predictably, with greater retail case storage time. The L* means increased inconsistently depending on product or dark storage time; however, in several instances, L* values were highest (P < 0.05) toward the end of retail case storage. Conversely, a* values generally declined (P < 0.05) with increased storage times indicating a shift from bright red to dull blue color. Few noticeable trends among product and dark storage time were observed for CIE b* values throughout display. Least squares means for TBAR analyses were either similar (P > 0.05) or increased (P < 0.05) with retail case storage time.
Open Access
Efficacy of antimicrobial compounds against Salmonella spp., Escherichia coli O157:H7, non-O157 Escherichia coli, and non-pathogenic Escherichia coli on beef and poultry
(Colorado State University. Libraries, 2015) Scott, Brittney R., author; Delmore, Robert J., advisor; Belk, Keith E., advisor; Woerner, Dale R., committee member; Bunning, Marisa, committee member
To view the abstract, please see the full text of the document.
Open Access
Efficacy of antimicrobial treatments against Salmonella enterica on pork and Campylobacter jejuni on poultry
(Colorado State University. Libraries, 2020) González Sánchez, Sara Victoria, author; Belk, Keith E., advisor; Geornaras, Ifigenia, advisor; Delmore, Robert J., committee member; Weir, Tiffany L., committee member
Two studies were conducted to evaluate efficacy of antimicrobial treatments against Salmonella enterica on pork and Campylobacter jejuni on poultry. The first study was conducted to (i) evaluate decontamination efficacy of six chemical treatments when applied to pork jowls inoculated with Salmonella enterica and (ii) determine the antimicrobial efficacy of the test solutions against a high and low inoculum level of Salmonella. Chilled pork jowls were cut into 10 × 5 × 1 cm portions and were surface-inoculated on the skin side with a mixture of six S. enterica serotype strains of swine origin. The inoculation levels targeted were 6 to 7 log CFU/cm2 (high) and 3 to 4 log CFU/cm2 (low). Following inoculation, samples were left untreated (control) or were treated by spray application (10 s, 18 to 19 psi, 1.0 gpm flow rate) with water, a proprietary blend of sulfuric acid and sodium sulfate (SSS, pH 1.2), formic acid (1.5%), peroxyacetic acid (PAA, 400 ppm), PAA (400 ppm) acidified with acetic acid (1.5%), PAA (400 ppm) acidified with formic acid (1.5%), or PAA (400 ppm) acidified with SSS (pH 1.2). Samples were analyzed for inoculated Salmonella counts immediately after treatment application (0 h) and after 24 h of refrigerated (4°C) storage. Overall, all seven spray treatments were effective (P < 0.05) at reducing the high and low Salmonella inoculation levels. At the high inoculum level (6.2 log CFU/cm2), pathogen counts ranged from 5.4 (water; 0.8 log CFU/cm2 reduction) to 4.3 (PAA acidified with SSS; 1.9 log CFU/cm2 reduction) log CFU/cm2 for samples analyzed immediately after spray treatment. Salmonella counts obtained at the 0-h sampling time for treated samples inoculated at the low inoculum level (3.5 log CFU/cm2) ranged from 2.8 (water; 0.7 log CFU/cm2 reduction) to 1.8 (PAA acidified with SSS; 1.7 log CFU/cm2 reduction) log CFU/cm2. Thus, regardless of inoculum concentration, similar reductions of Salmonella populations were obtained immediately following treatment application (0 h). For the high inoculation level, Salmonella counts of samples analyzed after 24 h of refrigerated storage were, in general, similar (P ≥ 0.05) to the counts of the corresponding treatment at 0 h. However, for the low inoculation level, pathogen counts of jowls treated with SSS, formic acid, or PAA acidified with formic acid, and held at 4°C for 24 h, were 0.6 log CFU/cm2 lower (P < 0.05) than the 0-h counts of the corresponding treatment. Regardless of inoculation level and sampling time, no (P ≥ 0.05) differences in efficacy were obtained between PAA on its own and any of the acidified PAA treatments evaluated. The second study was conducted to (i) evaluate decontamination efficacy of five chemical treatments when applied to chicken wings inoculated with Campylobacter jejuni and (ii) determine antimicrobial efficacy of the treatments as a result of applying test solutions by immersion or spraying. Skin-on chicken wings were surface-inoculated with a six-strain mixture of C. jejuni of poultry origin. The target inoculation level was 3 to 4 log CFU/mL of wing rinsate. Following inoculation, samples were left untreated (control) or were treated by immersion (500 mL solution per wing; 5 s) or spray application (10 to 12 psi; 4 s) with water, SSS (pH 1.2), formic acid (1.5%), PAA (550 ppm), PAA (550 ppm) acidified with SSS (pH 1.2), or PAA (550 ppm) acidified with formic acid (1.5%). Samples were analyzed for C. jejuni counts immediately after treatment application (0 h) and following 24 h of storage (4°C). All five acid treatments evaluated in this study were effective (P < 0.05) at reducing the initial inoculated (3.9 log CFU/mL) C. jejuni populations on chicken wings, regardless of the antimicrobial treatment application method. Pathogen counts for samples spray-treated with one of the chemical solutions and analyzed immediately (0 h) after treatment ranged from 3.4 (SSS; 0.5 log CFU/mL reduction) to 2.7 (PAA acidified with formic acid; 1.2 log CFU/mL reduction) log CFU/mL. When the chemical treatments were applied by immersion, C. jejuni counts of 2.2 (SSS; 1.7 log CFU/mL reduction) to 1.7 (PAA, and PAA acidified with SSS; 2.2 log CFU/mL reduction) log CFU/mL were obtained for wings analyzed at the 0-h sampling time. The PAA and acidified PAA treatments were equally (P ≥ 0.05) effective at reducing initial C. jejuni populations, regardless of treatment application method. However, following refrigerated storage, samples treated with SSS- or formic acid-acidified PAA had lower (P < 0.05) pathogen counts than those that had been treated with the non-acidified PAA treatment. Overall, findings of the two studies should be useful to the pork and poultry industries as they consider new interventions against Salmonella and Campylobacter contamination on pork and chicken parts, respectively.
Open Access
Efficacy of antimicrobials using an innovative, new electrostatic application system on Salmonella-inoculated poultry parts
(Colorado State University. Libraries, 2016) Davis, Haley E., author; Belk, Keith E., advisor; Delmore, Robert J., committee member; Martin, Jennifer N., committee member; Morley, Paul S., committee member
Two studies were conducted to evaluate efficacy of peroxyacetic acid (PAA) as an antimicrobial intervention treatment when applied electrostatically, in reducing inoculated populations of Salmonella serovars on chicken wings. The other objectives of these studies were: to determine critical operating parameters for reducing Salmonella serovars on poultry parts; to evaluate use of static electricity to maximize coverage of antimicrobial solutions applied electrostatically to poultry part surface areas while limiting volume to minimize weight gain; to evaluate use of vacuum to enhance absorption of antimicrobial spray into pores of poultry parts; and to determine optimal rotation speed of the Birko prototype application unit’s containment drum to expose all poultry part surfaces during antimicrobial solution application. Two different electrostatic spray systems (ES1 and ES2) were evaluated in two separate studies. For both studies, chicken wings were inoculated with nalidixic acid- and novobiocin-resistant Salmonella (5-strain mixture; 5-6 log CFU/ml of chicken wing rinse solution) sourced from poultry. Inoculated wings were either left untreated (control) or were treated with water or PAA. In study 1, water and PAA (at a wt/wt concentration of 2000 ppm) were applied (30 s) with one of four application methods: (i) electrostatic spray (ES1), (ii) vacuum, (iii) ES1 + vacuum, or (iv) immersion. Chicken wings were then placed into Whirl-Pak bags containing Dey/Engley (D/E) neutralizing broth and sample rinsates were serially diluted and surface-plated on both tryptic soy agar and tryptic soy agar supplemented with nalidixic acid (20 µg/ml) and novobiocin (25 µg/ml). Overall, least squares means for log10 Salmonella counts differed (P < 0.05) between all treated wings vs. the control. When PAA was applied, electrostatic spray was most effective (P < 0.05) at reducing Salmonella populations. In study 2, treatment solutions of water and two concentrations of PAA (2000 ppm and 4000 ppm) were evaluated. These were applied (30 s) using two differing application methods [a Birko prototype application system (ES2) and immersion]. Sampling methods were the same as those used in study 1, with the exception that analysis of efficacy occurred at both 0 and 24 h. Untreated and treated chicken wings were placed in Whirl-Pak bags and held at 4°C for 24 h before sampling. For study 2, mean bacterial counts for all treatments differed (P < 0.05) from the control and there was a treatment and sampling time interaction. For both water and PAA, the immersion treatment was most effective (P < 0.05) at reducing Salmonella populations after 24 h storage. Both electrostatic spray systems (ES1 and ES2) reduced (P < 0.05) bacterial populations of Salmonella, validating electrostatic application as a potential antimicrobial intervention method for chilled poultry parts.
Open Access
Evaluation of GENE-UP and TEMPO AC for determination of Shiga-Toxin producing Escherichia coli and total aerobic microbial populations from MicroTally sheets used to sample beef carcasses and hides
(Colorado State University. Libraries, 2020) Liu, Tianqing, author; Belk, Keith E., advisor; Yang, Hua, advisor; Weir, Tiffany L., committee member; Zagmutt, Francisco J., committee member
Two studies were conducted to evaluate GENE-UP and TEMPO AC (bioMerieux, Marcy-l'Étoile, France) for determination of Shiga-Toxin producing Escherichia coli and total aerobic microbial populations from MicroTally Sheets (Fremonta Corporation, Fremont, CA) used to sample beef carcasses and hides. The first study was conducted to evaluate the automated TEMPO® AC Test in comparison with traditional direct agar plating method for enumeration of aerobic mesophilic flora in MicroTally sheets used to sample beef carcasses and hides. A total of 160 MicroTally (MT) sheet samples were collected from commercial beef processing plants by swab-sampling on the surface of naturally contaminated pre-evisceration carcasses, hides and post-chill final carcasses, and analyzed within 24 h after sample collection. Of these, all 160 samples were within detection limit and analyzed by both automated TEMPO AC test and a traditional direct agar plating method. For these results, the aerobic count correlation coefficient was high (0.93) for pre-evisceration carcasses, which had mean (± standard deviation) counts of 3.3 ± 0.9 and 3.1 ± 0.8 log CFU/mL for those two methods, respectively. The aerobic count correlation coefficients were higher (0.95 and 0.96) for MT samples from hides and post-chill final carcasses, which had mean (± standard deviation) counts of 5.3 ± 1.2 and 5.0 ± 1.2, 3.0 ± 1.4 and 3.0 ± 1.3 log CFU/mL for those two methods, respectively. Overall, 98.8% of aerobic count results were within 1.0-log difference between the two enumeration methods. The correlation coefficient (r = 0.97) and linearity regression (log TEMPO MPN/mL = 1.06 x log PCA-CFU/mL +0.03) between the two methods was calculated for our whole sample set (n = 160). Our results demonstrated that the automated MPN method-TEMPO AC Test generated total aerobic mesophilic microflora counts that were highly correlated and consistent with the counts obtained by traditional plating methods on enumerating total aerobic mesophilic microbial populations recovered from MicroTally sheets. Use of TEMPO AC test for MicroTally sheet analysis could save time and labor for the meat industry as it conducts microbial analyses. The second study was conducted to determine the specificity of bioMérieux's GENE-UP, a PCR-based molecular diagnostic system, to detect Shiga Toxin-producing Escherichia coli (STEC) from samples collected from beef processing plants using MicroTally sheets with the manual sampling device method. A total of 194 MicroTally (MT) samples were collected from beef processing plants and analyzed for determination of the top 6 STEC and E. coli O157: H7 (top 7 STEC) using the GENE-UP system, BioRad commercial kits and BioControl GDS kits. Fifty MT samples were collected from swabbing pre-evisceration carcasses and inoculated with hide-derived inocula, while the remaining 144 MT samples were obtained from post-chill final carcasses in sales coolers and inoculated with E. coli strains. All inoculated MT samples were enriched for 8-hour and 10-hour at 42ᵒC in buffered peptone water (BPW) and re-collected after incubation. Eight-hour and 10-hour enrichment samples were analyzed using the GENE-UP system at Colorado State University and sent to U.S Meat Animal Research Center (USMARC, Clay Center, NE) for detection of top 6 STEC and E. coli O157: H7. The GENE-UP system uses EH1 assay to detect stx and eae genes, ECO assay to detect genes specific to O157:H7 serogroup, and EH2 assay to differentiate top 6 serogroups. These virulence genes including Shiga-toxin gene (stx), intimin-encoding eae gene and genes specific to top 7 serogroups are highly related to pathogenic STEC. The NM-EHEC assay targeting virulence genes espK, espV and CRISPR_O26E does not directly differentiate the top 7 STEC, but serves as additional screening test to help identify presence of any of the top 7 STEC. All potential positive samples determined by PCR screening were plated onto selective agar for culture confirmation. After the immunoconcentration step, isolates picked from selective agar were subjected to additional PCR screening. BioRad and BioControl GDS PCR screening methods were used following their standard protocols for determination of top 7 STEC at USMARC. Presumptive positive samples confirmed by the additional PCR test were designated as "true positives." Presumptive positive samples that were not confirmed by the additional PCR test were designated as "regulatory false positives." Overall, our results indicated that the GENE-UP system worked well in the detection of the top 7 STEC recovered from the MicroTally sheets. In order to reduce or eliminate false negative results, a 10-h enrichment time in BPW was required for detection of both the top 6 STEC and E. coli O157:H7. Compared to GENE-UP and GDS, BioRad generated a much higher number of potential positives that required cultural confirmation. Moreover, use of the NM-EHEC kit targeting virulence genes (espK, espV and CRISPR_O26E), as an additional PCR screening after EH1 PCR (stx and eae), has potential to reduce the number of samples that require further O-type determination. However, the GENE-UP E. coli O157:H7 detection system needs to reduce rates of false negative results caused by the shift of Tm when E. coli O157:H7 and O157: non-H7 co-exist in a sample.
Open Access
Identifying preferences for specific beef flavor characteristics
(Colorado State University. Libraries, 2012) O'Quinn, Travis Gene, author; Belk, Keith E., advisor; Tatum, J. Daryl, advisor; Woerner, Dale R., committee member; Engle, Terry E., committee member; Chapman, Phillip L., committee member
Descriptive sensory analysis of beef samples was conducted at culinary institutions in three regions of the United States to determine differences in beef flavor attributes and flavor preferences among 12 different beef product categories (treatments). Treatments were chosen specifically to permit identification and characterization of production-related beef flavor differences, including effects of USDA grade (Prime, Premium Choice, Low Choice, Select), cattle breed-type (Angus, Holstein, American Wagyu), finishing diet (grass-fed, corn-fed, barley-fed), use of growth technologies (non-implanted, implanted, implanted & fed β agonists), and postmortem aging method (wet-aged, dry-aged). Panelists (N = 307) rated ground strip loin samples from each treatment for 13 different flavor notes (beefy/brothy, browned/grilled, buttery/beef fat, nutty/roasted nut, earthy/mushroom, bloody/metallic, grassy, livery, fishy, sour, sweet, and bitter) and overall flavor desirability. Each sensory attribute was rated on a 10-cm, unstructured line scale with 0 cm verbally anchored at very low intensity for all flavors and dislike extremely for flavor desirability and 10 cm verbally anchored at very high intensity for all flavors and like extremely for flavor desirability. In addition, samples were analyzed to determine percentage chemical lipid, moisture, protein, and ash of raw products, fatty acid composition of cooked products, and quantities of volatiles produced during cooking. Of the factors analyzed, USDA Quality grade and finishing diet (grain-fed vs grass-fed) had the largest effects on beef flavor attributes. Differences in cattle-breed type (Angus vs Wagyu), grain source (corn vs barley), aging technique (dry-aged vs wet-aged), and use of growth technology (non-implanted vs implanted vs implanted & fed β agonists) had only minimal effects on flavor. Extending the wet-aging period from 14 to 46 d had a negative effect on flavor, producing samples that scored higher (P < 0.05) for sour flavor than all other treatments. Panelists preferred samples with flavors described as beefy/brothy, browned/grilled, buttery/beef fat, nutty/nutty roasted nut, and sweet, and disliked flavors identified as bloody/metallic, grassy, gamey, livery, fishy, sour, and bitter. Moreover, overall flavor desirability scores were positively correlated (P < 0.05) with the concentration of several monounsatured fatty acids including C12:1, C14:1, C16:1 c9, and C18:1 c9. Stearic acid (C18:0) concentration was negatively correlated (P < 0.05) with overall flavor desirability and positively correlated (P < 0.05) with bloody/metallic, grassy/hay like, gamey, livery, fishy, sour, and bitter flavors. The concentration of several polyunsaturated fatty acids including C18:2t (total), C18:3 n-3, and C22:5 n-3, were found highest (P < 0.05) in Organic grass-fed samples and were negatively correlated (P < 0.05) with overall flavor desirability. Overall flavor desirability was positively correlated (P < 0.05) with diacetyl (2, 3-butanedione), acetoin (3-hydroxy-2-butanone), 3-methyl butanal, and pentanal concentrations. Samples with higher concentrations of dimethyl sulfide were rated lower (P < 0.05) for overall flavor desirability. The concentrations of several volatile compounds were correlated with various beef flavors including beefy/brothy, buttery/beef fat, browned/grilled, earthy/mushroom, nutty/roasted nut, sour, bitter, and sweet.
Open Access
Impact of unconventional beef carcass rib separation, oven temperature, and degree of doneness on eating quality of beef
(Colorado State University. Libraries, 2016) de Paula e Mancilha, Talita, author; Belk, Keith E., advisor; Woerner, Dale R., advisor; Martin, Jennifer, committee member; Heuberger, Adam, committee member
To view the abstract, please see the full text of the document.
Open Access
Location of Salmonella in poultry fat intended for use in pet food and the influence of fat's physical characteristics on Salmonella prevalence and growth
(Colorado State University. Libraries, 2016) Kiel, Rinara C., author; Belk, Keith E., advisor; Woerner, Dale R., committee member; Martin, Jennifer N., committee member; Hess, Ann M., committee member
This study was conducted to: (i) utilize fluorescently-tagged Salmonella to assess distribution of Salmonella in a rendered fat matrix; (ii) assess the influence of post-inoculation time and moisture content on distribution of fluorescently-tagged Salmonella in rendered poultry fat; and, (iii) evaluate the impact of post-inoculation time and physical parameters (i.e., impurity level and moisture content) on survival of three Salmonella serotype strains in rendered poultry fat stored at 25˚C or 45˚C. Three studies, designated as Study I(a), I(b) and II were conducted to address the objectives. In Study I(a), a green fluorescent protein (GFP)-expressing strain of Salmonella Typhimurium was used to visually and microbiologically map the organism within warmed (45˚C) poultry fat formulations comprised of a low impurity level (<0.2%) and three moisture contents (low: 0.5%; medium: 2.2%; high: 4.5%). In Study I(b), using the same fat formulations as in Study I(a), survivability of GFP-expressing Salmonella was compared in samples that were either stored at 25˚C or 45˚C. In Study II, survivability of three Salmonella serotype (Enteritidis, Senftenberg, Typhimurium) strains was compared in fat formulations of two impurity levels (0.5%, 1.0%), three moisture contents (low: 0.5-0.7%; medium: 2.1-3.0%; high: 3.9-4.8%) and two temperatures (25˚C, 45˚C). Surviving populations of Salmonella Typhimurium and their location in a rendered fat matrix were achieved for each treatment combination (Study I). For Study I(b) and II, death/survival/growth curves were developed and comparisons among factors of time, temperature and moisture contents were made. In conclusion, the best option for the rendering industry to control Salmonella in poultry fat it is to control multiple factors when storing the final product, more specifically, low impurity poultry fat with low moisture content that is stored at a high temperature (45˚C and above) for a period of time would effectively control Salmonella contamination in poultry fat. Preventing recontamination is another crucial point for the rendering facilities, in that matter, GMP is essential, sanitation conditions that will not allow contamination and biofilm formation should be implemented and validated, as appropriate cleaning with scrubbing in holding bins, storage tanks, floors, walls, trucks, everything that have contact with the product.
Open Access
Quality and nutritional aspects of conventional and novel food proteins
(Colorado State University. Libraries, 2020) Thompson, Tyler Warren, author; Nair, Mahesh Narayanan, advisor; Belk, Keith E., advisor; Geornaras, Ifigenia, committee member; Weir, Tiffany, committee member
Cattle weights have increased during the last couple of decades and have not always been accompanied by improvements in facility capabilities and management. Alongside quality issues of color, tenderness, and water holding capacity, issues such as sour muscles and bone taints are now appearing with high frequency in the meat industry. Development of off-flavor/sourness in deep muscles such as knuckles (vastus femoris, vastus lateralis, vastus medialis, and rectus femoris) has been a long-standing issue in the beef industry, however, has not been well characterized. Therefore, the objective of this study was to investigate the potential cause and to characterize the sour odor associated with beef knuckles using microbial, odor panel, and gas chromatography-mass spectrometric (GC-MS) analyses. Knuckles (n = 10) identified as having no sour odor (control), slight sour odor (SLI-SO), or severe sour odor (SVR-SO) were collected from the fabrication line of a commercial beef processing plant. Upon collection of knuckles, synovial fluid and the femur surface were swabbed to determine psychrotrophic anaerobic sporeformer presence. The collected knuckles were transported on ice to the laboratory where they were aseptically separated into two halves, with one half destined for microbial, odor, and GC-MS analyses on the day of collection (day 0) and the other half for the same analyses (excluding GC-MS) after 35 days of vacuum packaged storage at 0 - 2°C (day 35). For microbial analysis, 15 g of tissue was excised from the muscle surface and was analyzed for aerobic plate counts (Petrifilm Aerobic Count plates) and lactic acid bacteria counts (Lactobacilli MRS agar). Samples (5 g) for GC-MS were held at -80°C until analysis. The remainder of the sample was diced and used for trained odor panels. Odor panelists identified differences (P < 0.05) for all tested attributes (off odor, oxidation, putrid, and sour notes) between control and sour knuckles (SLI-SO and SVR-SO) on day 0. Similarly, on day 35, differences (P < 0.05) were observed between control, SLI-SO, and SVR-SO knuckles for all attributes, with SVR-SO samples receiving the highest score for all categories. However, the microbiological analysis found no differences between aerobic plate counts and lactic acid bacteria counts of control, SLI-SO, and SVR-SO knuckles on day 0 or day 35. In addition, GC-MS analysis did not indicate a difference (P > 0.05) in the abundance of volatiles between the treatments (probably due to high variations within treatment groups). Overall, compounds such as acetic, acetoin, propionic, butyric, and isobutyric acid were trending towards having greater abundance in sour samples. Although animal proteins have been the primary source of protein in the human diet, plant-based proteins have gained popularity in recent years. While some studies have indicated lesser environmental impacts, the nutritional composition of plant-proteins has not been readily investigated. Therefore, the objectives were to evaluate the nutritional composition of Morning Star Farms spicy black bean burger (VB), Beyond Meat's Beyond Burger (BB), Impossible Food's Impossible Burger (IB), a boneless top loin pork chop (PC), and 80% lean 20% fat ground pork (GP). Six different cities were selected for product collection to give a representative view of the products (Seattle, WA; Peyton, CO; Memphis, TN; Newburgh, IN; Houston, TX; and Brooklyn, NY). Following collection, products were brought back to Colorado State University. Half of the products sampled from each city were cooked, and the remaining half were left in their raw state. All ground products were cooked to an internal temperature of 71°C while the PC was cooked to 63°C. Samples (both raw and cooked) were then homogenized individually and stored under vacuum-packaged conditions at -80°C until further analysis. Methodologies for proximate analysis, amino acids, fatty acids, minerals, vitamins, organic acids, and allergens were conducted following the Association of Official Analytical Chemist (AOAC) guidelines. Overall, the product state (raw or cooked) had little effect on the nutritional composition. Analysis indicated that the PC contained the highest (P < 0.05) amounts of protein, essential amino acids, and B-vitamins. Cholesterol was found highest (P < 0.05) in the pork products (PC and GP) with no cholesterol being identified in the plant-based products (VB, BB, and IB). However, when evaluating mineral make-up, the plant-based products contained the highest (P < 0.05) amounts, especially in sodium and iron levels. Sodium levels were about ten times higher, along with iron levels being 3 to 4 times higher in plant-based products. Overall, the pork products were found to contain the greatest amounts of amino acids, and B-vitamins needed in a diet. While the plant-based products were generally lower in nutrients, the IB was found at nutritional levels close to the GP and PC.
Open Access
Quantifying the "aging response" and nutrient composition for muscles of the beef round
(Colorado State University. Libraries, 2010) Dixon, Cheyenne Lee, author; Belk, Keith E., advisor; Chapman, Phillip L., committee member; Tatum, J. Daryl, committee member; Woerner, Dale R., committee member
The objective of this study was to determine the optimal postmortem aging period and nutrient composition for Beef Value Cuts of the round. For the postmortem aging study, 40 USDA Select and 40 premium USDA Choice beef carcasses were selected from a commercial beef packing plant in Colorado over a 12-week period. The bottom and inside rounds were collected from both sides of each carcass for further fabrication into the following muscles: Adductor, Gastrocnemius, Gracilis, Pectineus, and Superficial digital flexor. Each pair of muscles was cut into seven steaks, approximately 2.54 cm in thickness, and vacuum packaged. All steaks were randomly assigned to one of the following aging periods: 2, 4, 6, 10, 14, 21, and 28 days, and placed in refrigerated storage (2°C, never frozen). Upon completion of the designated aging period, steaks were removed from storage, cooked to a peak internal temperature of 72°C, and evaluated using Warner-Bratzler shear force (WBSF). A two-way interaction was detected (P < 0.05) between individual muscle and postmortem aging period. The WBSF of all muscles except the Superficial digital flexor decreased with increased time of postmortem aging. Quality grade did not affect (P > 0.05) WBSF values for the Adductor, Gastrocnemius, Pectineus, and Superficial digital flexor muscles. Exponential decay models were used to predict the change in WBSF from 2 to 28 days postmortem (aging response). The Adductor, Gastrocnemius, Select Gracilis, premium Choice Gracilis, and Pectineus required 21, 14, 23, 23, and 25 days, respectively, to complete the majority of the aging response. To determine the nutrient composition of the Adductor, Gastrocnemius, Gracilis, Pectineus, Semimembranosus, and Superficial digital flexor, bottom and inside rounds were collected from 10 USDA Select and 10 premium USDA Choice carcasses, fabricated into the respective muscles, cut into 2.54 cm cubes, frozen (-20°C), and then homogenized. The Adductor, Gracilis, Pectineus, Semimembranosus, and Superficial digital flexor were analyzed for dry matter, moisture, crude protein, and ash percentages. All muscles were evaluated for lipid percentage and fatty acid and cholesterol composition. When quality grades were combined, all muscles fell into the "extra lean" or "lean" categories specified by USDA guidelines based on the total fat, saturated fat, and cholesterol content present in each cut. Results of this study illustrate the potential for Beef Value Cuts of the round to be sold in foodservice operations and retail stores with marketing emphasis being placed on the exceptional leanness and acceptable tenderness of these cuts.
Open Access
Ractopamine withdrawal, depletion, and residue testing in beef cattle
(Colorado State University. Libraries, 2019) Davis, Haley E., author; Belk, Keith E., advisor; Engle, Terry, committee member; Geornaras, Ifigenia, committee member; Prenni, Jessica, committee member; Yang, Hua, committee member
Studies were conducted to evaluate use of ractopamine hydrochloride (RH) in beef cattle production and the effect of various withdrawal times and depletion periods on residues in tissues and fluids collected from live and harvested animals. Primary objectives of these studies were: i) to develop and validate a LC-MS/MS assay to determine if detectable and quantifiable levels of RH can be detected in digestive tract-derived edible offal items of cattle resulted from tissue residues or residual ingesta contamination; ii) to determine presence of ractopamine in tissues after 12 h, 2, 4, and 7 days of withdrawal (in comparison to negative control cattle which did not receive RH); iii) to develop U.S. beef industry best practices for RH use for export to the Chinese market; and iv) to test the impact of withdrawal from ractopamine hydrochloride in the diets of feedlot cattle for 2, 4, or 7 days on residues for parent and total ractopamine in muscle, fat, rendered tallow, and large intestines in contrast to a true negative control group as well as validate and test feed samples to verify ractopamine presence using LC-MS/MS protocols. In the first study, tissue samples and corresponding rinsates from 10 animals were analyzed for parent and total ractopamine (tissue samples only). The lower limit of quantitation was between 0.03 - 0.66 ppb depending on tissue type, and all tissue and rinsate samples tested had quantifiable concentrations of ractopamine. The greatest concentration of tissue specific ractopamine metabolism (represented by higher total vs. parent ractopamine levels) were observed in liver and small intestine. Contamination from residual ingesta (represented by detectable ractopamine in rinsate samples) only was detected in small intestine, with a measured mean concentration of 19.7 ppb (+/- 12.2 ppb). Taken together, these results underscored the importance of the production process and suggested that improvements may be needed to reduce likelihood of contamination from residual ractopamine in digestive tract-derived edible offal tissues for market. In the second study, liver and muscle samples were collected after 2, 4, and 7 days of withdrawal from RH due to regulatory issues surrounding 12-h samples. Parent and total ractopamine residues in individual liver samples ranged from a minimum of 3.40 and 3.46 ppb, respectively, for the control treatment group, to a maximum of 3.54 and 14.19 ppb, respectively, for the 2-day withdrawal treatment group. For the individual muscle samples, parent and total ractopamine concentrations ranged from below the limit of quantification (0.12 ppb) in the control samples, to 1.13 (parent ractopamine) and 1.72 ppb (total ractopamine) in 2-day withdrawal samples. Therefore, overall, parent and total ractopamine concentrations detected in the liver and muscle samples fell far below the MRL set by Codex and FDA. The greatest parent and total ractopamine levels (282.40 and 289.85 ppb, respectively) were detected after 12 h withdrawal in individual large intestine samples, followed by small intestine (142.26 and 181.91 ppb, respectively) and omasum (109.70 and 116.90 ppb, respectively) samples. Because detectable levels of ractopamine were identified in tissues collected from control animals (i.e., animals not receiving RH in their ration), further research was conducted to determine potential sources of ractopamine contamination, and frequency and accuracy of testing in global markets. For example, eight feed-grade tallow samples were analyzed for parent and total ractopamine presence as a potential source of contamination, especially in cattle not receiving ractopamine in their rations. Ractopamine concentrations of 0.40 to 50.80 ppb were obtained for these tallow samples. While this could potentially explain the detectable levels of ractopamine residues found in control samples and the fact that 7-day withdrawal did not result in non-detectable levels, further research looking at tallow recycling and residual proteins in tallow is necessary to understand the implications of contaminated tallow on residue levels across tissues. Data from the current study may be useful in developing new recommendations for RH use and withdrawal to beef cattle producers in the U.S. who intend to export to global markets. Results from the third study revealed several items of interest, for example; RH declines rapidly in the lower GI of beef cattle, with levels below detection by day four. Additionally, there is a very small likelihood of RH cross-contamination via tallow inclusion in diets. Finally, the fourth study indicated that RH residues can, in fact, be quite low; however, because of limits of detection which are above zero, it is nearly impossible to quantify a level as 0.00 ppb, making zero tolerance requirements insurmountable. Overall, results of these studies were promising in that they showed that RH levels were lower than once thought, but there is a long way to go before zero-tolerance requirements can be met.