Browsing by Author "Miller, Markus F."
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Item Application of antimicrobial treatments in a commercial simulation to reduce E. coli O157:H7 and Salmonella spp. in beef trim and in ground beef(2006-12) Harris, Deidrea D.; Miller, Markus F.; Brashears, Mindy M.; Brooks, Chance J.Pathogens are of great concern for processors for food safety issues and for economic reasons. While beef trimmings and ground beef are to be cooked by the consumer, the processor must recall the raw product if testing indicates the presence of Escherichia coli O157:H7. Processors have very few interventions for beef trimmings and ground beef. A limited amount of research has been completed to determine antimicrobial effects under commercially simulated conditions on beef trim to reduce pathogens. The objective of this study was to validate the effectiveness of acetic and lactic acids (2% and 5%), acidified sodium chlorite (1000 ppm), and sterile water in reducing pathogen levels in beef trim prior to and after grinding in a simulated processing environment utilizing a belt turning and spray application. The effectiveness of these interventions on Escherichia coli O157:H7 and Salmonella Typhimurium were determined prior to treatment and at the following processing points: 1) just after treatment (20 minutes); 2) just after grind (6 hours); and 3) 24 hours after anaerobic storage at 4°C. Trim was inoculated with Escherichia coli O157:H7 and Salmonella Typhimurium, with an inoculation level of 1x105 cfu/g. Sensory preparation was similar to the experimental design above except none of the trim was inoculated with pathogens. The organoleptic properties were evaluated during short term refrigerated storage at 6 and 24 hours after preparation. Raw patties were packaged on a Styrofoam tray and displayed in a retail display case. Visual panelists were trained to determine beef color, color uniformity, percentage of discoloration and browning evaluations of the raw patties based on appearance and composition. Muscle luminance, redness and yellowness of the raw product were objectively measured using the Minolta Spectrophotometer. Triangle test were used for comparison of the control and treated samples at 6 and 24 hours after production. Panelists (n = 24) were given three coded samples, including two of the same sample and one odd sample. Panelists were asked to determine the odd or different sample. Results from this study indicate that all antimicrobial interventions, including sterile water, reduced pathogen loads (P < 0.05) for both Escherichia coli O157:H7 and Salmonella Typhimurium in ground beef by almost 1 log cycle. The antimicrobial treatments of: sterile water, 5% lactic acid, 2% acetic acid, 5% acetic acid, and acidified sodium chlorite (1000 ppm) significantly reduced Escherichia coli O157:H7 (P < 0.05) in ground beef. The antimicrobial treatments of: acetic and lactic acids (2% and 5%), acidified sodium chlorite (1000 ppm), and sterile water significantly reduced pathogen loads of Salmonella Typhimurium (P < 0.0001) in ground beef 6 and 24 hours after processing. Utilizing a triangle test there was no significant difference P < 0.05 in the mean of correct responses between controls, 2% lactic acid, 5% lactic acid, 2% acetic acid, 5% acetic acid and acidified sodium chlorite (1000 ppm) within treatment, 6 or 24 hours samples from a non-trained sensory panel.Item Baseline of salmonella prevalence in retail beef and produce from Honduras and Mexico(2012-08) Maradiaga, Martha; Brashears, Mindy M.; Miller, Markus F.; Thompson, Leslie D.Salmonella is a common cause of food-borne illness worldwide, especially with must recent outbreaks. The sources of these outbreaks include contaminated animal products, including raw or undercooked meat as well as contaminated produce. The objective of the current study was 1) to develop a baseline for the prevalence and identification of Salmonella in beef and produce in Honduras, and produce in Mexico; and 2) to identify Salmonella serotypes in both Honduras and Mexico. A total of 393 retail whole muscle beef cuts samples and 383 produce samples (cantaloupes, cilantro, cucumbers, leafy greens, peppers, and tomatoes) were collected from major cities in different regions in Honduras in 4 different trips. A total of 514 produce samples were collected from major cities in Mexico in 6 different trips. Produce types and analysis followed the same as in Honduras. All retail beef and produce samples were tested using the BAX® System PCR Assay for Salmonella detection, with positive samples isolated for Salmonella using traditional cultural methods. Positive isolates were agglutinated and prepared for serotyping. Overall, the prevalence of Salmonella-positive samples in Honduras (N = 393) retail beef resulted in 5.9% with a 95% CI [3.9, 8.7]. Whereas positive beef carcass swabs was 7.8% in both beef plants in Honduras (11/141). The most common serotypes identified in Honduras were Salmonella serotype Typhimurium followed by Salmonella serotype Derby. The overall prevalence of Salmonella in Honduras produce (N 383) was 2.4% with a 95% CI [1.2, 4.5]. Overall, the prevalence of Salmonella-positive samples in Mexico (N = 514) produce resulted in 2.1% with a 95% CI [1.2, 3.8]. The most common serotype identified in Mexico was Salmonella serotype Meleagridis. Other serotypes found in Mexico were Typhimurium, Kentucky, and Newport.Item Consumer assessment and objective measures of beef flavor of four beef muscles from USDA choice and select graded carcasses(2013-08) Hunt, Mary R.; Miller, Markus F.; Brooks, Chance J.; Rathmann, Ryan J.A consumer study was conducted in Lubbock, Texas, to measure the effects of quality grade on the palatability traits of flavor, tenderness, juiciness, and overall liking of four beef muscles. The study was arranged as a 2 × 4 factorial representing two quality grade categories [Upper 2/3 (Top) Choice and Select] and four muscles [longissimus lumborum (LL), gluteus medius (GM), serratus ventralis (SV), and semimembranosus (SM)]. Sides (n = 40; 20 per quality grade category) of beef were selected from a commercial processing facility by trained Texas Tech University personnel to obtain subprimals containing the four muscles. Proximate analysis was conducted on each subprimal to determine percentage fat, moisture, protein, and collagen. Plus, fatty acid content (n = 48) and volatile analysis of cooked samples (n = 40) were analyzed for each treatment group. The muscles were then fabricated into 2.5-cm steaks, and further processed into 5 × 5 cm pieces. Consumers (n = 120) rated eight steak samples, one per treatment group, for tenderness, juiciness, flavor liking, and overall liking and rated each trait as either acceptable or unacceptable. According to proximate analysis means, SV had more desirable (P < 0.01) fat percentage (9.7%) than any other muscle and SM had the least (2.5%); while LM (4.9%) and GM (5.1%) were intermediate. Regardless of muscle, Upper 2/3 Choice had more desirable (P < 0.01) fat percentage (7.1%) than Select (4.0%). An interaction between muscle and quality grade was observed (P < 0.05) for juiciness, flavor liking, and overall liking. For juiciness, Upper 2/3 Choice SV had the most desirable (P = 0.02) consumer scores than any other muscle × quality grade combination. SM had the least juiciness scores, regardless of quality grade, which did not differ (P > 0.05). Consumer flavor liking and overall liking score exhibited similar trends indicating Upper 2/3 Choice LL, GM, and SV had more desirable (P < 0.02) scores than the remaining muscle × quality grade combinations. Consumer scores for flavor liking and overall liking for all muscles, except SM, were more desirable for Upper 2/3 Choice compared to Select. Similarly, tenderness scores were more desirable (P < 0.01) for Upper 2/3 Choice compared to Select, regardless of muscle. Consumers rated LL as more tender (P < 0.05) than SV and SM, but similar to GM (P = 0.52). Consumers scored the tenderness of SM less desirable (P < 0.01) compared to all other muscles. A decrease (P < 0.05) in consumer acceptability of each palatability trait was observed as quality grade decreased from Upper 2/3 Choice to Select. The SM showed the least acceptability scores for all the palatability traits. Overall and flavor acceptability were similar (P > 0.05) between LL, GM, and SV regardless of quality grade. Consumer overall liking was correlated (P < 0.01) with consumer tenderness (r = 0.75) and juiciness (r = 0. 68) ratings, but most highly correlated with flavor liking (r = 0.85). Results for fatty acids showed PUFA negatively affected consumer perceived flavor and overall liking in neutral lipid (NL) fractions. Within polar lipid (PL) fractions, linoleic acid (18:2)(r = -0.36) and Dihomo-gamma-linolenic acid (20: 3n6)(r = -0.30)], know for negative flavor properties, were shown to negatively correlated with flavor. Additionally, as fat percentage increased NL and PL concentration increased linearly. There were 42 volatile compounds detected in the headspace of cooked steak samples. The majority detected were classified as aldehydes. Very few volatile compounds correlated with consumer palatability scores. When tenderness was acceptable, flavor and juiciness play a major role in determining overall acceptability. Even when consumers scored tenderness low, as with the SM, superior flavor and juiciness could compensate and improve the overall liking and acceptability of beef. Overall liking of SV and GM from high quality carcasses was superior to LL from lower quality carcasses and comparable to LL from high quality carcasses. Therefore, results from this study showed additional value could be captured by marketing more underutilized cuts from the chuck and sirloin of high quality carcassesItem Consumer motivations and the impact of brand on purchasing preferences of fresh beef(Texas Tech University, 2006-08) Reicks, Angela; Miller, Markus F.; Brooks, Chance J.; Lyford, Conrad; Thompson, Leslie D.; McAdams, MollyA survey was completed by consumers in three geographical regions across the United States to determine the motivational factors affecting consumer purchase decisions for fresh beef steaks (n = 1,370) and fresh beef roasts (n = 1,361). Demographic characteristics and beef preference variables obtained included: city, gender, age, occupation, number of adults and children in the household, income and education as well as response to a statement regarding fresh beef liking, beef consumption and preference for cooking degree of doneness. Consumers were asked to indicate how important the following factors were in determining why they purchased fresh beef steaks and roasts: tenderness, juiciness, flavor, product consistency, ease of preparation, nutritional value, natural, organic and price per pound. A scale was provided with one labeled as not important at all and ten was labeled very important. Consumer ratings for flavor, as a motivator, reported the highest means for both steaks (8.7) and roasts (8.5) on a 10-point scale. This was followed by the importance of tenderness and juiciness. Overall palatability factors were most important followed by price for both steaks and roasts. Ratings for the importance of natural and organic as a factor in product purchasing were lower than all other motivators. When differences were reported by gender and age, consumer ratings by women were higher (P < 0.05) than ratings by men and generally increased as age increased. Also, motivator ratings generally decreased as level of education increased. Consumers were asked the location where they purchase the majority of fresh beef steaks and the greatest response was for supermarket/grocery store with 72.7%. Consumers responded to a question for which is a higher quality product, USDA Select or USDA Choice, 42.7% answered correctly. When consumers were asked if USDA Choice and USDA Select were fresh beef brands, 18.8% responded yes, 55.8% said yes and 25.4% reported that they did not know. Consumers were asked if they purchased fresh beef based on brand and results show 16.9% said yes while 83.1% said no. Consumers obviously realize the presence of branded food products, but branded beef products are more complex in their variability. Also, consumers do not fully understand the information regarding the current grading system and beef product variation. Increased consumer education for beef quality characteristics will allow the industry to develop improved marketing strategies to best fit the needs of the consumer. Beef motivating factors and demographics do influence consumer purchasing decisions for fresh beef steak. Results from this study can be used to help identify factors to positively influence purchasing decisions within targeted market segments.Item Consumer motivations and the impact of brand on purchasing preferences of fresh beef(2006-08) Reicks, Angela; Miller, Markus F.; Lyford, Conrad; McAdams, Molly; Brooks, Chance J.; Thompson, Leslie D.A survey was completed by consumers in three geographical regions across the United States to determine the motivational factors affecting consumer purchase decisions for fresh beef steaks (n = 1,370) and fresh beef roasts (n = 1,361). Demographic characteristics and beef preference variables obtained included: city, gender, age, occupation, number of adults and children in the household, income and education as well as response to a statement regarding fresh beef liking, beef consumption and preference for cooking degree of doneness. Consumers were asked to indicate how important the following factors were in determining why they purchased fresh beef steaks and roasts: tenderness, juiciness, flavor, product consistency, ease of preparation, nutritional value, natural, organic and price per pound. A scale was provided with one labeled as not important at all and ten was labeled very important. Consumer ratings for flavor, as a motivator, reported the highest means for both steaks (8.7) and roasts (8.5) on a 10-point scale. This was followed by the importance of tenderness and juiciness. Overall palatability factors were most important followed by price for both steaks and roasts. Ratings for the importance of natural and organic as a factor in product purchasing were lower than all other motivators. When differences were reported by gender and age, consumer ratings by women were higher (P < 0.05) than ratings by men and generally increased as age increased. Also, motivator ratings generally decreased as level of education increased. Consumers were asked the location where they purchase the majority of fresh beef steaks and the greatest response was for supermarket/grocery store with 72.7%. Consumers responded to a question for which is a higher quality product, USDA Select or USDA Choice, 42.7% answered correctly. When consumers were asked if USDA Choice and USDA Select were fresh beef brands, 18.8% responded yes, 55.8% said yes and 25.4% reported that they did not know. Consumers were asked if they purchased fresh beef based on brand and results show 16.9% said yes while 83.1% said no. Consumers obviously realize the presence of branded food products, but branded beef products are more complex in their variability. Also, consumers do not fully understand the information regarding the current grading system and beef product variation. Increased consumer education for beef quality characteristics will allow the industry to develop improved marketing strategies to best fit the needs of the consumer. Beef motivating factors and demographics do influence consumer purchasing decisions for fresh beef steak. Results from this study can be used to help identify factors to positively influence purchasing decisions within targeted market segments.Item Effects of postmortem calcium chloride injection on meat quality traits of steaks from cattle fed with zilpaterol hydrochloride(2011-08) Rodas, Argenis R.; Miller, Markus F.; Brooks, Chance J.; Jackson, Samuel P.; Ballou, Michael A.; Wester, David B.Two experiments were conducted to determine the effects of zilpaterol hydrochloride supplementation (ZH; 6.8 g/ton on a 90% DM basis for 20 d) and calcium chloride injection (CaCl2 200 mM at 5% wt/wt into 72 h postmortem) on palatability traits (Exp. 1) and shelf-life (Exp. 2) of beef strip loin steaks. Select (USDA) strip loins were obtained from control (non-ZH-fed) and ZH-fed cattle carcasses (Exp. 1= 39; Exp. 2= 20) and right and left sides were selected alternatively to serve as a control (non-injected) or CaCl2-injected and immediately vacuum packaged and stored at 4 °C. Before injecting the subprimals (at 72 h postmortem), two initial steak were cut for proximate, sarcomere length and myofibrillar fragmentation index (MFI) analysis, and stored at -20 °C (for proximate) and -84 °C (for sarcomere length and MFI). For Exp. 1, at 7 d postmortem each strip loin was portioned into steaks, vacuum packaged and aged until 28 d for Warner-Bratzler shear force values (WBSF; 7, 14, 21, and 28 d) and trained sensory analysis (14 and 21 d), purge loss (at 7d) and myofibrillar fragmentation index (MFI; at 3, 7, 28 d). For Exp. 2, treatments were evaluated at 7, 14, and 21 d postmortem using color analysis (trained panelist and Hunter colorimeter), pH, steak purge loss, metmyoglobin reducing activity (MRA) and lipid oxidation (TBARS) on steaks which were PVC-overwrapped and placed in retail cabinets for three days at 3 °C. Results from Exp. 1 indicate both feeding groups and injection treatments diminished their WBSF values as days of postmortem aging were increased; however, WBSF values of ZH-fed steaks were greater (P < 0.05) than non-ZH-fed steaks during all postmortem aging periods. The CaCl2-injected steaks showed lower WBSF values (P < 0.05) than non-injected steaks. Furthermore, trained panelist gave a lower tenderness score to ZH-fed steaks than none-ZH-fed steaks at 14 d and 21 d; contrary, the injection of CaCl2 improved (P < 0.05) tenderness ratings and flavor intensity, compared with their non-injected cohorts at 21 d. Non-ZH-fed steaks and CaCl2-injected presented higher MFI values (P < 0.05) with respect to their controls steaks indicating a higher postmortem proteolysis activity. Sub-primals from ZH-fed and CaCl2-injected showed higher purge loss (P < 0.05). Results from Exp. 2 indicate ZH-fed steaks showed better initial color (lighter; P = 0.04) and color stability during retail display than non-ZH-fed (P = 0.02); though there were no differences in discoloration over aging (P = 0.06). Similarly, injected steaks were lighter on initial color score than non-injected steaks (P = 0.005). Nonetheless, at 14 d of aging, injected steaks started to be more discolored and less color stability (P = 0.0001) than those non-injected steaks. These results were in accordance with the instrumental color results. On MRA values, feeding groups were not different (P = 0.2); but injection treatments groups diminished their MRA percentage at 21 d postmortem aging, but injected steak with CaCl2 showed better reducing ability than non-injected steaks. Regard of initial pH values and steaks purge loss, there was not any difference between feeding groups; while CaCl2-injected steaks became acid; but was not affected steak purge loss between injection treatments (P < 0.05). Respect to TBARS values, non-ZH-fed and CaCl2-injected steaks increased lipid oxidation compared to counterpart steaks (P = 0.05). Overall, the postmortem injection of CaCl2 solution to either ZH-fed or non-ZH subprimals can improve beef steak tenderness; however, it can be detrimental to shelf-life when aging is extended beyond 14 d.Item Incidence of escherichia coli O157 in feces between naturally and conventionally produced beef in Southwest Kansas(2012-05) Alexander, Clint; Miller, Markus F.; Brashears, Mindy M.; Brooks, Chance J.; Thompson, Leslie D.Changes in production methods of agricultural foods have evolved. Food and livestock are marketed in different ways including those from natural and conventional production methodologies. The objectives of this study were to evaluate the prevalence of Escherichia coli O157 between naturally and conventionally produced beef from a commercial feeding facility. Two sets of data for prevalence were obtained from two different southwest Kansas feed yards in two different trials. Positive samples from Feedlot A were evaluated for antimicrobial susceptibility. No differences (P = 0.8696) were found for prevalence of E. coli O157 between naturally- and conventionally-produced beef from samples obtained in both feedlots. A replication difference was detected (P < 0.001) with replications 1, 2 and 3 having lower prevalence of E. coli O157 as compared to replications 4 and 5. A production method by replication interaction was not detected (P = 0.3727). Feedlot A showed no difference (P = 0.5361) for prevalence of E. coli O157 with natural testing 5.11% positive and conventional testing 6.22% positive. No difference (P = 0.5747) for replication days or the production method by replication day interaction (P = 0.1608). Three of the positive isolates, all from naturally-produced cattle, from Feedlot A showed multi-drug resistance. Feedlot B showed positive results although no differences (P = 0.6568) were detected between naturally and conventionally produced beef for E. coli O157. Overall, 37.2% of the 500 samples were positive for E. coli O157:H7 with 42.4% of conventional samples and 32.0% of natural samples testing positive from Feedlot B. Sampling period did not affect (P = 0.8122) prevalence; day 1 had 38.4% positive, and 36.0% of samples tested positive on day 2. Comparing production type on sampling day, conventional positive samples dropped from day 1 to 2 (49.6% to 35.2%); however natural samples testing positive for E. coli increased from day 1 to 2 (27.2% to 36.8%). One pen of conventional samples was 100% positive. However, one pen of each treatment had 0% positive samples, both on day 2. Although no significant differences were detected between naturally and conventionally-produced beef for E. coli O157, the high percentage of positive samples for each production type as well as the multi-drug resistant isolates from naturally produced beef indicated a need for the beef and animal health industries to continue pre and post-harvest intervention methods to control E. coli O157 prevalence in the food supply to prevent food-borne illnesses.Item Interaction of Optaflexx® and terminal implant window on growth performance and carcass characteristics in heifers fed to harvest(2012-08) Jennings, Aaron; Johnson, Bradley J.; Miller, Markus F.; Vogel, Gary J.Objectives were to evaluate the interaction of ractopamine hydrochloride (OPT) and timing of terminal implant administration on growth performance, carcass characteristics, meat quality, serum metabolites and steroid hormones of finishing beef heifers. A 3x2 factorial randomized complete block design was used with 2 levels of OPT and 3 different durations of terminal implant windows for a total of 6 treatment groups with 9 replications. British x Continental heifers (n=216; 341.6 kg) were blocked by BW and randomly allotted to 54 pens (9 pens/treatment; 6 pens/block; 4 heifers/pen). The main effects of treatment were implant [TE-200 w/ Tylan (200 mg TBA + 24 mg E2) administered 140 d from slaughter (TI140); 100 d (TI100); and 60 d (TI60)] and OPT (0 or 200 mg/hd/d). Individual BW was collected at 0, 40, 80, 112, and 140 d and DMI recorded. No implant x OPT interactions were detected, so only main effects are reported. Average daily gain (0.14 kg/d difference), predicted carcass ADG (0.24 kg/d difference), HCW (5.6-kg difference) was increased (P<0.05) by OPT, but DMI was not affected. Heifers fed OPT tended (P≤0.09) to have a larger LMA (0.96 cm2 difference) and reduced marbling score. OPT supplementation decreased (P<0.05) Prime and Choice carcasses 16.5%. No affect of OPT was found on 12th-rib fat and KPH (P>0.10). Progesterone and blood urea nitrogen (BUN) were decreased (P<0.05) by OPT. No differences (P>0.10) in Warner Bratzler Shear Force (WBSF) were detected at d 3, 7, and 21 although at 14 d postmortem WBSF values of the OPT steaks were higher (0.45 kg; P<0.05). During the first 40 d on trial, ADG of the TI140 and TI100 groups was increased (P<0.05) compared to the TI60 (0.34 kg/d; 0.18 kg/d difference, respectively). From d 40-80, the TI100 had a higher ADG (P<0.05) than all other implant treatment 5 groups. TI60 had a higher ADG (P<0.05) than TI100 and TI140 from d 80-112. Predicted carcass ADG mirrored live ADG advantages (P<0.05). No differences (P>0.10) in DMI, final BW, carcass parameters, or WBSF were observed among the three implant strategies. Administering terminal implant decreased (P<0.05) BUN levels. Results from this study demonstrated that OPT, when fed to heifers, increased ADG, calculated carcass ADG, and HCW with minimal impact on carcass quality. Furthermore, this study indicated the duration of the terminal implant window did not affect overall performance, final BW, or carcass quality.Item Lipid and cholesterol composition of the longissimus muscle from Angus, Brahman, and Romosinuano(2006-12) Dinh, Thu T. N.; Blanton, John R.; Brooks, Chance; Thompson, Leslie D.; Miller, Markus F.Lipid and cholesterol composition of red meat has been extensively studied for years, especially on genetic variation. However, Romosinuano cattle were recently adopted into America and its lipid composition remains unclear. An investigation is needed to compare this breed to other well-known breeds of cattle in the U.S. Study in chapter II was to compare the fatty acid (FA) composition of the longissimus muscle (LM) from three divergent breeds of cattle: Angus (AN, n = 5), Brahman (BR, n = 4), and Romosinuano (RM, n = 9) regarding intramuscular (i.m.) fat content. Cattle were blocked by breed and fed the same identical commercial finishing diets in a commercial feedlot prior to harvest. LM samples were collected from each carcass between 10th and 13th ribs, trimmed of external fat, frozen in liquid nitrogen, homogenized, and utilized for fat extraction using the modified Folch procedure. Extracted fat was analyzed using GLC with an HP-88 capillary column. FA composition was determined using both normalized percentage (%) to the total fatty acids in samples and gravimetric calculation (mg/g of fresh muscle tissue), in relation to degree of saturation, which was expressed by saturation index (ratio of saturated fatty acids to unsaturated fatty acids, SI). Crude fat determination showed that LM from AN purebred cattle had the highest amount of i.m. fat (7%, P < 0.001). Intramuscular fat of LM from AN contained higher percentage of total SFA (P = 0.003) whereas that from RM had higher percentage of total PUFA (P = 0.002). The percentage of total MUFA was the same among three breeds (P = 0.9). Unlike the normalized percentage, the gravimetric calculation, which was a measure of actual FA concentration in LM, revealed a significantly higher concentration of SFA (26.39 mg/g) and MUFA (26.70 mg/g) in LM from AN cattle as compared to BR and RM cattle (P < 0.001). Additionally, BR purebreds had the lowest PUFA concentration (1.63 mg/g, P = 0.009) in the LM although this difference in percentage of total fatty acids was not found to be statistically significant as compared to AN and RM (P = 0.088, P = 0.015, respectively). Regardless of breeds, the MUFA proportion was always highest (48.2%, P < 0.001) while PUFA was least contributory to FA composition (1.33 mg/g to 2.69 mg/g and 2.91% to 10.98%, P < 0.001). Beef LM fatty acid composition was also characterized by palmitic and oleic acids being the most abundant fatty acids (P < 0.001). These results suggested a genetic variation in FA synthesis and deposition among breeds that influenced both marbling content and its composition. In chapter II, the fatty acid (FA) composition of the longissimus muscle (LM) from crossbred cattle of Angus, Brahman, and Romosinuano were analyzed, again, in relation to intramuscular (i.m.) fat content to investigate the effects on crossbreeding on lipid composition. Using the same methods, which were used for purebred cattle, results from this study showed that no difference in i.m. fat content was found among crossbred cattle, which resulted in their very similar fatty acid compositions. However, small but significant higher percentage of palmitic acid was found in ANxBR cattle (P < 0.001), which suggested a genetic variation of fatty acid synthesis. As compared to our previous study on purebred cattle, the results from this study indicated significant effect of crossbreeding, by which Angus cattle was most influenced. This study also confirmed the importance of muscle fatness, which is also genetically caused, in determining fatty acid composition. In chapter IV, cholesterol composition became the subject, in which the study was focused on development of a highly accurate and repeatable method for cholesterol quantification in meat samples and its application to evaluate the differences in cholesterol content of longissimus muscles (LM) from Angus (AN, n=5), Brahman (BR, n=4), and Romosinuano (RM, n=9) purebreds. Validation of this method was performed using SRM1546 sample, a meat homogenate from the National Institute of Standard and Technology (NIST), and three different LM test samples. The results indicated that the modified method was highly efficient and accurate with more than 95% cholesterol recovered. The method was also found to be repeatable with an average coefficient of variation of 3.12%. This modification reduced 90% of chemicals used and eliminated time-consuming steps that hindered high throughput application of the traditional method. Application of this method for cholesterol quantification of LM samples revealed differences among the three breeds evaluated. The Angus LM samples with higher fat content (50% higher than Brahman and Romosinuano) which was associated with significantly higher cholesterol concentration (70.25%, P=0.007). Interestingly, the cholesterol concentration was found to relate to fatness of muscle (r=0.90, PItem Non-O157 Shiga Toxin-producing Escherichia Coli(STEC), campylobacter and, salmonella prevalence in ground beef and whole muscle beef cuts at retail in the United States(2011-05) Vipham, Jessie L.; Miller, Markus F.; Brashears, Mindy M.; Loneragan, Guy H.; Brooks, Chance J.Salmonella, Campylobacter, Non-O157 STEC cause considerable human illnesses each year, and the vast majority of cases are food borne. Currently, very little is known about the burden of these pathogens in the U.S. beef supply. The purpose of this study was to establish the prevalence of Campylobacter, Salmonella, and Non-O157 STEC in beef products collected from U.S. retail markets. Sample collection occurred during the months of February through May, 2010. Thirty two American cities comprising 28 states were sampled in this study. Retail raw ground and whole muscle beef (n = 2,915) samples were purchased and examined for the presence of Salmonella. Samples were enriched in tryptic soy broth (TSB) and incubated for 24 h at 37°C. Salmonella positives were confirmed using the AOAC approved BAX® system rtPCR. Of the original samples purchased, 1,211 were randomly selected and tested for Campylobacter. Positive samples were confirmed through direct plating and latex agglutination. Samples were enriched using Bolton Broth incubated for 48 h at 42°C and grown on blood-free Campylobacter plates in required microaerophilic conditions. A sub-sample (n = 325) were enriched in TSB and glycerol (TSB+glyc) and frozen at -80°C to be analyzed at a later date. Samples were screened for putative non-O157 STEC using rtPCR methods. Salmonella was detected in 0.65% of the total samples purchased. The prevalence for whole muscle cuts was 1.02%, and Salmonella was present in 0.54% of ground beef samples. Campylobacter was recovered from 9.3% of samples (n = 112), with a prevalence of 17.24% in whole muscle cuts and 7.35% in ground beef. Putative non-O157 STEC antigens were detected in 5.9% of samples. Whole muscle cuts had a prevalence of 4.11%, and ground beef sample prevalence was 6.99%. The most common serotypes detected in this study were O26 (3.8%), O145 (2.2%), O103 (1.3%), and O111 (0.98%). A chi-square analysis was conducted using the FREQ procedure of SAS. A greater percentage of O26 was observed compared to O111 and O103 (P = 0.01 and P = 0.04, respectively); however, no other comparisons between putative non-O157 STEC were significant (P > 0.05). Whole muscle cuts had a higher prevalence of Campylobacter compared to ground beef (P < 0.01),; however, comparisons between whole muscle cuts and ground beef for the other two pathogens were not significant (P > 0.05). Creating pathogen baselines in U.S. retail beef is imperative for targeting interventions for pathogen control. These data can be utilized for a more complete understanding of these pathogens and their impact on public health from the consumption of beef products.Item Performance evaluation, carcass characterization, and palatability assessment of hair sheep(2005-08) Schilling, Bradley J.; Brooks, Chance J.; Jackson, Samuel P.; Miller, Markus F.; Galyean, Michael L.; Pond, Kevin R.Wether lambs and kids from five crossbred breed groups: 50% Rambouillet x 25% St. Croix x 25% Dorper (RR) (n = 20); 25% Rambouillet x 37.5% St.Croix x 37.5% Dorper (SD) (n = 19); 50% Barbados Blackbelly x 25% St. Croix x 25% Dorper (BB) (n = 20); 7/8 Dorper x 1/8 Barbados Blackbelly (DD) (n = 16); and Boer x Spanish goats (GG) (n = 20), were used to analyze dry matter intake (DMI), average daily gain (ADG), and feed efficiency. The animals were blocked by body weight and assigned to one of three pens per breed group. The hair sheep were fed a concentrate diet (% concentrate and primary grain/roughage) ad libitum until a common weight endpoint was obtained. The Boer x Spanish goats also were fed ad libitum, although on a pelleted diet formulated specifically for goats. The target weight endpoints for the hair sheep and goats were 53 and 36 kg, respectively. Feed was weighed daily to determine intake. Animals were weighed on day 0 and weekly thereafter to determine body weight gain and feed efficiency. The SD and RR breed groups possessed the greatest ADG (P < 0.05) out of the five breed groups, gaining approximately 0.35 kg/day. The GG and the BB group statistically gained the least weight per day (P < 0.05). There were no significant differences among the SD, RR, and DD when analyzing feed efficiency, all performing the highest in this comparison. The BB group had the poorest feed efficiency (P<0.05), requiring 6.8 kg feed for 1kg of live weight gain, and thereby performing lower than the goat group. With these findings, it is evident that breed profile somewhat played a role in performance characteristics, as the two breed groups with Rambouillet influence seemed to outperform the other groups. This, in part, could be due to the additional mature frame size that is associated with the Rambouillet genetics, thereby increasing the live weight gain of the animals.Item Performance evaluation, carcass characterization, and palatability assessment of hair sheep(Texas Tech University, 2005-08) Schilling, Bradley J.; Brooks, Chance J.; Jackson, Samuel P.; Miller, Markus F.; Galyean, Michael L.; Pond, Kevin R.Wether lambs and kids from five crossbred breed groups: 50% Rambouillet x 25% St. Croix x 25% Dorper (RR) (n = 20); 25% Rambouillet x 37.5% St.Croix x 37.5% Dorper (SD) (n = 19); 50% Barbados Blackbelly x 25% St. Croix x 25% Dorper (BB) (n = 20); 7/8 Dorper x 1/8 Barbados Blackbelly (DD) (n = 16); and Boer x Spanish goats (GG) (n = 20), were used to analyze dry matter intake (DMI), average daily gain (ADG), and feed efficiency. The animals were blocked by body weight and assigned to one of three pens per breed group. The hair sheep were fed a concentrate diet (% concentrate and primary grain/roughage) ad libitum until a common weight endpoint was obtained. The Boer x Spanish goats also were fed ad libitum, although on a pelleted diet formulated specifically for goats. The target weight endpoints for the hair sheep and goats were 53 and 36 kg, respectively. Feed was weighed daily to determine intake. Animals were weighed on day 0 and weekly thereafter to determine body weight gain and feed efficiency. The SD and RR breed groups possessed the greatest ADG (P < 0.05) out of the five breed groups, gaining approximately 0.35 kg/day. The GG and the BB group statistically gained the least weight per day (P < 0.05). There were no significant differences among the SD, RR, and DD when analyzing feed efficiency, all performing the highest in this comparison. The BB group had the poorest feed efficiency (P<0.05), requiring 6.8 kg feed for 1kg of live weight gain, and thereby performing lower than the goat group. With these findings, it is evident that breed profile somewhat played a role in performance characteristics, as the two breed groups with Rambouillet influence seemed to outperform the other groups. This, in part, could be due to the additional mature frame size that is associated with the Rambouillet genetics, thereby increasing the live weight gain of the animals.Item Reduction of Escherichia coli O157:H7 and salmonella following application of various sanitizing treatments to harvesting knives(2012-08) Tapp, William N.; Miller, Markus F.; Brashears, Mindy M.; Brooks, ChanceEscherichia coli O157:H7 (E. coli O157:H7) and Salmonella are enteric pathogens that can cause severe illness and possible death if consumed. These pathogens are potential contaminants to meat during animal harvest. If not properly sanitized, knives used during this process can become a vehicle to spread contamination of these pathogens from carcass to carcass during the harvest process. The purpose of this study was to assess the effectiveness of non-thermal sanitation along with changes to treatment application interval, while evaluating E. coli O157:H7 and Salmonella reduction on knives. Chemical dip treatments included, 1.1% sodium metasilicate (SMS), 200 ppm quaternary ammonium compounds (QAC), 200 ppm chlorine (Cl2), 5% lactic acid (LA), 82.2°C water (HW), and 21°C water (RTW). Three replications of 18 knives were processed after inoculation of both E. coli O157:H7 and Salmonella (separately) to show initial and treated pathogen survival on a CFU/cm2 basis. Knife blades were inoculated with a three strain cocktail of either E. coli O157:H7 or Salmonella. A single side of the knife blade was sampled with a sponge, which was pre-hydrated with 10 ml of a neutralizer specific to the sanitizing treatment; in the case of water treatments sponges pre-hydrated with buffered peptone water (BPW) were used for sampling. Thirty second immersion treatments in sanitizing solutions were applied. The other side of the knife blade was sampled just as pre-treated sides to evaluate reduction. Dilutions of E. coli O157:H7 samples were plated onto MacConkey agar, and Salmonella sample dilutions were plated onto Xylose Lysine Desoxycholate media. Arithmetic means of pathogen numbers on untreated knives inoculated with E. coli O157:H7 and Salmonella showed an attachment of 4.51 and 5.09 log CFU/cm2, respectively. Treatment * time interaction of least square (LS) mean log reductions of knives inoculated with E. coli O157:H7 were 1.16, 3.51, 3.38, 1.38, 3.82, and -0.41 CFU/cm2, following treatment in SMS, QAC, Cl2, LA, HW, and RTW, respectively (P ≤ 0.05). Furthermore, treatment * time interactions of knives inoculated with Salmonella resulted in LS mean log reductions of 0.78, 3.42, 3.40, 2.91, 4.12, and 0.36 CFU/cm2, following treatment in SMS, QAC, Cl2, LA, HW, and RTW, respectively (P ≤ 0.05). Results depict that utilization of sanitizing agents in ambient temperature water treatments have potential to provide significant reduction of E. coli O157:H7 and Salmonella on knives used during animal harvest.Item SALMONELLA AND E. COLI O157:H7 PREVALENCE IN CATTLE AND ON CARCASSES IN A VERTICALLY INTEGRATED FEEDLOT AND HARVEST PLANT IN MEXICO(2011-08) Bravo, Claudia A.; Brashears, Mindy M.; Miller, Markus F.; Thompson, Leslie D.; Warner, Ronald D.; Loneragan, Guy H.Microbial contamination can create serious health risks and trade problems in the international food trade, this is essential for the economy of many countries. In Mexico scientific information regarding Salmonella and E. coli O157:H7 prevalence at pre and post-harvest in Mexico is scarce. Therefore, this research has three general objectives: i) to determine the prevalence of Salmonella and E. coli O157:H7 in a Mexican cattle feedlots and its impact for subsequent contamination on carcasses, ii) to determine if there is a seasonal effect on the prevalence of E. coli O157:H7 at feed lot levels and iii) to compare the prevalence of Salmonella and E. coli O157:H7 on carcasses destined for different markets and processed under TIF certification in Mexico. Two-hundred-fifty animals were randomly selected and composite samples were taken from three anatomical carcass sites (inside round, hind shank and fore shank). Samples were taken from the hides, intestinal feces (IF), at pre-evisceration (PE), pre-cooler (PC) and after 24 hours of dry chilling (DC) in the coolers. Additionally, 250 samples from fecal (FL) and water samples were taken from the lairage area. E. coli O157:H7 and Salmonella detection was carried out using BAX (PCR), IMS and conventional methods. Logistic regression models were used to determine areas of highest risk. A total of 1,695 samples were collected from different locations of the integration, feedlot and harvesting slaughter plant. Salmonella was isolated from 52.5% of these samples. The highest prevalence was found in hides (92.4%), followed by feces from the holding pens (HP) (91.0%), feces from feedlots (FL) (55.56%), pre-evisceration (PE) (49.0%), intestinal feces (IF) (46.8%) and pre-cooler (PC) (24.8%) for all sampling periods combined. The lowest prevalence was found in the carcasses after 24 hours of DC in the cooler (6.0%). The overall prevalence of E. coli O157 was as follows: hides 11.7%, intestinal feces 5.2%, feedlots 2.7%, holding pens 2.0%, pre-evisceration 0.8%, pre-cooler 0.4% and cooler 0.4%. E. coli O157:H7 was recovered mainly in the summer, 6.8% (43/632), followed by winter 1.79% (12/670), however in spring all the samples at the feedlot and at the slaughter plant tested negative. Salmonella was recovered in all seasons with significant variations (P < 0.0001), the percentages being as follows: spring 59.7% (200/235), summer 53.64% (339/632) and winter 44.2% (297/672). An effect due to seasonality on Salmonella and E. coli O157:H7 was not clear. The prevalence of the carcasses destined for different markets did not show differences (P>0.05) for Salmonella and/or E. coli O157:H7 prevalence (P > 0.05). These results are an alert as to the risks of contamination in meats for these pathogens, show the necessity of implementing programs for food safety and microbiological interventions, and demonstrate the need for further research.Item Tenderness beef strip loin subprimals and USDA quality grades as evaluated by slice shear force and Warner-Bratzler force values and the relationship between slice shear and Warner-Bratzler(2008-12) Derington, Andrew J.; Miller, Markus F.; Brooks, Chance J.; Thompson, Leslie D.Beef tenderness is one of the primary beef quality attributes affecting consumer satisfaction and effects consumer purchasing decisions. Two methods of tenderness analysis are currently being used in both research and the meat industry. The Warner-Bratzler shear (WBS) method of tenderness analysis is the traditional method that utilizes an average of six 1.27 - cm samples from a single steak to generate a tenderness value. The WBS method is accurate but does not provide rapid results that could be utilized in a production setting to allow for tenderness based sorting of carcasses. A more recent method of analysis is the slice shear force (SSF) method which uses a single measurement from each steak and produces rapid results. The purpose of this study was to investigate the effect of steak location within a strip loin subprimal (IMPS 180) on SSF and WBS values and muscle fiber angles, the effectiveness of USDA quality grades on predicting beef tenderness as well as evaluate the relationship between SSF and WBS values. The study was conducted in two phases, phase one focused on the effect of steak location, the efficacy of USDA quality grades as a predictor of meat tenderness, and muscle fiber angle on SSF and WBS values. Fifteen USDA Top Choice, 15 Choice, 15 Select, and 15 no roll strip loin subprimals were fabricated into 12, 2.54 cm steaks and measured using SSF and WBS methods. Slice shear force measurements were obtained from the lateral and medial portion of each steak. Warner-Bratzler shear force measurements were obtained at the lateral, middle and medial sections. Phase two consisted of the evaluation of 1,538 2.54 - cm USDA Choice and Select strip loin steaks to determine the correlation between SSF and WBS measurements. Slice shear force measurements were obtained from the lateral and medial sections of each steak and WBS values were obtained from the lateral, middle and medial portions of each steak. Steak location within a strip loin subprimal had a significant effect on both SSF and WBS values (P < 0.001) with a linear increase in tenderness values as steak location moved closer toward the posterior end of the strip loin. The SSF method produced similar results in location 1 through 8, and WBS values were similar from steak locations 1 through 5 (P > 0.05). Furthermore, this study shows that USDA quality grade has a significant effect on beef tenderness (P < 0.002) when evaluated using SSF and WBS protocols. This study found that no differences in tenderness exists between USDA Select and no roll quality grades. The muscle fiber angle changes in steaks throughout a strip loin. A significant difference in the lateral muscle fiber angle occurred at steak location 7 indicating that SSF may not produce accurate results at this location. Finally, significant correlations between SSF and WBS values were obtained in this study. Slice shear force from the lateral portion correlated to the averaged WBS values produced a correlation coefficient (r) of 0.636 and a correlation of an averaged SSF value comprised of values obtained from the lateral and medial sections to an averaged WBS value produced a correlation coefficient (r) of 0.704.Item The effects of zilpaterol hydrochloride and chromium propionate on bovine muscle satellite cells and preadipocytes(2011-05) Tokach, Rebecca J.; Johnson, Bradley J.; Miller, Markus F.; Starkey, Jessica D.Numerous feed additives have been used in the beef industry for enhancing muscle growth, improving immune efficiency, and increasing carcass quality. Zilpaterol hydrochloride (ZH), a beta-2 adrenergic agonist, has been used for enhancing muscle growth in feedlot cattle. Chromium propionate has shown to increase immune efficiency in all livestock species, increase pork quality, and increase milk yield in dairy cattle. The objectives of these in vitro experiments were to determine the effects of each compound on enzymes and/or growth factors in bovine muscle satellite cells (BSC) and/or intramuscular and subcutaneous preadipocytes. In the ZH experiments, insulin-like growth factor I (IGF-I) mRNA abundance increased in cells treated with ZH for 48 h and 120 h. A β2-adrenergic receptor antagonist (ICI) was used to block the effects of ZH. The addition of ICI attenuated the effect of ZH on IGF-I mRNA abundance. Myosin heavy chain (MHC) isoform I and MHC IIX mRNA expression was increased in cells treated with ZH for 120 h. This effect was ameliorated when ICI was added to the media. When cells were treated with ZH for 48 h there was no effect of ZH on MHC I or MHC IIX mRNA abundance. Indicating that MHC isoform abundance may be affected by duration of treatment. In the chromium propionate experiments, glucose transporter type 4 (GLUT4) mRNA abundance tended to increase after 144 h of treatment of 1 µM or 10 µM chromium propionate in intramuscular preadipocytes and increased in subcutaneous preadipocytes. Relative mRNA abundance for PPARγ increased when differentiation media was added for intramuscular and subcutaneous preadipocytes. In BSC, GLUT4/GAPDH protein abundance decreased in a dose-dependent matter when chromium propionate was added to the cultures. Results indicated that ZH and chromium propionate affect enzymes and growth factors important to muscle and adipose tissue growth.Item The Heritability of Factors that Influence Tenderness in Beef Cattle(2010-12) Johnson, Paige A.; Miller, Markus F.; Moser, Dan; Thompson, Leslie D.; Johnson, Bradley J.; Jackson, Samuel P.The heritability, phenotypic correlations and genetic correlations of 63 factors were determined in this study. The traits studied (with their heritabilities and standard errors in parenthesis) included: days on feed (1.00 ± 0.116), longissimus muscle area (0.85 ± 0.183), marbling (0.83 ± 0.170), adjusted preliminary yield grade (0.61 ± 0.156), quality grade (0.59 ± 0.148), yield grade (0.56 ± 0.150), preliminary yield grade (0.48 ± 0.143), muscle score (0.44 ± 0.140), 21-day Warner-Bratzler Shear force (0.42 ± 0.148), 3-day initial juiciness (0.42 ± 0.148), hump height (0.40 ± 0.141), 7-day Warner-Bratzler Shear force (0.37 ± 0.147), 7-day initial tenderness (0.37 ± 0.140), 48-hour temperature (0.35 ± 0.121), lean color (0.34 ± 0.122), 14-day sustained tenderness (0.33 ± 0.135), 3-day initial tenderness (0.32 ± 0.131), 3-day sustained tenderness (0. 31 ± 0.129), 7-day sustained tenderness (0.31 ± 0.129), a* (0.29 ± 0.115), 3-hour temperature (0.29 ± 0.114), 14-day initial tenderness (0.28 ± 0.126), 14-day Warner-Bratzler Shear force (0.28 ± 0.121), b* (0.28 ± 0.120), final weight (0.26 ± 0.113), m-calpain (0.24 ± 0.195), 3-day overall mouthfeel (0.24 ± 0.119), 3-day Warner-Bratzler Shear force (0.23 ± 0.114), kidney, pelvic and heart fat (0.23 ± 0.107), temperament (0.23 ± 0.094), 3-day flavor intensity (0.22 ± 0.114), average daily gain (0.22 ± 0.105), 21-day initial tenderness (0.19 ± 0.110), frame score (0.19 ± .097), 21-day beef flavor (0.18 ± 0.110), 14-day overall mouthfeel (0.18 ± 0.107),14-day sustained juiciness (0.18 ± 0.105), μ-calpain (0.17 ± 0.197), 14-day initial juiciness (0.17 ± 0.104), lean firmness (0.17 ± 0.094), 21-day sustained tenderness (0.16 ± 0.108), 48-hour pH (0.16 ± 0.097), hot carcass weight (0.15 ± 0.091), 7-day overall mouthfeel (0.14 ± 0.097), 14-day beef flavor (0.12 ± 0.097), calpastatin (0.11 ± 0.095), 14-day flavor intensity (0.11 ± 0.094), 21-day flavor intensity (0.10 ± 0.087), lean texture (0.10 ± 0.086), initial weight (0.10 ± 0.078), L* (0.09 ± 0.087), 7-day flavor intensity (0.06 ± 0.081), 3-hour pH (0.06 ± 0.073), 3-day sustained juiciness (0.05 ± 0.081), heat ring (0.05 ± 0.061), 21-day overall mouthfeel (0.02 ± 0.076), 3-day beef flavor (0.01 ± 0.072), 7-day sustained juiciness (0.01 ± 0.062), 21-day sustained juiciness (0.00 ± 0.089), 7-day beef flavor (0.00 ± 0.080), sarcomere length (0.00 ± 0.075), 21-day initial juiciness (0.00 ± 0.072) and 7-day initial juiciness (0.00 ± 0.062). Phenotypic correlations and their respective p-values were determined and reported for all 3,969 relationships. Genetic correlations (n = 276) were determined for traits that were heritable including correlations for tenderness traits such as m-calpain activity, calpastatin activity, 48-hour pH, 48-hour carcass temperature, and marbling. Other genetic correlations studied included extensive sensory taste panel traits including 3-, 7- ,14- and 21-day initial tenderness, sustained tenderness, initial juiciness, sustained juiciness, flavor intensity, beef flavor and overall mouthfeel. The genetic correlations of color traits were also determined including Hunter colorimeter readings for a* and b*, as well as, subjective lean color scores. Other carcass traits studied using genetic correlations included lean texture, lean firmness, yield grade, hot carcass weight, and longissimus muscle area. Genetic correlations for 21-day Warner-Bratzler shear force, temperament, breed type and hump height were also determined.Item The survivability, growth and heat susceptibility of E. coli O157:H7 in enhanced beef brine solutions containing potassium lactate and lactic acid producing bacteria(2009-05) Rosenberg, Ashley; Brooks, Chance J.; Brashears, Mindy M.; Loneragan, Guy H.; Miller, Markus F.Meat enhancement is used to increase consumer satisfaction through improved palatability and uniformity. Brine solutions that are re-covered or reused during the processing of enhanced meat cuts have a high risk of cross contamination. The objectives of the present study were to determine the effect of potassium lactate and lactic acid bacteria on the survivability and heat susceptibility of E. coli O157:H7 in brine solutions used to enhance beef products and to determine the effect of these interventions on consumer sensory scores and shelf life characteristics. To characterize safety, beef strip loins were enhanced with brine solutions (0.3% sodium chloride and 0.35% phosphate at 10% pump level) inoculated with high or low levels of E. coli O157:H7 and one of the following interventions: 0, 1.5, 2.5% potassium lactate or lactic acid bacteria (LAB 107 CFU/ml). Treated subprimals were fabricated into steaks and randomly allotted to one of the following internal endpoint temperatures: 0 (not cooked), 50, 55, 60, 65, 70 and 75°C. Once endpoint temperature was reached, the interior of each steak was sampled and E. coli O157:H7 was enumerated (high level) or detected (low level). To characterize palatability and shelf life, beef strip loin subprimals were enhanced with brine solutions containing previously mentioned interventions plus a non-enhanced control. Consumer panelists evaluated palatability at 14 d postmortem and lean color on days 1, 3, and 7 of display (after a 14 d postmortem dark storage period). Display steaks were packaged in high-oxygen (80% O2 / 20%CO2) or low-oxygen (0.4%CO/30%CO2/69.6%N2) modified atmosphere packages. Data analysis showed no significant interactions between intervention treatment and steak temperature endpoints, indicating E. coli O157:H7 from treated brine solutions were not more susceptible to heat during cooking. Results also indicate the transference of pathogens into meat products was low for all interventions, regardless of inoculation level. Internal steak temperature (especially 70 and 75 °C) remains the most effective way to reduce pathogen levels in steaks enhanced with inoculated brine solutions. Steaks packaged in high-oxygen MAP and enhanced with a brine solution containing 1.5 or 2.5% potassium lactate maintained more desirable lean color scores throughout display and were more likely to be purchased by consumers than steaks enhanced with other treatments. Finally, the presence of potassium lactate (1.5 and 2.5%) and lactic acid producing bacteria had no detrimental impact on consumer palatability, while enhanced steaks were more desirable than non-enhanced controls.Item The use of lactic acid bacteria as a post-harvest intervention to control escherichia coli O157:H7 in fresh spinach(2008-12) Gragg, Sara E.; Brashears, Mindy M.; Brooks, Chance J.; Miller, Markus F.; Thompson, Leslie D.In recent years, fresh spinach has been identified as a vehicle for Escherichia coli (E. coli) O157:H7 transmission. Multiple studies have demonstrated the ability of lactic acid producing bacteria (LAB) to reduce the presence of Escherichia coli O157:H7 in food products and the efficacy of LAB cultures as a post – harvest intervention in fresh spinach production should be evaluated. To determine the effect of spinach inoculated with Escherichia coli O157:H7, spinach samples were rinsed with sterile distilled water and a four – strain LAB cocktail at a target concentration of 2.0x108 CFU/mL. Both treatments were compared to an inoculated control over a 24 – hour time period at 7oC. According to composite LS means data obtained for each treatment, water and LAB resulted in significant reductions of 0.88 logs (p<0.0001) and 1.03 logs (p<0.0001) in comparison to the control, respectively. The improved reduction of LAB was significantly better than that of water (p=0.0363), making it the most effective treatment. A triangle test was conducted to determine if a statistically significant difference in sensory characteristics exists when LAB is applied to fresh spinach. Two samples were rinsed with tap water and considered to be identical. The remaining sample was rinsed with LAB at a concentration of 2.0x108 CFU/mL. 40 panelists participated in the test and 16 correctly identified the LAB – treated spinach as being the one unique sample. These results indicate that a statistically significant difference does not exist (á=0.05, 0.01) when LAB is applied to fresh spinach and that the use of LAB may be acceptable from a consumer acceptance standpoint. The ability of LAB to control E. coli O157:H7 populations in combination with the industry standard chlorine rinse was determined in a 12 day shelf – life study at 7oC. The multi – hurdle intervention was evaluated in comparison to water, LAB and chlorine rinses. LAB cultures were applied at a concentration of 2.0x108 CFU/mL, while chlorine was utilized at the 200 ppm level. As indicated by composite LS means data, significant reductions in comparison to control populations were achieved by the LAB (p=0.0215), chlorine (p=0.0002) and multi – hurdle treatments (p<0.0001). However, the multi – hurdle treatment produced the greatest reductions with 1.35 logs. This reduction was significantly improved upon LAB (p=0.0012) and chlorine (p=0.0815), indicating that the application of chlorine and LAB is most effective as a combination treatment.Item The use of mechanically separated beef and other functional additives and extenders in restructured beef products(Texas Tech University, 1984-05) Miller, Markus F.Not available