Evaluating the Safety of Sous-Vide Cooking for Beef Products Inoculated with Single Strains of Salmonella enterica and Escherichia coli O157

Sous-videcooking is a growing trend among retailers and consumers. Foodborne pathogens may survive the cooking if nonvalidated parameters are used or if pathogens have enhanced thermalresistance. Pathogen inactivation from sous-vide cooking was determined when introduced directly to beef products or via contaminated spices, and with or without a finishing step. Beef products (ground beef, tenderized, and nontenderized steaks) were inoculated with pathogens (Salmonella Montevideo and Escherichia coli O157:NM) in three ways: 1) directly onto the meat 2) ground black pepper incorporated into the recipe 3) ground pepper equilibrated at 30% RH (4 d) prior to incorporation. Beef samples were vacuum-packaged and submerged in a 62.5°C water bath for 120 min. Samples were sampled at 5, 10, 20, and 120 min (recommended from a partner quality study), and a duplicate was grilled to a specific internal temperature (74°C for ground beef, 57°C for steaks) and sampled. Sous-vide cooking reduced pathogen populations by >5 log CFU/g after most treatment times, but less than grilled counterparts (ca. 1-2 log CFU/g difference; p < 0.05).There were no statistically significant differences between inoculation methods, but the tenderization of steaks resulted in significantly lower reductions of pathogens from sous-vide cooking (p < 0.05). Thisresearch challenged sous-vide cooking parameters (120 min, 62.5°C). It showed sous-vide alone lowered pathogens by >4 log CFU/g after most 20-min treatments, but 120-min sous-vide treatments or grilling would be needed for >5-log reductions.Contaminated pepper led to less consistent reductions during the cooking process, yet 2-h sous-vide still achieved a 5-log reduction. Sous-vide cooking instructions must be validated as more products and recipes are marketed.

Evaluation of growth, meat quality, and sensory characteristics of wool, hair, and composite lambs

The objectives of this study were to evaluate the growth rates, carcass quality, shelf-life, tenderness, sensory characteristics, volatile compounds, and fatty acid composition of wool, hair, and composite (wool × hair) lambs. Twenty-one wether lambs [wool (Suffolk × Polypay/Targhee; n = 7), hair (Dorper × Dorper; n = 7), and composite (Dorper × Polypay/Targhee; n = 7)] were fed from weaning to finishing at the University of Idaho Sheep Center and subsequently harvested under United States Department of Agriculture inspection at the University of Idaho Meat Lab. At 48 h postmortem, carcass measurements were taken to determine the percent boneless closely trimmed retail cuts, yield grade, and quality grade. Loins were fabricated from each carcass and wet-aged at 0°C until 10-d postmortem. Following aging, 2.54-cm bone-in loin chops were cut and randomly assigned to 4 d of retail display, Warner-Bratzler Shear Force (WBSF), or sensory analyses. Thiobarbituric acid reactive substances were analyzed on days 0 and 4 of retail display while subjective and objective color measurements were observed once daily. Samples (24 g) were also collected for volatile compound and fatty acid analysis. A mixed model analysis of variance was used to assess breed differences. Discernable effects were considered at P < 0.05. Wool lambs had heavier hot carcass weights (P < 0.001), larger rib-eye area (P = 0.015), and higher dressing percent (P < 0.001) than the other breeds. There was an interaction observed between breed and days of retail display for browning (P = 0.006). On day 1 chops from the composite breed had more browning than chops from the wool breed. No differences were observed between groups for lean muscle L* values (P = 0.432), a* values (P = 0.757), and b* values (P = 0.615). Differences were not observed in lipid oxidation (P = 0.159), WBSF (P = 0.540), or consumer acceptability (P = 0.295). There were differences found for 7 of the 45 fatty acids detected and in 3 of the 67 volatile compounds detected. In conclusion, wool lambs were heavier and had a greater carcass yield than the hair lamb carcasses. Regardless of breed, consumers did not detect sensory traits that would impact their eating experience.

Evaluation of Dry-Heat Cookery Method on Volatile Flavor Compound Development and Consumer Evaluation of Six Beef Muscles

The objective of this study was to determine the influence of dry-heat cookery on beef flavor development of multiple beef muscles. Beef strip loins, top sirloin butts, paired tenderloins, paired shoulder clods, and chuck rolls were collected from USDA Low Choice carcasses (Small00–Small100 marbling; N = 20). Subprimals were wet aged in the absence of light for 21 d at 0°C to 4°C. Subprimals were fabricated into 2.54-cm-thick steaks representative of the following muscles: Gluteus medius, Infraspinatus, Longissimus lumborum, Psoas major, Serratus ventralis, and Triceps brachii and randomly assigned to one of 4 dry-heat cookery methods: charbroiler grill (CHAR), clamshell grill (CLAM), convection oven (OVEN), and salamander broiler (SALA). Steaks were cooked to a medium degree of doneness (71°C) on the randomly assigned cooking method. Untrained consumer panelists (N = 300) evaluated each sample for flavor, tenderness, juiciness, and overall liking. No interactions were observed between cooking method and muscle (P ≥ 0.344) for any palatability traits evaluated. Consumers preferred CHAR steaks (P &lt; 0.05) over CLAM steaks for flavor, tenderness, juiciness, and overall liking. Additionally, CLAM steaks were rated lower (P &lt; 0.05) than all other methods for tenderness and juiciness. OVEN and SALA steaks were rated higher (P &lt; 0.05) than CLAM steaks by consumers for tenderness and juiciness but were similar (P &gt; 0.05) to CLAM steaks for overall liking. CHAR steaks produced a greater concentration of Maillard compounds compared with the other cooking methods. Steaks cooked using OVEN and SALA (P &lt; 0.05) produced more lipid oxidation products. Additionally, CHAR steaks produced the greatest (P &lt; 0.05) total volatile production compared with all other treatments, which may be a result of the combination of Maillard reaction products and the lipid degradation products.

25 Cooking method and muscle type impact volatile compound development in beef steaks

The objective of this study was to determine the influence of dry heat cookery on beef flavor development of multiple beef muscles. Beef strip loins, top sirloin butts, tenderloins, shoulder clods, and chuck rolls were collected from USDA Low Choice carcasses (Small00-Small100 marbling; n = 20). Subprimals were wet aged in the dark for 21 d at 0 - 4℃. Following aging, subprimals were fabricated into 2.54 cm thick steaks of the following muscles: Gluteus medius (GM), Infraspinatus (IF), Longissimus lumborum (LL\), Psoas major (PM), Serratus ventralis (SV), and Triceps brachii (TB). Steaks were cooked to a medium degree of doneness (71℃) on one of four randomly assigned cooking methods: charbroiler grill (CHAR), clamshell grill (CLAM), convection oven (OVEN), or salamander broiler (SALA). Volatile compound analysis was conducted using gas chromatography-mass spectrometry with solid phase microextraction. Data were analyzed as a split plot arrangement, with subprimal serving as the whole plot factor and cooking method serving as the subplot factor. The majority of compounds evaluated were impacted by the cooking method main effect (n = 21), followed by the cooking method × muscle interaction (n = 18), and muscle (n = 12). Charbroiler GM steaks produced the greatest amount of methional, 2,5-dimethylpyrazine, 3-ethyl-2,5-dimethylpyrazine, and 2-ethyl-3,5-dimethylpyrazine compared to all other treatments (P &lt; 0.05). Charbroiler and CLAM steaks produced the greatest concentration of methylpyrazine and trimethylpyrazine, as well as Strecker aldehydes (P &lt; 0.05), indicating that more direct applications of heat increased Maillard product production. Steaks cooked using OVEN and SALA produced more lipid oxidation products, such as alkanes, aldehydes, and lipid derived ketones. Gluteus medius and SV steaks produced the greatest concentration of volatile compounds, with SV steaks producing an increased concentration of lipid derived compounds (P &lt; 0.05) and GM steaks producing a greater concentration of Maillard products (P &lt; 0.05). These data indicate that cooking method has a direct impact on the flavor profile produced by steaks.

Thermophysical Properties of Beef Steaks of Varying Thicknesses Cooked With Low and High Grill Surface Temperatures

The objective of this study was to determine the thermodynamic and physical properties of beef strip loin steaks of varying thicknesses and USDA quality grades cooked with high and low grill surface temperatures. Thermal characteristics described by changes in the denaturation temperature (between 55°C – 60°C) and enthalpies of protein denaturation (70°C – 75°C) both differed (P = 0.031 and P = 0.001, respectively) among thick steaks, with thick steaks cooked on a high grill surface temperature having a lower denaturation temperature and enthalpy compared with thick steaks cooked on a low grill surface temperature. No differences (P &gt; 0.05) were observed among thin steaks for denaturation temperature or enthalpy. The elastic behaviors of the surface and center of the steaks were analyzed to determine how the microstructure of the beef responded to applied stress. The elastic behavior of steak centers was influenced in a three-way interaction (P = 0.029) between quality grade, steak thickness, and grill surface temperature. The elastic behavior of the surface of steaks was influenced by the interaction of quality grade and steak thickness (P = 0.031). These interactions, along with the differences in the thermal characteristic of proteins, suggest that the microstructure of steaks was affected by each cooking treatment group. Hardness, resilience, and chewiness were each influenced by a three-way interaction (P = 0.023; 0.014; and 0.030; respectively). Thin steaks possessed greater cohesiveness (P = 0.038) and shear force ( P = 0.007) values. Meanwhile, thin steaks exhibited lower springiness (P = 0.002). The measured alterations in thermal and physical proper- ties in the beef steaks suggest that the composition, thickness, and cooking regiments impact the microstructure of beef, and this was ultimately confirmed through textural measurements. The results of this research can be used in the design of cooking processes that match beef characteristics.

272 High oxygen packaging is detrimental to beef flavor and tenderness

This study determined the influence of packaging and muscle on beef flavor and tenderness. Strip loins and top sirloin butts (n = 20/subprimal) from USDA Low Choice carcasses were fabricated into 2.54 cm steaks (Longissimus lumborum and Gluteus medius) at 7 d postmortem. Steaks were randomly assigned to packaging treatments: carbon monoxide motherbag (CO), high oxygen modified atmosphere packaging (HIOX), polyvinyl overwrap (OW) and rollstock (ROLL) and aged for 14 d in dark storage. Steaks in OW were vacuum packaged during aging, then overwrapped for display. Steaks were placed in coffin-style retail display for 48-h under fluorescent lighting. For trained panels and Warner-Bratzler shear force (WBSF), steaks were cooked to 71℃ using clamshell grills. Seven trained panelists rated steaks for beef flavor identity, brown/roasted, bloody/serumy, fat-like, liver-like, oxidized, fishy, buttery, umami, bitter, sour, overall juiciness, and overall tenderness. Data was analyzed as a 2 × 4 factorial design, with packaging, muscle, and their interaction as fixed effects, peak temperature as a covariate, and collection, round, and panel as random effects. No interactions (P ≥ 0.103) or muscle main effects (P ≥ 0.063) were observed. Packaging impacted all traits (P ≤ 0.048), except for fat-like (P = 0.387), liver-like (P = 0.950), and salty (P = 0.357). Steaks from HIOX packaging were rated the lowest for positive flavor attributes and rated highest for negative flavor attributes. Conversely, OW and ROLL steaks produced the greatest positive flavor attributes in comparison with HIOX. Overwrap and ROLL steaks were juicier and more tender than HIOX steaks (P &lt; 0.05). High oxygen steaks exhibited the highest WBSF value compared to all other treatments (P &lt; 0.05). These results indicate HIOX packaging has detrimental effects on flavor and tenderness. Steaks should be stored and aged in anerobic packaging to maintain optimum levels of tenderness and flavor.

The Impact of Enhancement, Degree of Doneness, and USDA Quality Grade on Beef Flavor Development

The objective of this study was to determine the impact of enhancement, degree of doneness (DOD), and USDA quality grade on beef volatile flavor compounds from cooked strip loin steaks. This study also aimed to evaluate relationships between volatile compounds and consumer sensory responses. Beef strip loins (n = 72; 24/grade) of 3 quality grades (USDA Prime, Low Choice, and Low Select) were enhanced (8% of green weight with brine containing 0.35% salt and 0.4% sodium phosphate) or not enhanced, and cooked to 3 DOD (Rare: 60°C; Medium: 71°C; Very Well Done: 83°C) before volatile analysis. Volatile compounds were evaluated through a split-plot design where enhancement level and quality grade were used as the whole plot factors and DOD served as the subplot factor. Principal component analysis (PCA) was utilized to explore relationships between volatile compounds, consumer response, and treatments. The majority of compounds (n = 32) were impacted (P < 0.05) by the interaction between DOD × enhancement × quality grade. Four compounds- methanethiol, dimethyl-disulfide, methyl-benzene, and acetic acid were affected (P < 0.05) by enhancement × DOD. Two compounds- dimethyl sulfone and d-limonene, were impacted (P < 0.05) by quality grade × enhancement. Phenylacetaldehyde and hexanoic acid, methyl ester was affected (P < 0.05) by the interaction of USDA quality grade × DOD. The DOD main effect was only implicated in Maillard products (P < 0.05), including 2-methylbutanal, a Strecker aldehyde, and 2 pyrazines (methyl-pyrazine and trimethylpyrazine). Nonanal was the only compound impacted (P < 0.05) by a quality grade effect. No enhancement main effects were observed for any compounds (P > 0.05). In agreement, PCA indicated volatile compound production was primarily driven by degree of doneness and quality grade. There was no strong link between enhancement and beef volatile flavor compound development, despite the dramatically improved flavor liking scores from consumers.

79 Cooking method and beef flavor: a multivariate approach

The objective of this study was to determine the impact of sous vide cookery followed by finishing on four dry heat cookery methods and two quality grades on beef volatile flavor compound production in beef strip loin steaks. Beef strip loins (n = 40, 20/grade) were procured from two USDA quality grades: upper 2/3rds of Choice and Select. Strip loins were aged for 21 d at 2 to 4°C. Following aging, strip loins were sliced into 2.54 cm steaks, vacuum packaged, and frozen at -20°C. Steaks were thawed, then cooked sous vide in a circulating water bath at 63.5°C for 1.5 h. Steaks were finished to a medium degree of doneness (71°C) on one of four cooking methods: charbroiler grill (CHAR), clamshell grill (CLAM), convection oven (OVEN), and salamander broiler (SALA). Steaks were immediately submerged into ice to stop cooking, vacuum packaged and frozen at -20°C until analysis. Volatile compounds (n = 73) were identified using gas chromatography-mass spectrometry and were selected from the Maillard reaction and lipid degradation pathways. Principal component analysis (PCA) was used to observe the relationships between volatile compounds and consumer ratings of beef strip loin steaks. When PCA was conducted, principal component (PC) 1 represented 50.59% and PC 2 represented 29.76% of the variation. Salamander steaks of both quality grades were the most closely associated with flavor, tenderness, juiciness, and overall liking. Charbroiler steaks were the most closely related with Maillard products, especially pyrazines, sulfur containing compounds, and pyrroles. Oven steaks were more associated with compounds associated with lipid degradation, including hexanol, hexanal, and 2-pentylfuran. Clamshell steaks were negatively associated with consumer palatability traits, which was expected, due to the poor liking ratings from consumers. These data indicate cooking method can directly impact flavor of beef strip loin steaks, regardless of quality grade

Marbling Texture’s Effects on Beef Palatability

The objective of this study was to evaluate the effects of marbling texture on consumer and trained sensory panel ratings of beef strip loin steaks from 3 USDA quality grades. Beef strip loins (n = 117) were selected from 3 quality grades [Top Choice (Modest00 – Moderate100 marbling), Low Choice (Small00 – Small100 marbling), and Select (Slight00 – Slight100 marbling)] to equally represent three different marbling texture groups: fine, medium, and coarse, via visual appraisal. There were no quality grade × texture interactions (P > 0.05) for all of the traits evaluated. Consumers (n = 104) rated all marbling texture groups similar (P > 0.05) for tenderness, juiciness, flavor, and overall liking, as well as rated a similar (P > 0.05) percentage of samples from each marbling texture group acceptable for each palatability trait. Moreover, consumers indicated no preference (P > 0.05) among marbling texture groups for visual desirability or likelihood to purchase. However, trained sensory panelists rated coarse marbled steaks higher (P < 0.05) than fine or medium marbled steaks for both beef flavor intensity and sustained juiciness, as well as higher (P < 0.05) for initial juiciness than medium textured steaks. There were no differences (P > 0.05) among marbling texture groups for Warner-Bratzler shear force, slice shear force, and pressed juice percentage. Low Choice steaks were rated higher (P < 0.05) than Select steaks by consumers for tenderness, flavor liking, and overall liking, but similar (P > 0.05) to Top Choice. Results from this study indicate marbling texture had no impact on consumer evaluations of eating quality and only minimal effects on trained sensory panel palatability ratings and therefore provides no palatability-based evidence for the exclusion of coarse marbled carcasses from current and future branded beef programs.

Effects of Marbling Texture on Muscle Fiber and Collagen Characteristics

The objective of this study was to evaluate the effects of marbling texture on muscle fiber morphometrics, adipocyte cross-sectional area, perimysial thickness, collagen solubility, and thermal transition temperature of perimysial collagen of beef strip loin steaks from 3 marbling scores. Beef strip loins (n = 117) were selected from three marbling scores [Top Choice (Modest00 – Moderate100 marbling), Low Choice (Small marbling), and Select (Slight marbling)] to equally represent 3 different marbling texture groups: fine, medium, and coarse, via visual appraisal. There were no marbling texture × marbling score interactions for all traits evaluated. Marbling texture impacted (P < 0.05) adipocyte cross-sectional area, where coarse steaks displayed larger adipocytes in comparison to fine marbled steaks, but medium marbled steaks were similar (P > 0.05) to both coarse and fine marbled steaks for the same trait. However, marbling texture did not impact (P > 0.05) perimysial thickness. Marbling texture did not affect collagen traits, as no differences (P > 0.05) were found among marbling texture treatments for soluble collagen, insoluble collagen, and total collagen concentrations. Furthermore, all marbling texture groups (fine, medium, and coarse) were similar (P > 0.05) for the peak thermal transition phase of the perimysial fraction of collagen. Marbling score affected adipocyte size, as Top Choice and Low Choice possessed larger (P < 0.05) adipocytes than Select steaks. There were no differences (P > 0.05) among marbling scores for fiber type; nor were differences found among marbling textures or marbling scores for fiber cross-sectional area. These results indicate that marbling texture does not contribute to differences in collagen characteristics or fiber cross-sectional area that may impact eating quality of beef strip loin steaks.

A review of heavy weight market pigs: status of knowledge and future needs assessment

Marketing weight is an important economic variable that impacts the productivity and profitability of finishing pig production. Marketing weight has been increasing worldwide over the past decades driven by the dilution of fixed production cost over more weight per pig and the improvement of genetic selection of lean-type pigs. This review was aimed to summarize current knowledge and assess the future research needs on producing finishing pigs with marketing weight greater than 130 kg. Based on a thorough literature review, increasing marketing weight affected overall pig growth; in particular, cumulative average daily gain (ADG) decreased by 4.0 g, average daily feed intake (ADFI) increased by 78.1 g, and gain-to-feed ratio (G:F) decreased by 0.011 for every 10 kg increase of marketing weight. Increasing marketing weight by 10 kg increased carcass yield by 0.41% units, backfat by 1.8 mm, longissimus muscle (LM) area by 1.9 cm², carcass length by 2.2 cm, and belly yield by 0.32% units, but decreased percentage of fat-free-lean by 0.78 units and decreased loin, shoulder, and ham yields by 0.13, 0.16, and 0.17% units, respectively. Studies that investigated the effects of marketing weight on pork quality observed decreased pH by 0.02 and 0.01 at 45 min and 24 h postmortem, respectively, and increased a* value by 0.28 per 10 kg marketing weight increase. Heavier market pigs had increased concentrations of saturated fatty acids and intramuscular fat. However, studies reported conflicting results for L* and b* values, drip loss, Warner-Bratzler shear force, and sensory properties of pigs in response to increasing marketing weight. A limited amount of research has been conducted to estimate nutrient requirements for pigs greater than 140 kg. Increased weight and size of heavy pigs can create challenges to farm and packer facilities and equipment. Discussions and recommendations are provided concerning the adjustments for floor and feeder space, barn design, ventilation, disease control, transportation, and carcass processing needed for increasing marketing weight. In conclusion, increasing marketing weight creates both opportunities and challenges to current finishing pig production, and future research is needed to provide nutritional and management guidelines and improve feed efficiency and meat quality of heavy weight market pigs.