Duroc-cross pigs (n = 25) were assigned to one of three experimental finishing diets containing 0 (control), 40,000 (40), or 80,000 (80) IU of supplemental vitamin D3/kg of feed (as-fed basis)to test the effects of vitamin D3 on pork quality traits. Experimental diets were fed for 44 or 51 d before slaughter, and days on feed were blocked in the experimental design. A trend existed for pigs receiving the highest concentration of vitamin D3 supplementation to have a lower (P = 0.08) ADG (0.77 kg/d) compared with pigs fed either the 40-diet (0.88 kg/d) or control (0.92 kg/d). Diet did not (P > 0.10) affect backfat thickness measured along the midline, 10th-rib fat depth, longissimus muscle area, muscle score, or hot carcass weights. Longissimus pH, measured at 0.5, 1, 2, 3, 4, and 24 h postmortem, was higher (P < 0.05) for pigs on the 80-diet than those fed the control diet. Longissimus muscle color, measured at 24 h postmortem, from pigs fed either the 40- or 80-diet were darker (lower L* values; P < 0.05) than those fed the control diet. Objective longissimus color scores were higher (P < 0.01), and firmness/wetness scores lower (P < 0.05), for pigs on the 80-diet as compared to those on the 40-diet or control diet. The diet had no (P > 0.10) effect on Warner-Bratzler shear force values; percentage of cook loss; or trained sensory panel evaluations for tenderness, juiciness, and flavor. Feeding the 80-diet increased (P < 0.05) plasma vitamin D3 and calcium after 2, 4, and 6 wk on feed compared with the control diet. Vitamin D3 and 25-hydroxy vitamin D3 concentrations in the longissimus muscle increased (P = 0.001) with increasing vitamin D3 levels in the diet; however, muscle calcium concentrations and fiber type were not (P > 0.30) affected by diet. These results indicate that feeding supranutritional levels of vitamin D3 for at least 44 d improves pork color and increases pH, but may retard growth if fed at 80,000 IU/kg of feed.
Bovine viral diarrhea virus (BVDV) is a pestivirus that is enzootic in most cattle populations throughout the world. This virus is present throughout the body of persistently infected (PI) cattle. Previous research has not assessed the cooking temperature at which BVDV in meat from PI cattle can be inactivated. Therefore, muscle tissue from 6 PI cattle was harvested, refrigerated, frozen, and heated to various internal temperatures. The concentration of virus present was determined by virus isolation. Average cell culture infective doses (50% endpoint; CCID(50)) of BVDV per gram of frozen, uncooked meat from PI cattle were 10(5.85) CCID(50)/g of whole cuts and 10(6.02) CCID(50)/g of ground meat. The virus in whole and ground meat was consistently inactivated when cooked to temperatures greater than or equal to 75°C. A second objective of this research was to thoroughly reassess if Vero cells were permissive to BVDV infection in our laboratory to provide further indication of whether primates, including humans, might be susceptible to BVDV. Vero cells were not permissive to infection with any of 43 different strains of BVDV that readily replicated in Madin Darby bovine kidney cells. In conclusion, this bovine pathogen, which is not considered to be a human pathogen, can be inactivated by cooking ground or whole cuts of meat to 75°C or higher. Care should be taken to ensure that susceptible hosts such as pigs are not fed improperly cooked meat, meat by-products, or waste food originating from PI cattle.
Packaging technology is evolving, and the objectives of this study were to evaluate instrumental surface color, expert color evaluation, and lipid oxidation (TBARS) on beef longissimus lumborum steaks packaged in vacuum-ready packaging (VRF) or polyvinyl chloride (PVC) overwrap packaging. Paired strip loins (Institutional Meat Purchasing Specifications # 180) were cut into 2.54-cm-thick steaks and assigned randomly to one of two packaging treatments, VRF or PVC. Steaks packaged in VRF were lighter in color (p < 0.05) as the display period increased, whereas steaks packaged in PVC became darker (p < 0.05). Redness (a*) values were greater (p < 0.05) for PVC steaks until day 5, whereas VRF steaks had a greater (p < 0.05) surface redness from day 10 to 35 of the display period. Calculated spectral values of red to brown were greater (p < 0.05) for steaks in VRF than PVC. In addition, expert color evaluators confirmed VRF steaks were less brown and less discolored (p < 0.05) from day 5 to 35 of the display. Nonetheless, lipid oxidation was greater (p < 0.05) for PVC steaks from day 10 through day 35 of the display. Results from this study suggest that the use of vacuum packaging for beef steaks is plausible for maintaining surface color characteristics during extended display periods.
With current meat industry efforts focused on improving environmental influencers, adopting sustainable packaging materials may be an easier transition to addressing the sustainability demands of the meat consumer. With the growing popularity of vacuum-packaged meat products, the current study evaluated instrumental surface color on fresh ground beef using vacuum packaging films, recycle-ready film (RRF), standard barrier (STB) and enhanced barrier (ENB). Ground beef packaged using ENB barrier film was lighter (L*), redder (a*) and more vivid (chroma) than all other packaging treatments during the simulated display period (p < 0.05). By day 12 of the simulated retail display, the ground beef surface color became lighter (L*), more yellow (b*), less red (a*), less vivid (chroma) and contained greater forms of calculated metmyoglobin, oxymyoglobin (p < 0.05). The current results suggest that barrier properties of vacuum packaging film for ground beef are pivotal for extending the surface color during fresh shelf-life conditions.
The objective of this study was to validate the shelf-life of marinated and frozen chicken tenderloins. Treatments were randomly assigned to the age of the tenderloins post-harvest, days aged (DA): DA4, DA5, DA6, DA7, and DA8. Microbial analyses were used to analyze the growth of aerobic, psychotropic, and lactobacilli bacteria to assess the shelf-life of bulk-packaged chicken tenderloins. Tenderloins were sampled fresh, then vacuum tumbled in a marinade. After marination, the tenderloins were sampled with the remaining tenderloins packaged and frozen (−25 °C). After freezing the chicken tenderloins were slacked in a refrigerated cooler (2.2 °C) for up to 132 h (h) and sampled at 36 h, then every 24 h following. After marination, each treatment significantly (p < 0.05) decreased in aerobic and psychotropic counts except DA4. During slacking, no treatment crossed the threshold of 106 CFU/mL (Log 6) set for this study. Though none crossed the threshold, treatments DA4, DA5, and DA6 had significant (p < 0.05) increases in aerobic bacteria after 7 days of age. The psychotropic bacteria continuously grew at each sampling period, with DA4 and DA5 surpassing the other treatments (p < 0.05) at 108 h and 132 h reaching 105 CFU/mL. Every treatment remained below the spoilage threshold, suggesting that this method of storage is suitable for chicken tenderloin shelf-life.
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