The Effect of Cooking Method and Cooked Color on Consumer Acceptability of Boneless Pork Chops

The objective was to determine the effects of sous-vide cooking and degree of doneness on consumer eating experience of pork chops when cooked color was expected to differ. The hypothesis was consumers would prefer a cooked brown color and would rate grilled chops more acceptable than sous-vide chops. Chops were cooked to 63 °C or 71 °C using either an open-hearth grill or a sous-vide device. Participants evaluated four samples for tenderness, juiciness, flavor, and overall acceptability. Participants rated a greater percentage of chops cooked sous-vide at 63 °C as tender (82.82%), juicy (55.83%) and acceptable (60.34%) compared with all other cooking method and degree of doneness combinations. Participants rated a greater percentage of sous-vide chops as tender and acceptable compared to grilled chops. Participants rated a greater percentage of chops cooked to 63 °Cas tender, juicy, flavorful, and acceptable when compared to 71 °C. Even when participants could visualize cooked color, they preferred chops cooked to 63 °C compared with chops cooked to 71 °C. Overall, participants preferred chops cooked to 63 °C compared to 71 °C regardless of the cooking method and preferred chops cooked to 63 °C using the sous-vide cooking method the most among all treatments.

Characteristics of Pork Muscles Cooked to Varying End-Point Temperatures

M. biceps femoris (BF), m. semimembranosus (SM) and m. semitendinosus (ST) from fresh pork ham were evaluated for characteristics of quality after cooking to an internal endpoint temperature of 62 °C or 73 °C. Fresh ham muscles from the left side (N = 68) were cut into 2.54 cm thick chops and allocated to cooking loss, Warner–Bratzler shear force (WBSF), pH and instrumental cooked color analysis. Cooking losses were greater (p < 0.0001) for SM and chops cooked to an internal temperature of 73 °C (p < 0.0001), whereas WBSF did not differ (p = 0.2509) among the three muscles, but was greater (p < 0.0001) in chops cooked to 73 °C. Fresh muscle’s pH was greater (p < 0.05) in ST than BF or SM. Lastly, the interactive effect (p < 0.05) of muscle × endpoint temperature for ST chops cooked to 73 °C was lighter (L*), but, when cooked to 62 °C, they were more red (a*), more yellow (b*) and incurred less color change from red to brown than BF or SM. The current results suggest it is plausible for BF, SM and ST to be considered for alternative uses instead of traditional value-added manufacturing.

Endpoint Temperature Influences Sarcoplasmic Proteome Profile of Cooked Beef Longissimus Lumborum

ObjectivesCooking ensures safety and enhances the palatability attributes of meat. Denaturation of myoglobin results in the dull-brown color of cooked meats. The denaturation of sarcoplasmic proteins is influenced by the degree of heat treatment, and their solubility is decreased with an increase in the endpoint cooking temperature. While previous studies examined the relationship between myoglobin denaturation, cooked color, and internal temperature in beef, investigations are yet to be undertaken to characterize the association between endpoint temperature, sarcoplasmic proteome, and color attributes in cooked steaks. Therefore, the objective of the present study was to examine the influence of endpoint cooking temperature (60 and 71°C) on sarcoplasmic proteome and internal color of beef longissimus lumborum (LL) steaks.Materials and MethodsEight (n = 8) beef LL muscles (14 d postmortem; USDA Choice) were obtained from a commercial packing plant. Two 2.5-cm thick steaks were fabricated from the center of the muscles and were cooked to internal endpoint temperature of 60°C (C-60) or 71°C (C-71) in a clam-shell grill. Cooked steaks were immediately cooled in slushed ice, sliced parallel to the grilled surface, and internal redness (a* value) and color stability (R630/580) were evaluated instrumentally. Sarcoplasmic proteome from the interiors of the cooked steaks was analyzed using 2-dimensional electrophoresis, and the gel images were digitally analyzed. The protein spots exhibiting more than 2.5-fold intensity differences (P < 0.05) between C-60 and C-71 were subjected to in-gel tryptic digestion and were identified by tandem mass spectrometry.ResultsThe C-60 steaks demonstrated greater (P < 0.05) a* and R630/580 than their C-71 counterparts. Seven differentially abundant proteins were identified and were over-abundant (P < 0.05) in C-60 compared to C-71. The differentially abundant proteins belong to 6 functional groups, i.e., transport proteins (serum albumin and hemoglobin), energy metabolism (adenylate kinase isoenzyme 1), chaperones (heat shock protein β-1), antioxidant (thioredoxin-dependent peroxide reductase), glycolytic enzymes (fructose-bisphosphate aldolase B), and protease (cytosol aminopeptidase).ConclusionThe findings indicated that the endpoint cooking temperature influences the internal cooked color and the sarcoplasmic proteome profile of beef LL steaks. The overabundant proteins in steaks cooked to 60°C may be utilized as potential biomarkers for undercooked beef, which is a source for foodborne infections.

The Effect of Cooking Method and Cooked Color on Consumer Acceptability of Boneless Pork Chops

ObjectivesThe objective was to determine the effects of cooking method and degree of doneness on consumer eating experience of pork chops when consumers were allowed to observe differences in cooked color. The hypothesis was that when consumers were able to visualize cooked color, they would rate pork cooked to 63°C less acceptable than chops cooked to 71°C due to historical perceptions of pork degree of doneness. Additionally, consumers would find sous-vide chops less acceptable due to the lack of browning.Materials and MethodsSensory procedures for all consumer evaluations were reviewed and approved by the University of Illinois Office for the Protection of Research Subjects. Loins were purchased from a commercial abattoir at 1 d postmortem, vacuum packaged, aged until 10 d postmortem, then frozen. Frozen pork loins were cut into 3.2 cm thick chops. Loin origin was maintained for each chop such that consumers were served 4 chops that originated from the same loin. Frozen chops were vacuum packaged and allowed to thaw at approximately 4°C. Pork chops were cooked to either 63°C or 71°C using either an open-hearth grill or an immersion cooker sous-vide device. After cooking, chops were removed from the heating source and cut to expose the internal cooked surface. Cooked color was measured with a Minolta chroma meter. Chops were cut into 1 cm × 1 cm × 3.2 cm sections and served to 132 consumers. Consumers were seated in a breadbox style sensory booth room under fluorescent light to allow for cooked color appraisal. Each consumer was provided 4 samples (grill/63, grill/71, sous-vide/63, sous-vide/71). Consumers used a 9-point Likert-type score system to determine tenderness, juiciness, flavor, and overall acceptability. Data were organized as a percentage of responses to determine the effects of cooking method, degree of doneness, and their interaction.ResultsChops cooked to 63°C (4.10, 9.08) were more red and less yellow (P = 0.01) than chops cooked to 71°C (3.82, 9.39). There was an interaction of cooking method and degree of doneness for both tenderness and acceptability. Consumers rated a greater percentage (P < 0.001) of chops cooked sous-vide at 63°C as tender (82.82%) and acceptable (60.34%) compared with all other cooking method and degree of doneness combinations. There were no differences (P = 0.06) in the percentage of chops rated tender when cooked to 71°C between those sous-vide (33.07%) and grilled (22.42%). Additionally, there were no differences (P = 0.06) in the percentage of chops rated acceptable when cooked to 71°C between those sous-vide (26.35%) and grilled (28.63%). For juiciness, consumers rated a greater (P < 0.01) percentage of chops cooked to 63°C as juicy (44.37%) than those cooked to 71°C (14.78%) but ratings as juicy did not differ between cooking methods. For flavor, consumers rated a greater (P < 0.01) percentage of chops cooked to 63°C as flavorful (34.61%) than those cooked to 71°C (24.31%). Contrary to the expectation, ratings as flavorful did not differ between cooking methods (P = 0.88).ConclusionEven when consumers can identify cooked color, they preferred chops cooked to 63°C. However, the lack of browning on chops cooked using sous-vide did not compromise eating quality of chops.

Effect of Temperature on Oxymyoglobin and Metmyoglobin Denaturation Properties

ObjectivesPremature browning is a condition where the interior of patty/steak will appears fully cooked before the temperature necessary to kill foodborne pathogens is reached. Previous research reported that approximately 50% of ground beef retailed in the US is susceptible to premature browning. Myoglobin form present in the interior of steak or patties determines the cooked color appearance. Although previous studies noted that myoglobin denaturation is primarily responsible for the cooked color appearance, limited knowledge is currently available about the effect of temperature on oxymyoglobin and metmyoglobin denaturation properties. The objective of the current study was to determine the effects of myoglobin forms on thermal stability using circular dichroism spectroscopy.Materials and MethodsOxymyoglobin and metmyoglobin solutions at pH 5.6 in 50 mM sodium phosphate buffer were incubated in a continuous heat increment water bath for 10 min. At specific temperature points (65, 71, 73, and 76°C), myoglobin denaturation was determined by changes in myoglobin concentration and by protein unfolding (fluorescence and absorbance) methods. The myoglobin thermal stability was also determined by circular dichroism spectroscopy. Changes in secondary protein structure were determined every 2°C from 52 to 92°C. The data were analyzed as completely randomized using the Mixed Procedure of SAS. A significance level of 0.05 was used to determine differences between means.ResultsOxymyoglobin had greater (p < 0.05) unfolding (as indicated by absorbance changes) than metmyoglobin at all temperatures. However, at 65, 71, and 73°C there were no differences (p > 0.05) in fluorescence intensities between myoglobin forms. Circular dichroism spectroscopy indicates that oxymyoglobin is more heat labile than metmyoglobin.ConclusionThe results indicate that oxymyoglobin had greater denaturation and unfolding than metmyoglobin. Use of appropriate myoglobin denaturation quantification technique will help characterize premature browning.

Carcass traits and consumer acceptability of striploin steaks from band-castrated, intratesticular zinc-injected, or sexually intact beef cattle1

One hundred and eighty beef bulls (BW = 337 ± 10.9 kg) were blocked by BW (6 blocks) and assigned randomly to one of three treatments on day 0: 1) INJ; received 1 mL (100 mg Zn) of a Zn solution in each testis, 2) BAN; received blood-restrictive rubber band placed upon the dorsal aspect of the scrotum, and 3) BUL; bulls with testicles remaining intact. Cattle were grouped by weight block in a randomized complete block design (three treatment pens/block and 10 cattle/pen) and harvested by block on three separate dates when blocks reached similar BW and visual subcutaneous fat thickness depth. Striploins were removed from the left carcass sides, vacuum packaged and aged for 14 d, and then frozen at −20 °C. Frozen striploins were sliced into 2.54-cm-thick steaks and remained frozen until analyses. Steaks (n = 3/animal) were used to assess consumer acceptability via consumer taste panel (n = 152 panelists), Warner-Bratzler shear force, percentage cook loss, and cooked color values. Data were analyzed using mixed model procedures; pen was the experimental unit for all dependent variables. Hot carcass weights and LM area were greater (P &lt; 0.01) for the INJ and BUL treatments compared with BAN. Mean yield grade did not differ between treatments (P = 0.12), although BAN carcasses had smaller LM area (P &lt; 0.01) than BUL or INJ carcasses. Percentage of USDA Choice or better carcasses was greater (P &lt; 0.01) for BAN than INJ and BUL treatments. Consumer panelists detected a difference in perceived tenderness; BAN steaks had greater (P = 0.02) tenderness scores than BUL steaks, whereas INJ steaks were intermediate. Panelists rated juiciness of BAN steaks greater (P &lt; 0.01) than either BUL or INJ steaks. Panelists rated beef flavor greater (P = 0.01) for BAN and BUL steaks than INJ steaks. Overall acceptability was greater (P &lt; 0.01) for BAN compared with INJ steaks, whereas BUL steaks were intermediate. Percentage cook loss of striploin steaks (P = 0.47) and Warner-Bratzler shear force values (P = 0.11) did not differ. Cooked color lightness (L*) and redness (a*) values were not affected (P ≥ 0.23) by treatment. Striploin steaks from BAN and BUL treatments had greater (P = 0.02) yellowness values (b*) than INJ steaks. The ratio of red-to-brown (630:580 nm) of cooked striploin steaks was greater (P = 0.05) for INJ than either BAN or BUL treatments. Carcass and palatability outcomes of INJ were more similar to BUL than BAN, suggesting limited efficacy of INJ in mature beef bulls at feedlot entry.