Cooked Beef Research Articles

Signal Analysis of Optical Interference in Relation to Colorimetry for Measurements Made Along Individual Myofibers in Cooked Beef

Subsurface reflective interference from A-bands in roast beef persisted under water and some myofibers had interference peaks exceeding the reflectance of white barium sulfate. The number of interference peaks was correlated with CIE (Commission Internationale de l’Éclairage) Y% (r = 0.51, P < 0.001). As the number of peaks increased, the distance from the central white of the CIE chart decreased (r = - 0.52, P < 0.001).  Myofibers with low scattering had fewer interference peaks (2.9 ± 0.3, n =10) than myofibers with high scattering (4.9 ± 1.3, n = 31, P < 0.001). Thus, the number of reflecting and interfering layers may be important in relating light scattering along myofibers to surface iridescence. One or a few reflective layers may produce strong interference colors while many layers may produce colorless scattering.Â

Horse meat sold as beef and consequent clenbuterol residues in the unregulated Mexican marketplace

The final destination of the large volumes of horse meat produced in Mexico is not apparent. The current study therefore aimed to determine if horse meat is sold fraudulently under the guise of beef in Mexico and the levels of clenbuterol residues in samples. While more than a quarter of the sellers interviewed claim to know of suppliers for horse meat, only 7% would like to sell horse meat. Yet, 10% of the 433 samples tested positive for horse meat. The proportions of raw and cooked beef samples containing horse meat were similar at 9.5% and 11.0%, respectively. Burritos were the meat product in which horse meat was observed most prevalent at 28.6%, varying from 4.9 to 12.9% in the other meat and products. None of the samples from supermarkets tested positive for horse meat, whereas, at 18.2%, horse meat was most prevalent in the restaurant-type establishments. Clenbuterol was observed in all of the raw meat samples containing horse meat.

Relationships of a Detailed Mineral Profile of Meat with Animal Performance and Beef Quality.

Simply SummaryMinerals play direct or indirect role in different biological process of animals. These biological processes finally affect the meat quality. Therefore, analysis of minerals in cattle’s diet is important for assessing potential effects on beef quality. However, minerals profile and concentration in beef are affected by several factors such as animals rearing practices, age, environment, breed etc. Hence, we analyzed 20 minerals in 192 beef samples and studied the different sources of variation which affect the minerals profile in beef. In order to understand the complex and intriguing relations of beef qualities and minerals, we utilized correlation and factor analysis with 16 traits related to animal performance and beef quality. Our analysis shows many significant associations of minerals in beef with animal performance and beef qualities. Five groups of minerals (latent factors) were associated with almost all quality traits of beef. The knowledge about the mineral contents in beef is important to understand the complex interrelationships of animal rearing, farm management, environmental conditions with regard to animal performance and beef quality.The mineral profile of beef is a subject of human health interest, but also animal performance and meat quality. This study analyzes the relationships of 20 minerals in beef inductively coupled plasma-optical emission spectrometry (ICP-OES) with three animal performance and 13 beef quality traits analyzed on 182 samples of Longissimus thoracis. Animals’ breed and sex showed limited effects. The major sources of variation (farm/date of slaughter, individual animal within group and side/sample within animal) differed greatly from trait to trait. Mineral contents were correlated to animal performance and beef quality being significant 52 out of the 320 correlations at the farm/date level, and 101 out of the 320 at the individual animal level. Five latent factors explained 69% of mineral co-variation. The most important, “Mineral quantity” factor correlated with age at slaughter and with the beef color traits. Two latent factors (“Na + Fe + Cu” and “Fe + Mn”) correlated with performance and beef color traits. Two other (“K-B-Pb” and “Zn”) correlated with beef chemical composition and the latter also with carcass weight and daily gain, and beef color traits. Beef cooking losses correlated with “K-B-Pb”. Latent factor analysis appears be a useful means of disentangling the very complex relationships that the minerals in beef have with animal performance and beef quality traits.

Heat Resistance in Escherichia coli and its Implications on Ground Beef Cooking Recommendations in Canada

ObjectivesRecent reports of an extremely heat resistant but non-pathogenic beef Escherichia coli strain, AW 1.7, raised concerns over the adequacy of cooking ground beef to 71°C in Canada. The objective of this study was to assess the adequacy of the current cooking recommendations for ground beef in relation to heat resistant E. coli.Materials and MethodsIn total, 8 potentially heat resistant E. coli strains (4 generic and 4 E. coli O157:H7) from beef along with E. coli AW1.7 were included in this study. Heat resistance of the strains was first evaluated by decimal reductions at 60°C (D60°C-value), the time required to have a log reduction of the bacterial population at 60°C. The more heat resistant strains of each group (E. coli 62 and 68, and E. coli O157 J3 and C37) were further assessed for their heat resistance when grown in Lennox Broth without salt (LB-NS), LB + 2% NaCl and Meat Juice (MJ). Then, the two most heat resistant E. coli O157 strains (J3 and C37) and E. coli AW 1.7 were each introduced to extra lean ground beef (100 g) in vacuum pouches for determination of their D-values at three temperatures, 54, 57, and 60°C, from which a z-value for each strain was derived. The thermal characteristics of all three strains were fed into a predictive model to determine the process lethality of cooking burgers to 71°C with resting for up to 5 min. Finally, inactivation of the most heat resistant E. coli strain AW1.7, assessed in this study and reported in the literature, in ground beef was validated by grilling burgers containing 6.20 ± 0.24 log CFU/g of the organism to 71°C without or with a resting of 3 or 5 min.ResultsThe D60°C-values for these strains varied from 1.3 to 9.0 min, with J3 and AW1.7 being the least and most heat resistant strains, respectively. The D60°C-values for E. coli 62 and 68 were similar and were not affected by growth medium, while the heat resistance of C37, J3 and AW1.7 varied with the growth medium. When heated in extra lean ground beef (100 g) in vacuum pouches, the mean D54°C, D57°C, and D60°C-values were 44.8, 18.6 and 2.9 min for C37, 13.8, 6.9 and 0.9 min for J3, and 40.5, 9.1 6.1 min for AW1.7. The derived z- and D71°C-values were, respectively, 5.0, 5.1 and 7.3°C; and 0.022, 0.008, and 0.156 min. Burger temperatures continued to rise after being removed from heat when the target temperature was reached, by up to 5°C, and resting of 1 min would result in a destruction of 133, 374, and 14 log C37, J3 and AW1.7, estimated from process lethality. When burgers inoculated with AW1.7 were cooked to 71°C, 14 of the 15 burgers yielded no E. coli, while the 15th had a reduction of 4.5 log. Additional resting of 3 or 5 min resulted in complete elimination of AW 1.7.ConclusionIt has been predicted that 2% of E. coli from beef may carry heat resistant genes. The findings in this study, along with the very low level of total E. coli expected in ground beef in Canada, suggest that cooking ground beef to 71°C should be adequate to ensure the safety of such products.

Chef and Consumer Evaluation of the Degree of Doneness of Beef Strop Loin Steaks Cooked to Six Endpoint Temperatures

ObjectivesThe objective of this study was to assess if visual degrees of doneness (DOD) are in-line with current published cooking temperatures and to assess differences in perceptions between consumers and chefs.Materials and MethodsTwenty-four paired beef strip loins (IMPS #180) representing four quality grades [Prime, Top Choice, Low Choice, Select] and an additional 12 enhanced Select strip loins were fabricated into 2.54 cm thick steaks and used in the study. Steaks were randomly assigned to one of six DOD: very rare (55°C), rare (60°C), medium-rare (63°C), medium (71°C), well done (77°C), or very well done (82°C). Following cooking, a photograph of the cut steak surface was taken immediately using a digital camera (Canon PowerShot SX620 HS). A digital survey for chefs and consumers was created for the electronic evaluation of the pictures of the internal surface of the cooked steaks. Chefs (n = 83) and consumers (n = 1134) were asked to assess the DOD of digital steak pictures representing multiple DOD and quality grades. Participants were also asked several questions related to how they determine DOD when cooking steaks, about their use of thermometers, and the temperatures they associate with each DOD.ResultsThere were no quality treatment effects (P > 0.05) for any DOD for the images evaluated. Between 14 to 44% of chefs categorized the steak images as the DOD to which it was cooked. For all DOD, 9 to 48% of chefs classified the steak images as 2 or more DOD from the DOD to which the steak was cooked. Of the 1134 consumers, 27 to 35% of consumers categorized steaks as the appropriate DOD. For all DOD, 16 to 36% of consumers identified steaks as 2 or more DOD higher or lower than the DOD that the steak was cooked. When chefs were asked how they determined DOD when cooking beef steaks, 66% of chefs reported using feel or firmness, whereas 28% stated they use a thermometer. Within the chefs that reported use of thermometers, 15% indicated the specific temperature they used was pull-off the heat temperature and 13% used carry-over cooking temperature. To assess DOD when cooking beef at home, 54% of consumers reported they used color, 16% used feel or firmness, and 10% used time. Additionally, 3% of consumers responded that they do not determine DOD. Only 16% of consumers reported using temperature or food thermometer for determining the correct DOD when cooking beef. Consumers that answered to using a food thermometer were then prompted to state the temperature they utilize, being either pull off the heat temperature (69%) or temperature following the post-cooking temperature rise (31%). However, 48 to 61% of consumers that stated they use a thermometer then reported they did not know the temperatures that correspond with each DOD. Additionally, only 14 to 32% of consumers that utilized peak temperatures matched the NCBA temperatures.ConclusionAlthough consumers do not have a good understanding of beef cooking temperatures, they are able to identify DOD of steaks cooked to specified endpoint temperatures. Additionally, chefs do not consistently use the same method when determining DOD and are unable to accurately identify DOD of steaks cooked to specified endpoint temperatures. This lack of uniformity between chefs and consumers on DOD determination can create challenges for foodservice establishments to successfully meet consumer DOD expectations.

M301 ALLERGIC REACTION WHILE MAKING BURGERS—BLAME IT ON THE DOG!

A 5-year-old girl with history of significant eczema, severe dog allergy (IgE>100), and anaphylactic allergy to egg and treenuts developed urticaria on her bilateral arms after preparing hamburger patties. No other ingredients, such as egg, were handled. She had previously tolerated cooked beef and had no history of milk allergy.

Effects of clove extract on oxidative stability and sensory attributes in cooked beef patties at refrigerated storage

The antioxidant effects of clove extract (CE) by comparing with BHT and ascorbic acid (AA) in cooked beef patties were assessed at refrigerated storage. Four kinds of patties were formulated: without antioxidants (control), with added 0.02% BHT, 0.05% AA, and 0.1% CE. Addition of BHT, AA, and CE resulted in a significant (p < .05) decrease in thiobarbituric acid reactive substance (TBARS) value, carbonyl content, and hue angle; increasing of redness value; and improvement of the stability of sensory attributes. Addition of CE showed reduced protein and lipid oxidation when compared with BHT (p < .05). Moreover, CE presented lower lipid oxidation, and a higher redness value and overall color score than the AA (p < .05). Sensory assessment regarding overall color, discoloration, and odor showed that CE inclusion in patties extended the storage life up to 10 days. Therefore, the application of CE as a natural antioxidant can result in reduced protein and lipid oxidation and enhance the quality of cooked beef patties.

Identification of pork in raw meat or cooked meatballs within 20 min using rapid PCR coupled with visual detection

Meat adulteration is seriously damaging the interests of consumers. It is important to develop a rapid, simple, cost-effective and sensitive method to identify meat species. In this study, a pair of suitable pork-specific primers was determined by the comparison of three pairs of pork-specific primers and the annealing/extension temperature optimized here was set at 64 °C. Rapid polymerase chain reaction (PCR) with glass capillary as reaction vessel, which could complete 45 cycles in 5 min by using two ordinary water baths, was established to detect pork contents in raw beef meat or cooked beef meatballs. A SYTO 9-based visual detection method was used to evaluate the amplification results. The fluorescence signal of negative samples could be removed at 72 °C according to the results of original melt curves of positive and negative samples. Strong green fluorescence would be produced in positive samples while the color of negative samples still remained black under the blue light (470 nm). A simple and portable device was designed to prevent detection results disturbed by ambient light and make operation easier. As low as 0.01% pork contents in binary mixtures could be detected and the whole detection process could be finished in 20 min from sampling to results. The developed method would have great potential for rapid on-site detection of pork meat and identification of meat species.

Relationship between the antioxidant capacity of soy sauces and its impact on lipid oxidation of beef patties

The aim of this study was to determine the relationship between in vitro antioxidant capacity of soy sauces and its impact on lipid oxidation in raw and cooked beef patties during 10 days of refrigerated storage. Three commercial soy sauces were used: industrially fermented soy sauce (IS), traditionally fermented Korean soy sauce (KS), and mixed soy sauce (MS). In vitro antioxidant capacity, KS showed the highest total phenol content, whereas IS and MS had a higher Fe2+ chelating activity than KS (P < .05). Heat treatment decreased total phenol content but increased Fe2+ chelating activity of soy sauces (P < .001). In both raw and cooked beef patties, the addition of IS or MS caused a lower 2-thiobarbituric acid reactive substances (TBARS) level than KS throughout the overall storage period (P < .05). This preliminary study suggests that the Fe2+ chelating activity of soy sauce may be one of the major mechanisms in preventing lipid oxidation in meat products.

Mycological Assessment of Cooked Beef Products

Mycological Assessment of Cooked Beef Products

Mycological Assessment Of Cooked Beef Products

Mycological Assessment Of Cooked Beef Products

Vitamin K Content of Raw and Cooked U.S. Beef Variety Meat Items (FS14-03-19)

ObjectivesVitamin K is an essential nutrient that has been implicated in cardiovascular disease and other chronic diseases. There are two forms of vitamin K in nature. Phylloquinone (PK) is plant-based and has been well-quantified in the U.S. diet. Menaquinones (MK) are found in animal products and fermented food. However, the MK contents of food have not been well characterized. The objectives of this study were to: 1) quantify the different forms of MK (MK4 through MK13) in the beef variety meat items; and 2) determine if cooking has an effect on vitamin K content of beef variety meat items. MethodsRaw beef heart, liver, kidney, tongue, honeycomb tripe, oxtail, bone marrow, beef rocky mountain oysters (RMO), fat composite samples and blood (total samples n = 31) were obtained from processing facilities in the U.S., to provide national representation of retail-ready beef variety meat items. All raw beef samples were cooked, and final internal temperature was 80 °C. PK and the MKs in raw and cooked beef variety meat items were quantified using mass spectrometry technology. Wilcoxon Rank Signed test was used to compare PK and MK contents of raw and cooked samples. Differences were considered statistically significant at P < 0.05. ResultsThe highest concentration of any form was PK in bone marrow at 152 ± 11.9 ng/g. The fat composite samples contained between 20.9 ng/g to 63.0 ng/g of PK. Modest amounts of PK were found in liver, RMO and tripe. MKs were present in all samples analyzed with MK4, MK10, MK12 and MK13 present in the largest amount in the analyzed samples. MK4 concentrations in bone marrow and fat composite samples were 341 ± 116 and 374 ± 101 ng/g, respectively. Liver contained appreciable amounts of longer-chain MKs, primarily in the forms of MK11, MK12 and MK13, which together accounted for 95% of total vitamin K in liver. There were no significant differences in total vitamin K content between cooked and uncooked beef variety. ConclusionsTo the best of our knowledge, this is the first report of MK contents of U.S. beef variety meat items. The vitamin K content of beef items were not influenced by cooking (heating). Funding SourcesFunded by the Beef Checkoff and supported by the USDA, Agricultural Research Service under Cooperative Agreement.

Consumer Acceptability and Demand for Cooked Beef Sausage Formulated With Pre- and Post-Rigor Deboned Beef

The objective of this study was to compare consumer acceptability and demand between pre- and post-rigor cooked beef sausage. Consumers (N = 100) evaluated the appearance, aroma, flavor, texture, and overall acceptability on a 9-point hedonic scale and formulated an independent bid for each product. Consumers preferred the aroma and flavor of pre-rigor sausage to those of post-rigor sausage (P = 0.008 and 0.029, respectively). This resulted in a greater overall acceptability of pre-rigor sausage than that of post-rigor sausage (P = 0.011). Cluster analysis revealed that 45 consumers in clusters 3 and 4 led to such greater acceptability. Average predicted unit-demand for the experiment was 1.59 kg (3.50 lbs)/(USD)$ greater for pre-rigor than for post-rigor sausage (P ≤ 0.001). Overall, the results indicated that pre-rigor processing yielded sausage with greater consumer acceptability and demand.

Utilization of brown rice powder on the nutritional composition, cooking characteristics and sensory properties of beef patties

Beef patties are the most popular fast food worldwide, including Malaysia. As long as a beef patty is one of the Malaysians’ favorite western dishes and can be easily found in the high-end western restaurant, so far assessment of the nutrient composition, cooking characteristics and sensory properties of that was important for healthcare aspect. In the current study, the nutritional values of beef patties incorporated with various level of brown rice powder (BRP) (2%, 4% and, 6%) were evaluated. The result of protein content in raw and cooked beef patties incorporated with 6% of BRP demonstrated the highest percentage (17.41% and 17.48%, consequently). Further finding displayed that the lowest fat concentration was recorded in the formulation of 6% BRP and 4% BRP raw and cooked beef patties (12.44% and 11.45%) frequently. On the other hands, the results of moisture content of 4% BRP raw beef patties and 6% BRP cooked beef patty demonstrate that the lowest percentage (61.16% and 54.92%) while the carbohydrate concentration recorded the highest percentage in both formulations. In additional, beef patty formulated with 6%, BRP showed the lowest diameter reduction at 13.33% compared to other treatment. The calorie content of cooked beef patty and cooking yield of all formulations were recorded in the range of 584 kcal/100 g to 594 kcal/100 g and 78.09% to 80.48% accordingly. However, 2% BRP incorporation in beef patty did not change the sensory properties and consumer acceptability of BRP-based beef patties. In conclusion, beef patty formulation of more than 4% BRP in beef patties was effective in improving protein, ash, carbohydrate content and percentage of diameter reduction while reducing fat content.

Quantitative Detection of Beef Contamination in Cooked Meat Products by ELISA.

Background: Concerns about the contamination of meat products with undeclared meats, and new regulations for the declaration of meat adulterants have established the need for a rapid test to detect beef adulteration to 0.1% sensitivity. Objective: To address this need, Microbiologique, Inc. has developed an ELISA that can quantify the presence of beef down to 0.1% (w/w) in cooked pork, horse, chicken, goat, and sheep meat. Results: The beef-authentication ELISA has an analytical sensitivity of 0.00022 and 0.00012% (w/v) for cooked and autoclaved beef, respectively, and an analytical range of quantitation of 0.025 to 2% (w/v), in the absence of other meats. Moreover, the assay is specific for cooked beef and does not cross react with common food matrixes. Conclusions: The assay is rapid, can be completed in 70 min, and can detect a 0.1% level of meat adulteration. The assay is an improvement over a previous U.S. Department of Agriculture's tested assay, which is sensitive to 1% adulteration and takes 2.5-3 h to complete. Highlights: The Microbiologique Cooked Beef ELISA can quantitate cooked beef in the presence of pork, horse, chicken, goat, and sheep meat to 0.1% (w/w) and is not affected by common food matrixes.

A predictive model for the evaluation of flavor attributes of raw and cooked beef based on sensor array analyses.

There are currently no standardized objective measures to evaluate beef flavor attributes, especially the comparison between raw beef and cooked beef. Beef flavor attribute is one of the most significant parameters for consumers. This study described a predictive model using a 12-ion-sensor array and sensory properties to evaluate beef flavor attributes based on potential. Then the number of sensors was reduced to six via variance of analysis, and these six sensors were reserved with the saturated calomel reference electrode to constitute a new sensor array. Sensitive flavors of each sensor were selected through multiple comparative analysis. Results showed that the accuracy rate of classifying five basic flavors (acidity, sweetness, bitterness, saltiness, freshness) using the new sensor array was 100%. The processing methods used were based on multivariate statistical methods done with the cluster analysis (CA). Results were compared to sensory evaluation using genetic algorithm (GA). From GA, the accuracy rates of raw and cooked beef were 85.0% and 90.0%, which was consistent with the sensory analysis results. Moreover, reducing the number of sensors could decrease the data dimensionality and detection time. Also raw beef instead of cooked beef could be used in flavor attributes evaluation. This model could become an important method for evaluating beef flavor attributes repeatedly and objectively.

Lipid oxidation and antimicrobial activity of cooked beef patties as influenced by leaf extracts of “Cemba” (Albizia lebbeckoides [DC.] Benth)

Cemba (Albizia lebbeckoides [DC.] Benth.) leaf extract (CLE) was evaluated for some physical properties, antioxidant and antimicrobial activities incorporated into beef patties during cold storage. Four Formulation employed were control, butylated hydroxytoluene (BHT) 0.01, CLE 0.5, and CLE 1% (w/w). The variables measured were proximate composition, cooking parameters, pH, aw, WHC, color, total phenolic content, antioxidant capacity, DPPH scavenging activity, TBARS value, and microbial total. The data were analyzed using ANOVA one factor for proximate and cooking parameters, and ANOVA with factorial 4x5 for pH, aw, WHC, color, total phenolic content, antioxidant capacity, DPPH scavenging activity, TBARS value, and microbial total and continued with Tukey test. The results of the study showed that the addition of the CLE did not affect the proximate composition and cooking parameters of the patties. The cooked beef patties with 1% CLE showed significantly lower (P&lt;0.05) for TBARS value, pH, bacterial total (mesophilic and psychrophilic) compared to 0.5% CLE and controls. The total phenolic content, antioxidant capacity, scavenging activity of CLE 1 % were significantly higher (P&lt;0.05) than 0.5% CLE and controls during the cold storage period (0, 7, 14, 21, and 28 days). Addition of both 0.5 and 1% CLE in cooked beef patty reduced bacteria total. The addition of 1% CLE had equivalent to BHT 0.01% effect in retarding lipid oxidation. In conclusion, the CLE 1% was effective to retard lipid oxidation and inhibit bacteria growth of cooked beef patties.

Rhombencephalitis caused by Listeria monocytogenes with hydrocephalus and intracranial hemorrhage: A case report and review of the literature

BACKGROUNDListeria monocytogenes (L. monocytogenes), a Gram-positive facultatively intracellular bacterium, is the causative agent of human listeriosis. Listeria infection is usually found in immunocompromised patients, including elderly people, pregnant women, and newborns, whereas it is rare in healthy people. L. monocytogenes may cause meningitis, meningoencephalitis, and some very rare and severe complications, such as hydrocephalus and intracranial hemorrhage, which cause high mortality and morbidity worldwide. Up to now, reports on hydrocephalus and intracranial hemorrhage due to L. monocytogenes are few.CASE SUMMARYWe herein report a case of rhombencephalitis caused by L. monocytogenes in a 29-year-old man. He was admitted to the hospital with a 2-d history of headache and fever. He consumed unpasteurized cooked beef two days before appearance. His medical history included type 2 diabetes mellitus, and contaminated beef intake 2 d before onset. Cerebrospinal fluid analysis revealed Gram-positive rod infection, and blood culture was positive for L. monocytogenes. Magnetic resonance imaging findings suggested rhombencephalitis and hydrocephalus. Treatment was started empirically and then modified according to the blood culture results. Repeated CT images were suggestive of intracranial hemorrhage. Although the patient underwent aggressive external ventricular drainage, he died of a continuing deterioration of intracranial conditions.CONCLUSIONHydrocephalus, intracranial hemorrhage, and inappropriate antimicrobial treatment are the determinations of unfavorable outcomes.

Chef and Consumer Evaluation of the Degree of Doneness of Beef Strop Loin Steaks Cooked to Six Endpoint Temperatures

ObjectivesThe objective of this study was to assess if visual degrees of doneness (DOD) are in-line with current published cooking temperatures and to assess differences in perceptions between consumers and chefs.Materials and MethodsTwenty-four paired beef strip loins (IMPS #180) representing four quality grades [Prime, Top Choice, Low Choice, Select] and an additional 12 enhanced Select strip loins were fabricated into 2.54 cm thick steaks and used in the study. Steaks were randomly assigned to one of six DOD: very rare (55°C), rare (60°C), medium-rare (63°C), medium (71°C), well done (77°C), or very well done (82°C). Following cooking, a photograph of the cut steak surface was taken immediately using a digital camera (Canon PowerShot SX620 HS). A digital survey for chefs and consumers was created for the electronic evaluation of the pictures of the internal surface of the cooked steaks. Chefs (n = 83) and consumers (n = 1134) were asked to assess the DOD of digital steak pictures representing multiple DOD and quality grades. Participants were also asked several questions related to how they determine DOD when cooking steaks, about their use of thermometers, and the temperatures they associate with each DOD.ResultsThere were no quality treatment effects (P > 0.05) for any DOD for the images evaluated. Between 14 to 44% of chefs categorized the steak images as the DOD to which it was cooked. For all DOD, 9 to 48% of chefs classified the steak images as 2 or more DOD from the DOD to which the steak was cooked. Of the 1134 consumers, 27 to 35% of consumers categorized steaks as the appropriate DOD. For all DOD, 16 to 36% of consumers identified steaks as 2 or more DOD higher or lower than the DOD that the steak was cooked. When chefs were asked how they determined DOD when cooking beef steaks, 66% of chefs reported using feel or firmness, whereas 28% stated they use a thermometer. Within the chefs that reported use of thermometers, 15% indicated the specific temperature they used was pull-off the heat temperature and 13% used carry-over cooking temperature. To assess DOD when cooking beef at home, 54% of consumers reported they used color, 16% used feel or firmness, and 10% used time. Additionally, 3% of consumers responded that they do not determine DOD. Only 16% of consumers reported using temperature or food thermometer for determining the correct DOD when cooking beef. Consumers that answered to using a food thermometer were then prompted to state the temperature they utilize, being either pull off the heat temperature (69%) or temperature following the post-cooking temperature rise (31%). However, 48 to 61% of consumers that stated they use a thermometer then reported they did not know the temperatures that correspond with each DOD. Additionally, only 14 to 32% of consumers that utilized peak temperatures matched the NCBA temperatures.ConclusionAlthough consumers do not have a good understanding of beef cooking temperatures, they are able to identify DOD of steaks cooked to specified endpoint temperatures. Additionally, chefs do not consistently use the same method when determining DOD and are unable to accurately identify DOD of steaks cooked to specified endpoint temperatures. This lack of uniformity between chefs and consumers on DOD determination can create challenges for foodservice establishments to successfully meet consumer DOD expectations.

Heat Resistance in Escherichia coli and its Implications on Ground Beef Cooking Recommendations in Canada

ObjectivesRecent reports of an extremely heat resistant but non-pathogenic beef Escherichia coli strain, AW 1.7, raised concerns over the adequacy of cooking ground beef to 71°C in Canada. The objective of this study was to assess the adequacy of the current cooking recommendations for ground beef in relation to heat resistant E. coli.Materials and MethodsIn total, 8 potentially heat resistant E. coli strains (4 generic and 4 E. coli O157:H7) from beef along with E. coli AW1.7 were included in this study. Heat resistance of the strains was first evaluated by decimal reductions at 60°C (D60°C-value), the time required to have a log reduction of the bacterial population at 60°C. The more heat resistant strains of each group (E. coli 62 and 68, and E. coli O157 J3 and C37) were further assessed for their heat resistance when grown in Lennox Broth without salt (LB-NS), LB + 2% NaCl and Meat Juice (MJ). Then, the two most heat resistant E. coli O157 strains (J3 and C37) and E. coli AW 1.7 were each introduced to extra lean ground beef (100 g) in vacuum pouches for determination of their D-values at three temperatures, 54, 57, and 60°C, from which a z-value for each strain was derived. The thermal characteristics of all three strains were fed into a predictive model to determine the process lethality of cooking burgers to 71°C with resting for up to 5 min. Finally, inactivation of the most heat resistant E. coli strain AW1.7, assessed in this study and reported in the literature, in ground beef was validated by grilling burgers containing 6.20 ± 0.24 log CFU/g of the organism to 71°C without or with a resting of 3 or 5 min.ResultsThe D60°C-values for these strains varied from 1.3 to 9.0 min, with J3 and AW1.7 being the least and most heat resistant strains, respectively. The D60°C-values for E. coli 62 and 68 were similar and were not affected by growth medium, while the heat resistance of C37, J3 and AW1.7 varied with the growth medium. When heated in extra lean ground beef (100 g) in vacuum pouches, the mean D54°C, D57°C, and D60°C-values were 44.8, 18.6 and 2.9 min for C37, 13.8, 6.9 and 0.9 min for J3, and 40.5, 9.1 6.1 min for AW1.7. The derived z- and D71°C-values were, respectively, 5.0, 5.1 and 7.3°C; and 0.022, 0.008, and 0.156 min. Burger temperatures continued to rise after being removed from heat when the target temperature was reached, by up to 5°C, and resting of 1 min would result in a destruction of 133, 374, and 14 log C37, J3 and AW1.7, estimated from process lethality. When burgers inoculated with AW1.7 were cooked to 71°C, 14 of the 15 burgers yielded no E. coli, while the 15th had a reduction of 4.5 log. Additional resting of 3 or 5 min resulted in complete elimination of AW 1.7.ConclusionIt has been predicted that 2% of E. coli from beef may carry heat resistant genes. The findings in this study, along with the very low level of total E. coli expected in ground beef in Canada, suggest that cooking ground beef to 71°C should be adequate to ensure the safety of such products.