Thermal stress responses of two sympatric crayfishes in Louisiana, Procambarus clarkii Girard, 1852 and Procambarus zonangulus Hobbs & Hobbs, 1990 (Decapoda: Astacoidea: Cambaridae)

Water temperature is an important abiotic component in farmed and wild crayfish habitats as it influences individual and population characteristics including growth, metabolic activity, and overall population vigor. Thermal limits, however, have not been established for the two commercially important crayfishes in Louisiana, the red swamp crayfish Procambarus clarkii (Girard, 1852) and the southern white river crayfish P. zonangulus (Hobbs & Hobbs, 1990). We aimed to determine the thermal stress responses for the two species. Thermal stress was examined by the critical thermal maxima (CTmax) for crayfish acclimated to 24, 27, or 30 °C for two weeks prior to experimentation. Water temperature in all acclimation trials was increased 1 °C h–1 and the end-point temperature for an individual was determined by the failure of righting response within 30 seconds. CTmax values (±SD) for P. clarkii acclimated at 24, 27, and 30 °C were 39.5 ± 0.5, 39.1 ± 0.3, and 39.4 ± 0.7 °C respectively, and 39.8 ± 0.8, 38.8 ± 0.8, and 39.0 ± 0.6 °C for P. zonangulus. CTmax did not differ significantly between species in any of the acclimation treatments. Thermal stress was also examined by measuring P. clarkii and P. zonangulus hemolymph glucose concentration every two hours for crayfish acclimated at 26 °C for two weeks and water temperature increased 1 °C h–1. Hemolymph glucose concentration began to increase at 36 °C in P. zonangulus and 38 °C in P. clarkii. Large increases in mean hemolymph glucose concentration (±SE) were observed in both P. clarkii (67.19 mg–dl ± 24.55) and P. zonangulus (74.11 mg–dl ± 18.04) at 40 °C.

Sintering Properties of Magnetic Separation Nonferrous Metallurgical Tailings

In this paper, the tailings produced by non-ferrous metallurgy were magnetically separated to obtain magnetic separation tailings. The sintering performance of magnetic separation tailings was studied by sintering cup experiment platform. In the research process, the differences in sintering process of different magnetic separation tailings were compared, including vertical sintering speed, sintering coefficient, drum strength, finished product rate, end point temperature and other sintering indexes. At the same time, the obtained sinter was subjected to chemical analysis to obtain its specific components. The influence of magnetic separation tailings with different contents on sintering was obtained by ore blending. The experimental results showed that the copper tailings are not sintered and the yield is only 0%. Tin tailings are not sintered and the yield is only 22.30%. The aluminum tailings can be sintered into lumps with a yield of only 57.10%. As the proportion of magnetic separation tailings increases, the vertical sintering speed decreases, the sintering utilization coefficient decreases, the sinter drum index decreases, the yield decreases, the sinter grade decreases, and the SiO2, S and P contents increase. In actual production, the proportion of magnetic separation tailings should be controlled below 10%.

Detection of Differences in Cook Loss and Tenderness of Aged Pork Chops Cooked to Differing Degrees of Doneness Using Sous-Vide

ObjectivesThe objective was to determine the ability to detect differences in cook loss and Warner-Bratzler shear force (WBSF) value between chops aged for differing time periods and cooked to varying degrees of doneness in a sous-vide style cooker.Materials and MethodsLoins (n = 68) from pigs humanely slaughtered at the University of Illinois Meat Science Laboratory were separated between the 10th and 11th rib into anterior and posterior sections. The posterior section was cut into 6 separate 2.54 cm thick chops. The middle 4 chops were randomly designated for aging of 3 d and cooked to 63°C, aged 7 d and cooked to 63°C, aged 14 d and cooked to 63°C, or aged 14 d and cooked to 71°C. Chops (n = 272) were cooked by placing them in a water bath with an immersion circulator set to the desired end-point temperature for 90 min. Cook loss was calculated for each chop by measuring initial and final weight, and accounting for packaging weight. Four cores measuring 1.25 cm in diameter were cut parallel to the muscle fibers from each chop and analyzed for WBSF. Data were analyzed using a 1-way ANOVA. Least squares means were separated using the probability of difference (PDIFF) option in the MIXED procedure of SAS.ResultsCook loss increased as aging period or degree of doneness increased. Among chops cooked to 63°C, chops aged 3 d had 1.14% units less (P < 0.01) cook loss than those aged 7 d, and chops aged 7 d had 1.13% units less (P < 0.01) cook loss than those aged 14 d. Among chops aged for 14 d, chops cooked to 71°C had 10.06% units greater (P < 0.001) cook loss than chops cooked to 63°C. Differences in tenderness were also detected between aging periods. Among chops cooked to 63°C, chops aged 3 d required 0.27 kg more (P = 0.02) force to shear than those aged 7 d, but chops aged 7 d did not differ (P = 0.15) from those aged 14 d. End-point cooking temperature had a greater effect on tenderness, with chops aged 14 d and cooked to 71°C requiring 0.83 (P < 0.001) kg more force than those aged 14 d and cooked to 63°C. Previous studies have reported a decrease in Warner-Bratzler shear force between 7.10–21.29% when comparing early (1–3 d) and mid (7 or 9 d) aging and decreased between 3.53–15.38% when comparing mid and late (14–21 d) aging. In the present study, Warner-Bratzler shear force decreased 9.00% from early-to-mid aging and 5.86% from mid-to-late aging.ConclusionOverall, these data indicate sous-vide is an acceptable cooking method for use in experiments as expected differences in cook loss and WBSF were detected in chops aged to differing time points or cooked to differed degrees of doneness.

TECHNICAL NOTE: A method for detection of differences in cook loss and tenderness of aged pork chops cooked to differing degrees of doneness using sous-vide

The objective was to determine the ability to detect differences in cook loss and Warner–Bratzler shear force (WBSF) values between chops aged for differing time periods and cooked to varying degrees of doneness with in a sous-vide style cooker. Loins from pigs (HCW = 96 kg) humanely slaughtered at the University of Illinois Meat Science Laboratory were separated between the 10th and 11th rib into anterior and posterior sections. The posterior section was cut into 6 separate 2.54-cm-thick chops. The middle 4 chops were randomly designated for aging of 3 d and cooked to 63 °C, aged 7 d and cooked to 63 °C, aged 14 d and cooked to 63 °C, or aged 14 d and cooked to 71 °C. Chops were cooked by placing them in a water bath with an immersion circulator set to the desired end-point temperature for 90 min. Cook loss was calculated for each chop by measuring initial and final weight, and accounting for packaging weight. Four cores measuring 1.25 cm in diameter were cut parallel to the muscle fibers from each chop and analyzed for WBSF. Data were analyzed using a 1-way ANOVA. Least squares means were separated using the probability of difference option in the MIXED procedure of SAS. Among chops cooked to 63 °C, chops aged 3 d has less (P < 0.01) cook loss than those aged 7 d, and chops aged 7 d had less (P < 0.01) cook loss than those aged 14 d. Among chops aged for 14 d, chops cooked to 71 °C had greater (P < 0.001) cook loss than chops cooked to 63 °C. Differences in tenderness were also detected between aging periods. Among chops cooked to 63 °C, chops aged 3 d required more (P = 0.02) force to shear than those aged 7 d, but chops aged 7 d did not differ (P = 0.15) from those aged 14 d. Chops aged 14 d and cooked to 71 °C required (P < 0.0001) more force than those aged 14 d and cooked to 63 °C. Overall, these data indicate that sous-vide is an acceptable cooking method for use in experiments as expected differences in cook loss and WBSF were detected in chops aged to differing time points or cooked to differed degrees of doneness.

Changes in Lighting Source Can Produce Inaccurate Assessment of Visual Poultry Doneness and Induce Consumers To Eat Undercooked Ground Turkey Patties

ABSTRACT Undercooked poultry is a potential source of foodborne pathogens, such as Salmonella and Campylobacter. The best way to avoid eating undercooked poultry is to use a food thermometer during cooking. However, consumers who cook poultry often use visual appearance for determining doneness, which relies on extrinsic factors, including lighting conditions. Because the United States recently mandated changes in lighting to promote energy conservation, this study evaluated the effect of lighting sources on consumer perceptions of doneness and willingness to eat cooked poultry patties. Consumers (n = 104) evaluated validated photographs of turkey patties cooked to different end point temperatures (57 to 79°C) and rated the level of perceived doneness and willingness to eat each sample. Evaluations were conducted under different lighting sources: incandescent (60 W, soft white), halogen (43 W, soft white), compact fluorescent lamp (13 W, soft white), light-emitting diode (LED; 10.5 W, soft white), and daylight LED (14 W). Lighting changed perception of doneness and willingness to eat the patties, with some of the energy-efficient options, such as LED and halogen making samples appear more done than they actually were, increasing the willingness to eat undercooked samples. This poses a risk of consuming meat that could contain bacteria not killed by heat treatment. Recent changes in lighting regulations can affect lighting in homes that affects perceptions of poultry doneness, requiring that educators place extra emphasis on the message that properly using a meat thermometer is the only way to ensure meat is cooked to a safe end point temperature.

Food Handling Behaviors Observed in Consumers When Cooking Poultry and Eggs

ABSTRACT Previous research has shown that many consumers do not follow recommended food safety practices for cooking poultry and eggs, which can lead to exposure to Salmonella and Campylobacter. Past research has been done primarily through surveys and interviews, rather than observations. The objective of this project was to determine through observations whether consumers follow food safety guidelines. Consumers (n =101) divided among three locations (Manhattan, KS; Kansas City, MO area; and Nashville, TN) were observed as they prepared a baked whole chicken breast, a pan-fried ground turkey patty, a fried egg, and scrambled eggs. The end point temperature for the cooked products was taken (outside the view of consumers) within 30 s after the consumers indicated they were finished cooking. Thermometer use while cooking was low, although marginally higher than that of some previous studies: only 37% of consumers used a thermometer for chicken breasts and only 22% for turkey patties. No one used a thermometer for fried or scrambled eggs. Only 77% of the chicken and 69% of the turkey was cooked to a safe temperature (165°F [74°C]), and 77% of scrambled and 49% of fried eggs reached a safe temperature (160°F [71°C]). Safe hand washing was noted in only 40% of respondents after handling the chicken breast and 44% after handling the ground turkey patty. This value decreased to 15% after handling raw eggs for fried eggs and to 17% for scrambled eggs. These results show that there is a high prevalence of unsafe behaviors (undercooking and poor hand washing technique) when cooking poultry and eggs and a great need for improvement in consumer behavior with poultry and eggs.