Influence of Rapid Cooking Methods on the Survival of Trichinella spiralis in Pork Chops from Experimentally Infected Pigs

Pork chops (1.3, 2.5 or 3.8 cm thick) cooked to an internal temperature of 17 or 77°C by conventional oven, convection oven or flat grill contained no motile trichinae, whereas chops cooked to 66°C sometimes contained motile trichinae. Chops cooked by either charbroil or deep fat fry and pretreated in a microwave oven sometimes had motile trichinae even after cooking to an end point of 77°C. Chops, which had been frozen for 18 hr at -23°C and were thawed by microwave to 0°C then deep fat fried to an end point temperature, sometimes had infectious trichinae as confirmed by tests with rats and mice. Additional research is underway to verify the thermal death times and temperatures for T. spiralis larvae.     

Effects of Internal Temperature and Thickness on Palatability of Pork Loin Chops

Three thicknesses (2.54, 1.90 and 1.27 cm) of pork chops were cutl alternately from 20 paired loins of similar quality. Chops were cooked on Farberware grills or in a convection oven to internal temperatures of 60, 70 and 80°C for sensory and objective evaluations. Juiciness, percent moisture and tenderness decreased and cooking losses increased (P < 0.05) as temperature increased for both cooking methods. Pork flavor intensity increased in oven- prepared chops, while no change was observed in grilled chops at each level of increased temperature. Thickness had no effect (P > 0.05) on tenderness, juiciness or total cooking loss of oven-prepared or grilled chops. The thickest chops received the highest (P < 0.05) pork flavor scores.     

Evaluation of Microwave Cooking Procedures and Ovens for Devitalizing Trichinae in Pork Roasts

Pork roasts from pigs experimentally infected with Trichinella spiralis were cooked in five microwave ovens. Twenty-nine procedures, generally recommended by the oven manufacturers or pork interest groups, were used. Infective trichinae were present after cooking in 50 of 189 roasts. Factors affecting infectivity included procedure used, use or nonuse of post-cooking standing or temperature holding, weight of roast, and internal temperatures attained. Five visually well done roasts contained infective trichinae including one in which all five temperatures taken exceeded 76.7°C. One other infective roast, with a small red spot, also had all temperatures at or above the 76.7°C level. Recommendations are made to minimize the potential that trichinae may survive in microwaved-cooked pork.     

Effect of carbon monoxide in modified atmosphere packaging,storage time and endpoint cooking temperature on the internal color of enhanced pork

The objective of this research was to evaluate the effects of gas atmosphere, refrigerated storage time, and endpoint temperature on internal cooked color of injection-enhanced pork chops. Enhanced chops were packaged in 0.36% CO/20.34% CO₂ (CO-MAP), 80% O₂/20% CO₂ (HO-MAP), or PVC-overwrapped (PVC-OW; controls), stored at 4 °C for 0, 12, 19 or 26 days, displayed for 2 days then cooked to six endpoint temperatures (54, 60, 63, 71, 77, and 82 °C). L¹, a¹, and b¹ values, hue angle and chroma were determined on the internal cut surface of cooked chops. Chops packaged in CO-MAP had the highest a¹ values; a¹ value began increasing on day 14. The lowest hue angles occurred in chops cooked to lower endpoint temperatures. Chops in CO-MAP had lower hue angles and higher chroma than those in HO-MAP and PVC-OW. Above 71 °C, hue angle and chroma increased. Overall, CO-MAP packaged chops stored for longer time periods then cooked to lower endpoint temperatures appeared reddest. HO-MAP packaged chops were less red, did not change over time, and appeared more well done at lower endpoint temperatures than those in other gas atmospheres. CO-MAP packaged chops retained redness even after cooking at 82 °C.     

Effect of Heat Treatment and Selected Antimicrobials on the Shelf-life and Safety of Cooked, Vacuum-Packaged, Refrigerated Pork Chops

The shelf-life of refrigerated (2–4°C) pork chops inoculated with Clostridium sporogenes PA3679 and Staphylococcus aureus Z88 was examined in products sliced from loins cooked to 66°C (150°F), dipped in 5% polyphosphate blend, 2.5% potassium sorbate or 2% acetic acid solutions, vacuum-packaged and stored at 2–4°C. The effect of a second in-the-bag cooking step to 66°C (150°F) after vacuum packaging was also studied. Pork chops not reheated after packaging showed incipient spoilage after 15 days at 2–4°C, depending on surface treatment. The second cooking increased the shelf-life of refrigerated product to more than 60 days and reduced counts of inoculated cultures to undetectable levels. However, on exposure of the chops to simulated mishandling (24–25°C), clostridial growth was detected in all samples except those dipped in polyphosphate or acetic acid solutions.     

Sensory and Cooking Properties of Lamb Chops Cooked With and Without External Fat and Epimysium

When lamb loin chops with or without 0.64-cm subcutaneous fat layer and epimysium (fat-on or fat-off chops) were broiled to an internal temperature of 77°C, cooking losses were higher (P<0.05) for fat-off chops than for fat-on chops. The concentration of ether-extractable fat (g/100g cooked lean) was also higher for the cooked lean from fat-off chops while the opposite was observed for moisture. Sensory properties of the cooked lean were adversely affected by the removal of subcutaneous fat before cooking. TBA-reactive substances in a given amount of the cooked lean, after 4 days of storage at 4°C, were slightly higher (P<0.10) for the lean from fat-off chops than for the lean from fat-on chops.     

Cholesterol and Selected Attributes of Pork Tenderloin Steaks Heated by Conventional, Convection, and Microwave Ovens to Two Internal Endpoint Temperatures

Six treatment combinations for determination of cholesterol and selected quality attributes of pork tenderloin steaks were studied with three oven types (conventional, convection and microwave) and two internal endpoint temperatures (71°C and 77°C). In general, pork tenderloin steaks heated in the microwave oven had lower evaporative loss and higher drip loss. Cholesterol (wet weight basis) of the pork steaks was not affected by oven type; however, heating to the higher internal endpoint temperature (77°C) increased (concentrated) the cholesterol. On a dry weight basis, microwave-heated steaks contained more cholesterol when compared to conventional and convection-heated samples.     

RETENTION OF VITAMIN B-6, THIAMIN,VITAMIN E,AND SELENIUM IN GRILLED BONELESS PORK CHOPS PREPARED AT FIVE GRILL TEMPERATURES1

Fresh pork Canadian backs, cut into boneless pork chops, were cooked to 71C internal temperature by grilling at 93, 121, 148, 176, or 204C. Cooking times were significantly longer for chops grilled at 93C than for those grilled at the higher temperatures. Yield, moisture, and crude fat values of the chops in the different treatments were similar. Chops grilled at 204C had significantly lower retention values for thiamin and vitamin E and had lower mean retention values for vitamin B-6. Retention values for selenium were similar for all treatment groups. Shorter cooking times along with higher vitamin retentions were obtained in boneless pork chops grilled at 121, 148, and 176C.     

Effect of carbon monoxide in modified atmosphere packaging, storage time and endpoint cooking temperature on the internal color of enhanced pork

The objective of this research was to evaluate the effects of gas atmosphere, refrigerated storage time, and endpoint temperature on internal cooked color of injection-enhanced pork chops. Enhanced chops were packaged in 0.36% CO/20.34% CO₂ (CO-MAP), 80% O₂/20% CO₂ (HO-MAP), or PVC-overwrapped (PVC-OW; controls), stored at 4 °C for 0, 12, 19 or 26 days, displayed for 2 days then cooked to six endpoint temperatures (54, 60, 63, 71, 77, and 82 °C). L^*, a^*, and b^* values, hue angle and chroma were determined on the internal cut surface of cooked chops. Chops packaged in CO-MAP had the highest a^* values; a^* value began increasing on day 14. The lowest hue angles occurred in chops cooked to lower endpoint temperatures. Chops in CO-MAP had lower hue angles and higher chroma than those in HO-MAP and PVC-OW. Above 71 °C, hue angle and chroma increased. Overall, CO-MAP packaged chops stored for longer time periods then cooked to lower endpoint temperatures appeared reddest. HO-MAP packaged chops were less red, did not change over time, and appeared more well done at lower endpoint temperatures than those in other gas atmospheres. CO-MAP packaged chops retained redness even after cooking at 82 °C.     

Effects of Potassium Sorbate, Sodium Acetate, Phosphates and Sodium Chloride Alone or in Combination on Shelf Life of Vacuum-Packaged Pork Chops

Microbiological and some physical and chemical effects of treating pork chop surfaces with sodium acid pyrophosphate, a commercial phosphate blend, potassium sorbate and phosphate/sorbate/sodium acetate solutions, with or without sodium chloride, before packaging were studied in pork chops vacuum-packaged and stored at 2–4°C for 10 weeks. All treatments containing potassium sorbate reduced (P<0.05) counts of mesophiles, psychrotrophs, EnterobacteriaCeae, facultative anaerobes, and lactobacilli. Treatment of chops with 10% phosphates/ 10% potassium sorbate solutions improved pork color and decreased purge. Potassium sorbate alone reduced microbial counts more than it did when combined with phosphates, but chops were darker and had more exudate (P<0.05). Combined use of 10% phosphates/10% potassium sorbate extended shelf life in vacuum-packaged fresh pork chops to 10 weeks at 2–4°C compared with 4 weeks for untreated pork and protected meat color.     

Cooking loss and juiciness of pork in relation to raw meat quality and cooking procedure

The study comprised two experiments with the aim to investigate the influence of raw meat quality and cooking procedure on cooking loss and juiciness of pork. The first experiment determined the cooking loss at 60, 70 and 80 °C centre temperature of 10 raw meat qualities (defined according to ultimate pH, drip loss, breed and rearing conditions) when cooked as steaks on a pan or as a roast in oven at a oven temperature of 90 or 190 °C. The differences in cooking loss between the raw meat qualities and the cooking procedures did decrease as the centre temperature increased and were almost negligble at 80 °C. Low water holding capacity (WHC) and low pH resulted in high cooking loss while no difference in cooking loss was observed between meat having medium or high WHC and pH. In the second experiment four raw meat qualities (standard, Duroc, low pH and heavy carcass weight) chosen from the first experiment to ensure a wide variation in cooking loss, were cooked in oven at 90 or 190 °C oven temperature. Juiciness was assessed three times during the chewing process. The results suggested that juiciness experienced initially in the chewing process depended only on the water content of the meat, whereas juiciness experienced later in the chewing process was determined by a combination of the water and intramuscular fat contents and the saliva production during chewing.     

An Approach to Safe Microwave Cooking of Pork Roasts Containing Trichinella spiralis

Pork roasts, obtained from pigs experimentally infected with Trichinella spiralis, were cooked at 50% power in four microwave ovens. The attainment of consistently well done roasts is the primary requisite for development of safe cooking methods. Recommendations for cooking of trichinous pork roasts, with adequate margins of safety, are made for each oven.     

Bioassay Analysis of Dry-Cured Ham Processed to Affect Trichinella spiralis

Effects of curing time and temperature to destroy Trichinella spiralis in dry-cured hams were evaluated. Five muscle groups from small, medium and large, short-cure hams and large, bag-cure hams were subjected to a digestion technique to determine the number of spiralis larvae. Trichinae in small hams held at 10°C for 90 days, in medium hams at 23.9 and 32.2°C for 35 and 11 days, and in large hams at 10 and 23.9°C for 90 and 35 days, respectively, were rendered non-infective. Medium hams contained a number of trichinae after 90 days at 10°C. Bag-cure hams aged at 23.9°C for 35 days were free of trichinae. Results could indicate insufficient aging time at 10°C for medium hams and the need for reviewing current USDA-FSIS regulations for the destruction of T. spiralis.     

Effect of Trim Level, Cooking Method, and Chop Type on Lipid Retention, Caloric Content, and Cholesterol Level in Cooked Pork

The effect of external fat trim on fat, caloric, and cholesterol content of pork lean was investigated. Paired top-loin chops (TL), rib chops (RC) and blade steaks (BS) were obtained and trimmed free of all subcutaneous fat before (NF) or after (SF) cooking. Cuts were cooked to 71°C by roasting, pan-frying, braising or microwaving. Lean from TL chops having SF contained more fat and calories and similar amounts of cholesterol compared with NF chops, regardless of cooking method. Few differences were observed in fat and caloric content of RC and BS cooked with SF versus NF, perhaps due to seam fat. Eliminating external fat prior to cooking reduced fat and caloric content of pork lean.     

Changes in the texture,microstructures, colour and volatile compounds of pork meat loins during superheated steam cooking

We evaluated changes in the texture, colour, microstructure and volatile compounds of pork loins after superheated steam (SHS) cooking at 120, 140, 160 or 180 °C for 5, 10, 15 and 20 min. Results showed that the texture changed significantly with heating temperature and time. Hardness increased significantly with increasing temperature above 140 °C. Scanning electron microscopy micrographs showed that cooked pork with SHS had more complete muscle fibre bundle structure than that of pork in HA. The L* value indicating colour was significantly increased during the early period and then decreased, whereas the a* and b* values showed a continuous increase. Ninety-five volatile compounds were identified in cooked pork from SHS by gas chromatography/mass spectrometry with solid-phase microextraction. The amount of volatile compounds increased during cooking and decreased as cooking time increased and was well retained at 140 °C. Considering those variations, samples cooked at 140 °C showed better quality attributes.     

Changes in Microflora and Other Characteristics of Vacuum-packaged Pork Loins irradiated at 3.0 kGy

Effects of 3.0-kGy irradiation on microflora and other attributes of fresh, vacuum-packaged pork loins were examined during storage (2–4°C, 98 days) and mishandling (24–25°C, 24 and 48 hr). Shelf life of pork chops from irradiated loins was determined at 5°C. Irradiated loins kept at 2–4°C tested negative for Salmonella spp., Campylobacter spp., Clostridium perfringens and Staphylococcus aureus. Yersinia spp. was detected in pork chops held at 5°C; this organism, C. perfringens and Aeromonas spp. were present in abused samples. In two irradiated samples Listeria monocytogenes was found. Irradiation reduced aerobic, anaerobic and Aeromonas spp. counts; lactobacilli were least affected. Chemical spoilage began after 91 days at 2–4°C. With irradiation, TBA values were unaffected but Hunter a color values increased.     

Spectra of Pigments Responsible for Pink Color in Pork Roasts Cooked to 65 or 82°C

Undenatured oxymyoglobin and deoxymyoglobin were the pigments responsible for pink color in pork roasts cooked to 65°C. Roasts cooked to 82°C had gray internal color after cooking, but panelists noted development of pink internal color after refrigerated storage. Reflectance spectra of pink slices from roasts cooked to 82°C, then stored for 12 days at 2°C, were characteristic of denatured globin hemo-chromes or related nonnitrosyl hemochromes.     

Thermal Inactivation of Salmonella spp. and Listeria innocua in the Chicken Breast Patties Processed in a Pilot-Scale Air-Convection Oven

ABSTRACT Salmonella spp. or Listeria innocua containing chicken patties were processed via a pilot-scale air-convection oven to a final temperature of 55 to 80 °C. Thermal processing was conducted at an air temperature of 149 °C, an air velocity of 7.1 to 12.7 m3/min, and a wet bulb temperature of 39 to 98 °C. The cooking time was correlated with cooking conditions using a standardized least square regression model. The models were developed to correlate cooking time and the thermal inactivation of Salmonella or Listeria with cooking conditions. The thermal lethality of Salmonella and Listeria increased with increasing product temperature and wet bulb temperature. This study bridged the gap between laboratory studies and commercial applications and will help commercial processors to evaluate and validate their thermal processes.     

Cholesterol Content and Sensory Analysis of Ground Pork as Influenced by Fat Level and Heating

Eight treatment combinations for the formulation and heating of fresh ground pork were investigated: four raw fat levels (4, 9, 18, 23%) and two internal end point temperatures (71°C and 77°C). In the raw state, ground pork containing 4 or 9% fat contained less cholesterol, more moisture and was judged to be more red than samples containing 18 or 23% fat. Tenderness, juiciness and amount of mouthcoating increased as fat level in the cooked patties increased. Internal end point temperature (71°C or 77°C) did not affect sensory scores of cooked pork patties. Cooked patty cholesterol content (wet weight) did not differ among the four fat levels. High-fat ground pork retained less cholesterol than low-fat ground pork.     

Spermine and spermidine concentrations in pork loin as affected by storage, curing and thermal processing

Spermine and spermidine concentrations in pork loin as affected by three factors used in food processing [immersion-curing (10% brine: NaNO₂ and NaCl content of 0.6 and 99.4 g/l, respectively, and 20% brine: NaNO₂ and NaCl content of 0.6 and 199.4 g/l, respectively), boiling and grilling (70 °C core temperature) and storage of raw loin chops (“non-stored” versus storage at 4 °C for 5 days)] were studied. Spermidine and spermine concentrations of the “non-stored” raw loin chops were 2.7±0.7 and 19.8±1.5 mg/kg (fresh weight), respectively. Storage effects were negligible. Curing in 20% brine resulted in statistically significant spermidine decreases as compared to non-cured meat (p=0.04). Statistically significant decreases of spermine were observed for curing in 20% brine as compared with 10% brine (p=0.08), and boiling of meat in an equal amount of water compared to raw meat and grilled meat (p=0.03). Combined curing in 20% brine and cooking in an equal amount of water resulted in 2.0±1.0 mg/kg spermidine and 14.4±2.6 mg/kg spermine. Combined common food processing techniques resulted in a decrease of spermine and spermidine concentrations in pork loin of maximum 26% only. The latter should be considered as relevant for consumers for which the dietary polyamine uptake is critical.