Residual triose phosphate isomerase activity and color measurements to determine adequate cooking of ground beef patties

The objectives were to (i) compare the use of triose phosphate isomerase (TPI) activity and internal color scores for determination of cooking adequacy of beef patties and (ii) determine the effect of frozen storage and fat content on residual TPI activity in ground beef. Ground beef patties (24.4% fat) were cooked to five temperatures ranging from 60.0 to 82.2 degrees C. TPI activity decreased as beef patty cooking temperature was increased from 60.0 to 71.1 degrees C; however, no difference (P > 0.05) in activity (6.3 U/kg meat) was observed in patties cooked to 71.1 degrees C and above. Degree of doneness color scores, a* values and b* values, of ground beef patties decreased as internal temperature was increased from 60.0 to 71.1 degrees C; however, temperature had no effect on L* values. TPI activity in raw ground beef after five freeze-thaw cycles did not differ from the control. Three freeze-thaw cycles of raw ground beef resulted in a 57.2% decrease in TPI activity after cooking. TPI activity of cooked beef increased during 2 months of frozen storage, but TPI activity in ground beef stored for 3 months or longer did not differ from the unfrozen control. While past research has shown color to be a poor indicator of adequate thermal processing, our results suggest that undercooked ground beef patties could be distinguished from those that had been adequately cooked following U.S. Department of Agriculture guidelines using residual TPI activity as a marker.     

Optimising the frying temperature of gluten balls using response surface methodology

The continuous frying process of gluten balls involved three consecutive deep frying pans. The effects of the temperatures of the first and the second deep frying pans on the quality indices of the obtained fried gluten balls, including expansion volume, expansion ratio, measured value of textural property, Hunter colour b value, and sensory evaluation score, were investigated using response surface methodology while fixing the temperature of the third deep frying pan at 195±3°C. Based on the obtained sensory evaluation scores, the peak force and brittleness breakdown of textural properties, as well as Hunter colour b value of the fried gluten balls, it was found that the optimum temperature ranges for the first and the second deep frying pans were 130–143°C and 155–161°C, respectively. © 1998 SCI.     

Color Changes of Chicken Leg Patties Due to End-point Temperature, Packaging and Refrigerated Storage

Patties of broiler leg muscle were heated to end-point temperatures (EPT) of 60, 65, 70, 75, 80 or 85°C, packaged in polyethylene bags or vacuum skin packs and stored at 4°C for up to 14 days. As EPT increased, lightness (“L”) and yellowness (“b”) increased whereas redness (“a”) decreased. Patty top surface center color “L” and “a” values correlated highly with the interior cut surface values. Patties stored in plastic zipper bags tended to show a lower “b” (P<0.05) reading than patties stored in vacuum skin packs and plastic film. Storage for 2 wk at 4°C increased “L”, and decreased “a” and “b” for all patties. As EPT increased, the color difference (AE) at the interior cut surface of patties heated to lower EPT and those heated to 85°C were reduced.     

INFLUENCE OF FRY COLOR ON QUALITY OF COATED BROILER THIGHS

An untrained sensory panel judged preference, acceptability, and color of equally cooked, breaded broiler thighs prepared at frying temperatures of 163, 177, and 191°C. Fry color (shade) was perceived by panelists as being darker (P < .01) at higher frying temperatures. Objective color measurement indicated that coated parts decreased in lightness (Hunter L), increased in redness (a), and decreased in yellowness (b) with increasing frying temperature. Although a frying temperature of 163°C is recommended for preparing fried, breaded broiler parts, panelists preferred the darker breading color produced at the higher frying temperatures (177 and 191°C).     

Effects of processing conditions on the quality of vacuum‐fried carrot chips

The effects of pretreatment and vacuum frying conditions on the quality of fried carrot chips were studied. The moisture and oil contents of fried carrot chips were significantly (p < 0.05) reduced when blanched carrot slices were pretreated by immersion in fructose solution and freezing prior to vacuum frying. Furthermore, more uniform porosity was observed on the vertical cross‐section of carrot chips when examined by scanning electron microscopy. During vacuum frying, the moisture content, colour and breaking force of carrot chips decreased while the oil content increased with increasing frying temperature and time. However, there was no apparent change in Hunter ΔE with time when the frying temperature was below 100 °C and the frying time was below 25 min. Results of this study suggest that vacuum frying at moderate temperature (90–100 °C) for 20 min can produce carrot chips with lower moisture and oil contents as well as good colour and crispy texture. Copyright © 2005 Society of Chemical Industry     

Natural Antioxidant Extract from Fenugreek (Trigonella foenumgraecum) for Ground Beef Patties

Ground beef patties (75% lean) containing synthetic antioxidants, or Fenugreek (Trigonella foenumgraecum) extracts were cooked to internal temperature 70°C, and evaluated for storage stability at 4°C. Thiobarbituric acid values of raw or cooked samples containing fenugreek extracts were lower than controls (P<0.05). Fenugreek extracts delayed the induction period of oxidative rancidity. No differences were observed in psychrotrophic bacterial counts, and samples containing fenugreek extracts had lower Hunterlab “a” and higher “b” values. Samples with Fenugreek extracts had better oxidative stability and Fenugreek may be a promising natural antioxidant source.     

Process optimization and consumer acceptability of salted ground beef patties cooked and held hot in flavored marinade

Food safety is paramount for cooking hamburger. The center must reach 71 °C (or 68 °C for 15 s) to assure destruction of E. coli O157:H7 and other food pathogens. This is difficult to achieve during grilling or frying of thick burgers without overcooking the surface. Thus, the feasibility of partially or completely cooking frozen patties in liquid (93 °C water) together with hot holding in liquid was investigated. Initial studies demonstrated that compared to frying, liquid cooking decreased (P < 0.05) patty diameter (98 compared with 93 mm) and increased (P < 0.05) thickness (18.1 compared with 15.6 mm). Liquid cooked patties had greater weight loss (P < 0.05) immediately after cooking (29 compared with 21%), but reabsorbed moisture and were not different from fried patties after 1 h hot water holding (61 °C). Protein and fat content were not affected by cooking method. However, liquid cooked patties were rated lower (P < 0.05) than fried patties for appearance (5.7 compared with 7.5) and flavor (5.9 compared with 7.5). An 8-member focus group then evaluated methods to improve both appearance and flavor. Salted, grill-marked patties were preferred, and caramel coloring was needed in the marinade to obtain acceptable flavor and color during liquid cooking or hot holding. Patties with 0.75% salt that were grill-marked and then finish-cooked in hot marinade (0.75% salt, 0.3% caramel color) were rated acceptable (P < 0.05) by consumers for up to 4 h hot holding in marinade, with mean hedonic panel ratings > 7.0 (like moderately) for appearance, juiciness, flavor, and texture. PRACTICAL APPLICATION: Grill-marked and marinade-cooked ground beef patties reached a safe internal cooking temperature without overcooking the surface. Burgers cooked using this method maintained high consumer acceptability right after cooking and for up to 4 h of hot holding. Consumers and foodservice operations could use this method without specialized equipment, and instead use inexpensive and common equipment such as a soup pot or a restaurant steam table. Use of marinades (salt/caramel color or others) in this cooking and holding method provides a nearly endless culinary flavoring opportunity.     

Effects of frying parameters on the colour development of fried potatoes

The effects of frying time and temperature on the colour development of potatoes during frying was studied. Potato disks 0.025 m in diameter and 0.005 m thick were used. Sunflower oil was used as a frying medium at temperatures 150 °C, 160°C, 170°C and 180°C. Colour parameters of Hunter L and b values followed first-order reaction kinetics during frying. The temperature dependence of the rate constants for Hunter L and b values showed good agreement with Arrhenius relation, the activation energies, Ea, being equal to 22.67 kcal/mol and 17.13 kcal/mol, respectively. Hunter a value increased as frying time and/or temperature increased. A multiple regression equation was developed for total colour change as a function of time and temperature. The increase in time and temperature increased total colour change. Received: 22 October 1999     

Endpoint Temperature, Internal Cooked Color, and Expressible Juice Color Relationships in Ground Beef Patties

Ground beef patties from A- and E-maturity carcasses and imported trimmings were cooked to 55 to 77°C. Internal patty color became less red as endpoint temperature increased. However, some patties cooked to lower temperatures turned brown prematurely. Visual evaluation of internal patty color was not an accurate indicator of patty doneness. Raw material source had little effect on internal patty color. Expressible juices from imported trimmings were less red than those from A-and E-maturity carcasses. Expressible juice became less red and more yellow with increasing endpoint temperature; however, expressible juice never “ran clear.” A more appropriate guideline would be “cook until juices lack redness.”     

Influence of Cooking Rate, Endpoint Temperature, Post-cook Hold Time, and Myoglobin Redox State on Internal Color Development of Cooked Ground Beef Patties

ABSTRACT: Three experiments investigated cooking rate, endpoint temperature, post-cook holding time, and raw myoglobin redox-state effects on ground beef internal cooked color. In Experiment 1, patties were cooked to endpoint temperatures of 65.6°C, 71.1°C, 76.7°C, 82.2°C, or 87.8°C rapidly (1°C/s), slowly (0.2°C/s), or rapidly with 6-min post-cook holding time at 104°C. Patties cooked slowly to less than 76.7°C were more well done ( P < 0.05) in appearance than those cooked rapidly. Rapidly-cooked patties cooked to less than 82.2°C and held for 6 min after cooking had less pinkness, more myoglobin denaturation, and a more well-done appearance than did rapidly cooked patties with no holding time ( P < 0.05). In Experiment 2, increasing post-cook holding time (1, 3, 6, or 12 min) after rapid cooking to 71.1°C, 76.7°C, or 82.2°C decreased pinkness and increased myoglobin denaturation ( P < 0.05), with no benefit beyond 6 min ( P > 0.05). In Experiment 3, patties cooked rapidly to 71.1°C, 76.7°C, or 82.2°C from a predominantly raw oxymyoglobin state were less pink and had more denatured myoglobin than did those cooked from a predominantly deoxymyoglobin state ( P < 0.05). Prediction equations determined that 80% of myoglobin must be denatured to create a well-done appearance. Using a slow cooking rate, post-cook holding time, or cooking from a highly oxygenated state will increase myoglobin denaturation and foster a well-done appearance.     

Effects of processing conditions on the quality of vacuum fried apple chips

The effects of pretreatment and processing conditions on the quality of vacuum fried apple chips were studied. As blanched apple slices were pretreated by immersing in fructose solution and freezing prior to vacuum frying, more uniform porosity was observed on the surface (or cross-section) of apple chips as examined by scanning electron microscopy (SEM). During vacuum frying, the moisture content and breaking force of apple chips decreased with increasing frying temperature and time while the oil content increased. The L values of fried apple chips decreased apparently with increasing frying temperature. However, when apple slices were fried at 100°C for up to 20 min, both a and b values increased rapidly. Statistical analysis with the central composite rotatable design showed that the moisture content, oil content, color, and breaking force of apple chips were significantly (P⩽0.05) correlated with concentration of immersing sugar solution, frying temperature and frying time. Based on surface responses and contour plots, optimum conditions were: vacuum frying temperature of 100–110°C, vacuum frying time of 20–25 min, and immersing fructose concentration of 30–40%.     

Response Surface Methodology Study for Optimization of Effects of Fiber Level, Frying Temperature, and Frying Time on Some Physicochemical, Textural, and Sensory Properties of Wheat Chips Enriched with Apple Fiber

In this study, wheat chips enriched with apple fiber were produced, and response surface methodology was used for the determination of the simultaneous effects of processing variables selected as fiber level (0–15 %), frying temperature (160–180 °C), and frying time (40–60 s) on some physicochemical, textural, and sensorial properties of chips. Ridge analysis was conducted to determine the optimum levels of processing variables. Predictive regression equations with high coefficient of determination (R ²?≥?0.728) were constructed. Addition of apple fiber increased the dry matter; ash content; L, a, and b values of samples, while increase of frying temperature caused decrease of the hardness values. Overall acceptability of chips enriched with apple fiber decreased with the increase of frying temperature, but wheat chips enriched with apple fiber and fried at low temperatures received highest sensory score. Ridge analysis showed that maximum taste score would be attained at fiber level?=?15 %, frying temperature?=?170 °C and frying time?=?40 s.     

Optimization of processing conditions for vacuum frying of high quality fried plantain chips using response surface methodology (RSM)

Optimization of processing conditions (temperature 122 to 136°C, vacuum pressure 9.91 to 19.91 cmHg, and frying time 3 to 9 min) during vacuum frying of plantain chips was investigated using a Box-Behnken experimental design with response surface methodology (RSM). Models for various responses were developed and optimized frying conditions using numerical solutions were established. Optimized vacuum fried samples were compared with atmospheric fried samples based on the concept of equivalent thermal driving force (ETDF). Frying parameters had significant (p<0.05) effects on the moisture content, texture, and color with a coefficient of determination (R ²) for quadratic model responses varying between 0.53 and 0.99. Optimum vacuum frying conditions for plantain chips were a frying temperature of 133°C, vacuum pressure of 9.91 cmHg, and frying time of 6 min based on desirability concepts. Vacuum fried plantain chips had more acceptable sensory properties, based on ETDF values, than atmospheric fried samples.     

Effects of deep‐fat frying temperature on antioxidant properties of whole wheat doughnuts

The total phenolic (TP) content, phenolic acid composition and in vitro antioxidant capacity of whole wheat doughnuts fried at 120–180 °C were determined to identify the effects of frying temperature. Significant differences (P < 0.05) in TP content were observed between doughnuts fried at different temperatures. The TP content of doughnuts decreased significantly when doughnuts were deep‐fat fried. The TP content of doughnuts increased with elevation with frying temperatures. These increases in TP content of doughnuts were also detected in the determination of individual phenolic compounds using HPLC. DPPH radical and iron‐chelating capacity of deep‐fat fried doughnuts exhibited increases with elevation of frying temperature from 120 to 180 °C. Deep‐fat frying at 120 °C lowered lipid peroxidation inhibition capacity of doughnuts prepared from both refined flour and whole‐grain meals and increased consistently with increased frying temperature from 120 to 180 °C. Moderate deep‐fat frying temperature would increase the content and activity of antioxidants of doughnuts.     

Effects of Metmyoglobin Reducing Activity and Thermal Stability of NADH‐Dependent Reductase and Lactate Dehydrogenase on Premature Browning in Ground Beef

Premature browning is a condition wherein ground beef exhibits a well‐done appearance before reaching the USDA recommended internal cooked meat temperature of 71.1 °C; however, the mechanism is unclear. The objectives of this study were: (1) to determine the effects of packaging and temperature on metmyoglobin reducing activity (MRA) of cooked ground beef patties and (2) to assess the effects of temperature and pH on thermal stability of NADH‐dependent reductase, lactate dehydrogenase (LDH), and oxymyoglobin (OxyMb) in‐vitro. Beef patties (lean: fat = 85:15) were packaged in high‐oxygen modified atmosphere (HiOX‐MAP) or vacuum (VP) and cooked to either 65 or 71 °C. Internal meat color and MRA of both raw and cooked patties were determined. Purified NADH‐dependent reductase and LDH were used to determine the effects of pH and temperature on enzyme activity. MRA of cooked patties was temperature and packaging dependent (P < 0.05). Vacuum packaged patties cooked to 71 °C had greater (P < 0.05) MRA than HiOX‐MAP counterparts. Thermal stability of OxyMb, NADH‐dependent reductase, and LDH were different and pH‐dependent. LDH was able to generate NADH at 84 °C; whereas NADH‐dependent reductase was least stable to heat. The results suggest that patties have MRA at cooking temperatures, which can influence cooked meat color.     

Application of electron‐beam irradiation pasteurization of ground beef,from steers fed vitamin E fortified diets: microbial and chemical effects

The effects of vitamin E supplementation of diets and electron‐beam irradiation (EBI) processing of ground beef patties on microbial and chemical qualities were investigated during 21 days of storage at 4 °C. Oxidative damage to lipids induced by EBI in ground beef patties containing different fat contents was first determined at 3 day intervals throughout a 7 day storage period at 4 °C. Significantly (P ≤ 0.05) higher values for thiobarbituric acid reactive substances (TBARS) were detected in beef patties of higher fat content (ie at 17 and 30%), which was further enhanced by irradiation at 5 kGy. Since lipid oxidation proceeded to a greater extent in beef patties with higher fat levels, ground beef patties of 30% fat were prepared from steers fed basal (diet I) or basal + 500 IU (diet II) of the antioxidant (vitamin E) supplemented diets. Plasma vitamin E concentrations in cattle fed diets I and II were 1.58 ± 0.42 µg ml^?1 and 2.49 ± 0.40 µg ml^?1 respectively. Patties were processed with three doses (2, 5, or 10 kGy) of EBI and compared with non‐irradiated patties. Microbial indices monitored at 3 day intervals included total aerobic plate count, psychrotrophic counts, and total coliform and Escherichia coli counts. Bacterial growth in ground beef patties stored at 4 °C was significantly (P ≤ 0.05) reduced by EBI at 2 kGy dose. Complete inhibition of bacteria occurred at 5 kGy or higher (P ≤ 0.05) dosage of EBI over 21 days of storage at 4 °C. Quality indices monitored at 3 day intervals throughout a 21 day storage (4 °C) study involving 30% fat ground beef patties made from steers fed vitamin E supplemented diets I and II included TBARS and colour. Results indicated that irradiation at the highest dosages was associated with higher (P ≤ 0.05) TBARS values, which in turn corresponded to lower linoleic acid content. With all three levels of irradiation, Hunter a values of beef patties decreased (P ≤ 0.05) significantly. Lipid oxidation was significantly (P ≤ 0.05) retarded in stored beef patties derived from cattle fed vitamin E (diet II). Copyright © 2003 Society of Chemical Industry     

Effect of Inorganic Polyphosphates on Ground Beef Characteristics: Some Chemical, Physical, and Sensory Effects on Frozen Beef Patties

Chemical, physical, and sensory effects of 0.4% sodium tripolyphosphate (STPP), tetrasodium pyrophosphate (TSPP) and three commercial phosphate blends were studied in frozen beef patties over a 90-day storage period at ?20°C. Addition of phosphates significantly (P<0.05) increased pH, soluble orthophosphates, Hunter color a values, cook yields and overall acceptability scores. Phosphate addition did not affect (p>0.05) proximate analysis, texture, and flavor scores. Hunter L (lightness) and b (yellowness) values were also unaffected by phosphates. Overall quality of patties, as measured by thiobarbituric acid (TBA) numbers and cooking yields, was improved by all phosphates. There were indications that phosphates interfered with the distillation TBA test.     

QUALITY EVALUATION OF DEEP-FAT FRIED ONION RINGS1

Battered and breaded onion rings were deep-fat fried at 170 or 190C for 30, 45, or 60s and subjected to several physical tests and to an overall desirability sensory evaluation. Hunter a color values (redness), specific shear force, and toughness increased (p < 0.01) with both frying temperature and frying time. Onion rings deep-fat fried at 190C for 60s had the highest mean overall desirability sensory score. Onion moisture content and coating redness were positively (p < 0.05) correlated with overall desirability. Coating moisture content and coating fat content were negatively (p < 0.05) correlated with overall desirability.     

EFFECTS OF END-POINT TEMPERATURE AND FAT LEVEL ON THE RESIDUAL CHOLESTEROL IN GROUND BEEF PATTIES1

Patties of lean ground beef with 2% fat (L2PF) and 6% fat (L6PF) were used to study the fat and cholesterol composition of raw and cooked ground beef and to determine how the end-point cooking temperature affects the amount of fat and cholesterol in a lean ground beef patty as it would be eaten by the consumer. The two patty types were obtained from the longissimus muscle of steers with marbling scores associated with “Standard” to “Select” and “Select” to “Choice” U.S. carcass grades of beef, respectively. All steers were fed a diet of roughage and concentrates to ensure fat deposition over the 12th and 13th ribs; longissimus muscles between the 7th and 10th ribs were removed, trimmed of all external fat, ground and formed into three 130-g patties. One patty was fried to an internal temperature of 60C, another to 71C and the third was uncooked. After frying, the patties were measured for drip loss, moisture and total fat. The fat extract was used for cholesterol analysis. The cooked L2PF sample had significantly less fat than the cooked L6PF samples, but there was no difference between the L2PF and L6PF in cholesterol. End-point temperature had no effect on the fat and cholesterol contents for either L2PF or L6PF samples, but the higher end-point temperature resulted in a significant loss of moisture.     

Formation of amino-imidazo-azaarenes and carbolines in fried beef patties and chicken breasts under different cooking conditions in Korea

The effect of cooking temperature and time on amino-imidazo-azaarenes (AIAs) and carbolines in fried ground beef patties and chicken breast under different cooking conditions in Korea was evaluated. Beef patties were fried at different temperatures (150, 180, and 230°C) for 4, 8, 12, and 16 min per each side and then the amount of AIAs and carbolines was evaluated by solid-phase extraction and HPLC-MS analysis. In fried ground beef patties, formations of 9H-pyrido [3,4-b]indole (Norharman) and 1-methyl-9H-pyrido [3,4-b]indole (Harman) were dramatically increased at 230°C for 16 min. Concentrations of Norhanrman and Harman formed at 230°C for 16 min/side were 12 and 40 times greater than level those of Norharman formed at same cooking condition. In fried chicken breasts, 2-amino-3,7,8-trimethylimidazo[4,5-f] quinoxaline (7,8-DiMeIQx) and 2-amino-3,4,7,8-tetramethylimidazo[ 4,5-f]quinoxaline (Tri-MeIQx) were not found at 150 and 180°C. Norhanrman formed at 230°C for 16 min was approximately 4 times higher than fried chicken breasts at 180°C. These results suggest that increase of cooking temperature and time was directly affected on AIAs and carbolines formation in Korean cooked meat.