Free Amino Acids of Raw and Cooked Ground Beef and Pork

Ground beef and ground pork were cooked for 15 min on an electric griddle heated to a surface temperature of 121°C. Cooking reduced the total free amino acid (FAA) content from 25.23 to 17.60 mg/25g fresh weight in pork and from 32.77 to 30.09 mg/25g fresh weight in beef. Sixteen FAA were detected in both beef and pork; most individual FAA decreased during heating. Residues remaining after extraction of FAA from raw pork, when rehydrated (70% moisture) and heated (121°C, 15 min), contained only trace amounts of FAA. Free amino acids apparently were not produced under the cooking conditions employed in this study.     

Adaptation of a Method for the Determination of Soluble Orthophosphates in Cooked and Uncooked Pork Containing Acid-Labile Poly- and Pyrophosphates

A colorimetric method developed for determining μg levels of soluble orthophosphates in soils was successfully used in cooked and uncooked pork to monitor hydrolysis and residual levels of added sodium acid pyrophosphate (SAPP). The method is based on the formation of blue color by reacting existing orthophosphate with molybdate ions in an acid medium and preventing further reaction by rapidly sequestering excess, unreacted molybdenum ions with a citrate-arsenite reagent. The usefulness of the method to monitor poly- and pyrophosphate hydrolysis in meat is discussed.     

Control of Lipid Oxidation in Cooked Ground Pork with Antioxidants and Dinitrosyl Ferrohemochrome

A number of antioxidants were added to ground meat prior to cooking to achieve oxidative stability. The 2-thiobarbituric acid (TBA) numbers of cooked-meat samples after storage for up to 35 days were determined. Of the antioxidants tested, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), t-butylhydro-quinone (TBHQ), trihydroxybutyrophenone (THBP), nordihydro-guaiaretic acid (NDGA), catechol, and ethoxyquin were effective at a level of 200 ppm giving TBA values of less than one. BHA, TBHQ, and ethoxyquin were equally effective at a level of 30 ppm. Ascorbyl acetal and ascorbyl palmitate retarded lipid oxidation effectively (TBA values of slightly over one after five weeks of storage). The cooked cured-meat pigment showed some antioxidant effect which increased with increasing concentration, and at 18–24 ppm was better than that of 200 ppm of α-tocopherol.     

Physical and Sensory Characteristics of Fresh Pork Leg Roasts Cooked at Low Temperatures

The effects of oven temperatures of 82, 93, 121 and 163°C were studied using 31 fresh pork leg roasts cooked to 74°C in oven bags. Warmed-over-flavor (WOF) was measured by sensory analysis after holding 3 hr at 68°C and after holding 24 hr at 2°C and then reheating to 68°C prior to serving. Roasts cooked at 82 and 93°C tended to have less WOF after refrigeration and reheating than roasts cooked at 121 and 163°C. Roasts cooked at 93°C had fewer aerobic mesophilic bacteria than those cooked at 121 and 163°C. In general, objective and sensory perception measurements indicated that roasts cooked at 82 and 93°C were of higher quality.     

Extension of the Shelf-Life of Fresh Ground Pork with Polyphosphates

The antimicrobial effects of 1.0% sodium acid pyrophosphate (SAPP) and sodium orthophosphate monobasic (ORTHO), alone or combined, were studied in fresh ground pork held at 2–4°C for 6 days. Addition of 1.0% SAPP to the meat inhibited psychrotrophic bacterial growth (P<0.01) and resulted in 50% longer meat shelf-life (equivalent to 2 days) in relation to control samples or to meat treated with 0.5% or 1.0% ORTHO. Addition of a 0.5% SAPP/0.5% ORTHO combination was less inhibitory to meat bacteria than 0.5% SAPP alone. Bacterial inhibition did not correlate with soluble orthophosphate content in ground pork.     

Sensory and Chemical Characteristics of Fresh Pork Roasts Cooked to Different Endpoint Temperatures

Pork roasts cooked to various endpoint temperatures were evaluated by sensory and chemical analyses. Increased endpoint temperatures were associated with increased cooking losses; decreased juiciness, pink color, and metallic flavor; increased graininess, brown color, and pork flavor. Increased endpoint temperatures also led to a concentration of lipid, protein and certain fatty acids. Cholesterol levels were not significantly influenced by endpoint temperature. Lipid content was decreased by removal of external fat before cooking. To minimize pink color in some muscles and maximize other sensory characteristics and yield of cooked meat, at least 71.1°C and no more than 76.6°C is recommended as the endpoint temperature for fresh pork roasts.     

Final Cooked Temperature Effects of Ground Pork on its Ability to React with Nitrite

ABSTRACT: Fresh ground pork patties from longissimus dorsi muscle were cooked to endpoint temperatures of 54.4 °C, 60.0 °C, 65.6 °C, 71.1 °C, 76.7 °C, or 82.2 °C. After cooking, patties were immersed in a solution of sodium nitrite (125 ppm) and water for 24 h. All patties then were heated again to a final endpoint temperature of 82.2 °C to allow possible formation of nitrosohemochrome. Instrumental color data, spectrophotometric 650/570 nm reflectance ratio, and visual panelists' scores on both exterior and interior surfaces revealed greater redness (pinking) at the lower initial cooked temperature endpoints. Most importantly, this study showed that all patties developed pink color on reheating, regardless of initial endpoint cooked temperature.     

Evaluation of Antioxidant Effects of Raisin Paste in Cooked Ground Beef, Pork, and Chicken

ABSTRACT:  The objective of this study was to evaluate the possible antioxidant activity of raisin paste added to raw ground beef, pork, or chicken before cooking to 163 °C. Samples were held at 2 °C for up to 14 d. TBA values were measured using a distillation method, to avoid yellow color interference found in "wet" TBA methods. Sample meat flavor intensity, rancid flavor intensity, and raisin flavor intensity were evaluated by a trained panel (n = 6). Addition of raisin paste lowered ( p < 0.05) TBA values and decreased panel scores for rancid flavor scores of all meat samples in a concentration-dependent manner. Highest antioxidant effects were obtained with a minimum of 1.5%, 2.0%, or 2.0% raisin paste in cooked ground beef, pork, or chicken, respectively. There was a high correlation (0.93, 0.94, 0.94) between TBA values and sensory rancid flavor scores in beef, pork, and chicken samples respectively. Addition of a reducing sugar (glucose) was nearly as effective as raisins for maintenance of low TBA values and rancid flavor scores, probably due to antioxidant effects of Maillard browning products. There was no detectable raisin flavor in cooked ground beef samples with added raisins. However, all meats with added glucose had a higher raisin flavor intensity score than controls, indicating that panelists associated sweetness with raisin flavor. Maillard browning (sample darkening) was evident after cooking of ground chicken with either raisins or glucose.     

Lipid Oxidation and Warmed-Over Aroma in Cooked Ground Pork from Swine Fed Increasing Levels of Iron

Fifteen crossbred feeder pigs were fed to market weight on corn-soy rations containing either 62, 131, or 209 ppm iron. After slaughter, pork was ground, cooked, and stored at 4°C for 12 days. Heavily fortifying swine rations with iron (≥200 ppm) increased nonheme iron (NHI) and thiobarbituric acid reactive substances (TBARS) in cooked, stored ground pork (GP) but did not increase warmed-over aroma (WOA) (p>0.05). NHI, TBARS, and WOA increased during storage. TBARS strongly correlated with WOA during storage (r=0.903) and with NHI (r=0.901).     

Antioxidative Maillard Reaction Products from Reducing Sugars and Free Amino Acids in Cooked Ground Pork Patties

Fifteen preformed Maillard reaction products (MRP) were prepared by refluxing 0.2M of three individual reducing sugars (glucose, xylose, and dihydroxyacetone) with 0.2M of five free amino acids (arginine, histidine, leucine, lysine, and tryptophan). MRP were added (3% v/w basis) to fresh ground pork patties prior to cooking and cooked to internal temperature 68°C and stored ai 4°C for 10 days. Samples were analyzed for TBA value on dav 0. 5. and 10. MRP were effective inhibitors of lipid oxidation in groind‘pdrk patties. The most effective were xyloselysine, xylose-tryptophan, dihydroxyacetone-histidine, and dihydroxy-acetone-tryptophan when compared to controls. A significant interaction (P < 0.001) existed between reducing sugars and amino acids.     

Effects of pH and Time of Grinding on Lipid Oxidation of Fresh Ground Pork

Experiments detected effects of pH on lipid oxidation of fresh ground pork. Pigs received antemortem epinephrine injections or postmortem carcass electrical stimulation to manipulate ultimate postmortem pH. High-pH (>6.10) samples had lower TBA values than low-pH samples. Nonsignificant difference in TBA values between high-pH prerigor- and postrigor-ground samples indicated that, at common high pH, time of grinding had no effect on lipid oxidation. Differences in TBA values between prerigor high- and low-pH samples and postrigor high- and low-pH samples indicated that, with identical grinding treatments, inhibition of oxidation occurred at high pH. Metmyoglobin was relatively high in both low- and high-pH muscle and was not catalytically active at high pH.     

Histological Characteristics of Beef and Pork Cooked by Dry or Moist Heat in a Conventional or Microwave Oven

Samples of raw or heat treated (moist or dry heat; conventional or microwave oven) bovine or porcine muscle were examined to determine effects of those treatments on histological characteristics of the muscle. Relationships between histological characteristics and sensory properties of the muscle were studied. Generally, effects of the four heat treatment combinations on histological characteristics of bovine or porcine muscle did not differ significantly. Histological characteristics of muscle should not be used exclusively to study relationships between muscle structural components and sensory tenderness of the muscle.     

Sodium Lactate/Sodium Chloride Effects on Sensory Characteristics and Shelf-Life of Fresh Ground Pork

Fresh ground pork was formulated with sodium lactate (SL) (0, 1.5 or 3%) and sodium chloride (0, 0.5, 1, l.5, 2, 2.5 or 3%) to evaluate effects on sensory characteristics. Aerobic plate count (APC) over retail storage (25 days) was evaluated on samples rated in the mid-range (±0.5 S.D. of mean) of salty flavor intensity (SI) by a trained sensory panel. SL increased (P<0.05) SI and juiciness, and enhanced ground pork flavor. Sodium added as SL was less perceptible as “salty” than that added as NaCl. SL significantly reduced (P<0.05) APC; based on spoilage level of 10⁶ CFU/g SL extended shelf-life (3% SL) by about 12 days compared to controls.     

鲜猪肉中磺胺类抗生素残留的检测与分析

采用高效液相色谱法（HPLC）对64份来自某城市市区及郊区鲜肉市场的生鲜猪肉样品中10种磺胺类抗生素的残留进行检测。结果显示,磺胺类抗生素的检出率和超标率分别为20.31%和10.94%,其中郊区的检出率和超标率均高于城区。10种磺胺类药物中检出率最高的是磺胺嘧啶（SD）,为7.81%,其次是磺胺甲二唑（SMT）和磺胺吡啶（SP）,分别为6.25%和4.69%。此结果表明,部分鲜猪肉中磺胺类抗生素的残留量较高,有诱发产生耐药菌的潜在威胁,相关部门应加强指导养殖业抗生素的合理使用。     

HPLC Quantitation of Alginate or Pectin Added to Lean Ground Pork

A method was developed to isolate and quantify uranic acid(s) of alginate or pectin added at various concentrations to lean (5–7% crude fat) ground pork. The method used an Aminex HPX-87-H+ column, isocratic 0.009N H₂SO₄ eluent and ultraviolet detection. For regression equations derived from mean uranic acid concentrations to predict percentage of alginate or pectin, R² values were 0.99 for total uranic acids (alginate) and 0.97 for galacturonic acid (pectin). Reproducibility was 84% for alginate and 94% for pectin contents. Recoveries were: alginate 85% and pectin 80%.     

Nutrient Composition of Fresh Retail Pork

The nutrient composition of fresh pork was studied in samples from 71 carcasses. On separable lean, nutrient composition was determined for 7 raw retail cuts from one side of each of 11 carcasses, and nutrient retention was determined on the 7 matching cuts from the other side that had been cooked by common household methods. Loins from 60 additional carcasses were analyzed to determine whether USDA grades 1, 2, and 3 and region of production affected nutrient composition. The data indicated that variation in nutrient composition of pork is more dependent on the retail cut within the carcass than either the grade or the region of production of the carcass. Cooking method significantly affected retention of most of the nutrients analyzed.     

蒸煮猪肉不同冷却工艺的对比分析

为解决不同熟食品对不同冷却条件的要求,使用复合真空冷却机对蒸煮猪肉分别进行冷风冷却、真空冷却、冷风加真空的混合冷却以及超声补水真空冷却试验,从冷却速率、冷却后的失重率和能耗3个方面综合考虑选出1种最优的冷却方式.结果表明:蒸煮猪肉真空冷却在冷却速率和能耗方面均优于冷风冷却,但失重率均大于冷风冷却,单一的冷却方式均不是最...     

Psychrotrophic Bacteria in Prerigor Ground Pork

The numbers of psychrotrophic bacteria in prerigor ground pork were slightly greater than in postrigor ground pork throughout an 11-day storage period at 2°C. Freezing both types of samples and subsequent thawing before storage at 2°C reduced the initial psychrotrophic counts but the freezing effects did not persist beyond 8 days of storage. Differences in psychrotrophic counts between prerigor and postrigor ground pork were not sufficiently great in any comparison to limit the use of prerigor grinding of pork.