Biomedical subjects

P L Dawson

Publications and source records attributed to P L Dawson.

At least 19 recordsLinked to original sources

PubMed2006

Effect of dry honey on the shelf life of packaged turkey slices.

The development of off-flavors from oxidation reactions in cooked turkey products is a common problem and results in a less desirable, rancid flavor. Various strategies have been evaluated to minimize this off-flavor development, including vacuum and modified atmosphere packaging, feeding antioxidants to animals, and use of antioxidants in the final product. A natural protein-sugar reaction called the Maillard reaction produces a brown pigment, flavors, and antioxidants. This research tested the addition of honey to turkey breast meat before processing to retard production of oxidation products related to off-flavor. Three levels (0, 5, 15%) of dry honey were mixed with raw turkey breast meat pieces, then the mixture was stuffed into casing and cooked. The cooking process facilitated the Maillard reaction and the development of an antioxidative effect. The cooked chubs were then cooled, sliced, and vacuum-packaged as individual slices. The slices were refrigerated and tested for color, flavor, oxidative rancidity, and microbial growth over 11 wk. Sensory panelists detected increased sweetness and no negative flavor impact on acceptability for turkey with added honey. The addition of honey enhanced the oxidative stability of the meat, as indicated by lower TBA values, hexanal content, and oxidative stability index. Honey did impart a slightly darker color with lower lightness values but had no effect of redness and yellowness values.

Animals↗

PubMed2006

Growth depth effects of bacteria in ground turkey meat patties subjected to high carbon dioxide or high oxygen atmospheres.

Modified atmosphere packaging (MAP) is used to extend the shelf life of ground meats by altering the gas atmosphere surrounding the meat. This study evaluated how deep MAP bactericidal effects penetrate into a ground meat patty. Patties made from freshly ground turkey breasts were subjected to 2 MAP treatments of high CO(2) (97%) or high O(2) (80% O(2), 20% CO(2)). Total plate and lactic acid bacterial counts were determined for 3 patty depths (top, middle, bottom). Meat surface color and the package gas headspace composition were also measured. All analyses were performed on 0, 3, 6, 9, and 12 d. Changes in gas headspace and meat surface color were also measured at 0, 3, 6, 9, and 12 d. High CO(2) atmosphere maintained a better meat surface color than high O(2) atmosphere over the whole storage period. Overall counts were lower (P < or = 0.05) in a high-CO(2) atmosphere compared with a high-O(2) modified atmosphere. Patties stored under a high-CO(2) atmosphere displayed slower bacterial growth in the top layer compared with the middle and bottom layers. Total plate count did not differ (P > or = 0.05) in layers for patties pack-aged in a high-O(2) atmosphere Lactic acid bacterial counts increased in the high-O(2) modified atmosphere by d 9 and 12 of storage; no increase was observed in CO(2)-packaged patties. Thus, high-CO(2) MAP slowed the growth of total bacteria as well as lactic acid bacteria. Also, there was slower growth in the top meat layer exposed to CO(2) compared with interior layers.

Animals↗

PubMed2004

Thickness and compositional effects on surface heating rate of bologna during in-package pasteurization.

The surface heating rate (gamma) and final surface temperature (alpha) during in-package pasteurization were determined for different thickness levels of 2 types of bologna having different (13 and 18%) fat contents. Three thicknesses (4, 12, and 20 mm), corresponding to 1, 3, and 5 slices of bologna, were vacuum-packaged separately in a clear polymer pouch after placing a thermocouple on the surface. Refrigerated samples were immersed in a water bath set to 1 of 4 predetermined temperatures (60, 70, 80, and 90 degrees C), and time and temperature data were recorded for 10 min. Surface heating rate was fastest in the thinnest (4 mm) and slowest in the thickest (20 mm) samples for all 4 temperatures. Surface heating rate was slower in bologna with the higher fat content compared with the lower fat bologna. Final surface temperature attained after 3 min was lower with increased thickness levels for all temperatures. Thus, meat sample thickness and fat content significantly affect surface heating rate and final surface temperature during in-package pasteurization of bologna.

Animals↗

PubMed2003

D and z-values for Listeria monocytogenes and Salmonella typhimurium in packaged low-fat ready-to-eat turkey bologna subjected to a surface pasteurization treatment.

The D-values of Listeria monocytogenes and Salmonella Typhimurium at various surface pasteurization temperatures were determined for low-fat turkey bologna. Four cm2 meat squares were sterilized by irradiation prior to inoculation with 0.1 mL of a 10(8) cfu/mL culture, aseptically packaged in a linear low-density polyethylene pouch, and vacuum-sealed. Thermal treatments were administered by submerging packages in a heated water bath maintained at various set temperatures. At an 85 degrees C water bath temperature, no L. monocytogenes cells were detected (<10(2)) after 10 s of exposure, whereas at 61 degrees C cells viable were detected (>10(2)) up to 10 min of heating. No S. Typhimurium cells (<10(2)) were detected after 10 s at 70 degrees C, but cells survived up to 7 min at 60 degrees C. The D-values for L. monocytogenes at 61 and 65 degrees C were 124 and 16.2 s, respectively; whereas S. Typhimurium D-values were 278 s at 57 and 81 s at 60 degrees C. Z-values were 4.44 and 5.56 degrees C, respectively, for L. monocytogenes and S. Typhimurium. This study demonstrated that significant reductions in bacterial populations and complete inactivation of S. Typhimurium and L. monocytogenes cells can be achieved using an in-package thermal pasteurization process.

Animals↗

PubMed2002

Effect of lauric acid and nisin-impregnated soy-based films on the growth of Listeria monocytogenes on turkey bologna.

Research in development of antimicrobial packaging applications for further processed meats has become more common with recent outbreaks of contamination of these products. In this present study, lauric acid (8%, wt/wt) and 2.5% pure nisin (4%, wt/wt) were incorporated singly and together into thermally compacted soy films. Biocide-impregnated films were compared to control films containing no biocide for inhibition of Listeria monocytogenes in liquid medium and on turkey bologna surface. L. monocytogenes suspended in 1% peptone medium exposed to control films increased from 106 to 10(9) after 48 h exposure at 22 C. Films with nisin alone suppressed cell numbers 1 log cfu/mL after 2 h but cell numbers increased to 10(8) after 24 and 48 h at 22 C. Films containing lauric acid and nisin completely eliminated detectable cells from a 10(6) culture after 8 h of exposure to the liquid medium (22 C). Refrigerated bologna exposed to control films increased by 0.5 log from 10(6) after 21 d at 4 C. Nisin films reduced cell numbers on turkey bologna from 10(6) to 10(5) after 21 d, as did films containing nisin and lauric acid. Films with lauric acid alone reduced L. monocytogenes culture from 10(6) to < 102 after 48 h and by 1 log on turkey bologna after 21 d.

Animals↗

PubMed2001

The effect of shell egg pasteurization on the protein quality of albumen.

The effect of a low-temperature, extended-time, in-shell pasteurization process on the protein quality of egg albumen was evaluated. Ten dozen fresh chicken eggs were pasteurized in a hot-air oven at 55 C for 180 min. The eggs were refrigerated and broken out for analysis on Days 0, 7, 14, 28, 42, and 56 following pasteurization. There were no significant differences in total or soluble protein over the experimental period for the pasteurized or unpasteurized albumen. Mean protein content was 80.6 +/- 0.5% for the pasteurized albumen and 80.9 +/- 0.5% for the unpasteurized albumen. In vitro digestibility, as measured by the AOAC method, was 82.4 +/- 0.7% for the pasteurized albumen and 81.7 +/- 0.6% for the unpasteurized albumen. There were no significant differences over the experimental period in the digestibility of the samples. Free amino acids and discriminant-computed protein efficiency ratio (DC-PER) also did not differ between the pasteurized and unpasteurized albumens or over the experimental period. The in-shell pasteurization process used had no effect on the protein quality of albumen.

Amino Acids↗

PubMed2001

Antimicrobial effects of corn zein films impregnated with nisin, lauric acid, and EDTA.

Bacterial growth during food transport and storage is a problem that may be addressed with packaging materials that release antimicrobials during food contact. In a series of five experiments, EDTA, lauric acid (LA), nisin, and combinations of the three antimicrobial agents were incorporated into a corn zein film and exposed to broth cultures of Listeria monocytogenes and Salmonella Enteritidis for 48 h (sampled at 2, 4, 8, 12, 24, and 48 h). Four experiments used starting cultures of 10(8) CFU/ml in separate experiments tested against each bacterium; the fifth experiment examined the inhibitory effect of selected antimicrobial agents on Salmonella Enteritidis with an initial inoculum of 10(4) CFU/ml. L. monocytogenes cell numbers decreased by greater than 4 logs after 48 h of exposure to films containing LA and nisin alone. No cells were detected for L. monocytogenes (8-log reduction) after 24-h exposure to any film combination that included LA. Of all film agent combinations tested, none had greater than a 1-log reduction of Salmonella Enteritidis when a 10(8)-CFU/ml broth culture was used. When a 10(4) CFU/ml of Salmonella Enteritidis initial inoculum was used, the films with EDTA and LA and EDTA, LA, and nisin were bacteriostatic. However, there was a 5-log increase in cells exposed to control within 24 h. The results demonstrate bacteriocidal and bacteriostatic activity of films containing antimicrobial agents.

Anti-Bacterial Agents↗

PubMed2000

Antioxidative effect of maillard reaction products formed from honey at different reaction times.

Maillard reaction products (MRP) were synthesized from honey-lysine by refluxing with water for 4, 8, 12, 16, and 20 h. The MRP from each reaction time were added to and reacted with a linoleic acid buffered emulsion at 37 degrees C. The MRP from each of the five reaction times were added to the linoleic acid emulsion (LAE) at 1%, 5%, 10%, 15%, and 20% (v/v). The antioxidative effect of MRP on the LAE was determined spectrophotometrically at 234 nm. The MRP pH and brown pigment formation (450 nm) was measured. Absorbance at 450 nm increased from 0.6 to 1.6 between the 4 h and 20 h MRP treatments, respectively. The pH of the MRP decreased from 4 h to 20 h reaction solutions, ranging from 4.2 to 3.65. The antioxidative effect increased at each reaction time increment. Within each reaction time, the antioxidative effect was maximized between 10% and 15% addition levels.

Antioxidants↗

PubMed2000

Effect of dry honey on oxidation in turkey breast meat.

The effect of adding dry honey to turkey breast meat on oxidative stability was measured using TBA, volatile headspace, and oxidative stability index. Ground turkey breast meat was mixed with different concentrations of dry honey (0, 1, 5, 10, 15, and 20%) then cooked in polyethylene bags to 72 C. Oxidative stability measurements were taken for raw meat and cooked meat and for cooked meat after 48 h of storage at 4 C. The proximate composition of the raw meat was 73.9% moisture, 23.2% protein, and 1.3% fat. Gas headspace analysis determined hexanal to be the most abundant volatile compound. Hexanal content decreased as the amount of added honey increased in both freshly cooked meat and in meat stored for 48 h at 4 C. The TBA values also decreased with increasing levels of added honey in the freshly cooked and 48-h-stored meats. The percentage inhibition of oxidation for the 5, 10, 15, and 20% samples increased from 50 to 76% for the freshly cooked meat and from 34 to 88% for the 48-h-stored meat. The oxidative stability index increased with increasing concentrations of honey from 0.28 h (control) to 7.73 h (20% honey). Addition of up to 15% honey inhibited the development of oxidative compounds in cooked turkey meat, with little further inhibition observed compared to 20% honey.

Aldehydes↗

PubMed1999

Packaging effects on shell egg breakage rates during simulated transportation.

Shell eggs were packaged in either expanded polystyrene (EPS) foam or molded paper pulp (MPP) one dozen cartons, then were bulk packaged in either polypropylene crates or corrugated boxes. The packages were then subjected to a well-defined computer-simulated vibration test on an electrohydraulic test machine. The percentage and the location on the egg (side, top, bottom) of breakage was determined in the secondary (corrugated box or polypropylene crate) and primary (EPS or MPP carton) package after 15, 75, and 180 min. For each of three trials, 60 dozen Grade A large eggs were randomly assigned to each primary package and cross-stacked in a secondary container that contained three cartons in a row and a total of five layers. When cartons were packed in 15-dozen corrugated boxes, no significant difference was found in total eggshell damage rates between the MPP carton and the EPS carton. However, when eggs were packed in 15-dozen plastic crates, the MPP cartons caused significantly less eggshell damage than the EPS cartons. The EPS cartons packed in corrugated boxes had the lowest breakage (4.63%), whereas the EPS foam cartons packed in plastic crates had the highest breakage (12.59%). When the effect of secondary packaging and vibration time were not considered, no significant difference was found between MPP and EPS cartons. In addition, when the effect of primary packaging was not taken into account, the corrugated boxes had significantly lower breakage rates than the plastic crates. Nearly 55% of the breakage occurred in the bottom section of the eggshell as compared to the side and top. When the test periods were compared, the EPS cartons packed in plastic crates had the highest breakage (16.28%) at 180 min.

Animals↗

PubMed1998

Using response surface analysis to optimize the quality of ultrapasteurized liquid whole egg.

Response surface analysis (RSA) is used to show the effects of a range of heat pasteurization times and temperature combinations on several quality factors of liquid egg. The purpose of this paper is not to suggest the rigid processing time and temperature combinations to give maximum quality but to illustrate that RSA can be used as a tool to predict individual and multiple egg functional properties resulting from various processing conditions. The application of heat will change the quality and functional properties of the liquid egg. This paper describes the application of RSA to the changes in soluble protein, alpha-amylase, solids content, viscosity, and the height of cakes made with processed liquid whole egg (LWE). The Mallow's Cp statistic is used to determine the best model while minimizing the number of terms in the model. By using this method of choosing the model, the number of terms desired in the model can be first determined then the best fit can be determined from the possible models. The time and temperature combinations are in the ultra-high temperature range for eggs (30, 60, and 95 s each at 64, 68, and 72 C). The RSA may be used to optimize the quality and functionality of LWE while ensuring the safety of the product. This information can be used (with further testing) to maximize desirable and minimize undesirable product properties.

Analysis of Variance↗

PubMed1998

Protein-to-film adhesion as examined by amino analysis of protein binding to three different packaging films.

A weak protein solution extracted from chicken breast meat was exposed to three types of packaging materials. The crude myofibrillar protein solution (12.0 mg protein/mL buffer) was suspended in a 0.6M NaCl/NaPO4 buffer, then placed in bags made from either polyethylene (nonbinding film), a nylon blend (binding film), or Surlyn (binding film). Two separate experiments were conducted to determine the effects of exposure time at a constant temperature and varying endpoint exposure temperatures on the amount of bound protein by amino acid analysis. Bound amino acids were quantified and grouped by class based on functional side group. It was theorized that differences in the amount of bound amino acid class was linked to the mechanism by which the meat-to-film binding occurs. The protein solution was sealed in bags and held in a water bath for 5 s, 20 min, 40 min, and 60 min at 25.8 C for the timed experiment and heated from 25.8 C to 40, 55, 70, and 80 C for the temperature experiment. Protein adhesion occurred due to exposure of the solution to all films at 25.8 C. Greater protein adhesion was found in the two binding films than in the nonbinding film after 60 min of exposure. Heating the protein solution increased adhesion for the Surlyn film and showed a clear delineation in the degree of binding between the film types. Surlyn bound the most protein, followed by the nylon blend and then polyethylene. Bound protein increased in the Surlyn film with heating to 80 C, whereas the polyethylene did not show an increase in the amount of bound protein. Increases in binding observed between 55 and 80 C for Surlyn may be associated with transitional and conformational changes in muscle proteins that affect the adhesion of meat to the film surface.

Adhesiveness↗

PubMed1998

Incorporation of food-grade antimicrobial compounds into biodegradable packaging films.

Lysozyme and nisin are both antimicrobial proteins effective against gram-positive bacteria. The use of these antimicrobials in combination with chelating agents displays increased effectiveness against gram-negative bacteria. Packaging films with lysozyme or nisin incorporated into the film structure were tested separately for inhibition against Lactobacillus plantarum. Both lysozyme and nisin were used in combination with EDTA in films and were evaluated for inhibition against Escherichia coli. Two packaging film-forming methods were used to incorporate lysozyme or nisin into biodegradable protein films to determine if antimicrobial properties could be induced in the film. Heat-press and casting methods were used to produce films made from soy protein and corn zein. Circular samples were cut from the finished films, which were then placed on a bacterial lawn, incubated, and measured for any zones of inhibition. Both cast and heat-press films with added lysozyme or nisin formed excellent films and exhibited inhibition of bacterial growth. The lysozyme and nisin retained their bacteriocidal properties throughout both the heat-press and cast film-forming processes. The cast films exhibited larger inhibitory zones, as compared to the heat-press films, when the same levels of lysozyme or nisin were incorporated. L. plantarum was inhibited by films containing nisin or lysozyme. The addition of EDTA increased the inhibitory effect of films against E. coli.

Anti-Bacterial Agents↗

PubMed1997

Effect of dietary vitamin E on the oxidative stability, flavor, color, and volatile profiles of refrigerated and frozen turkey breast meat.

In this study, the effect of varying dietary vitamin E levels on the oxidative stability, flavor, color, and volatile profiles of refrigerated and frozen turkey breast meat was examined. Nicholas turkey toms were reared on diets containing vitamin E levels as dl-alpha-tocopheryl acetate equivalent to the NRC recommendations (12 and 10 IU/kg from 0 to 8 and 9 to 18 wk, respectively) and 5x, 10x, and 25x the NRC diet. Two other diets were evaluated and included feeding the NRC diet until 15 and 16 wk followed by a diet containing 20x the NRC vitamin E level. All turkeys were processed in a commercial turkey processing plant and breast meat scored for color. Breast meat was excised from four carcasses per treatment and evaluated after refrigeration (1 and 7 d) or frozen storage (30, 90, 150 d) for oxidative stability and sensory quality by TBA analysis, descriptive flavor profiling, and headspace gas chromatography. The TBA values were inversely related to the dietary vitamin E levels. Refrigerated samples had TBA values 78 to 88% lower for the 10x and 25x vitamin E treatments, respectively, than for the NRC control treatment. No differences in TBA values (refrigerated samples) were detected for the 10x, 25x, and 20x (3 wk feeding duration) or across all treatments for samples frozen for 5 mo. The 10x and 25x NRC diets produced the most typical and acceptable turkey meat flavors with the fewest oxidized off-flavor notes for both fresh and frozen samples as opposed to the more oxidized flavor notes detected in the control samples. Mean color scores increased, indicative of less pale meat, as the level and duration of feeding dietary vitamin E increased. These findings showed that varying dietary vitamin E levels significantly influenced the oxidative stability and functionality of turkey breast meat.

Aldehydes↗

PubMed1997

High temperature processing effects on the properties of fowl meat gels.

The effects of three moisture levels (0, 10, and 20% added water) and three processing temperatures (115.6, 121.1, and 126.7 C) on texture and collagen solubilization of fowl meat gels were examined. Meat gels were formulated from spent fowl breast meat that were cooked in water (71.1 C internal temperature) prior to heat processing. The water-cooked gels were heat processed at the three temperatures to an F0 value of 6.0 (Z value = 10 C). The addition of 20% water resulted in a reduction of the soluble collagen compared to the 10% water-added treatment. The lowest processing temperature increased the soluble collagen compared to the highest processing temperature. Shear stress and hardness decreased as the amount of added water was increased; and the lowest processing temperature resulted in the lowest hardness values. The increase in soluble collagen parallels the decrease in hardness in the samples processed at the lowest temperature. Because each sample was processed to equivalent F values, the lowest processing temperature had the longest exposure time (26 min at 115.6 C, 12 min at 121.1 C, and 6 min at 126.7 C). The longer exposure to moist heat allowed for greater collagen solubilization and lower hardness values. The 0% added-water treatment had the highest yield from before and after heat processing. However the 10% water-added samples had the greatest overall water retention when each treatment was placed on an equal level of initial water content. Furthermore, the highest processing temperature (shortest processing time) resulted in the greatest yield and moisture retention compared to the other processing temperatures.

Analysis of Variance↗

PubMed1996

Processing temperature and moisture content effects on the texture and microscopic appearance of cooked fowl meat gels.

New aseptic processes are being used and refined to produce convenient, shelf stable liquid products containing meat particles. These processes utilize high temperature, short time thermal treatments to minimize food quality change; however, little research has been conducted on the effects of this process on the texture of meat from mature hens traditionally used for canning. The objective of this study was to examine textural and structural changes in meat structure due to different high temperature (HT) heat treatments and meat moisture contents were examined by use of electron microscopy and torsion analyses. Cooked gels of different moisture contents (71.2 to 74.8%) were formulated from spent fowl breast meat and exposed to processing temperatures of 120 or 124 C. The HT processing resulted in stronger (tougher) meat gels that were more deformable (more chewy) than gels that were not processed by HT. Water added prior to cooking was not retained in samples that were cooked and then processed at 124 C, but was retained in the samples processed at 120 C. Electron micrographs showed a more organized and open gel structure in the samples with higher moisture content and lower temperature (120 C) processing compared to the lower moisture and higher (124 C) temperature treatments.

Animals↗

PubMed1995

The effects of ultrapasteurization with and without homogenization on the chemical, physical, and functional properties of aseptically packaged liquid whole egg.

The effects of ultrapasteurization with and without homogenization on some chemical, physical, and functional properties of liquid whole egg were observed. Heat treatments of 64, 68, and 72 C each at 30, 60, and 95 s were conducted on liquid whole egg, unhomogenized and homogenized [10.34 mPa (1,500 psi)]. The viscosity of the egg increased with increased processing temperature, and unhomogenized egg was more viscous than homogenized egg. alpha-Amylase was inactivated at 68 C for 30 s. Although cake height was highly correlated to soluble protein content, this relationship did not hold for all time-temperature combinations. Due to homogenization effects on soluble protein results, soluble protein is not a reliable predictor of egg functionality when homogenization is used in the process. Homogenization had no effect on the population reduction of aerobic bacteria in all but three of the nine time-temperature combinations.

Bacteria, Aerobic↗

PubMed1995

Film oxygen transmission rate effects on ground chicken meat quality.

Effects of the packaging film oxygen transmission rate (OTR) on the odor, color, aerobic plate count, and cooked volatile compounds in ground chicken leg meat were evaluated over a 14-d refrigerated storage (4 C) period. Freshly desinewed and ground chicken leg meat was packaged under minimal vacuum in five films of different OTR. Films ranged from 30 to 12,000 mL oxygen/m2 per 24 h. Odor scores of meat in packages opened after 10 d were lower for the lowest OTR film than films with higher OTR. Aerobic plate counts increased at a faster rate in the higher OTR films, and cooked meat volatile profiles showed little variation due to OTR film type. Specific products will require different packaging to optimize shelf-life quality. For ground chicken leg meat, an intermediate OTR film is best to maintain a majority of the quality attributes during refrigerated storage.

Analysis of Variance↗