Biomedical subjects

D P Smith

Publications and source records attributed to D P Smith.

At least 19 recordsLinked to original sources

PubMed2007

Spoilage microflora of broiler carcasses washed with electrolyzed oxidizing or chlorinated water using an inside-outside bird washer.

The effect of acidic, electrolyzed oxidizing (EO) water and chlorinated water on the spoilage microflora of processed broiler carcasses was examined. Carcasses were sprayed for 5 s at 80 psi with tap, chlorinated, or EO water in an inside-outside bird washer. Treated carcasses were then stored at 4 degrees C for 0, 3, 7, or 14 d, and the microbial flora of the carcasses was sampled using the whole-carcass rinse procedure. Populations of psychrotrophic bacteria and yeasts in the carcass rinsates were enumerated. Results indicated that immediately after spraying the carcasses, significantly fewer psychrotrophic bacteria were recovered from carcasses sprayed with chlorinated or EO water than from carcasses sprayed with tap water. Furthermore, significantly fewer yeasts were recovered from carcasses sprayed with EO water than from carcasses sprayed with tap or chlorinated water. The population of psychrotrophic bacteria and yeasts increased on all carcasses during refrigerated storage. However, after 14 d of storage, significantly fewer psychrotrophic bacteria and yeasts were recovered from carcasses sprayed with EO water than from carcasses sprayed with tap or chlorinated water, and significantly fewer microorganisms were recovered from carcasses sprayed with chlorinated water than from carcasses sprayed with tap water. Pseudomonas spp. and Candida spp. were the primary microbial isolates recovered from the broiler carcasses. Findings from the present study indicate that EO water can effectively be used in inside-outside bird washers to decrease the population of spoilage bacteria and yeasts on processed broiler carcasses.

Animals↗

PubMed2006

Prevalence and numbers of bacteria in broiler crop and gizzard contents.

Crops or gizzards in broiler carcasses are frequently damaged during processing. The contents from either organ, defined by the USDA Food Safety and Inspection Service as ingesta, may contaminate the carcass. Previous research has shown crop contents are a source of Salmonella contamination on processed carcasses, although less information is available on gizzard contents. The purpose of this study was to determine the prevalence and numbers of total aerobic bacteria, coliforms, Escherichia coli, and Campylobacter in ingesta collected from the crop and gizzard. In each of 3 replicate trials, 10 uneviscerated broiler carcasses were obtained from a processor at the shackle transfer point just prior to evisceration. Liquid crop contents and solid gizzard contents were aseptically collected from each carcass and quantitatively cultured. Total aerobic bacteria, coliforms, E. coli, and Campylobacter were determined for contents from both organs. Crop contents (log cfu/mL), compared with gizzard contents (log cfu/g), contained significantly (P < 0.05) higher numbers of total aerobic bacteria (5.6 vs. 2.9), coliforms (4.2 vs. 2.3), E. coli (3.9 vs. 2.2), and Campylobacter (4.6 vs. 2.2). Escherichia coli prevalence was higher in crop samples (28 of 29) than gizzard samples (19 of 30). Campylobacter prevalence was also higher for crop vs. gizzard samples (29 of 29 vs. 12 of 30). An average of 2.4 g of crop contents and 8.4 g of gizzard contents were recovered. Crop contents contain more bacteria than gizzard contents and contained a higher incidence of E. coli and Campylobacter contamination. However, because of the numbers of bacteria and amount of material in the crop and gizzard, it is unlikely that ingesta contamination would increase overall bacterial counts of prechill broiler carcasses.

Animals↗

PubMed2006

Broiler carcass bacterial counts after immersion chilling using either a low or high volume of water.

A study was conducted to investigate the bacteriological impact of using different volumes of water during immersion chilling of broiler carcasses. Market-aged broilers were processed, and carcasses were cut into left and right halves along the keel bone immediately after the final bird wash. One half of each carcass pair was individually chilled at 4 degrees C in a separate bag containing either 2.1 L/kg (low) or 16.8 L/kg (high) of distilled water. Carcass halves were submersed in a secondary chill tank containing approximately 150 L of an ice-water mix (0.6 degrees C). After chilling for 45 min, carcass halves were rinsed with 100 mL of sterile water for 1 min. Rinses and chill water were analyzed for total aerobic bacteria (APC), Escherichia coli, Enterobacteriaceae, and Campylobacter. After chilling with a low volume of water, counts were 3.7, 2.5, 2.6, and 2.1 log(10) cfu/mL of rinse for APC, E. coli, Enterobacteriaceae, and Campylobacter, respectively. When a high volume of chill water was used, counts were 3.2, 1.7, 1.6, and 1.8 log(10) cfu/mL of rinse for APC, E. coli, Enterobacteriaceae, and Campylobacter, respectively. There was no difference in bacterial counts per milliliter of chill water among treatments. These results show that using additional water during immersion chilling of inoculated broilers will remove more bacteria from the carcass surfaces, but numbers of bacteria per milliliter in the chiller water will remain constant. The bacteriological impact of using more water during commercial immersion chilling may not be enough to offset economic costs.

Animals↗

PubMed2006

Recovery of bacteria from broiler carcasses rinsed zero and twenty-four hours after immersion chilling.

Microbiological sampling of processed broiler carcasses often relies on the technique of whole-carcass rinsing; however, the rinse sampling is sometimes done immediately after immersion chilling and sometimes as long as 24 h after immersion chilling. To test whether carcass rinses done immediately after chilling can be compared with rinses 24 h after chilling, 20 whole broiler carcasses exiting the chiller of a broiler processing plant were sampled on each of 3 d. All carcasses were bagged aseptically and rinsed for 1 min in 400 mL of sterile water. Recovered rinse liquid was poured into a sterile container, and rinsed carcasses were placed in clean plastic bags; all materials were held overnight at 4 degrees C. On the following day, all carcasses were rinsed again in 400 mL of sterile water as before, and all rinse samples were cultured by standard methods to enumerate coliforms, Escherichia coli, and Campylobacter and to determine incidence of Salmonella. Statistical analysis used paired comparisons between the same carcasses rinsed at 0 and 24 h after chilling; numbers of bacteria were expressed as log cfu/mL of rinse. In 2 of 3 replications, significantly higher numbers of coliforms and E. coli were found in the rinse samples taken immediately after chilling vs. rinse samples done at 24 h. There were no differences in numbers of Campylobacter or incidence of Salmonella between rinses taken at 0 and 24 h. More study is required to determine whether whole-carcass rinse samples performed at 0 and 24 h after chilling are microbiologically equivalent.

Animals↗

PubMed2006

Application of distilled white vinegar in the cloaca to counter the increase in Campylobacter numbers on broiler skin during feather removal.

Because of the escape of highly contaminated gut contents from the cloaca of positive carcasses, Campylobacter numbers recovered from broiler carcass skin samples increase during automated feather removal. Vinegar is known to have antimicrobial action. The objective of this study was to determine the effect of vinegar placed in the cloaca prior to feather removal on the numbers of Campylobacter recovered from broiler breast skin. Broilers were stunned, killed, and bled in a pilot processing plant. Vinegar was placed in the colons of the chickens prior to scalding. Carcasses were scalded, and Campylobacter numbers were determined on breast skin before and after passage through a commercial-style feather-picking machine. Campylobacter numbers recovered from the breast skin of untreated control carcasses increased during feather removal from 1.3 log CFU per sample prior to defeathering to 4.2 log afterward. Placement of water in the colon before scalding had no effect on Campylobacter numbers. Campylobacter numbers recovered from the breast skin of carcasses treated with vinegar also increased during defeathering but to a significantly lesser extent. Treated carcasses experienced only a 1-log increase from 1.6 log CFU per sample before feather removal to 2.6 log CFU per sample afterward. Application of an effective food-grade antimicrobial in the colon prior to scald can limit the increase in Campylobacter contamination of broiler carcasses during defeathering.

Acetic Acid↗

PubMed2005

Microbiological impact of spray washing broiler carcasses using different chlorine concentrations and water temperatures.

A study was conducted to investigate the microbiological impact of spray washing broiler carcasses with chlorinated water (0 or 50 ppm) at different temperatures (21.1, 43.3, or 54.4 degrees C). A whole carcass rinse (WCR) was performed on each carcass before (control) and after spray washing (final). After the control WCR, carcasses were inoculated with 0.1 g of cecal material containing 2 x 10(5) cells per gram of Campylobacter and 2 x 10(5) cells per gram of nalidixic acid-resistant Salmonella. Carcasses were held at room temperature for 12 min before washing in an inside-outside bird washer (80 psi for 5 s). Chlorine level and water temperature had no effect on total aerobic bacteria, Escherichia coli, or Campylobacter numbers recovered from the final WCR. Levels of bacteria found on carcasses before and after washing were 4.6, 3.6, and 3.5 log10 cfu/mL rinse for total aerobic bacteria, E. coli, and Campylobacter, respectively. Average counts for nalidixic acid-resistant Salmonella after washing were 3.1 log10 cfu/ mL rinse irrespective of water temperature or chlorine level (P < 0.05). In addition, chlorine level and water temperature had no effect on the breast skin color, with average values of L* = 66.6; a* = -0.09; b* = -0.05 (P < 0.05). Under the conditions outlined in the present study, adding chlorine and/or elevating the water temperature during spray washing in an inside-outside bird washer did not enhance the removal of bacteria from broiler carcasses and had no effect on carcass skin color.

Animals↗

PubMed2005

Descriptive sensory analysis of broiler breast fillets marinated in phosphate, salt, and acid solutions.

Sensory attributes of fully aged broiler breast fillets marinated in a 6% NaCl solution containing 2% sodium tripolyphosphate (2P), 2% citric acid (2C), 2% acetic acid (2A), 1% citric acid plus 1% phosphate solution (1C), or 1% acetic acid solution plus 1% phosphate (1A) were studied. A 6% NaCl (6S) solution with no additives was used as control. Oven-cooked samples (177C degrees oven; 75 degrees C internal temperature) were evaluated by a 9-member trained descriptive analysis sensory panel that rated the intensities of 26 different flavor and texture attributes using 15-point line scales. Data were analyzed using general linear model SAS procedures to determine significant differences (P < or = 0.05) in individual sensory attributes due to marinade treatment. All sensory attributes were scored in the low intensity range (1.5 to 5.0). Brothy, vinegar, and residual particles were the only individual attributes rated significantly different (P < or = 0.05) due to treatment. Multivariate analyses indicated that all sensory attributes formed 2 dimensions that explained 57% of variation in the data. The low intensity values for texture attributes indicated possible negative consequences due to phosphates, salt, and acids when used with fully aged fillets.

Acetic Acid↗

PubMed2005

Physical and functional properties of intact and ground pale broiler breast meat.

The functional and physical properties of intact and ground meat were determined during 4 replicate trials on a total of 180 pale [lightness (L*) > 53] and normal (46 < L* < 53) boneless, skinless breast fillets collected from 2 commercial processing plants. At 24 h postmortem, L*, redness (a*), yellowness (b*), and pH were determined on each fillet. The left fillet from each breast was ground and used to determine cook loss (CL) and Allo-Kramer (AK) shear on meat patties as well as moisture uptake (MU) and CL on meat slurries before and after adjustment to the normal meat pH of 5.9. The right fillet from each breast was kept intact and used to determine expressible moisture (EM), CL, and AK shear on the intact meat. Compared with normal fillets, pale fillets exhibited significantly higher L* values, lower ultimate pH (5.67 vs. 5.94), higher AK (3.5 vs. 2.9 kg/g), higher EM, lower MU, and higher CL measured on the intact fillets, ground meat patties, and meat slurries. Adjustment of the pH of the pale meat slurries to normal meat pH (5.9) resulted in a higher MU (11.05 vs. 3.69%), indicating a partial restoration of protein functionality. These results indicate that wide differences in raw broiler breast meat color, mainly due to differences in the muscle pH, are related to important variations in the water-holding and binding capacities of the meat. The effect of low meat pH can be partially ameliorated in ground meat by pH adjustment.

Animals↗

PubMed2005

Subversion of the Bcl-2 life/death switch in cancer development and therapy.

The Bcl-2 protein family, which largely determines commitment to apoptosis, has central roles in tumorigenesis and chemoresistance. Its three factions of interacting proteins include the BH3-only proteins (e.g., Bim, Puma, Bad, Noxa), which transduce diverse cytotoxic signals to the mammalian pro-survival proteins (Bcl-2, Bcl-x(L), Bcl-w, Mcl-1, A-1), whereas Bax and Bak, when freed from pro-survival constraint, provoke the mitochondrial permeabilization that triggers apoptosis. We have discovered unexpected specificity in their interactions. Only Bim and Puma, which mediate multiple cytotoxic signals, engage all the pro-survival proteins. Noxa and Bad instead bind subsets and cooperate in killing, indicating that apoptosis requires neutralization of different pro-survival subsets. Furthermore, Mcl-1 and Bcl-x(L), but not Bcl-2, directly sequester Bak in healthy cells, and Bak is freed only when BH3-only proteins neutralize both its guards. BH3-only proteins such as Bim are tumor suppressors and mediate many of the cytotoxic signals from anticancer agents. Hence, compounds mimicking them may prove valuable for therapy. Indeed, the recently described ABT-737 is a promising "BH3 mimetic" of Bad. We find that, like Bad, ABT-737 kills cells efficiently only if Mcl-1 is absent or down-regulated. Thus, manipulation of apoptosis by targeting the Bcl-2 family has exciting potential for cancer treatment.

Animals↗

PubMed2005

Distribution of Listeria monocytogenes subtypes within a poultry further processing plant.

Samples from environmental sites and raw product in a chicken further processing plant were collected every 6 weeks for 12 months. Each sample site was examined before and after a complete production shift. All samples were examined for the presence of Listeria monocytogenes, which was detected in floor drains on the raw product side of the plant preoperation and in drains on both raw and cooked sides following 8 h of processing operation. L. monocytogenes also was detected in raw product and once in fully cooked product but never on cooked product contact surfaces. One hundred sixty-one isolates were collected from 75 positive samples. All isolates were subtyped using a sequence-based method, and 14 unique subtypes were detected through the course of the study. Four of these types were found repeatedly and appeared to be resident in the plant. Three of the four resident strains were detected on raw product at some point during the year-long study, suggesting that raw product may be one source of L. monocytogenes in the processing plant environment. These data highlight the need for research to investigate why some types of L. monocytogenes persist in a processing plant environment but others do not.

Animals↗

PubMed2005

Effect of fecal contamination and cross-contamination on numbers of coliform, Escherichia coli, Campylobacter, and Salmonella on immersion-chilled broiler carcasses.

The effect of prechill fecal contamination on numbers of bacteria on immersion-chilled carcasses was tested in each of three replicate trials. For each trial, 16 eviscerated broiler carcasses were split into 32 halves and assigned to one of two groups. Cecal contents (0.1 g inoculated with Campylobacter and nalidixic acid-resistant Salmonella) were applied to each of eight halves in one group (direct contamination) that were placed into one paddle chiller (contaminated), whereas the other paired halves were placed into another chiller (control). From the second group of eight split birds, one of each paired half was placed in the contaminated chiller (to determine cross-contamination) and the other half was placed in the control chiller. Postchill carcass halves were sampled by a 1-min rinse in sterile water, which was collected and cultured. Bacterial counts were reported as log CFU per milliliter of rinsate. There were no significant statistical differences (paired t test, P < 0.05) from direct contamination for coliforms (mean 3.0 log CFU) and Escherichia coli (mean 2.7 log CFU), although Campylobacter numbers significantly increased from control values because of direct contamination (1.5 versus 2.1 log CFU), and the incidence increased from 79 to 100%. There was no significant effect of cross-contamination on coliform (mean 2.9 log CFU) or E. coli (mean 2.6 log CFU) numbers. Nevertheless, Campylobacter levels were significantly higher after exposure to cross-contamination (1.6 versus 2.0 log CFU), and the incidence of this bacterium increased from 75 to 100%. Salmonella-positive halves increased from 0 to 42% postchill because of direct contamination and from 0 to 25% as a result of cross-contamination after chilling. Water samples and surface swabs taken postchill from the contaminated chiller were higher for Campylobacter than those taken from the control chiller. Immersion chilling equilibrated bacterial numbers between contaminated and control halves subjected to either direct contamination or cross-contamination for coliforms and E. coli. Campylobacter numbers, Campylobacter incidence, and Salmonella incidence increased because of both direct contamination and cross-contamination in the chiller. Postchill E. coli numbers did not indicate which carcass halves were contaminated with feces before chilling.

Animals↗

PubMed2004

Moisture retention by water- and air-chilled chicken broilers during processing and cutup operations.

The objective of this study was to evaluate effects of storage and cutting on moisture retention by air- and water-chilled broiler chickens. Sixty-four broilers were slaughtered, chilled by cold air or immersion in water, stored over night, cut into fore- and hindquarters, and then stored an additional 24 h. Air chilling conditions were 4 degrees C with air velocity of 2.2 m3/min. Water chilling conditions were 1 degree C with mechanical agitation. Moisture absorption and retention were observed as weight changes throughout the process. Air-chilled carcasses lost an average of 0.68% of their postslaughter weight in storage prior to cutting but lost no more during cutting or postcutting storage. The water-chilled carcasses absorbed 11.7% moisture in chilling but retained 6.98% through precutting storage, 6.00% through cutting and 3.90% through postcutting storage. These data offer baseline values for use in complying with new USDA processing standards.

Air↗

PubMed2004

Effect of vacuum on moisture absorption and retention by marinated broiler fillets.

Effects of vacuum on moisture retention and quality characteristics of aged chicken breast fillets were evaluated. One hundred twenty-eight broilers (2 replicates of 64 birds each) were manually slaughtered, chilled in ice water, placed in unsealed plastic bags, and then aged overnight at 4 degrees C. Both pectoralis major muscles were harvested from each carcass. Left muscles were marinated for 30 min en vacuo with 20% (vol/wt) of a 10% NaCl (wt/vol) solution containing 4% (wt/vol) commercial food-grade polyphosphate. Right fillets were marinated similarly but without vacuum. Moisture absorption, cooked yield, pH change during marination, and shear values of vacuum-marinated fillets were compared to those on fillets marinated without vacuum. Use of vacuum during marination increased moisture absorption during marination, but after cooking, yields were similar. Nor did vacuum effect pH or shear values. Under the conditions of this study, use of vacuum during marination appeared to offer no significant advantage over marination at atmospheric pressure.

Absorption↗

PubMed2004

Effects of diet and feed withdrawal on the sensory descriptive and instrumental profiles of broiler breast fillets.

Effects of diet and feed withdrawal times on the sensory profile and shear values of broiler breast meat were determined. Feeds were formulated with 3 dietary carbohydrate sources (corn, milo, and wheat). Birds (n = 192) were processed between 42 and 52 d of age. Feed was withdrawn for 0 or 8 h prior to pilot plant processing under simulated commercial conditions. Pectoralis major muscles were removed 4 h postmortem and frozen until evaluated. Thawed breast fillets were cooked in heat-seal bags immersed in 85 degrees C water until an internal temperature of 80 degrees C was reached. Color, shears, and sensory profiles (18 attributes) were determined. Meat from corn-fed birds required significantly less force to shear (6.0 kg) than meat from birds fed milo (6.7 kg) or wheat (7.1 kg). Feed withdrawal did not affect the flavor profile; however, meat from birds at 0 h feed withdrawal were darker and redder. Diet significantly affected the sensory profile. Brothy scores were significantly higher in meat from corn-fed birds than in meat from birds fed wheat or milo. Diet and feed withdrawal significantly affected sensory texture. Meat from wheat-fed birds was harder, more cohesive, and more chewy and exhibited larger particle size than meat from birds fed corn or milo. Moisture release values were lower and toothpack values were higher in meat from birds processed at 0 h feed-withdrawal time compared with meat from birds held 8 h without feed. Dietary carbohydrate source appears to have a measurable impact on flavor and texture of broiler breast meat.

Animal Feed↗

PubMed2004

Effect of intestinal content contamination on broiler carcass Campylobacter counts.

Intestinal contents may contaminate broiler carcasses during processing. The objective of this study was to determine what effect various levels of intestinal contents had on the numbers of Campylobacter detected in broiler carcass rinse samples. Eviscerated broiler carcasses were collected from the shackle line in a commercial processing plant immediately after passing through an inside/outside washer. Broiler carcasses were cut longitudinally into contralateral halves using a sanitized saw. Cecal contents from the same flock were collected, pooled, homogenized, and used to contaminate carcass halves. Paired carcass halves were divided into groups of eight each, and then cecal contents (2, 5, 10, 50, or 100 mg) were placed onto one randomly selected half of each carcass, while the corresponding half of the same broiler carcass received no cecal contents. Campylobacter counts from carcass halves with cecal contamination were compared to the uncontaminated halves of the same carcasses using a paired t test. Carcass halves with 5 mg or more of surface cecal contamination had significantly higher numbers of Campylobacter than those without (P < 0.01). Carcass halves contaminated with only 5 mg of cecal contents had an average of 3.3 log CFU Campylobacter per ml of rinse, while corresponding uncontaminated carcass halves had 2.6 log CFU Campylobacter per ml of rinse. These data indicate that even small (5 mg) amounts of cecal contents can cause a significant increase in the numbers of Campylobacter on eviscerated broiler carcasses. Therefore, it is important to keep such contamination to a minimum during processing.

Animals↗

PubMed2004

Detection of Bacillus cereus on selected retail chicken products.

Samples from five chicken meat products, obtained at retail stores, were evaluated for the presence of Bacillus cereus. The products tested were as follows: breaded, fully cooked, frozen nuggets (NUGGETS); breaded, fully cooked, frozen tenders (TENDERS); fully cooked, frozen, white-meat fajita-style strips (STRIPS); raw, refrigerated, boneless, skinless, marinated breast fillets (FILLETS); and raw, refrigerated, cut-up, tray-pack bone-in parts (PARTS), either split breasts or thighs. Four packages of each item were obtained on three different days (n = 60). Frozen and refrigerated products were held overnight in their respective environments as appropriate; then packages were opened aseptically, and a total of 25 g of tissue was excised from multiple pieces within a package. The 25-g samples were enriched in 225 ml of Trypticase soy-polymixin broth for 18 to 24 h at 30 degrees C and then plated on mannitol-egg yolk-polymixin agar and incubated for 18 to 24 h at 30 degrees C. Colonies characteristic of B. cereus were chosen and replated for isolation on mannitol-egg yolk-polymixin agar. Suspect colonies were confirmed as Bacillus spp. by Gram stain, hemolysis on blood agar, and a biochemical test strip. Isolates were further confirmed as B. cereus using Bacteriological Analytical Manual procedures, including tests for motility, rhizoid growth, hemolysis, and protein toxin crystal production. B. cereus was detected in 27 of 60 total samples. By product, the prevalence levels were as follows: NUGGETS, 11 of 12 positive; TENDERS, 8 of 12 positive; STRIPS, 6 of 12 positive; FILLETS, 0 of 12 positive; and PARTS, 2 of 12 positive. Isolates were tested by PCR for presence of the toxin-encoding genes bceT, nheABC, hblACD, and cytK. Results indicate that B. cereus organisms were present on four of the five retail poultry products tested in this study, with the highest rates reported for the three fully cooked items, especially the two breaded products. All strains isolated contained the gene(s) for at least one of the toxins, although none of the strains contained the cytK gene.

Animals↗

PubMed2003

Oxylipins and ascospore morphology in the ascomycetous yeast genus Dipodascus.

Immunofluorescence microscopy was used to assess members of the yeast genus Dipodascus for the presence of 3-hydroxy oxylipins. Fluorescence was associated with the aggregating ascospores in all species tested, thus suggesting the association of 3-hydroxy oxylipins with these cells, especially the surrounding slime sheaths. An ultrastructural study of the ascospores revealed sheaths with indentations, probably caused by the close packing of the ascospores to form clusters. In addition, an increase in the neutral and glycolipid fractions as well as a decrease in the phospholipid fraction during ascosporogenesis in D. ambrosiae was found.

Fatty Acids, Unsaturated↗

PubMed2003

Identification of a distinct family of genes encoding atypical odorant-binding proteins in the malaria vector mosquito, Anopheles gambiae.

We performed a genome-wide analysis for candidate odorant-binding protein (OBP) genes in the malaria vector Anopheles gambiae (Ag). We identified fifty-seven putative genes including sixteen genes predicted to encode distinct, higher molecular weight proteins that lack orthologues in Drosophila. Expression analysis indicates that several of these atypical AgOBPs are transcribed in chemosensory organs in adult and immature stages. Phylogenetic analysis of the Anopheles and Drosophila OBP families reveals these proteins fall into several clusters based on sequence similarity and suggests the atypical AgOBP genes arose in the mosquito lineage after the divergence of mosquitoes and flies. The identification of these AgOBP genes is the first step towards determining their biological roles in this economically and medically important insect.

Amino Acid Sequence↗