Validation of food-grade salts of organic acids as ingredients to control Listeria monocytogenes on pork scrapple during extended refrigerated storage.

This study was conducted to investigate control of Listeria monocytogenes on pork scrapple during storage at 4°C. In phase I, scrapple was formulated, with or without citrate-diacetate (0.64%), by a commercial processor to contain various solutions or blends of the following antimicrobials: (i) lactate-diacetate (3.0 or 4.0%), (ii) lactate-diacetate-propionate (2.0 or 2.5%), and (iii) levulinate (2.0 or 2.5%). Regardless of whether citrate-diacetate was included in the formulation, without the subsequent addition of the targeted antimicrobials pathogen levels increased ca. 6.4 log CFU/g within the 50-day storage period. In the absence of citrate-diacetate but when the targeted antimicrobials were included in the formulation, pathogen numbers increased by ca. 1.3 to 5.2 log CFU/g, whereas when citrate-diacetate was included with these antimicrobials, pathogen numbers increased only by ca. 0.7 to 2.3 log CFU/g. In phase II, in the absence of citrate-diacetate, when the pH of the lactate-diacetate-propionate blend (2.5%) was adjusted to pH 5.0 or 5.5 pathogen numbers remained unchanged (≤0.5 log CFU/g increase) over 50 days, whereas when citrate-diacetate was included with the lactate-diacetate-propionate blend adjusted to pH 5.0 or 5.5, pathogen numbers decreased by 0.3 to 0.8 log CFU/g. In phase III, when lower concentrations of the lactate-diacetate-propionate blend (1.5 or 1.94%) were adjusted to pH 5.5, pathogen numbers increased by ca. 6.0 and 4.7 log CFU/g, respectively, whereas when the mixture was adjusted to pH 5.0, pathogen numbers increased by ≤0.62 log CFU/g. Thus, scrapple formulated with lactate-diacetate-propionate (1.5 and 1.94% at pH 5.0) is an unfavorable environment for outgrowth of L. monocytogenes.

Effect of storage and subsequent reheating on viability of Listeria monocytogenes on pork scrapple.

We evaluated the fate of Listeria monocytogenes on commercial pork scrapple, a regionally popular, ready-to-eat (RTE) meat. We also conducted an informal survey to address consumer practices for storing and reheating scrapple. Of the 129 consumers who responded to at least one of the eight questions posed in the survey, about half (46.4%; 52 of 112) considered scrapple RTE, the majority (69.7%; 76 of 109) stored it in the refrigerator, and all (100%; 112 of 112) preferred to reheat it prior to consumption. Most respondents (83.9%; 94 of 112) reheated the scrapple by pan frying for 1 to 10 min at medium to high temperature. To study pathogen behavior, slices of pork scrapple were surface inoculated with a five-strain cocktail of L. monocytogenes (ca. 2.0 log CFU/g), vacuum sealed, and stored for up to 60 days. Pathogen levels increased to 8.9, 9.5, and 9.9 log CFU/g after 44 (4 degrees C), 21 (10 degrees C), and 5 (21 degrees C) days, respectively. When slices 1.3 cm (ca. 55 g) and 1.9 cm (ca. 85 g) thick were surface inoculated with L. monocytogenes (ca. 7.0 log CFU/g) and then reheated in a skillet (191 degrees C) for 0.5 to 4 min per side or to target instantaneous internal temperatures of 48.9 to 71.1 degrees C, it was possible to achieve pathogen reductions ranging from ca. 2.2 to 6.5 log CFU/g. These data confirm that in the unlikely event of postprocessing contamination of pork scrapple by L. monocytogenes, proper reheating can appreciably reduce levels of the pathogen before consumption.

Influence of dietary taurine on performance and fat retention in broilers and turkey poults fed varying levels of fat.

Taurine, an amino acid synthesized from Met, primarily functions in bile acid conjugation. Four experiments were conducted to determine whether Tau supplementation of broiler cockerels and female turkey poults to 3 wk of age would influence performance and fat retention at different levels of dietary fat. In these experiments, Tau was added at 0 or .8% to a corn and soybean meal basal diet with dietary poultry fat added at 0, 5, or 10%. Taurine did not affect BW gain of broiler cockerels; however, in one experiment feed efficiency was improved (P less than .01) during the 1st wk and fat retention was improved (P less than .06) at 7 days of age. In experiments with turkey poults, dietary Tau did not affect weight gain but improved feed efficiency (P less than .01) during the 1st wk and decreased overall feed efficiency (P less than .01) in one experiment. Improvement of fat retention by Tau at 14 days was significant (P less than .02) in one experiment and approached significance (P less than .07) in the other experiment. Fat supplementation of both the broiler and turkey diets significantly (P less than .05) improved weight gain, feed efficiency, and fat retention. Supplementary Tau appears to have little effect on performance of broilers and turkeys.

Effect of age of hen, egg weight, and sex on chick performance and lipid retention.

Experiments were conducted to determine whether age of hen, weight of the egg, and sex of the chick affected fat retention and growth of the broiler chick. Chicks were fed a corn and soybean meal diet containing 5% supplemental poultry fat. In the first study, eggs from two ages of hens were compared (30 and 52 wk) with six egg weight classes per age. The second experiment consisted of three hen ages (31, 37, and 47 wk) with three egg weight classes per age. The results indicated that as hen age and egg weight increased, BW gain of the chicks increased but feed efficiency and fat retention were not affected. Females had improved fat retention when compared with males. When analyzed within each egg weight class, there was no age effect on fat retention, BW gain, or feed efficiency.

The effects of stress, Escherichia coli, dietary ethylenediaminetetraacetic acid, and their interaction on tissue trace elements in chicks.

The present study determined effects of Escherichia coli infection, crowding stress, and EDTA supplementation on Cu, Fe, and Zn levels in the serum, liver, bursa of Fabricius, and spleen of chickens. Organ weights as a percentage of BW were affected by treatments prior to and after infection. Liver and spleen weights as a percentage of BW increased with infection but bursa weight decreased. One week of stress increased hepatic Cu, but 3 wk of EDTA ingestion increased serum Cu and serum, hepatic, bursal, and splenic Fe. These elemental changes resulting from EDTA may have predisposed the chicks to a higher mortality rate from E. coli compared with controls. Peak mortality occurred 2 days after infection, coincident with an increased serum Cu, decreased serum and bursal Fe and Zn, and increased hepatic and splenic Zn. At 7 days postinfection, recovering chicks experienced decreased hepatic Fe, elevated hepatic Zn, decreased bursal Cu, Fe, and Zn, and increased splenic Cu, Fe, and Zn. The current study demonstrates the interactive effects of EDTA, stress, and E. coli infection on serum and organ trace element concentration.

Effects of Escherichia coli on iron, copper, and zinc metabolism in chicks.

The present report describes the effects of Escherichia coli endotoxin and infection on kinetic changes of copper (Cu), iron (Fe), and zinc (Zn) levels in the transport (serum), storage (liver), and immune organs (spleen and bursa of Fabricius) of the chicken. During infection and endotoxin challenge, increased serum and bursal Cu were noted. Infection and endotoxin both led to a redistribution of Fe with a decrease in serum and an increase in the spleen. Infection decreased serum Zn and concomitantly increased hepatic and splenic Zn. Seven days postinfection, when recovery was well underway, hepatic and splenic Cu and splenic Zn were elevated. Hepatic Fe decreased with recovery, whereas splenic Fe increased. Endotoxin and infection changed trace element kinetics. The endotoxin produced tissue elemental alterations similar to the early stages of infection. This indicated that in early infection, some of the disease responses may be due to endotoxin, whereas the later responses may be due to other aspects of infection such as stress.