J. A. Carpenter

Prevalence of Clostridium perfringens in Pork during Processing

The prevalence of Clostridium perfringens on pork carcasses, fluid from the body cavity, livers, hearts, spleens, visceral pans, scalding vat water and pork sausage was determined. Clostridium perfringens was not detected on pork carcasses, hearts, spleens nor visceral pans. Fluid from the body cavity had 11.8% positive incidence while livers had 21.4% for interior tissues and 11.8% for exterior tissues. The organism could always be isolated from scalding vat water. Commercial pork sausage had 38.9% prevalence of C. perfringens . Numbers of spores and their heat resistance are also reported.

Types of Bacteria and Shelf-Life of Evacuated Carbon Dioxide-Injected and Ice-Packed Broilers

Broiler carcasses were packed in low-permeability film bags that were evacuated, injected with CO2, then held at 2 C. Broilers were examined microbiologically and for off-odor to determine the shelf-life and types of bacteria. Vacuum level did not significantly affect bacterial counts. Broilers stored in 65% CO2 had a 1-day longer shelf-life than those held in 20% CO2 and about a 5-day longer shelf-life than ice-packed broilers. Spoiled carcasses from either 20 or 65% CO2 packages had an acid-sour off-odor, and more than 90% of the bacteria present were Lactobacillus . Ice-packed broilers had the typical putrid off-odor at spoilage, and more than 95% of the bacteria were non-pigmented Pseudomonas .

Airborne Aflatoxin in Corn Processing Facilities in Georgia

Problems affecting the health of agricultural workers in processing facilities where grains are contaminated with aflatoxin have been noted previously. Airborne particulates produced during processing are reported to produce various carcinomas when inhaled by factory workers. Two corn processing plants within Georgia were surveyed during the fall of 1984 and 1985 with utilization of an Andersen 6-stage air sampler, a high-volume air sampler and a slit sampler. No airborne aflatoxin was found; however, 10% of settled dust samples were contaminated with aflatoxin. The average particles were found to be globular in shape with an effective diameter between 2 to 3 microns. Only 30% of the bulk corn samples contained aflatoxin, which was present at low levels (0.15 to 8 ppb).

Effect of Anthocyanin Pigments on Certain Enzymes.

Summary The activities of alpha glucan phosphorylase and glutamic acid decarboxyl-ase increased when increasing amounts of 4 anthocyanin compounds were added to the substrate. The activities of glycerol dehydro-genase, malate dehydrogenase and hexokinase decreased except at the lowest concentration, 0.01%. At this level, the tendency was to increase slightly the activity of the enzymes studied. Possible explanations for the effect of anthocyanin pigments on the enzyme systems studied are discussed.

Comparison of Particulate Air Samplers for Detection of Airborne Aspergillus flavus Spores

Four air samplers (Millipore, all-glass impinger, Andersen and absorbent cotton) were evaluated for their ability to collect airborne grain particles contaminated with Aspergillus flavus spores. Corn dust containing 6.4 × 106 spores/g was aerosolized within a containment system. Each device sampled 100 L of air, thus exchanging the air in the chamber two times. Spores were enumerated from all sampling matrices using Aspergillus flavus / parasiticus agar. The efficiencies of the Millipore and the cotton samplers were almost identical, while that of the all-glass impinger was less. Measurement of particle size with the Andersen sampler revealed that these spores were associated with particles of various sizes.

Antibiotic Resistance of Salmonella Isolated from Pork Carcasses in Northeast Georgia

One hundred twenty-one isolates of Salmonella , isolated from 225 pork carcasses in Northeast Georgia during a two year period, were examined for resistance to nine anti-microbial agents. The most commonly found resistances were to penicillin (95%), trimethoprim (80.2%), ampicillin (80.1%), and tetracycline (64.5%). No resistance to gentamicin nor neomycin was detected. Chloramphenicol showed an 11.6% resistance in all strains tested. Eight different antibiotic resistance patterns were observed with 84.3% of isolates showing multiple resistance patterns with two or more drugs.

Evaluation of particulate air samplers for airborne aflatoxin B1.

Five air samplers (Millipore, all-glass impinger, centrifugal, Andersen, and absorbent cotton) were evaluated for their ability to collect airborne grain particles contaminated with aflatoxin B1. Corn dust containing 100 micrograms aflatoxin B1/g was aerosolized within a containment system. Each device sampled 100 I air, thus exchanging the air in the chamber two times. Aflatoxin B1 was extracted from all sampling matrices and was detected and quantitated with thin-layer chromatography and scanning fluorodensitometry. The highest efficiency was obtained with the Millipore sampler, while the efficiencies of the centrifugal and the cotton samplers were almost identical. Efficiency of an Andersen was less, with no toxin recovered from an all-glass impinger. Measurement of particle size was accomplished with the Andersen sampler.

Interaction between Salmonella enteritidis and Candida albicans

Summary Injection of Candida albicans ic facilitated establishment of disease as evidenced from the LD50 studies. The LD50 at 14 days for mice injected ic with C. albicans was log 5.2 ± 0.5 cells and log 7.2 ± 0.5 cells when injected ip. The LD50 at 14 days for Salmonella enteritidis injected ic was log 6.6 ± 0.5. Interaction between mixed cultures of C. albicans and S. enteritidis was studied under various environmental conditions. Retardation of growth of C. albicans was noted in broth in presence of actively growing S. enteritidis. Cell-free culture filtrates of S. enteritidis or of C. albicans failed to inhibit proliferating cells of competing organisms. Also, test cultures grew commensally on all plates incubated aerobically as well as under anaerobic or microaerophilic conditions. Proliferation of S. enteritidis in the spleen, ceca, kidneys, and liver depended upon number of cells injected. Several organ tissues showed the presence of large populations of S. enteritidis when infected ip with log 6.0 or more S. enteritidis cells. No deaths occurred among animals receiving log 5.0 S. enteritidis cells. The spleen and blood of mice infected with C. albicans were able to eliminate the organisms rapidly. When mice received only C. albicans (log 5.0 cells), large populations of the organism were noted in both kidney and cecum. Lower concentrations of C. albicans were readily eliminated by these organs. Mice infected with S. enteritidis 24 hr prior to infection with C. albicans exhibited three conditions depending upon the numbers of cells of S. enteritidis. High numbers (above log 7.0) of S. enteritidis cells produced greater mortality rates in infected animals similar to those where no C. albicans were injected. Log 6.0 S. enteritidis cells plus log 5.0 C. albicans cells (lethal dosages) prevented mortality to mice. Lower numbers of S. enteritidis (log 5.0 or less) did not produce disease syndrome in mice and did not alter lethal effect of C. albicans. Organ tissues of mice preinfected with log 6.0 S. enteritidis and then injected with log 5.0 C. albicans cells showed a decrease in growth of C. albicans. The cecum of these mice did not support growth of Candida. Evidence indicated that interaction between these test cultures prevented invasion of the tissues by C. albicans.

Inhibition of Enzymes by the Anthocyanin Malvidin-3-Monoglucoside.∗†

Summary The cytoplasmic, particulate, and cell wall fractions were isolated from disrupted bacterial cells and assayed for MADH, GDH, HX, and GLD enzymes in absence of pigment (control) and presence of various M-3-G concentrations. The magnitude of enzymatic inhibition due to increasing concentrations of M-3-G (1 to 4 μM) was not the same for each enzyme. Two μM of M-3-G inhibited glycerol dehydrogenase (35% of control) in particulate fraction, whereas, 76% inhibition was noted in cytoplasmic fraction with 4 μM of pigment. MADH was inhibited to the extent of 10 and 20% in particulate fraction with 2 and 4 μM of M-3-G respectively and 4% in cytoplasm with both pigment concentrations. For comparative purposes, the effect of M-3-G on the same enzymes obtained commercially from other sources revealed that GDH (Aerobacter aerogenes) was inhibited 85% with 4 μM pigment. Inhibition (87%) of MADH (pig heart) and (17%) GLD (Escherichia coli) was noted with 2 μM M-3-G. Stimulation of HX (yeast) (21% over control) was observed with 1 μM M-3-G; 2 μM had no effect, whereas 4 μM caused 6% inhibition. Competitive and non-competitive inhibition of GLD by M-3-G, depending on how substrate, inhibitor and enzyme were mixed, followed Michaelis-Menton kinetics as indicated by the linear relationship in the Lineweaver-Burk plot with Km = 2.3 × 10-5 M for enzyme and inhibitor equilibrated together and substrate added at zero time.

Effect of added water, sodium erythorbate and storage time on the functional properties of prerigor beef preblends in a model system.

Singular and combined effects of added water, sodium erythorbate and storage time on salt soluble protein extractability, bacteriological and chemical characteristics of preblended hot-boned beef were evaluated. Waterholding and gel forming capacities of preblended hot-boned beef containing either 0, 10 or 20% added water were determined. Significant interactions between added water level and storage time on microbial counts and between sodium erythorbate level and storage time on thiobarbituric acid values and residual nitrite levels were noted. The presence of sodium erythorbate resulted in a more (P < 0·05) rapid rate of nitrite disappearance, but it did not affect (P > 0·05) microbial counts. Salt-soluble protein extractability was not affected (P > 0·05) by added water, but more protein could be extracted with increasing storage time. A trend existed to suggest that the presence of added water in the meat preblends slightly improved the gel formation and waterholding capacities.