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H Riemann

Publications and source records attributed to H Riemann.

84 records · Page 5Linked to original sources
PubMed1968

Detection of Salmonella by a single-culture technique.

Dulcitol-selenite enrichment medium in a motility flask was used for the detection of Salmonella in food. A drop in pH of the dulcitol-selenite enrichment motility broth indicated the presence of Salmonella; this phenomenon was confirmed by fluorescent-antibody staining. A complete correlation was found between fluorescent-antibody staining and recovery on Brilliant Green agar. Testing of 332 samples of 8 different kinds of foods and feeds indicated no significant difference in sensitivity between the new technique and a conventional Salmonella detection technique. The new technique permitted detection of even small numbers of Salmonella in 1 to 2 days.

Alcohols↗
PubMedDate not supplied

Survival of Salmonella typhimurium and Escherichia coli O157:H7 in poultry manure and manure slurry at sublethal temperatures.

Exponential inactivation was observed for Salmonella typhimurium and Escherichia coli O157:H7 in poultry manure with decimal reduction times ranging from half a day at 37 C to 1-2 wk at 4 C. There was no material difference in inactivation rates between S. typhimurium and E. coli O157:H7. Inactivation was slower in slurries made by mixing two parts of water with one part of manure; decimal reduction times (time required for 90% destruction) ranged from 1-2 days at 37 C to 6-22 wk at 4 C. Escherichia coli O157:H7 consistently exhibited slightly slower inactivation than S. typhimurium. Log decimal reduction time for both strains was a linear function of storage temperature for manure and slurries. Chemical analysis indicated that accumulation of free ammonia in poultry manure was an important factor in inactivation of the pathogens. This finding was experimentally confirmed for S. typhimurium by adding ammonia directly to peptone water or to bovine manure, which was naturally low in ammonia, and adjusting pH to achieve predetermined levels of free ammonia.

Ammonia↗
PubMedDate not supplied

Heat destruction of Salmonella in poultry feed: effect of time, temperature, and moisture.

Salmonella enteriditis in poultry feed declines with increasing time of exposure to heat. The interactions of temperature, time, and moisture and their effect on the thermal death of S. enteriditis were established in a factorial randomized experiment. Two other serotypes were tested, and though there was some variation, the thermal death rate followed the same basic pattern. A number of samples of poultry feed were collected and dried. After drying, the water was added back to give specific percentages of moisture contents. The feed was then inoculated with salmonella and heated at specific temperatures, with samples being removed at certain time intervals. These samples were then cultured, and the surviving salmonella were counted. A linear relationship was obtained when the logarithm of survivors was plotted against the logarithm of exposure time. These results permitted the construction of a graph depicting that the rate of reduction in numbers of S. enteriditis when plotted against increasing temperatures is linear. This linear relationship is apparent for other salmonella serotypes such as S. typhimurium and S. haardt. Our results show that the thermal death rate of salmonella in poultry feed can now be predicted at varying time, temperature, and moisture contents.

Animal Feed↗
PubMedDate not supplied

Destruction of Salmonella enteritidis in poultry feed by combination of heat and propionic acid.

A factorial laboratory experiment was conducted to assess the effects of heating times of 0, 20, 40, and 80 sec at 160 F and propionic acid concentrations of 0, 0.1%, and 0.2% on reduction of Salmonella enteritidis in poultry feed with approximately 15% moisture. The results showed that after 80 sec heating time an approximately 10,000-fold reduction in living salmonella was obtained in the samples with 0.2% propionic acid. Survival in the 0.2% acid group was 2 log10 lower than in the 0.1% and control groups. This difference was statistically significant. Multivariate analysis with repeated measures showed there was no interaction between heating time and propionic acid concentration (P = 0.4113). There were overall significant effects for both acid concentration (P < 0.00001) and heating time (P < 0.0001).

Animal Feed↗
PubMedDate not supplied

A survey for Salmonella by drag swabbing manure piles in California egg ranches.

A cross-sectional study was conducted between August 1995 and November 1996. Sixty California egg-producing ranches were chosen at random; 39 ranches agreed to participate in the study. The surface of the manure pile in one house on each ranch was sampled by drag swabbing. The drag swabs were tested for Salmonella using a most probable number procedure that had a detection level of one to five Salmonella per drag swab. In 12 ranches (32.4%), the drag swabs were negative for Salmonella; the remaining had Salmonella counts in the range of 1 to over 1700 per swab. Twenty-two different serotypes were found. Salmonella heidelberg and Salmonella cerro represented the majority of the typed isolates. Salmonella enteritidis (SE) was found on only one ranch. This study found SE to be rare in California egg ranches, which implies that these ranches are not a major source of S. enteritidis.

Animals↗