RESUMO
Oyster ( Crassostrea gigas ) and water samples from Live Holding Tanks at five different Seattle area retail markets were analyzed for microbiological quality indicators and for potential pathogens monthly from March to September, 1987. Aeromonas hydrophilia was the most frequently isolated potential pathogen in this study with a higher incidence in oysters (78%) compared to water (53%). Vibrio cholerae non 01 and V. fluvialis were isolated from oyster samples from two different markets but not from water. V. alginolyticus was isolated from 53% of the water samples but was not found in any of the oysters. One oyster sample had a non-pathogenic Yersinia entercolitica . Yersinia spp. were isolated from oyster samples from one tank at two sampling periods. Salmonella typhimurium was isolated from one oyster sample. Samples were examined for Listeria spp. during the August sampling period and none were detected. The aerobic plate count was similar for both oyster and water samples and averaged 2000 CFU/gm. Total coliform levels were significantly higher (P<.05) for oysters (525MPN/100gm) compared to water (11MPN/100ml). The degree of water turbidity, crowding and species diversity varied between markets and sampling periods.
RESUMO
Spotted shrimp ( Pandalus platyceros ) were stored head on and head off on melting ice in air and controlled atmosphere for 14 d to test effects of controlled atmosphere on storage life of the shrimp. Pure carbon dioxide was allowed to flow through the controlled atmosphere chamber at the rate of 0.5 L/min maintaining a 100% CO2 atmosphere. Aerobic bacteria counts, ammonia, weight loss and sensory analyses were determined initially and after 7 and 14 d. Bacterial counts increased more rapidly and to higher levels in air pack than controlled atmosphere samples. The levels of ammonia were very low in the fresh shrimp and increased to 21 and 16 mg% in head-on and head-off air-pack samples, respectively. The levels reached only 12 and 6 mg% in similar samples stored in CO2. Weight loss was greater for shrimp stored in CO2 than in air. Sensory evaluation showed air-pack head-off samples to be unacceptable after 14 d of storage but CO2-packed samples had only moderate discoloration and no detectable off-odors. These data show that spotted shrimp could be shipped on ice under controlled atmosphere to fresh fish markets.
RESUMO
Shrimp ( Pandalus platyceros ) were packed head-on and head-off in pouches with air or 50 or 100% CO2 and stored at 0 to 2°C for up to 23 d. Carbon dioxide in modified atmosphere pouches dissolved in the liquid phase and the pH decreased. As storage progressed, the pH increased. Only 100% CO2 was effective in extending the lag in bacterial growth, but the greatest weight or drip was also obtained with this atmosphere. The bacterial flora changed from mixed gram-negative and gram-positive organisms to a predominantly gram-positive flora. Ammonia was produced throughout storage in all atmospheres, but was delayed longer in head-off than in head-on shrimp. Indole was produced readily in air packs but only at low levels in CO2 packs.
RESUMO
Bacterial isolates (244) identified to genera were tested for their ability to produce ethanol, isopropanol and propanol in a fish tissue extract. All of the isolates produced ethanol and 241 and 227 produced isopropanol and propanol, respectively. One high alcohol producing member of each of the groups Moraxella -like, Pseudomonas , Flavobacterium , Micrococcus and coryneforms was selected for utilization of fish components as substrates in production of alcohol. The substrates tested included four sugars, nine amino acids and lactic and pyruvic acids. Although there were some variations in the levels of alcohols produced by the test organisms from the substrates, the organisms appeared to prefer simple 5 and 6 carbon sugars and then utilized the free amino acids. The level of oxygenation greatly affected the levels of alcohols produced.
