A survey of process hygiene in the Sri Lankan prawn industry. 1. Hygiene status of raw materials and products

A survey of processing hygiene in the Sri Lankan prawn industry has shown that the incoming raw material has extremely high bacterial loadings; about 50% of samples analysed had a total count in excess of 10,000,000/g. Although beheading reduces the count, ineffective temperature control during processing means that the final total count of raw, shell-on, P.U.D. and P.A.D. prawns, as well as cooked prawns, is in excess of 1,000,000/g. - the maximum level specified by many importing countries.

Seasonal Changes in Chemical Composition of Eurasion Watermilfoil (Myriophyllum spicatum L.) and Water Temperature at Two Sites in northern California: implications for Herbivory

We compared seasonal changes in Eurasian watermilfoil (Myriophyllum spicatum L.) characteristics and water temperature for a shallow poind in Davis, CA, and the Truckee River, near Tahoe City, CA. Tissue C and N were 15% lower in plants from the Truckee River than in plants from the Davis pond. Seasonal fluctuations in tissue N were also different. Mean phenolic acid content of Truckee River palnts (162yM g-1) was less than those from the shallow pond (195 yM g-1). Phenolic acid content was positively related to tissue C for Truckee River and Davis pond plants and, tissue C:N ratio for Truckee River plants. Mean monthly water temperature (1990 to 1998) for the Truckee River site was less than 20 C. Water temperatures were warmer in August and September at this site. However, Eurasian watermilfoil collected during these months was characterized by lower levels of tissue N. During a 29-month period beginning January 1994, mean monthly water temperature for the Davis pond exceeded 20 C, only during July to September 1995. Tissue N was generally greater during summer for watermilfoil growing in the pond. These results imply that Eurasian watermilfoil biological control agents may have different developmental rates in these habitats, and thus different impacts on watermilfoil populations.

Influence of water temperature on the efficacy of diquat and endothall versus curlyleaf pondweed

determine the impact of water temperature on the efficacy of the contact herbicides diquat (6,7-dihydrodipyrido [1,2- α:2’,1’-c] pyrazinediium ion) and endothall (7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic acid) for control of the exotic nuisance species curlyleaf pondweed (Potamogeton crispus L.) across a range of water temperatures.

Factors to consider when using native biological control organisms to manage exotic plants

Biological control of exotic plant populations with native organisms appears to be increasing, even though its success to date has been limited. Although many researchers and managers feel that native organisms are easier to use and present less risk to the environment this may not be true. Developing a successful management program with a native insect is dependent on a number of critical factors that need to be considered. Information is needed on the feeding preference of the agent, agent effectiveness, environmental regulation of the agent, unique requirements of the agent, population maintenance of the agent, and time to desired impact. By understanding these factors, researchers and managers can develop a detailed protocol for using the native biological control agent for a specific target plant. . We found E. lecontei in 14 waterbodies, most of which were in eastern Washington. Only one lake with weevils was located in western Washington. Weevils were associated with both Eurasian ( Myriophyllum spicatum L.) and northern watermilfoil ( M. sibiricum K.). Waterbodies with E. lecontei had significantly higher ( P < 0.05) pH (8.7 ± 0.2) (mean ± 2SE), specific conductance (0.3 ± 0.08 mS cm -1 ) and total alkalinity (132.4 ± 30.8 mg CaCO 3 L -1 ). We also found that weevil presence was related to surface water temperature and waterbody location ( = 24.3, P ≤ 0.001) and of all the models tested, this model provided the best fit (Hosmer- Lemeshow goodness-of-fit = 4.0, P = 0.9). Our results suggest that in Washington State E. lecontei occurs primarily in eastern Washington in waterbodies with pH ≥ 8.2 and specific conductance ≥ 0.2 mS cm -1 . Furthermore, weevil distribution appears to be correlated with waterbody location (eastern versus western Washington) and surface water temperature.

Mathematical models for the prediction of temperature distributions resulting from the discharge of heated water into large bodies of water

Mathematical models for heated water outfalls were developed for three flow regions. Near the source, the subsurface discharge into a stratified ambient water issuing from a row of buoyant jets was solved with the jet interference included in the analysis. The analysis of the flow zone close to and at intermediate distances from a surface buoyant jet was developed for the two-dimensional and axisymmetric cases. Far away from the source, a passive dispersion model was solved for a two dimensional situation taking into consideration the effects of shear current and vertical changes in diffusivity. A significant result from the surface buoyant jet analysis is the ability to predict the onset and location of an internal hydraulic jump. Prediction can be made simply from the knowledge of the source Froude number and a dimensionless surface exchange coefficient. Parametric computer programs of the above models are also developed as a part of this study. This report was submitted in fulfillment of Contract No. 14-12-570 under the sponsorship of the Federal Water Quality Administration.

Geographic patterns in the lag of temperature response to insolation for El Niño vs. La Niña conditions [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): The most important control on the annual cycle of temperature is insolation, with secondary influences from terms related to moisture, yet direct statistical analysis of the moisture-driven modulations (such as El Niño) of the response of temperature to insolation are not available. We have examined one aspect of the relationship between insolation and the instrumental record of maximum daily temperature - the lag between the two - at 252 stations in the western United States.

Chemical control of psychrophilic bacterial spoilage of fish 1. Isolation and identification of psychrophilic bacteria from marine fish

Making use of the streak plate technique and low temperature incubation, 28 cultures belonging to six genera namely, Achromobacter, Flavobacterium, Pseudomonas, Micrococcus, Vibrio and Alcaligenes were isolated from different varieties of marine fish. The growth studies indicated that all of them were able to grow between -5 and +5°C within a week's time and none of them showed growth at 37°C. The optimum temperature of growth for all these cultures was in the range 25-28°C. Among these only one, i.e., a Vibrio sp., was found to be an obligate psychrophile.

High temperature processing of fish sausage 2. - Effect of certain preservatives on the shelf life

The effects of preservatives like fat coated sorbic acid (FCSA) and glucono-deltalactone (D-lactone), both separately and in combination, on the shelf life of high temperature (115.6°C for 20 min) processed fish sausage, stored at three different temperatures namely, ambient (28±2° C), cooler storage (2±2°C) and refrigerator (10±2° C) were studied. Whereas the control (without preservative), FCSA, D-lactone and FCSA + D-lactone treated samples could be stored for 9, 11 and 13 days respectively at ambient temperature, those stored at lower temperatures were found to be in acceptable condition for 70 and 80 days respectively. Organoleptic evaluation of taste, flavour the products carried out by panelists revealed that FCSA and FCSA + D-lactone treated samples were unacceptable with regard to the taste, flavour and texture. However, the taste flavour and texture of the control and D-lactone treated samples were in acceptable condition.