TEST AT PRAWN FARMS Two objectives:
1. A more effective way of controlling microbial contamination in brine shrimp (Artemia) hatchery to improve food supply to the larval prawns. Currently using chlorine and/or peroxide with minimal success. High mortality due to chemical exposure. Have been working for some time with government funded consultants on natural options for control, such as lemon myrtle extract with no success. 2. A more effective method of washing and preserving the mature prawns to increase “shelf life” – an extra 7 days equate access to 20-30 more international markets.
Conditions were as follows: • Water and ice loaded into tanks and dosed with CleanShield Disinfectant concentrate at levels indicated below. • Mixture was stirred to ensure an even distribution of the ingredients. • Solution temperature was maintained at 4°C. • Prawns were loaded into tanks and gently stirred to ensure even exposure to the fluid. • Contact time was maintained at 12 hours (overnight storage) after which representative samples of prawns were drained and bagged in sealed, clear plastic bags to accelerate bacterial degradation. • Microbiological testing was conducted at the site using “3M Quick swabs” as indicators then enumeration was conducted according to AOAC international methods, where required.
Main trial: The main trials were focused on extending the shelf life of grown and harvested prawns. Testing was conducted in 1000 insulated tanks each containing 300kg of fresh prawns.
Summary: • • • •
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Prawn Quality Untreated prawns were unfit for display or consumption after 10 days. Storage bags exhibited excessive bottom liquid due to microbial breakdown of the fish. Prawns treated with 1000 ppm CleanShield Disinfectant concentrate remained fit for display and consumption for 15 days with no slime, odour or taste reduction. Very little liquid was detected in the bags. Appearance remained equal to fresh prawns. Subsequent to these trials, several 600kg batches were treated with 1000 ppm CleanShield Disinfectant and shipped to markets for customer reaction. The result was no detectable difference from fresh prawns after 15 days.
Provided by CleanShield Group