Even when using a 4-hexylresorcinol dip the protection provided is not uniform (Guandalini et al., 1998). The residue from a once off dip drops rapidly over a number of days storage. The authors found that towards the end of organoleptic acceptability 20-30% of prawns were unaffected by blackspot. This researcher noted similar uneven blackspot development during storage (Slattery et al., 1995). This outcome is obviously due to uneven exposure and retention of the limited amount of 4-hexylresorcinol that a quick dip in a solution of the chemical can supply.

There is limited information on the effect of longer term treatment with 4-hexylresorcinol but only at the same concentration as the short dip (Iyengar et al., 1991 and Slattery et al., 1995). Providing industry with this type of information will lead to more adoption of a safer chemical and less chemical treatment of prawns.

Unlike Australia, many importing countries have defined residue limits which the product has to comply with. It is unknown what residues are likely from any long term exposure. The only information available is from a one hour dip of live prawns in the standard concentration which resulted in very high residues.

A range of methods of using Everfresh that will provide good protection from blackspot, yet result in low residues, is needed by the prawn industry. This research will assist the APFA Tactical R&D Plan by increasing profitability through reduced usage and wastage of expensive chemicals. The QSMA have been trying to convince the wild capture prawn industry to adopt the use of Everfresh for some time. This work would meet ASIC concerns for quality and safety of seafood. This project also complies with the SSA Plans for Seafood Quality and Safety in Segment 3.