The CODEX standard versus the enthalpy method: comparison of two techniques for determination of ice-glaze uptake on prawns

摘要

Glazing is the application of water (or sometimes a salt-sugar solution) to the surface of frozen foodstuffs, so that a layer of ice is formed. This procedure protects the product from the effect of dehydration and oxidation during long term storage. However, glaze is often applied in an uncontrolled manner and considerable variation in the quantity of glaze may result. Today the CODEX standard is most widely used to determine the glaze-uptake of individually quick frozen (IQF) seafood products. However, the method exhibits considerable variations with respect to accuracy and precision. We propose a conceptually totally different method for ice-glaze determination of cold-water prawns. The method is denoted the enthalpy method and is based on noncontact mea- surement of the prawn filet temperature elevation during glazing. Comparisons of the CODEX and the enthalpy methods against weight reference measurements of the glazing percentage show that the enthalpy method is superior, provided performance indices like precision and sampling rate are used as evaluation criteria.