Effect of calcium and magnesium impurities in common salt on the carotenoid pigments in canned prawns.

Sea-fresh catches of Penaeus indicus, Metapenaeus dobsoni and Parapenaeopsis stylifera were prepared and blanched in various 6% brines containing impurities (e.g. calcium and magnesium chlorides and sulphates) at 0, 0.05, 1.00 and 5.00%, cooled and filled into S-resistant lacquered cans using similarly impure hot-fill 2% brines. Cans were processed, sealed, cooled and stored at room temp. for 7 days before opening. Prawn flesh was analysed for carotenoids and results are tabulated. Colour intensity due to carotenoids increased as % impurity increased, the extent varying with spp. and size of individuals caught.