The Removal of Trimethylamine Oxide and Soluble Protein From Intact Red Hake Muscle by Washing

Soaking red hake fillets in water (1:20) removes significant amounts of TMAO and water-soluble proteins from the exterior but not interior muscle layers. Scoring the muscle before soaking allowed these components to be removed from the muscle interior. The water uptake which occurred on soaking was increased after scoring. Changing the pH of the soak water had no effect on TMAO or protein removal, but there was inhibition of water uptake at pH 4.0. The addition of NaCl to the extracting solution did not affect TMAO removal but decreased both soluble protein loss and water uptake. The size and shape of the red hake fillets did not materially affect loss of TMAO or soluble protein, but water uptake was related to the surface area to volume ratio. A short-term wash or spray treatment also reduced TMAO and soluble protein contents in the exterior layers of the fillet.