Effect of precooking and polyphosphate treatment on the quality of catfish fillets cooked in pouch in boiling water

Cooking or reheating food in a vacuum-sealed bag has been a common method of preparing vegetables, meats and poultry products. However, there are very few examples of vacuum-sealed bags designed for cooking catfish fillets. The objective was to examine properties of raw frozen and precooked frozen catfish fillets that were cooked in a vacuum-sealed pouch in boiling water. The effect of a commercial polyphosphate blend (IQF) on product properties was also evaluated. Sample analyses included weight loss, proximate content, colour (CIE L*a*b*), pH, mechanical texture and lipid peroxidation (TBARS) measurements. Both raw frozen and precooked frozen IQF fillets showed a significantly lower per cent moisture loss after cooking, of less than 2.7% relative to the fillets without polyphosphate (6.2-7.4%). Colour analysis showed a significantly higher b*(C) (yellowness) value for fillets without polyphosphate. Similar texture properties were observed between cooking treatments, with a harder texture (similar to 1.3-1.7 times) determined for fillets without polyphosphate.