RETAINED WATER AND BACTERIAL LOAD FOR SILURIFORMES Ictalurus furcatus × Ictalurus punctatus FILLETS BEFORE, DURING AND AFTER PROCESSING

The USDA-FSIS adopted existing meat and poultry net weight and retained water labeling  regulations for Siluriformes products including channel (Ictalurus punctatus) and hybrid ( Ictalurus furcatus x Ictalurus punctatus ) catfish. Proximate composition, retained water and bacterial load of two sizes of hybrid catfish fillets was determined . The overall mean (± SD) baseline moisture, protein and fat content of the fillets were 77.8% (1.4), 16.7% (0.5) and 5.7% (1.6) , respectively. B aseline moisture (78.6 vs 76.8%) content was greater (P≤0.05) and fat content (4.7% vs 6.8%) was lower (P≤0.05) for small fillets (111 g) in comparison to large fillets (247g), whereas protein content was similar (P>0.05) for both sizes. The retained water of the final fresh and frozen fillets were 1.2 ± 2.0% and 3.1 ± 1.0%, respectively and was not size dependent. PPC and TCC of the baseline fillets were ~  4 log CFU/g and 1.6 log CFU/g, respectively and did not change (P>0.05) during processing, except  at  injection. Moisture-protein ratio and fat content were good (P≤0.05) predictors for retained water of the catfish fillets during processing.

This work showed that  market-ready  catfish fillets (fresh)  did not retain any water even after water and slush-ice chilling. The apparent moisture gain is lost during the process and probably after the process, regardless of fillet size.

Retained water and bacterial load for Siluriformes (hybrid catfish: Ictalurus furcatus x Ictalurus punctatus ) from reception to final product (BT=Before Trimming (Baseline); BC= After trimming/before chilling; AC=After water chilling; AS= After slush ice chilling; BIP = Before ice packing (Fresh fillets) ; AI= After injecting (polyphosphate injection), AF=After freezing (Frozen fillets).