Qualitätsvergleich zwischen panierten Filetportionen aus einfach- und doppelgefrorenen TK-Blöcken

Single and double frozen fillet blocks of Alaska pollack and cod both commercially processed of unknown shelf life were further processed to breaded battered portions. The quality of these fillet portions were compared using sensory (QDA), physical and chemical methods. It was difficult to differentiate between SF and DF fillets by sensory method because of the absence of differences in flavour attributes. While no differences could to be found in the texture of cod fillets, in Alaska pollack fillets some texture attributes were significantly different. These differences could not be verified by instrumental texture measurement. In all cases the lightness was different between SF and DF fillets. Probably, after having fixed L* values for SF fillets of commercially important fish species as limit this could be employed in the future to differentiate between single and double frozen products. Due to the unknown shelf life it is difficult to evaluate the results. Therefore, the investigation of the influence of double freezing on the quality needs a special sample preparation. The use of randomly taken commercially processed samples seems not to be useful.

Vergleichende Texturuntersuchungen an Filets von Kliesche (Limanda limanda) und Scholle (Pleuronectes platessa) in Abhängigkeit von Eislagerzeit post mortem, TK-Lagerung und Erhitzen

Instrumental investigations of texture have been performed using texture profile analysis. The following textural parameters have been assessed: hardness, gumminess, chewiness, springiness, cohesiveness and adhesiveness. The fillets of both species have been prepared from deep frozen headed and gutted raw material without fins after frozen storage of 0, 23 and 34 weeks, respectively. Deep freezing of fishes has been performed on board immediately after hauling or after 6 day’s storage in ice. Before texture measurement the raw material has been thawed and the measurement was carriedout on both thawed and microwave-heated fillets. In general, it can be concluded that both fish species are comparable in their texture parameters. The hardness of heated dab has been slightly higher comparing with that one of plaice. All other texture parameters showed a fairly good conformity between both species. While the hardness of dab increased during heating, it was decreasing in plaice. This was the only one significant difference between both fishes during heating. Adhesiveness as well as cohesiveness increased remarkably during heating. Changes effected by ice storage were only slight. Frozen storage, in contrast, caused a significant decrease of adhesiveness measured after heating the fillets of both species.