Quality aspects and species identification of cephalopod products on the German market

Commercial deep-frozen products of cuttlefish (labelled as Sepia spp, Sepiella spp.), squid (Illex spp., Loligo spp., Todarodes spp.), and octopus (Octopus spp., Eledone spp.) were analysed to give an overview of the current product quality on the German market and to see if the contents of total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), trimethylamine oxide nitrogen (TMAO-N), ammonia, and pH are appropriate indicators to confirm the sensory data of such products. All cuttlefish, octopus, and squid tubes had TVB-N contents ranging between 1.6 and 16.2 mg/100 g which agreed with a satisfactory sensory quality. Only a few products made from whole and skinned squid had elevated TVB-N values up to 27.8 mg/100 g muscle tissue. TMA-N and TMAO-N levels were low in all samples (<= 1.0 and <15 mg/100 g, respectively). Measurement of pH and ammonia content were not useful in assessing quality deterioration. The spoilage potential of defrosted products kept at 4 degrees C in a refrigerator was followed by chemical and sensory assessment. The increase of cadaverine, putrescine, and tyramine in the products varied. Free amino acids seemed notable as precursors of biogenic amines and due to nutritional aspects. Declaration of cephalopod species was investigated by PCR-based DNA analysis. A DNA segment of 208 base pairs from the cytochrome b gene was amplified and sequenced. Mislabelling of species was detected in a number of products.