Hydrocolloids were added to blue whiting mince in order to study their distribution in the gel and obtain more information on the mechanism through which these additives act on gel characteristics. The hydrocolloids expanded in cavities of varying morphology. The anionic hydrocolloids were mixed throughout the protein matrix, probably through interaction with the myofibrillar protein. The neutral hydrocolloids were dispersed throughout the matrix but did not interact with it and were located simply by inclusion. The thickening hydrocolloids (locust bean gum, guar gum, xanthan gum, carboxymethylcellulose) formed a mesh of filaments inside the cavities; while the gelling hydrocolloids (carrageenans, alginate) covered or lined the cavity interiors with a continuous structure.

A new proteolytic activity assay was devised to avoid the interference of paramyosin which causes gelling during the enzymatic assay. Extremely high autolytic activity was observed in octopus arm muscle, which was 40–500 fold higher than those of various other fish species. The proteinase was inhibited strongly by leupeptin and iodoacetic acid and, to a lesser degree, by transepoxysuccinyl‐L‐leucylamino (4‐guanidono)butane (E‐64), indicating the class as a thioi proteinase. The proteinase exhibited optimum activity at pH 2.5 and 40C, although it contained a sulfhydryl group in the active site. Myosin heavy chain was the primary myofibrillar protein which was hydrolyzed during the autolysis of octopus arm followed by paramyosin. Actin showed no signs of hydrolysis during the incubation of up to 8 h. Due to its high affinity for myosin, the enzyme activity should be controlled during processing octopus to ensure the functionality of myosin.

Samples were subjected to continuous and step-pulsed pressurization, in both cases at 7 and 40 ЊC. There was a reduction of microbial flora (total viable count and lactic bacteria) after pressurization and during storage at 2.5 to 3.0 ЊC, chiefly in the lot pressurized by step-pulse at 400 MPa, 40 ЊC. Pressure-induced modification of the microbial flora resulted in a lower level of nitrogenous compounds. Pressurization reduced autolytic activity, but shear strength values remained stable throughout storage. There was less drip loss in the pressurized lots at 7 ЊC that at 40 ЊC, and the WHC values decreased during storage. Shelf life of the pressurized octopus overall was 43 d longer than unpressurized.

Materials and MethodsF RESH (FROM 18 TO 24 H IN ICE AFTER CAPTURE) SQUIDS (LOLIGO vulgaris) were gutted and skinned. Tentacles were removed ABSTRACT: Viscoelastic changes during thermal gelation of squid (Loligo vulgaris) muscle with protease inhibitors were studied, in order to evaluate the contribution of different proteinases to gel degradation. Calcium chloride was also tested as enzyme activator. A minimum in elastic modulus without inhibitors was achieved at 38 to 40 °C. Although denaturation temperature was around 55 °C, pronounced melting of connective tissue started at 40 °C. Proteolysis occurred between 25 and 75 °C, with maximum at 40 to 45 °C. Addition of PMSF led to highest values of G'. The strong inhibition of autolytic activity by PMSF confirmed the predominance of serine proteases. Addition of CaCl 2 favored thermal protein aggregation from 40 °C upwards.

The effect of 4 food-grade protease inhibitors-bovine plasma, potato powder, ethylenediaminetetraacetic acid, and sodium pyrophosphate-on heat gelation of squid (Todaropsis eblanae) muscle was studied. The action of these ingredients was characterized by determining the proteolytic activity in batters containing them and the rheological properties of gels made with them. The gelation profile showed that the setting effect was greatest with pyrophosphate (PPI) and that gel rigidity was highest with bovine plasma (BP). All 4 inhibited proteolytic activity to some extent at 65 °C. BP was the most effective. At 40 °C, only EDTA and PPI were active. Rheologically, the most effective combination was PPI plus bovine plasma in that this combined inhibition of proteolytic activity with gel enhancement.