Comparative study of proteolysis in short-finned (Illex illecebrosus) and long-finned (Loligo pealei leseur) squid

Properties of Proteolytic Enzymes from Muscle of Octopus (Octopus vulgaris) and Effects of High Hydrostatic Pressure

“…They were highly sensitive to cysteine-proteinase inhibitors, that is, E-64 and leupeptin, and the principal target of the protease was myosin followed by paramyosin (Hurtado and others 1999). Other studies have also verified the existence of a high level of autolytic activity in cephalopod mantle and verified its preference for acidic pH for its activity in muscle of several species of squid: Ommastrephes sloani pacificus Sakai and others 1981;SakaiSuzuki and others 1983); Illex illecebrosus (Leblanc and Gill 1982;Hameed and Haard 1985) and Loligo pealei (Leblanc and Gill 1982); and Todaropsis eblanae (Ayensa and others 1999).…”

“…Kolodziejska (1985) found high proteolytic activity in the acidic pH range with an optimum at pH 3.0 in the mantle of flying squid (Illex illecebrosus). In this species and another species of squid (Loligo pealei), the optimum pH for proteolysis are 2.6 and 3.6, respectively, although some activity has also been reported in the alkaline range (Leblanc and Gill 1982). Stanley and Hultin (1984) also found maximum activity in the acid pH range (pH 3.0) for flying squid (Illex illecebro- Octopus proteolytic enzymes after high pressure… sus), although, again, there was activity at higher pH levels, with the maxima at pH 5.8 and 6.6 at an incubation temperature of 25°C.…”

Chilled Storage of Pressurized Octopus (Octopus vulgaris) Muscle

“…Over the storage period, there was no difference in the lots (p Յ 0.05) with respect to either the temperature or pulsed pressurization. In the unpressurized lot, softening during storage was due to gradual proteolysis of the myofibrillar proteins by the enzymes (Leblanc and Gill 1982;Yamashita and Konagaya 1992;Ashie and others 1997) and their effect on the connective tissue (Montero and Borderías 1990;Sato and others 1991). In the case of the pressurized lots, despite the possible release of lysosomal enzymes to the medium, as noted above, the muscle was not softer, probably because, as it was mentioned before, these enzymes were inactivated by the high pressure.…”

Effects of Additives on the Selected Quality Attributes and Cooking Yield of Squid: Modelling and Optimization

“…Thus, non-protein nitrogenous (NPN) compounds are important since many chemical indices for freshness evaluation of fish, crustaceans, and molluscs are based on changes of NPN components during storage. [8][9][10] Total volatile basic nitrogen (TVBN) is one of the most commonly used spoilage indices in many countries, and the maximum allowed levels in fish muscle are regulated in the EU according to Directive 95/149/EEC. The native micro-flora constitutes another important source of proteolytic enzymes; however, Vaz-Pires et al [2] reported that the numbers of microorganisms found in the squid surface until rejection were lower than in fish, suggesting predominance of autolytic degradation.…”

“…Squid mantle muscle contains strong endogenous metalloproteases degrading the myosin molecule selectively into heavy meromyosin and light 580 AGRAFIOTI AND KATSANIDIS meromyosin while cathepsins B, L, D, and E have also been identified in squid tissue. [4][5][6][7][8] This proteolytic activity is the cause of rapid post-mortem degradation with accompanying release of high levels of nitrogen from the muscle. Thus, non-protein nitrogenous (NPN) compounds are important since many chemical indices for freshness evaluation of fish, crustaceans, and molluscs are based on changes of NPN components during storage.…”