Effect of the processing of four marine species on their in vitro digestibility of Octopus vulgaris adults

Abstract

The determination of in vitro digestibility of acid proteases in the digestive gland (DG) of adult O. vulgaris (> 1.2 kg) was performed, using the flesh of four different prey species (mackerel, Scomber scombrus; green crab, Carcinus maenas; swimming crab, Necora puber; Shortfin squid, Illex coindetii). For each, four processing treatments were applied: (1) frozen, (2) boiled at 100 °C for 1 min, (3) lyophilized, and (4) oven dried at 70 °C. A pH-Stat method was used to determine in vitro digestibility at pH 3. Results showed that digestibility was higher for lyophilized and frozen flesh, compared to the other treatments involving heating (boiled and oven dried), regardless of the species tested. Also, differences were found between species, within each treatment, with higher digestibility for crab (N. puber) and squid (I. coindetii). Regarding “in vitro” acid proteases digestibility, which is the most important for O. vulgaris, results indicate that heat treatments close and/or higher than 70 °C promoted changes in the flesh that prevented or reduced their assimilation by the DG of O. vulgaris.