Obtaining reduced-salt restructured white tuna (Thunnus alalunga) mediated by microbial transglutaminase

Abstract

White tuna (Thunnus alalunga) is a blue fish with nutritional significance and high benefits to health. The aim of this work was to develop white tuna restructured products with reduced-salt (15 g/kg) using transglutaminase. Textural profile analysis, expressible water, dry matter, water activity and colour parameters were measured. In a first study, the temperature effect of the setting phenomenon was evaluated at three conditions: 4 °C/12 h, 25 °C/2 h or 40 °C/20 min. The results showed that texture parameters were improved using transglutaminase at 4 °C/12 h. Considering the results, in a second study the setting at 4 °C was selected and the transglutaminase concentration (150, 300, 450 U/kg) and setting time (6, 12, 18 h) were optimized. The better setting treatment was at 4 °C for 18 h using 450 U/kg of transglutaminase. Restructured products were obtained under these conditions and in a third study the microbial load was evaluated during the storage at 4 °C for 12 days. Different microbiological groups (psychrotrophs, aerobic mesophiles, anaerobes, proteolytic bacteria and Enterobacteriaceae) were measured. The results showed that the manipulation after the cooking step is critical. Overall, it was demonstrated that the restructuring of white tuna is feasible.