Trypsin inhibitor from yellowfin tuna (Thunnus albacores) roe: Effects on gel properties of surimi from bigeye snapper (Priacanthus macracanthus)

•Novel trypsin inhibitor was partially purified from yellowfin tuna roe.•Trypsin inhibitor improved gel-forming ability of bigeye snapper surimi.•Trypsin inhibitor from tuna roe could be an alternative food-grade inhibitor.

Effects of partially purified trypsin inhibitor from the roe of yellowfin tuna (Thunnus albacores) (TIYTR) at different levels (0-3.0 g/100 g) on gelling properties of bigeye snapper (Priacanthus macracanthus) surimi were investigated. TIYTR showed inhibitory activity against proteolysis in kamaboko (40/90 °C) and modori (60/90 °C) gels in a concentration-dependent manner. Myosin heavy chain (MHC) was more retained in both gels when the level of TIYTR increased up to 3.0 g/100 g. This was associated with the increased breaking force and deformation as well as lowered protein degradation as evidenced by the decrease in trichloroacetic acid-soluble peptide content (p < 0.05). Whiteness of kamaboko and modori gels slightly decreased with increasing TIYTR levels (p < 0.05). However, water-holding capacity of both gels was improved as TIYTR level increased (p < 0.05). Incorporation of TIYTR, beef plasma protein (BPP) and egg white (EW) at a level of 3.0 g/100 g resulted in the increased breaking force and deformation of surimi gels. Nevertheless, TIYTR and BPP showed the higher gel strengthening effect than EW. Therefore, TIYTR could be used as an alternative cheap proteinase inhibitor to improve gel strength of surimi.