Process optimization,texture and microstructure of novel kelp tofu

Laminaria japonica Aresch as an edible and medicine dual-purpose marine algae,has been gradually accepted by people.Tofu was Chinese traditional food,combining kelp function ingredients with tofu has practical value.The extraction-optimization methodology and the sequences of kelp antihypertensive peptide(KAP)were investigated.The sensory,whiteness,water retention ability(WRA)and microstructure of KAP tofu were evaluated.The scanning electron microscope(SEM)results showed KAP addition(20%)significantly improved the tofu texture,with a denser network composed of relatively even pores.Compared with gypsum tofu and glucose-δ-interior fat(GDL)tofu,KAP tofu had significantly higher WRA(94.49±0.49)%and sensory evaluation score value(92.54±0.52),and a significantly lower IC_(50) value at(2.06±0.04)mg/mL(P<0.05).The maximum IC_(50) value(4.14 mg/mL)of kelp enzymatic hydrolysate was observed at enzyme(at an alkaline protease:trypsin ratio of 2:1)concentration 1.5%,temperature 55℃ and time 2 h.The sequences of 8 identified peptides were Lys-Tyr,Phe-Tyr,Gly-Lys-Tyr,Ala-Lys-Tyr,Ser-Lys-Thr-Tyr,Lys-Lys-Phe-Tyr,Lys-Phe-Lys-Tyr and Ala-Lys-Tyr-Ser-Tyr with IC_(50) values of 5.24,4.83,7.94,7.52,20.63,15.33,10.73 and 2.42μmol/L,respectively.These results indicated the potential use of KAP tofu as a valuable resource for development of functional foods.