Abstract:To promote the high-value utilization of tuna mince in surimi-based products，tuna mince was used to partially replace conventional surimi for preparing protein bars. Replacement levels of 20%，30%，40%，50%，and 60% were designed，and texture，gel properties，and color parameters were compared to identify the optimal substitution ratio. Based on the optimized formulation，samples were fabricated by microwave-assisted 3D printing and subsequently subjected to combined heating treatments，including water bath heating（MW-S），steam heating （MW-Z），low-temperature baking （MW-D），and air convection heating （MW-K）.Product quality and flavor characteristics were evaluated by texture analysis，low-field nuclear magnetic resonance，electronic tongue，gas chromatography-ion mobility spectrometry，and scanning electron microscopy.The results showed that different tuna mince substitution ratios significantly affected the hardness and chewiness of surimi protein bars （P＜0.05）. At the 40% substitution level，hardness and chewiness reached 1 927.59 N and 1 646.09 N/mm，respectively，both of which were higher than those of the 60% group（1 109.02 N and 1 036.28 N/mm）. In addition，the L*value and whiteness of the 40% group were 69.68 and 66.62，respectively，indicating the best overall performance in texture and color. Different combined heating methods markedly affected water distribution，volatile flavor compounds，and microstructure. Among them，MW-K formed a dense gel network and exhibited good water-holding capacity，a more pronounced umami taste，and weaker bitter and astringent responses. MW-Z showed a microstructure inferior only to that of MW-K，although its overall flavor harmony remained weaker than that of MW-K. By contrast，MW-S and MW-D exhibited varying degrees of structural looseness. In conclusion，a40% substitution ratio of tuna mince combined with microwave-air convection heating was considered the optimal processing combination for producing highquality surimi protein bars.