Microwave-vacuum heating parameters for processing savory crisp bighead carp (Hypophthalmichthys nobilis) slices

The effects of moisture content of the pre-dehydrated fish slices, microwave (MW) power output, and vacuum degree on the quality of the savory crisp bighead carp slices were studied. The single factor tests indicated that, the optimal moisture content, microwave power output, and vacuum degree were 19.8 ± 2% (50 °C hot air drying for 3 h), 686 ± 3.5 W and 0.09 MPa, respectively. The results showed that proper moisture content of the pre-dehydrated fish slices and microwave power could increase the expansion ratio and crispness of the fish slices, and then improve the sensory quality of the finished products. The higher vacuum degree could enhance the puffing effect, improve the crispness of the fish slices, increase the energy efficiency of microwave heating, and obviously decrease the burnt spots formation on the surface of the finished products. The processing parameters of the savory crisp bighead carp slices were optimized by a L15(51 · 32) orthogonal design based on the single factor tests. The optimum processing parameters were finally determined as that the moisture content of the pre-dehydrated fish slices controlled at 15.3 ± 1% (50 °C hot air drying for 3.5 h), microwave power output selected at 686 ± 3.5 W, microwave heating for 12 s at vacuum degree of 0.095 MPa, and then heating for another 10 s after balanced for 1 min