Process optimization and quality evaluation of freeze-dried kelp and egg soup cubes

In this study, we developed an instant freeze-dried kelp and egg soup cube by optimizing raw material selection, formulation parameters, and freeze-drying conditions, thus establishing an optimal preparation process. Tender kelp exhibited significantly lower fracture property and hardness than mature kelp ( p < 0.05) and contained significantly higher levels of key aroma compounds (β-ionone and geranyl acetone) and lower levels of the key fishy odor compound 1-octen-3-one. Therefore, tender kelp was selected as the preferred raw material. The optimal formulation was determined as: 800 g water, 1.4 g carboxymethylcellulose sodium (CMC-Na), 0.05 g tender kelp powder, 64 g tender kelp, 2.6 g salt, 10 g ginger, 56 g egg, 1.2 g starch, 1.2 g monosodium glutamate (MSG), and 1.6 g scallion. The optimal freeze-drying conditions included a pre-freezing temperature of −20 °C, a sublimation temperature of −5 °C, and a desorption temperature of 60 °C. The resulting soup cubes exhibited excellent sensory quality, good rehydration properties, and high freeze-drying efficiency. These findings provide novel insights and a technical basis for future research and innovation in kelp pre-made dishes. • Tender kelp selected as raw material for superior texture and flavor • HS-SPME-GC-MS identified key aroma and odor compounds in kelp • Optimal formulation: 64 g kelp, 2.6 g salt, 1.4 g CMC-Na, 0.05 g kelp powder • Optimal freeze-drying: −20 °C pre-freezing, −5 °C sublimation, 60 °C desorption • Soup cubes showed excellent sensory quality and rehydration properties