Effect of phlorotannin extracts from Ascophyllum nodosum on the textural properties and structural changes of Apostichopus japonicus

In this work, phlorotannin extracts (PhTEs) were isolated from Ascophyllum nodosum. The effects of PhTEs on the textural properties, structural changes and oxidation level of Apostichopus japonicus (A. japonicus) were investigated. The results showed that thermal treatment could lead to the dissolution of TCA-soluble peptides and free hydroxyproline and promote the degradation of A. japonicus. The chemical compositional changes and texture profile analysis results indicated that PhTEs could effectively inhibit the degradation of A. japonicus and improve the hardness and chewiness of A. japonicus. Analysis of multiple spectroscopic methods suggested that the secondary and tertiary conformations tended to be stable after PhTEs were added. In addition, electron spin resonance results indicated that PhTEs could reduce the oxidation level of A. japonicus. These results suggest that the degradation of A. japonicus during mild heat treatment can be regulated by PhTEs, which provides insights for quality control in A. japonicus heat treatment.