Improvement of gel properties of mackerel mince by phlorotannin extracts from sporophyll of Undaria pinnatifidai and UVA induced cross‐linking.

The effects of phlorotannin extracts (PTE) (from sporophyll of Undaria pinnatifida) added at different concentration (0, 1.6, 8, and 40 mg/g protein) with and without ultraviolet A (UVA) irradiation treatment on gel properties of mackerel (Scomberomorus niphonius) mince (MM) were investigated. The results indicated that both the breaking force and water‐holding capacity (WHC) of the MM gel increased with addition of PTE, and the highest breaking force and WHC were observed with 40 mg/g PTE under UVA irradiation. Low‐field nuclear magnetic resonance revealed that free water significantly decreased in this PTE‐MM gel as well. UVA irradiation treatment led to reduction of total sulfhydryls and free amines in the PTE‐MM gel, indicating more cross‐linking between proteins. Electrophoresis results indicated that myosin heavy chains were aggregated in the UVA‐treated PTE‐MM gel. The microstructure of the UVA‐treated PTE‐MM gel showed that protein formed more evenly distributed cross‐linked structures and was more compact than the untreated control gel. As a conclusion, PTE addition with UVA irradiation is shown to improve gelling properties of mackerel mince. [ABSTRACT FROM AUTHOR]