Undervalued Atlantic brown seaweed species (Cystoseira abies-marina and Zonaria tournefortii): influence of treatment on their nutritional and bioactive potential and bioaccessibility

Abstract

The brown seaweed species Cystoseira abies-marina and Zonaria tournefortii are abundant Atlantic resources that remain undervalued. This results from an insufficient knowledge of their nutrients’ and bioactive potential. There is also uncertainty regarding the adequate culinary treatment of these seaweeds prior to their consumption. Thus, the current study evaluated the composition, bioactivity, and bioaccessibility of target compounds and bioactivities of these two species as a function of two treatments, simple rehydration and steaming, in comparison to sun-dried seaweed. The proportion of SFA, MUFA, and PUFA differed between species. C. abies-marina was richer in PUFA (30–31% vs 20–21%) and Z. tournefortii was richer in SFA (53–57% vs 46–47%). Main contributors to ω3 PUFA content were different in each species: alpha-linolenic acid in C. abies-marina, 4.5–5.1%, and eicosapentaenoic acid in Z. tournefortii, 5.8–6.7%. The sum of Mg and Ca contents in Z. tournefortii was two-fold the same sum in the other species. Furthermore, rehydration led to an elemental concentration reduction in most instances. The As content in C. abies-marina was very high, ranging between 295 ± 5 mg/kg dw and 369 ± 2 mg/kg dw, in rehydrated and steam-cooked seaweed, respectively. While aqueous extracts of C. abies-marina had the highest phenolic contents, 620–1280 mg GAE/100 g dw, aqueous extracts of Z. tournefortii contained 170–280 mg GAE/100 g dw. Regarding bioaccessibility, Mg, K, Ca, As, and Cd showed relatively high bioaccessibility levels and it was shown that only a limited part of the original antioxidant activity in both species is bioaccessible.