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

The brown seaweed speciesCystoseira abies-marinaandZonaria tournefortiiare 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-marinawas richer in PUFA (30-31% vs 20-21%) andZ. tournefortiiwas richer in SFA (53-57% vs 46-47%). Main contributors to omega 3 PUFA content were different in each species: alpha-linolenic acid inC. abies-marina, 4.5-5.1%, and eicosapentaenoic acid inZ. tournefortii, 5.8-6.7%. The sum of Mg and Ca contents inZ. tournefortiiwas two-fold the same sum in the other species. Furthermore, rehydration led to an elemental concentration reduction in most instances. The As content inC. abies-marinawas 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 ofC. abies-marinahad the highest phenolic contents, 620-1280 mg GAE/100 g dw, aqueous extracts ofZ. tournefortiicontained 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.