Polar lipids of commercial Ulva spp. of different origins: profiling and relevance for seaweed valorization

Macroalgae of the genus Ulva have long been used as human food. Local environmental conditions, among other factors, can have an impact on their nutrient and phytochemical composition, as well as on the value of the seaweed for food and non-food applications. This study is the first to initiate a comparison between commercial Ulva spp. from different European origins, France (FR, wild-harvested Ulva spp.), and Portugal (PT, farm-raised Ulva rigida), in terms of proximate composition, esterified fatty acids (FA), and polar lipids. The ash content was higher in PT samples, while FR samples had higher levels of proteins, lipids, and carbohydrates and other compounds. The profile of esterified FA, as well as FA-containing polar lipids at the class and species levels were also significantly different. The FR samples showed about three-fold higher amount of n-3 polyunsaturated FA, while PT samples showed two-fold higher content of monounsaturated FA. Quantification of glycolipids and phospholipids revealed, respectively, two-fold and three-fold higher levels in PT samples. Despite the differences found, the polar lipids identified in both batches included some lipid species with recognized bioactivity, valuing Ulva biomass with functional properties, increasing their added value, and promoting new applications, namely in nutraceutical and food markets.UIDB/50011/2020+UIDP/50011/2020, UID/QUI/00062/2019, UIDB/50006/2020, UIDB/50017/2020+UIDP/50017/2020, LISBOA-01-0145-FEDER-402-022125, POCI-01-0145-FEDER-030962, BPD/UI51/5041/2017, BPD/UI51/5042/2018; EC/H2020/727892/EUinfo:eu-repo/semantics/publishedVersio

Seasonal plasticity of the polar lipidome of Ulva rigida cultivated in a sustainable integrated multi-trophic aquaculture

Green macroalgae of the genus Ulva, commonly known as sea lettuces, are currently traded worldwide for multiple applications, including human consumption. In this work, we evaluated the seasonal variation of the total content of lipids, esterified fatty acids (FAs) and polar lipids (the major carriers of FAs) at the level of the classes and molecular species of Ulva rigida cultivated in Portugal in a land-based integrated multitrophic aquaculture (IMTA) system. Comparing winter, spring, summer and autumn samples, the lipid content and abundance of unsaturated FAs, namely n-3 polyunsaturated FAs, were highest in winter and lowest in summer. However, regardless of seasonal variations, U. rigida had a low n-6/n-3 ratio in all seasons, which is associated with health benefits. Among the polar lipids, those that varied the most were betaines, glycolipids and phospholipids, including a high number of lysolipid species that increased during autumn and spring. Multivariate analysis using principal component analysis (PCA) showed better discrimination of the four seasons when the dataset on molecular lipid species was used. Knowledge of the seasonal variability of lipid composition in biomass of Ulva rigida can be used to better explore these green macroalgae as a source of bioactive polar lipids with high market value.publishe