Heat treatment increases the protein bioaccessibility in the red seaweed dulse (Palmaria palmata), but not in the brown seaweed winged kelp (Alaria esculenta)

Bioaccessibility of plant proteins has been shown to be inferior to that of proteins of animal origin. Heat treatment has been shown to positively affect this in some plants. The aim of this study was to investigate the effect of heat treatment on bioaccessibility of seaweed proteins. An in vitro gastrointestinal digestion model was used for evaluation of potential effects on the brown seaweed Alaria esculenta and the red seaweed Palmaria palmata proteins. In P. palmata, the content of accessible amino acids increased by 86-109 % after heat treatment. Following a simulated in vitro gastrointestinal digestion, the amount of liberated amino acids was 64-96 % higher in heat-treated samples compared to their raw counterparts. The increase was largest in samples boiled for 15 and 30 min. No deterioration of single amino acids was seen, and hence, the amount of available essential amino acids was increased accordingly. In A. esculenta, no equivalent changes were observed. In conclusion, a short heat treatment may be a simple way of increasing the utilization potential of seaweed proteins in food and feed. However, there are species differences, and the effects observed in the in vitro digestion model need to be confirmed in clinical studies.