Incorporation of microalgae (Nannochloropsis oceanica) into plant-based fishcake analogue: Physical property characterisation and in vitro digestion analysis

This study examined how incorporating microalgae into plant-based fishcake (PFC) analogue affected its physical properties and in vitro digestive profiles. PFCs were prepared using pea protein isolate blended with varying amounts of defatted Nannochloropsis oceanica biomass. Increasing the concentration of N. oceanica (up to 30%) progressively influenced the texture and rheological properties of PFC: the hardness and gel strength of PFC significantly increased, while springiness, expressible moisture and oil content decreased, making PFC more similar to the surimi-based fishcake. In vitro protein digestibility of PFCs varied with the concentration of N. oceanica: from 59.8% in the control PFC (without N. oceanica) increased to 74.9% with 10% N. oceanica, but only to 70.1% with 30% N. oceanica, which highlighted the role of microalgae concentration on the PFC's digestive profile. Furthermore, the release of metabolites in the PFC samples after in vitro digestion was evaluated using nuclear magnetic resonance (NMR) spectroscopy. The results showed that the digesta of PFC with 30% N. oceanica had reduced levels of most amino acids and linoleic acid, which might have ripple effects on the associated amino acid and fatty acid metabolisms in the human body upon consumption. Overall, the combination of pea proteins and N. oceanica biomass had the potential to contribute to the development of innovative plant-based seafood alternatives with modified physical properties and unique digestive characteristics. This study also provided valuable insights into the bioavailability of nutrients from N. oceanica-incorporated PFC, laying the foundation for their further launch on the market.