Lightning Talk & Poster 28th Annual Lorne Proteomics Symposium 2023

Nutrition and allergenicity of food-grade protein extracts in novel food Nannochloropsis oculata (#33)

Sara Hamzelou 1 , Damien Belobrajdic 1 , Angela Juhasz 2 , Henri Brook 1 , Utpal Bose 2 3 , Michelle L Colgrave 2 3 , James A Broadbent 3
  1. Health & Biosecurity, CSIRO, Adelaide, SA, Australia
  2. Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, School of Science , Edith Cowan University, Perth, WA, Australia
  3. Agriculture and Food, St Lucia, CSIRO , Brisbane, QLD, Australia

Microalgae have great potential in becoming a sustainable source of dietary protein for human consumption. A marine microalgae — Nannochloropsis — has been commercially produced for its lipid content, but its high content of protein and essential amino acids (EAAs) provides an additional opportunity for food applications. To support the potential use of Nannochloropsis oculata in food products, the aim of this study was to evaluate a range of food-grade protein extraction methods and establish the nutritional quality and safety of the protein extracts.

Food grade (FG) protein extracts were obtained by hypotonic osmotic shock using milli-Q water. To identify the maximum number of proteins, a common proteomic extraction method (TCA-acetone followed by chloroform-methanol) was used in parallel. Food grade (FG) and non-food grade (NFG) extraction buffers were compared along with three different cell disruption methods including bead beating, probe sonication and a combination of both methods. The tryptic peptides resulting from both FG and NFG extracts were measured by data-independent acquisition (DIA) using a SCIEX 6600 LC-QqTOF and DIA-NN data processing. The data were used to identify and quantify proteins, including putative allergens using four different in-silico methods. Trace metals in the FG extracts were also measured to provide an overall understanding of the extracts’ nutritional and anti-nutritional characteristics.

The effect of disruption methods on dried ground Nannochloropsis oculata was investigated in both FG and NFG extracts. Although the protein extracts obtained from all NFG methods had a similar number of identifiable proteins, there was a small improvement in identifiable proteins when bead beating (B) was used in food-grade protein extraction. Putative allergen protein assessment of the FG extracts identified five proteins with a high similarity to fish allergens. These include algal proteins with high similarity to fructose-bisphosphate aldolase in salmon and nucleoside diphosphate kinase in Atlantic cod. Metal ion analysis showed that FG protein extracts contained potassium, magnesium, and calcium, whereas chromium, arsenic and lead were at levels considered safe for human consumption.

In conclusion, for both FG and NFG protein extracts, applying cell processing methods beyond hypotonic osmotic shock on commercial ground N. oculata did not enhance protein yield; however, the identification of fish allergens deserves further investigation such as IgE binding tests.