Introduction

Microalgae are well known for their competitive nutritional value. They contain polyunsaturated fats, proteins, vitamins, minerals and bioactive compounds which can be used to create nutrient-rich foods and feeds. But those same qualities of microalgae also have the potential to contribute to non-nutritional purposes in food production, also known as functional properties of foods and feeds.

ProFuture researchers at ILVO are studying the functional properties of single cell proteins from Chlorella vulgaris, Nannochloropsis oceanica and Tetraselmis chui single cell proteins, and assess their potential as functional ingredients for food and feed production.

Functional properties of proteins in food production

Functional properties of foods concern the way ingredients behave during food production, which affect the sensorial characteristics of the final products, such as their appearance, mouthfeel and expiration date.

Some important functional properties include foaming, gelling and emulsifying capacity and water/oil holding, many of which are dependent on the presence (or addition) of proteins or protein-rich ingredients. Since microalgae have high amounts of protein - often exceeding 50% of their dry weight – they have the potential of being highly functional ingredients in food and feed production.

In fact, microalgae can provide two main types of protein-rich ingredients: single cell proteins or protein extracts. Protein extracts from microalgae cells need to be further purified from the biomass through processes which often have low efficiency. In turn, single cell proteins can be used in foods without any further processing, which presents as an advantage. As so, researchers at ILVO are studying the functional properties of single cell properties from three microalgae species to assess their potential as functional ingredients for foods and feeds.

Methods and preliminary results

To assess such properties, different techniques were used. The water and oil binding capacity of the single cell proteins were determined by weighing the amount of water or oil that could be bound.

Foaming capacity was explored with a lab-grade mixer that whips up the single cell protein by introducing air in the mixture. The emulsion properties were tested by thoroughly mixing the cells in a solution in water with oil, which under normal circumstances would not mix. Lastly, the gelling ability was assessed by exposing the microalgae cells to high temperature in a water bath.

Interestingly, the three species showed different functionalities. Chlorella vulgaris proved to have good water binding and foaming capacity. Tetraselmis chui showed good water/oil binding, foaming and emulsifying capacity. In turn, Nannochloropsis oceanica displayed good water/oil binding capacity, but lacked foaming properties.

Fig 1. On the left: gelling properties - Tetraselmis chui; in the middle - foaming properties – (smooth) Chlorella vulgaris; On the right: emulsion properties – Tetraselmis chui

Considerations and next steps

Overall, microalgae show promising functional properties for the use in the food and feed industry, but single cell proteins still seem to present some limitations, such as the case of low gelling capacity. Additional processing steps like protein extraction will tell if functional properties can be further improved.

As for next steps: researchers at ILVO will understand how the different drying techniques affect the functional properties of single cell proteins, as well as of microalgae protein extracts.

Stay tuned for more ProFuture news!