Optimization of protein extraction of microalgae fron wwt: Effect of different variables on alkaline hydrolysis

Abstract

Microalgae have potential as human and animal nutrition, emulsifier agents and a source of multiple bioactive compounds. They can be cultivated without competing for land or water with crops or even can be cultivated using wastewaters with high concentrations of N and P, and they generally have a favourable nutritional profile, having a protein fraction with an equilibrated amino acid profile, and a lipid fraction where essential PUFAs are present. Increasing interest in health qualities of algal proteins, as well as a strong financial need to valorise all fractions of the cultivated biomass has encouraged the development of alternative, safe and scalable technologies to access quality algal proteins. An appropriate cell disruption process should maximize the yield and the value of the compounds extracted, disintegrating most cells without contamination or degradation of the target compounds. For large scale production, it is also important that the disintegration process can be scaled up and that it is rapid. In addition, the integration of the cell disruption into the downstream processing must be easy and it should not have a negative impact on subsequent processing steps. In this work, alkaline hydrolysis was tested as an appropriate method for extracting and solubilising proteins from microalgae biomass from pig manure wastewater treatment, evaluating the optimal conditions of NaOH concentration, temperature and time. Ultrasounds and microwave will be tested as additional treatments prior to alkaline hydrolysis to maximize yields and purity of extracts and minimising chemicals and energy requirements.