Investigating Microalgae Using GC and HPLC–MS

Photo Credit: Trieu Tuan/Shutterstock.com

Researchers from the Technical University of Denmark (DTC) have used gas chromatography (GC) and high performance liquid chromatography–mass spectrometry (HPLC–MS) to investigate microalgae biomass as an alternative resource for fishmeal and fish oil in the production of fish feed (1).

Alternative and sustainable aquatic feed ingredients are in short supply; this is despite intense efforts in recent years to find new sources. Currently, industrial fish not fit for human consumption and fish waste are used to create fishmeal, but this process is rapidly becoming unsustainable both environmentally and economically. An expanding world population-compounded by uncertainty in future fishing capacities-has led to a predicted shortage in fishmeal, which is used as a protein supplement in animal feed but can also be used as fertilizer.

Microalgae have emerged as a potential alternative for use in aqua culture, however, the commercial production of microalgae through photosynthesis is costly. Furthermore, the nutritional content of microalgae varies considerably between species, with environmental conditions and growth medium composition also having an effect. The study evaluated different microalgae species based on their capacity to grow on industrial process water and their ability to produce a biomass containing high levels of protein, long-chain polyunsaturated fatty acids (LC PUFA), and bioactive compounds. The two species selected were Nannochloropsis salina and Chlorella pyrenoidosa. Researchers then used this data to upscale the process from laboratory-scale experiments to large-scale flat panel photobioreactor systems. Chromatographic methods were employed for characterizing algal biomass at both pre- and post-harvest stages. A GC method was used for the analysis of fatty acids and HPLC–MS was used for the analysis of pigments. Both methods represented rapid, routine, and reliable control measures to verify the variations in the microalgae biomass during cultivation, and its quality during processing and storage.

A new downstream process was developed including a crossflow microfiltration stage by silicon carbide (SiC) ceramic membranes, heat treatment for inactivation of enzymes, up concentrations by bowl centrifuge, and drying via a swirl flash dryer. This process reduced energy consumption and reduced the deterioration of valuable bioactive compounds such as LC PUFA, natural antioxidants, and carotenoids.

These positive findings point towards microalgae as a solution to future fishmeal requirements in industry. - L.B.Reference

• H. Safafar, National Food Institute, Technical University of Denmark (2017) http://orbit.dtu.dk/en/publications/micro-algae-biomass-as-an-alternative-resource-for-fishmeal-and-fish-oil-in-the-production-of-fish-feed(9be0ea8c-70bb-4a29-b9ff-4503343f64d6).html