Microalgae are essential for many hatchery operations, particularly in shellfish and finfish production. As reliance on microalgae increases, there is a growing need for more efficient production methods that not only maximize cell density and volume but also maintain nutritional value over time. Microalgae contain polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are crucial for the development and health of marine species. The nutritional quality of cultured microalgae can decline over time due to nutrient depletion and reduced photosynthetic activity. However, the effects of newer techniques, such as ultrafiltration and cold storage, on the degradation of PUFAs have yet to be thoroughly examined. This study aims to determine the impact of cold storage on the preservation of fatty acids in concentrated microalgae, identifying when stored cultures lose their nutritional value.
In this study, three microalgae species, Chaetoceros muelleri, Tisochrysis galbana, and Tetraselmis spp., were concentrated using crossflow configuration ultrafiltration (CF-UF) and stored under aeration in a refrigerator for up to two months. Samples were periodically collected and frozen during this storage period. These samples were then processed and analyzed using Gas Chromatography-Mass Spectroscopy (GC-FID or MS) to assess their fatty acid profiles. Multivariate analysis was conducted to identify patterns and changes in the nutrient profiles of the different microalgae species over time.
Understanding the nutritional stability of concentrated microalgae during cold storage is key to improving hatchery outcomes. This knowledge enables the reliable use of concentrated microalgae stocks, reducing the time and effort required for culturing and harvesting while providing a safeguard against culture crashes. The ability to cold store live microalgae concentrates for extended periods will be extremely beneficial in the aquaculture and shellfish industries, ensuring a consistent, high-quality feed supply.