Effects of pH-shift processing on the bioaccessibility of lipids in the microalgae Nannochloropsis – an in vitro model approach

Poster (konferens), 2015

Introduction: Microalgae are a potential source of human nutrition and animal feed due to the high content of long-chained n-3 fatty acids (LC n-3 PUFA) and favorable amino acid profile of some species. Furthermore, microalgae can be cultivated with minimal nutrient requirements on otherwise non-arable land. We have previously shown that application of the pH-shift process on Nannochloropsis yields a product enriched in essential amino acids and with the original amount of LC n-3 PUFA retained (120 mg/g dry weight). Therefore, the product has potential as a functional food and/or feed ingredient. However, it is not known to which extent the nutrients are bio-accessible; earlier work has suggests that algal cell walls limit digestibility in the gastrointestinal tract. Based on the physical changes that take place during pH-shift processing, e.g. cell lysis and protein solubilization/precipitation, we hypothesize that the pH-shift process renders the algal nutrients more available for hydrolysis. The aim of the present study is to test this hypothesis using a static in vitro digestion model. Method: Nannochloropsis is subjected to the pH-shift process and nutrient content (fatty acids, protein, amino acids) is determined before/after processing. To determine the bio-accessibility of Nannochloropsis processed in various ways, the microalgae is digested using a static in vitro model of human digestion, based on the recent international consensus method emerging from the COST FA 1005 Infogest. Intestinal digesta will then be analyzed in respect to degree of lipolysis using solid phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS). Results and conclusion: The study is ongoing, and results will be presented in June.