In the frame of the master’s thesis, we investigated the influence of the duration of lactic acid fermentation on the nutritional value of microalgae Arthrospira platensis. Lactic acid bacteria Lactobacillus plantarum was used for the inoculum. We performed fermentations in three biological replicates. The lactic acid fermentation on the prepared samples took place under anaerobic conditions; for 72 hours in an incubator at 30 °C. The nitrogen content was determined by the Kjeldahl method. Trichloroacetic acid extraction was previously used for the analysis of non-protein nitrogen. The content of protein nitrogen was calculated, which we then multiplied by a general empirical factor 6,25 and calculated the proteins. The ashes were determined by burning the sample over a gas burner and annealing it in a furnace at 550 °C. Total fat content was determined by an extraction in a Soxhlet apparatus and the fibres content by enzyme-gravimetric method AOAC 991.43. We found out that lactic acid fermentation influenced some nutritionally important compounds of microalgae. The content of non-protein nitrogen increased during lactic acid fermentation, but this did not affect the content of protein nitrogen and protein. The insoluble fiber content decreased significantly with fermentation time, while the soluble fiber content did not change significantly. As a result, the ratio of insoluble to total fibre has decreased. Fermentation provoked a significant increase of fat content, although these changes are insignificant from nutritioanl point of view due to the very low fat content.
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