FERMENTED ALGAL MEAL OF GREEN SEAWEED Ulva flexuosa USING Saccharomyces cerevisiae: EFFECT ON NUTRIENT ENHANCE

Macroalgae (or seaweeds) can be an alternative ingredient for aquafeeds and fermentation process might be applied to improve their nutritional qualities. When treated with appropriate microorganisms, seaweeds can show better nutritional efficiency when incorporated into aqua- feed's formulations. This study's purpose was to evaluate the nutritional content of fermented and unfermented a green seaweed  Ulva flexuosa .

The algal biomass was washed using freshwater to remove epiphytes and epizoans . Then, the seaweeds were dried in an oven at 60° C for 24 hours. The dry seaweed biomass was grounded and sieved with a 0.3 mm mesh. The fermentation occurred in erlenmeyer flask with a 1:9 proportion of  U. flexuosa meal and freshwater, respectively.  Saccharomyces cerevisae was inoculated at 10% (v/v). The fermentation process started at a constant temperature of 30ºC and ended after 24 hours. After, the biomass was dried in oven at 70° C for 48 hours. The nutritional content of the unfermented and fermented seaweed meal was analyzed using the following methods: dry matter content determinated by oven method, crude protein content with Kjhedal titration, crude fat using Soxhlet extractor, crude fiber using Weende method while ashes were obtained in muffle furnace.

The result of the study showed that all nutritional components showed significant difference except ash content: crude protein raised 4,43 %; crude fat content increased 0,49% and crude fiber reduced 0,94%. From this result it was concluded that the fermentation of seaweed using yeast can enhance its nutritional value by enriching protein, fatty acid, vitamin and mineral contents, as well as improve its digestibility value. The use of microbial fermentation on seaweeds can also yield a range of beneficial by-products.

Therefore, it is concluded that the fermentation of  U. flexuosa meal using Saccharomyces cerevisiae may be a viable alternative to obtain ingredient with better nutritional properties. Further studies are needed to evaluate the optimum fermentation condition for  Ulva flexuosa.