Optimization of growth and functional food ingredients in the edible cyanobacterium, Nostoc commune Vaucher, for commercial production

Nostoc commune Vaucher, is a freshwater cyanobacterium (blue-green alga (BGA), belonging to the order Nostocales, family Nostocaceae. This BGA is locally known as 'tab-taba' or 'bold-boldyok' in Ilokano. It grows naturally and commonly in rice paddies an in fertile hilly places, especially in northern Luzon, such as Pangasinan up to Ilocos Norte and Isabela. However, the BGA has also been noted in Laguna (Calamba), Palawan (Puerto Princesa) and in Cebu (Argao). Among the soil properties that seemed to favor the growth of the BGA in these places were low levels of available phosphorus (P) (11-33ppm, Olsen's method) Fe (4-44ppm) and Mn (7-127ppm). While high pH (pH 8.5) and low levels of water soluble P (0.35.2.1ppm) favoured the growth of the alga. The alga has the ability to withstand long desiccation and high water temperature (up to 41 deg C). One of the beneficial nutritional products that could be derived from the alga is its high protein content (max. 51% CP). It has also relatively high dietary fiber content, which is derived from oxalate-oxalic soluble substance was about 357.67 mg/g. The total dietary fiber can also be discerned from the total carbohydrates (CHO) is also rough measurement of the total amount of polysaccharides or the measure of a total amount of gelatinous sheath enveloping the colonies and the group of trichomes. This was estimated to be about 70% of the total dry wt. Total phenolic content was analyzed and showed a value of 0.76mg/g based on gallic equivalent. Although the presence of phenolic compounds could adversely affect protein digestion, it has been reported lately there are several beneficial effects of tannins and polyphenols, such as, inhibition of lipid predoxidation, anti-tumor, antiviral and antibacterial effects. The alga exhibited high antioxidant activity (IC sub 50 equal 144.96 plus 0.61 mg/L) towards scavenging DPPH (2,2 diphenyl picryl hydrazal) radical. Another beneficial trait of this alga is its capacity to grow after storage in desiccated form (air-dried or freeze-dried). Growth of the BGA was enhanced with orbital shaking and supplied with 1.5% carbon dioxide in air. While the best concentration of Calcium Chloride that promoted growth was at 40mg/l after 30days based on increment in biomass and chlorophyll content. However, nitrogenase activity was highest at 5mg/L. Sensory evaluation and acceptability trials for food preparations with Nostoc commune Vaucher, using dried, disk type included as vegetable dish (I), as pickles (II), as dried 'dates' (III), and as sweetened for dessert (IV). By evaluating the mean comparisons through graphical representation from type to type, the overall most acceptable was Nostoc vegetables dish (I), followed by Nostoc pickles (II), based on evaluation for five properties i.e, odor, taste, texture, general acceptability and general appearance.