# Assessment of the Resource Potential of Baltic Sea Macroalgae
## 4 Discussion
Given the relatively low total fat content of the considered algae, 2.3-4.3 percent per a.d.w., and the relatively low content of the most valuable unsaturated fatty acids (for example, linolenic has 0.03-0.08%), it is not recommended to use their biomass as a raw material for the extraction of commercial lipids for use in pharmacology and cosmetology. However, even a 2-4% content of saturated fatty acids may indicate the possibility of obtaining significant amounts of biodiesel during thermochemical or hydrothermal processing [51]. When the content of carbohydrates in algae biomass was compared to the literature data (25.8-55.4%), it was discovered that the content established in the course of the studies was significantly lower, possibly due to differences in the methods of determination and seasonal variability of biomass composition. In this study, the biomass sampled at the end of September 2021 was subjected to analysis. The maximum sugar content was found in algae of the genus _Furellaria_, which correlates with known data [63]. These algae are widely used to obtain valuable polysaccharides [64]. The analysis of the carbohydrate composition of macroalgae revealed a high content of fucose (2.3-6.5%, Table 4). Fuose is another rare sugar that is currently used in anti-carcinogenic and anti-inflammatory drugs, hepatoprotectors, creans for accelerated wound healing, and as moisturizing and anti-aging supplements [76, 77]. It has been proven that the addition of fucose to infant formulas contributes to a more complete mental development and formation of immunity in infants [77, 78]. Galactose, whose content in algae biomass varied from 1.2-2.5% (Table 4), has proven immunomodulatory [79, 80, 81, 82], antioxidant [83], and antiviral [84, 85, 86, 87, 88, 89] effects. Rhamnose is a valuable carbohydrate that is used in consentology for skin regeneration and the stimulation of collagen production [90]. However, its content was quite low in the algae biomass (0.3-1.2%). Common sugars (glucose, xylose, and arabinose) do not have significant pharmaceutical potential, but are excellent raw materials for biotechnological processes--yeast cultivation, bioethanol production, etc. We can draw conclusions about the feasibility of using algal biomass for the extraction of marketable carbohydrates since there is a significant amount of readily available, soluble, and hydrolysate sugars in the biomass. The biomass of _Furellaria_ algae has a particularly high potential, containing up to 22% of a.d.m. reducing sugars. The high potential of using _Furellaria lumbricalis_ as a source of polysaccharides, including agar and furelloran, is also confirmed by a number of publications [91]. Thus, a detailed analysis of the content of carbohydrates indicates the potential expediency of extracting commercial polysaccharides from the biomass of _Furellaria lumbricalis_ algae, as well as the possibility of using the biomass of the considered algae as a source of polysaccharides for the implementation of biotechnological processes for obtaining liquid (bioethanol) and gaseous fuels. The elemental composition was analyzed to determine whether algae biomass might be converted to fuel using thermochemical methods. The algae biomass exhibited a high carbon content (31.3-37.5%), but a low hydrogen concentration (4.96-5.82%), which was 2.2 times lower than the content in coniferous wood, according to elemental analysis. A distinctive feature of the biomass of red algae (_Polysiphonia_ and _Furellaria_) was a high nitrogen content associated with the presence of a significant amount of proteins in the composition. For comparison, the nitrogen content in the other types of biomass under consideration does not exceed 0.7%, while its concentration in microalgae is 2.06-3.6%. In the application of hydrothermal liquefaction and biomass pyrolysis processes, a high nitrogen concentration can obviously become a difficulty on the route to high-quality liquid fuel (Table 6).