According to reports, seaweeds can contain up to 76% of their dry weight in carbohydrates. Water-soluble and highly hydrophilic are the polysaccharides found in seaweed. The presence of other polysaccharides in the cytoplasm and chloroplast, such as laminarin starch and floridean starch, may vary depending on the kind of seaweed. Comparable to human glycogen, seaweed’s stored carbohydrates serve as its main energy source. According to
Dibya et al., (2024), the food industry widely uses seaweed polysaccharides known as xylans, agar, carrageenan, or alginates as clarifying, gelling, emulsifying, stabilizing, thickening and flocculating agents in a variety of food products, including ice cream, yogurt, candies, meat products and beverages. Proteins, fats, polysaccharides, minerals, vitamins and enzymes are all abundant in seaweeds. Based on thallus color, seaweed can be divided into three groups: Brown, red and green. Additionally, they differ in a number of ultrastructural and biochemical characteristics, such as storage compounds, photosynthetic pigments, cell wall composition and flagella presence or absence. Na, K, Mg, Cl, S, P, I, Fe, Zn, Cu, Se and Mo are abundant in seaweeds. Seaweeds improved ruminant growth rate and feed conversion efficiency when added to livestock feed. Numerous macroalgal species contain antimicrobial, antiviral, antioxidant and anti-inflammatory qualities that enhance the health and functionality of animals
(Bomalee et al., 2022). The current study provides a thorough review of seaweed’s nutritional makeup, health advantages, variety of applications, growth techniques and possibilities for creating processed goods for the food and agriculture industries.
Microscopic observation of starch granules
Trinocular microscopic examination of
G.
salicornia thalli exposed starch deposition on the cell wall of algae (Fig 4). The result obtained was under 10 and 40 power magnification, where 10x shows two adjacent cells containing a few granules onto their cell wall, while 40x shows a single cell enclosing their granules, which was in accordance with starch deposition
(Prabhu et al., 2019) under various microscopes such as light, confocal, phase contrast and TEM in a green algal member.
FESEM for floridean starch and cellulose nanocrystal
FESEM Microscopic analysis revealed that the polysaccharides obtained from
G.
salicornia under various magnifications such as 10x, 25x, 50x, 100x and 150x and sizes 1 µm, 200 nm and 100 nm all appear rigid, polymeric and starchy Fig 5a, 5b in comparison to starch extracted from
Gracilariopsis lemaneiformis sps by Yu, 1992 and, green macroalgae
Ulva ohnoi by
Prabhu et al., (2019).
Thermo gravimetric differential thermal analysis (TG-DTA)
Thermal analysis of the floridean starch and cellulose nanocrystal (Fig 6) revealed sequential weight loss (mg) from 0.111 mg to 0.467 mg with a percentage rate of 0.082% to 0.345% through the entire screening with an increased temperature from 32
oC to 299
oC for the simultaneous TGA-DTA curve. The overall weight loss was 0.647% for
G.
salicornia while and 60.73% for green algae in a similar temperature range
(Prabhu et al., 2019).
Raman spectroscopy
The spectrum is depicted in a Raman spectroscopy graph in Fig 7a and 7b. Table 1 shows that the polysaccharides of
G.
salicornia have anhydrogalactose concentration, sulfur, gel strength and gelling temperature that are all higher than the usual range (
Marinho- Soriano and Bourret, 2003). The species
G.
salicornia (
Said and Vuai, 2022) exhibits the highest gel strength of 458 15.5 g cm
2 (treated) and 394.4 16.4 g cm
2 (untreated), followed by species
G.
corticata 259.4 16.4 g cm
2 (treated) and 229.2 28.3 g cm
2 (untreated). However,
G.
edulis species recorded the least amount of gel strength, 133.8 64.4 gm
2 s
2 (treated).
The gelling temperature of 29.05±3.34 observed was much lower than the temperature observed in two other red algal members by (
Yu, 1992) suggesting starch from
G.
salicornia to be a fast gelling compound. The sulphur and AG content, in extracted Carrageenan isolated from
Hypnea sps (Rafiquzzaman et al., 2016) was 20-25% for sulphur and 30-35% for AG content which were higher than current observations, while the sulphur and AG content in extracted agar from two red algae (
Marinho-Soriano and Bourret, 2003) was similar to current findings in Table 1.
Sulfated polysaccharides derived from red algae are known as carrageenans and agarans. These polymers’ rheological characteristics are crucial to their industrial uses. These two polymers properties make them important thickeners and gelling agents, primarily in the food industry
(Jiao et al., 2011). Sulfated polysaccharides also exhibit a number of biological functions, such as antioxidants
(Godard et al., 2009; Qi et al., 2012; Shao et al., 2013; Souza et al., 2011). Algal polysaccharide depositions, such as carrageenan, agar and floridean starch, can be compared. Approximately 65% of the 7.5 tons of agar generated annually worldwide come from red algae belonging to the genus
Gracilaria, which are also important in the production of phycocolloids
(Martin et al., 2013) (Niu et al., 2013). Sulfated polysaccharides derived from
Gracilaria species include 3-linked-β-D-galactopyranose (G unit) and 4-linked-3,6-anhydro-á-L-galactopyranose (LA unit) (
Rodríguez-Montesinos et al., 2013;
Maciel et al., 2008; Lahaye et al., 1988; Araki, 1966). The hydroxyl groups are replaced by ester sulfate, methyl groups and pyruvic acid
(Maciel et al., 2008; Lahaye et al., 1988; Araki, 1966). On the north eastern Brazilian coast, gracilaria is extremely common and its extraction has emerged as a viable option for some of the province’s residents to profitably integrate
(Barros et al., 2013; Vidotti et al., 2004). Good degrees of encapsulation were demonstrated by the produced polysaccharide beads. The MIC beads were tested on brinjal plants for their potency and the nursery soil used for planting was characterized for physical and chemical properties both prior to and after bead treatment. The parameter was obtained as shown in Table 2 in comparison with the critical value suggested by
(Sultana et al., 2022). Table 3 summarizes the results of polysaccharide beads, whose values were found to be higher than both the control and critical values. The polysaccharide MIC beads treated brinjal plant also showed improved growth when monitored over a 15-day interval Fig 8. The obtained results were compared with those presented by
(Sultana et al., 2022) and both values seem greatly higher and satisfactory. The bacteria that produce EPS aid in retaining free phosphorous and circulating vital nutrients for the plant. In interactions between plants and microbes, extra cellular polysaccharides producing bacteria shield plants against desiccation, invasion and defense. One macronutrient found in plants is phosphorus. Inorganic phosphorus is dissolved by PSB from insoluble substances
(Mugip et al., 2025). The extra cellular polysaccharides protects themselves against unfavorable environmental conditions.