*4.2.6 Ulvans*

Use dichloromethane and ethanol for the most removal of the lipids and pigment that exist in Ulva. Hot-water extractions of the pre-treatment algae are for 7 hours at 75–85°C under continuous stirring. The filtration and centrifugation are for collecting the supernatant. Removal of starch and proteins is continuously by using enzymatic hydrolysis. Afterward, running the solution is via activated charcoal for centrifuging, filtering, and precipitating with absolute ethanol. Finally, the precipitate is ulvan (**Figure 13**) [73].

#### *4.2.7 Pectins*

The first step in plant pectin extraction is always the color removal step with organic solvents. After de-colorant from the plants, pectin extraction is by using the solvents with different pH. The filtrate is concentrated and hydrolyzed to remove protein and starch. At this time, semi-pectin was collected and continued to run through activated carbon to remove impurities. Finally, 80% of ethanol is useful for precipitation and purification of pectin (**Figure 14**).

#### **Figure 10.**

*Extraction schematic of antioxidant glucosamine hydrochloride.*

#### **4.3 Secondary metabolites**

#### *4.3.1 Polyphenols*

Phlorotanins dissolve into the organic solvent, such as ethanol, methanol, ethyl acetate. Phlorotannins in brown algae grown in Vietnam mainly dissolve in ethanol *Functional-Antioxidant Food DOI: http://dx.doi.org/10.5772/intechopen.96619*

#### **Figure 11.**

*Extraction schematic of antioxidant inulin from dangshen.*

and focus on the fraction ethyl acetate. Sephadex LH20 is useful for the purification of phlorotannins (**Figure 15**). For polyphenol of terrestrial plants also used ethanol as a useful solvent.

According to Neeraj et al., lignins exist in various four styles, such as kraft, lignosulfonate, organosolv, and soda [74, 75].

There are three methods for the extraction of lignin; (i) 7.5% NaOH, (ii) organosolv (85% formic acid/85% acetic acid), and (iii) poly-ethylene glycol (PEG). Method (ii and iii) use heating assistance.

In method (i), the material-to-solvent ratio of 1/10 (w/v) at 90 ± 2°C for 90 min with pH (12) of the black liquor is useful for the extraction of lignin. After hot filtration and allowing to cool for the precipitation is using acidification with 0.5 M H2SO4. Meanwhile, the current authors extracted successful kraft lignins from corn stalks according to the **Figure 16**. This difference can be from material differences.

In method (ii), the condition is as follows: Formosolv/acetosolv ratio of 70/30 (v/v), the biomass-to-solvent ratio of 1/8 (w/v) for 2 hours at 98 ± 2°C and allowing to cool for filtration. The residue cleaning is with 80% formic acid and distilled water. The dilution of black liquor is with distilled water, stirred, centrifuged for 1 hour.

In method (iii): Lignin extraction is with the material-to-solvent (1% (w/w) 98% H2SO4) ratio of 1/4 (w/v) at 160 ± 2°C for 2 hours and down to room temperature for the collection of the supernatant. The residue washing is with 1,4-dioxane and removed 1,4-dioxane in the black liquor by rotary evaporation.

#### **Figure 12.**

*Extraction schematic of antioxidant laminarin from brown algae.*

During the black liquor dilution by using distilled water, stir and centrifuge are for 1 hour. The precipitated lignin(s) is separated, neutral with distilled water, and oven-dried at 50°C for 48 hours.

#### *4.3.2 Alkaloids*

Alkaloids are one of the main photochemical components of plants, so they are also extracted with organic solvents, and most claims indicate that alkaloids are soluble in ethanol. According to Surya et al., alkaloid extract after chasing ethanol solvent added 5% CH3CO2H, filter, and separated with CH2Cl2. The aqueous phase is collected and adjusted to pH 10 for the continuous fraction with CH2Cl2. Finally, the obtain of CH2Cl2 fraction because alkaloids exist in the CH2Cl2 phase (**Figure 17**) [76].

#### *4.3.3 Flavonoids*

About 5000 flavonoids have been identified and noticed. Each group of substances in flavonoids can dissolve in different solvents. Apigenin-7-methyl ether and flavone aglycone are among the substances found in 70% ethanol extracts that support the boiling point of water after the plant pre-treatment with Petroleum ether at 40 to 60°C. Ethyl acetate fractionated with ethyl acetate to obtain the ethyl acetate fraction. Then run via the polyamide column, which will select the purified Apigenin-7-methyl ether and flavone aglycone (**Figure 18**) [77].

*Functional-Antioxidant Food DOI: http://dx.doi.org/10.5772/intechopen.96619*

**Figure 13.** *Extraction scheme of antioxidant ulvan from green algae.*
