Effect of processing on the biochemical contents of Acanthus montanus (Nees) T. Anderson (Acanthaceae) leaves

The effect of processing on the biochemical contents of Acanthus montanus leaves was investigated. The moisture, crude protein, lipid, fiber, ash, and total carbohydrate contents of the raw vegetable were 59.15, 1.85, 2.32, 3.76, 2.04, and 34.65 g/100 g, respectively. The saponin, alkaloid, tannin, flavonoid, phenol, and anthocyanin contents of the raw vegetable were 5.35, 4.04, 1.10, 3.53, 2.87, and 1.27 g/100 g, respectively, while it contained 2.65 mg/100 g calcium, 1.14 mg/100 g magnesium, 7.66 mg/100 g potassium, 350.75 μg/g vitamin A, 50.87 mg/100 g vitamin C, and 0.25% titratable acidity. There were significant reductions (p < .05) in the protein, lipid, fiber, ash, saponin, alkaloid, tannin, phenol, anthocyanin, calcium, magnesium, potassium, vitamin A, vitamin C, and titratable acidity of the boiled or boiled + sun-dried A. montanus leaves; significant elevation of the moisture contents but significant reduction of the total carbohydrate contents of the boiled; and significant reduction of the moisture contents of the boiled + sun-dried vegetable compared with the raw. There were significant increases (p < .05) in the total carbohydrate contents of the boiled + sun-dried leaves; significant reductions (p < .05) in the moisture, saponin, alkaloid, and vitamins A and C contents of the sun-dried vegetable; and no significant differences (p > .05) in the lipid, calcium, potassium, and ash, but significant increases (p < .05) in the protein, crude fiber, total carbohydrates, tannins, flavonoids, phenols, anthocyanin, magnesium, and titratable acidity of the sun-dried vegetable when compared with the raw. Sun drying alone either retained or enhanced the release of some important bioactive compounds in A. montanus leaves. Furthermore, the reduced moisture content of the sun-dried vegetable together with its increased titratable acidity will make the sun-dried vegetable uninhabitable for microorganisms, thereby increasing its shelf life.