Production of essential oils and sugar-rich hydrolysate from betel leaves (Piper betle)

The study was carried out to fully utilize betel leaves for the extraction of essential oils and production of sugar-rich hydrolysates from the betel leaves residues. Essential oils in the betel leaves were extracted by hydrodistillation and the betel leaves residues were enzymatically hydrolyzed to obtain sugar-rich hydrolysates. Antioxidant and antibacterial activity of the essential oils and the hydrolysates were investigated. Chemical composition analysis of the betel leaves showed that they contained 2.23% reducing sugars, 21.10% polysaccharides, 68.01 mg/g phenolics, 6.17 mg/g flavonoids, 12.05% ash, and 1.63% tannins. Betel essential oils content was 3.14%, with the main components being eugenol (50.37%), γ-muurolene (9.65%), and α-copaene (8.22%). Betel essential oils exhibited antioxidant activity with the IC50 of 0.13 mg/mL and antibacterial capacity against three strains of bacteria, including Escherichia coli, Samonella sp. and Bacillus cereus. The enzymatic hydrolysis of betel leaves residues using Ultraflo Max with a ratio of enzyme to substrate of 5% for 96 h produced the highest amount of reducing sugars of 10.66 g/L containing 48.31% glucose. The results suggest that betel leaves residues hydrolysate can be used as carbon sources for fermentation processes to produce value-added commodities in further investigation.