Extracts of cocoa (Theobroma cacao L.) leaves and their antioxidation potential
Author: H. Osman and R. Nasarudin and S.L. Lee
Cocoa shoot (CS), young leaves (CL) and tea leaves (GT) were processed according to green tea processing procedures. Polyphenol components was extracted and analysed using high pressure liquid chromatography. The total polyphenol of CS, CL and GT were 19.0, 28.4 and 17.3 mg/100 mg, respectively. The main catechin-polyphenols in extracts were epicatechin (EC), epigallocatechin gallate (EGCG), epigallocatechin (EGC), gallic acid (GA) and epicatechin gallate (ECG). The concentrations of caffeine for CS, CL and GT were 2.24, 1.33 and 3.34 mg/100 mg, respectively. The concentrations of EGCG, in both cocoa leaves, were lower than commercial green tea. However, the concentrations of EC in CS (5.93 mg/100 mg) and in CL (2.82 mg/100 mg) were significantly higher that those found in green tea (0.65 mg/100 mg). The antioxidation properties of the polyphenol extracts were tested, using ferric chloride reduction, and compared against a synthetic antioxidant (BHA). The polyphenol extracts (CS and CL) showed similar antioxidation powers to GT and BHA throughout the entire concentration range (100–2000 ppm). In the oil-based test medium; the antioxidative performance of polyphenol extracts were better than BHA at 50 ppm. At 200 ppm, the performance is quite similar to BHA. At higher concentration (400 ppm) the antioxidant activities are much better than BHA. In the presence of Cu2+ prooxidant (20 ppm), BHA (200 ppm) and all the extracts (200 pmm) showed similar performances. Since the oxidation test was conducted at 65 °C, the 8 days of stability provided by 200 ppm addition of CL and CS extracts, can be equated to 8 months of room temperature (25 °C) stability. Hence, the cocoa leaves extracts have the potential to complement or replace synthetic antioxidants in aqueous and oil-based food applications.
