Polyphenol extracts from low quality cocoa beans: antioxidant, antibacterial and food colouring properties

Good quality cocoa beans are well studied and known as rich source of natural polyphenols. On the contrary, little research has been done regarding polyphenol extracts (PE) from low quality cocoa beans i.e. partially fermented dry cocoa beans (PFDCB) and unfermented dry cocoa beans (UFDCB). The following research was carried out to study the antioxidant, antibacterial, and food colouring properties of polyphenol extracts from PFDCB (PE-PFDCB) and UFDCB (PE-UFDCB). Antioxidant activity of PE-PFDCB and PE-UFDCB showed IC50 value of 1.1604 mg/ml and 0.2500 mg/ml respectively. Antibacterial activity of PE-PFDCB and PE-UFDCB was effective at inhibiting the growth of Staphylococcus aureus and Salmonella typhimurium at 25,000 ppm to 100,000 ppm respectively. As food colouring for yogurt, PE-PFDCB and PE-UFDCB showed the best color stability at 3% in refrigerated storage (2 - 5°C). As food colouring for syrup, 3% of PE-PFDCB and PE-UFDCB showed the best color stability at room temperature storage (24 - 25°C) and refrigerated storage (2 - 5°C) respectively. This study showed that polyphenol extracts from unfermented dry cocoa beans have higher polyphenol contents and stronger antioxidant activity than partially fermented cocoa bean, and can be used at 3% as natural functional food colors.