Development of coffee silver skin into food beverage and
testing antioxidant activity

Coffee silver skin (CS) is an outer layer of coffee beans. The conversion of CS into a higher-value product offers a promising approach to managing waste because of its rich antioxidant contents. Cinnamon powder (CP) is abundant in antioxidants but does not contribute to a pleasant aroma, whereas Bael powder possesses a sweet scent. This study aims to optimize the combination of CS with Bael powder (BP) and cinnamon powder and assess their antioxidant capacity using brewing (100 mL of water) and tea bags (100 mL, 100°C, 3 min). Combinations ranging from 100%, 75%, 50%, and 25% of CS were studied. The results of the sensory evaluation show that the most favorable ratio was 25% CS with 75% BP, yielding a total phenolic content (TPC) of 43.85 mg GAE/100 mL and antioxidants of 14.39 mgAAE/100 mL for brewing, while 41.45 mg GAE/100 mL with antioxidant at 10.82 mgAAE/100 mL for tea bags. The highest sensory scores are optimal for CS and CP combination, with a ratio of 75% CS and 25% CP for brewing and 50% CS and 50% CP for tea bags. The results revealed a TPC of 17.81 mgGAE/100 mL with antioxidants of 19.39 mgAAE/100 mL for brewing and a TPC of 16.82 mgGAE/100 mL with antioxidants of 17.60 mgAAE/100 mL for teabag. The study highlights that blending CS with BP or CP at specific ratios produces antioxidant-rich beverages with maintained sensory acceptability. A combination of CS below 50% shows promise for developing a sustainable beverage for waste management.