Effects of Cocoa Bean (Theobroma cacao L.) Fermentation on Phenolic Content, Antioxidant Activity and Functional Group of Cocoa Bean Shell

Background and Objective: Cocoa bean shell (CBS) has phenolic content and potential as cheaper source of antioxidants. The objective of this study was to evaluate the effects of cocoa bean fermentation on total phenolic content and antioxidant activity of cocoa bean shell. Materials and Methods: Cocoa beans were placed in fermentation box following spontaneous fermentation for 24, 48, 60, 72, 96 and 120 h. The CBS was separated from the cocoa beans and extracted with acetone-water (70:30 v/v). Folin-Ciocalteu method, 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and Fourier Transform Infrared Spectroscopy (FTIR) analysis were used to determine total phenolic contents, antioxidant activity and functional group of the samples, respectively. Results: For total phenolic contents, absorbance of various samples concentrations was plotted against gallic acid standard curve and the value indicated that CBS from partially fermented cocoa beans (24 h) contained the highest amount of phenolic content. Various concentrations of samples were also used for antioxidant activity measurement. Highest scavenging activity of 88.67±1.12% was obtained by 100 μg mL–1 CBS from partially fermented cocoa beans (24 h), while the lowest of 44.60±2.48% was obtained by CBS from 120 h fermented cocoa beans. A high correlation was observed between phenolic content and antioxidant activity. The FTIR analysis shows that CBS from 24 h fermented cocoa beans had more functional group compare to other samples. Conclusion: Fermentation of cocoa bean can affect total phenolic content and antioxidant activity of the CBS. Fermentation also causes functional group shift of CBS. The results of the study showed that CBS is a good source of antioxidants and phenolic compounds. Further study on the structural elucidation of the CBS individual phenolic compounds and evaluation of their mechanisms of action is recommended.