Oxygen Uptake Rate and Carbon dioxide Evolution Rate on the Fermentation Process of Cocoa Beans (Theobroma Cacao L.)

Abstract

Fermentation is one of the most critical stages in the postharvest handling process of cocoa beans. Temperature changes during the fermentation process characterize the success of the cocoa bean fermentation process. In general, aeration conditions during the fermentation process effects changes in fermentation air temperature. This study aims to determine cumulative oxygen uptake and cumulative carbon dioxide evolution during cocoa bean fermentation. Fermenter equipped with a controlled system of air temperatures and aeration rates was used to determine changes in oxygen uptake rate and carbon dioxide evolution rate during the fermentation process. The variables observed were including: length of pod storage time before fermentation (X₁; days), aeration rate (X₂; l.min-1), and fermenter temperature (X₃; ℃). Response surface methodology was used to determine the relationship between cumulative oxygen uptake as well as cumulative carbon dioxide evolution and the observed variables (X₁, X₂, X₃) The results shows that cumulative oxygen uptake and cumulative carbon dioxide evolution obtained in various treatments during the fermentation process are consecutive: 6.66-34.29 g O₂ kg vs-¹ and 12.15-50.97 g CO₂ kg vs-¹. Based on the variance analysis of response surface methodology, R² value of the cumulative oxygen uptake is about 88.1%, while R² value of the cumulative carbon dioxide evolution value is about 87.3 %. The highest amount of oxygen consumption and carbon dioxide production was obtained at X₁ = 5 days, X₂ = 0.25-0.4 l.min-1 , and X₃ ≤ 50℃.