Rapid and Non-Destructive Evaluation on Cacao Pigments, Flavonoids and Nitrogen Contents during Pod Development and Maturity Using A Fluorescence Sensor

Abstract

The detection of pigments in cacao pods together with colourless flavonoids serves as a useful indicator for pod maturity using a fast and non-destructive multiparametric fluorescence sensor. In this study, the contents of anthocyanin, flavonol, chlorophyll and nitrogen balance were determined monthly (1-5 months) after flower fertilization as pod developed and matured using a fluorescence-based portable sensor on cacao pods from five different clones of DESA1, KKM22, KKM25, MCBC1 and PBC221. There were significant differences (P≤0.05) observed between the interaction of five different cacao clones and pod development periods in flavonol, chlorophyll and nitrogen balance contents. As pods developed, anthocyanin and flavonol accumulated while the content of chlorophyll decreased only when pod matured with nitrogen balance showed a decreasing trend in cacao pods. Among these clones, as expected, natural red appearance in cacao pods of DESA1 showed significantly highest index of anthocyanin (0.637), following by KKM22 (0.255). In addition, there was no significant difference observed in KKM25, MCBC1 and PBC221 for anthocyanin content. During pod development, MCBC1 showed the least content in flavonol (P≤0.05) and the chlorophyll contents in KKM22 and MCBC1 were lower compared to other clones. As a conclusion, non-destructive fluorescence-based indices can be used to measure the pigments and flavonoids in cacao which can provide valuable non-destructive indicators for cacao pod maturity across different cacao cultivars.