Impact of Processing and Extraction Methods on the Phytochemical Composition of Garcinia Kola Stem Bark and Stone Breaker Leaves

Abstract

This study investigates the effects of three processing methods; blanching, drying, and fermentation on the phytochemical properties of Garcinia kola stem bark and stone breaker leaves, both of which are traditionally used in medicine. The primary aim was to evaluate how these processing techniques enhance the phytochemical profiles of these plant materials and to determine the most effective extraction method for retaining their beneficial properties, particularly for cardiovascular health. The contents of saponins, flavonoids, oxalates, phytates, tannins, and phenolic compounds in aqueous and ethanolic extracts were quantified. The results demonstrated that the fermented samples exhibited the highest flavonoid content (3.90 mg/g in fermented stone breaker ethanolic extract (FSBE) and 4.17% in fermented stone breaker aqueous extract (FSBA)) and phenolic content (75.29 mg/g in FSBA and 75.92 mg/g in FSBE). Furthermore, fermentation yielded the lowest oxalate (1.35 mg/g in fermented Garcinia kola stem bark aqueous extract (FGBA) and 1.84 mg/g in fermented Garcinia kola stem bark ethanolic extract (FGBE)) and phytate levels (20.92 mg/g in FSBA and 22.75 mg/g in FSBE). In contrast, the dried samples contained the highest saponin levels ranging from 0.09% in blanched stone breaker ethanolic extract (BSBE) to 1.34% in blanched Garcinia kola stem bark aqueous extract (BGBA). Tannin content was consistently low across all samples, ranging from 0.01 to 0.05 mg/g. While aqueous extracts displayed higher values for some components, ethanolic extracts outperformed in others. The findings underscore the health benefits of these plant materials, particularly highlighting the superiority of fermented samples due to their enriched flavonoid and phenolic content, which may significantly contribute to overall well-being, especially for cardiovascular patients.