Germinated Cocoa Beans and Cocoa Husks as Sources of γ-Aminobutyric Acid: Effects of Solvent Extraction (Deionized Water, 70% and 90% Ethanol) and Geographical Variation Across Thailand

Gamma-aminobutyric acid (GABA), a non-protein amino acid, functions as the chief inhibitory neurotransmitter in mammals and is associated with several health benefits, including hypotensive, diuretic, tranquilizing, and antidiabetic effects. Although cocoa has been identified as a potential source of GABA, information regarding its concentration in cocoa-derived materials remains limited. This study evaluated the GABA content of dried germinated cocoa beans and dried cocoa husks (shells) collected from different geographical regions in Thailand. GABA was extracted using solid–liquid extraction with deionized water, 70% ethanol (v/v), and 90% ethanol (v/v), and quantified by high-performance liquid chromatography coupled with diode array detection (HPLC/DAD). The results revealed that both germinated cocoa beans and cocoa husks contain considerable amounts of GABA. The highest GABA content in cocoa beans was detected in samples from Tak province (242 ± 18 mg/100 g), while cocoa husks from Nan province exhibited the highest GABA content (361 ± 11 mg/100 g), both obtained using 70% ethanol extraction. Among the solvents tested, 70% ethanol demonstrated superior extraction efficiency compared with deionized water and 90% ethanol. In conclusion, germinated cocoa beans and cocoa husks represent promising natural sources of GABA, and extraction with 70% ethanol provides an effective approach for maximizing GABA recovery for potential functional foods and bioactive product development.