Effect of farm and industrial processing on the amino acid profile of cocoa beans

An investigation into the amino acid profiles of unfermented and fermented cocoa nibs, as well as process-line cocoa nibs (P-LCN) and processed cocoa cake samples (PCCS) was carried out. In the unfermented cocoa nibs, Glu (128 mg/g crude protein i.e. 128 mg/gcp) was the most abundant amino acid whilst the most concentrated essential amino acid in the same sample was Leu (72.2 mg/g crude protein); in the fermented cocoa nibs, a similar trend was observed, with respective values of Glu (153 mg/gcp) and Leu (62.4 mg/gcp). Lys (181 mg/gcp) was most abundant amino acid in P-LCN and Ile (63.3 mg/gcp) was the second most abundant; also, in PCCS, Lys (52.7 mg/gcp) was the most abundant amino acid but Asp (43.7 mg/gcp) was the second most abundant. The total amino acid content was (mg/gcp), 641 (unfermented nibs), 708 (fermented nibs), 635 (P-LCN) and 368 (PCCS), with corresponding essential amino acids of 300, 287, 478 and 185 (all with His), respectively. Based on whole hen’s egg, the limiting amino acids for the samples were: Ser (unfermented nibs), Met (fermented nibs), Ala (P-LCN) and Val (PCCS), whereas under provisional amino acid scoring pattern, they were: Met + Cys (unfermented nibs), Met + Cys (fermented nibs), Thr (P-LCN) and Val (PCCS). Prolonged and high heat treatments appeared to have reduced the essential amino acids of the PCCS as compared to the P-LCN. Significant differences existed between contents of essential amino acids and non-essential amino acids at p < 0.05 in unfermented cocoa nibs, fermented cocoa nibs and P-LCN.