Aroma Precursors and Methylpyrazines in Underfermented Cocoa Beans Induced by Endogenous Carboxypeptidase

Abstract

Cocoa-specific aroma precursors and methylpyrazines in underfermented cocoa beans obtained from fermentation induced by indigenous carboxypeptidase have been investigated. Fermentation conditions and cocoa bean components were analyzed during 0 to 3 d of fermentation. Underfermented cocoa beans were characterized as having hydrophilic peptides and free hydrophobic amino acids much higher than unfermented ones. These 2 key components of cocoa aroma precursors may be produced from the breakdown of proteins and polypeptides by endogenous carboxypeptidase during the fermentation process. The enzyme was activated during fermentation. Polypeptides of 47, 31, and 19 kDa were observed in the samples throughout the 3-d fermentation period; however, only the first 2 polypeptides were remarkably reduced during fermentation. Since the 1st day of fermentation, underfermented cocoa beans contained methylpyrazines, a dominant group of cocoa-specific aroma. This might be due to microbial activities during fermentation, observed through a decrease of pH value and an increase of temperature of cocoa beans. The concentration of tetramethylpyrazines was significantly increased during the 3 d of fermentation. This may increase the cocoa-specific flavor to the beans.

Amino acid analysis of cocoa fermented by high performance liquid chromatography (HPLC)

“…Furthermore, the hydrophobic amino acids are considered as the most potent precursor formation for methylpirazins. The study of Jinap et al (2008 and2010) and Yusep et al (2002) showed that hydrophobic free amino acids and acid group amino acids directly contribute to the formation of cocoa flavor because they act as substrates for Maillard reaction to form methylpirazins. Methylpirazin is allegedly associated with chocolate flavor intensity, while the hydrophobic amino acids are considered to be the most potent precursor formation for methylpirazins.…”

“…Those are significantly different with amino acids produced by cacao beans of fermented 72, 96 and 120 h. Amino acid deteriment specifically alannine 1.37 ± 0.01 increase to 1.65 ± 0.01, tyrosine 0.78±0.01 decrease to 0.63±0.01, valine 0.82±0.01 increase to 0.95 ± 0.01, phenylalanine 1.26±0.01 decrease to 1.19±0.01, isoleucine 0.92±0.01 just same after 120 h and leucine 1.41±0.01 increase to 1.48±0.01.Most types of amino acids in the cacao beans are aspartic, glutamic and lysine. Yusep et al (2002) and Jinap et al (2008) described that amino acid is a precursor of certain aroma that acts as a substrate for a Maillard reaction to form methylpyrazines (Eichner et al, 1994).…”

Use of High Performance Liquid Chromatography (HPLC) for the Analysis of Amino Acid of Sulawesi and Local Clone Cocoa Bean Fermentation

“…Furthermore, the hydrophobic amino acids are considered as the most potent precursor formation for methylpirazins. The study of Jinap et al (2008Jinap et al ( , 2010 and Yusep et al (2002) showed that hydrophobic free amino acids and acid group amino acids directly contribute to the formation of cocoa flavor because they act as substrates for Maillard reaction to form methylpirazins. Methylpirazin is allegedly associated with chocolate flavor intensity, while the hydrophobic amino acids are considered to be the most potent precursor formation for methylpirazins.…”

“…Most types of amino acids in the cacao beans Sulawesi clone are aspartic, glutamic and lysine. Yusep et al (2002) and Jinap et al (2008) described that amino acid is a precursor of certain aroma that acts as a substrate for a Maillard reaction to form methylpyrazines (Eichner et al, 1994).…”

Peningkatan Kualitas Biji Kakao Non Fermentasi Melalui Perlakuan Pendahuluan Sebelum Inkubasi

“…Pengukuran nilai pH biji kakao berdasarkan metode Jinap, Ikrawan, Bakar, Saari, & Lioe (2008). Biji kakao sebanyak 5 g yang telah dihaluskan dengan mortar dimasukkan ke dalam erlenmeyer 150 ml, kemudian ditambahkan 45 ml akuades dan diaduk menggunakan pengaduk magnetik selama 10 menit.…”