<![CDATA[Being the world’s third largest producer of cocoa (Theobroma cacao), Indonesia provides abundant cocoa pod husk byproduct. Despite its high content of biological materials, its use as animal feed, however, has been limited due to its low nutritive values and significant content of antinutritive substances. Thus, this study was aimed to investigate the changes of selected amino acids glutamate, aspartate, valine, alanine, and proline, as well as the antinutritional compound theobromine in cocoa byproduct-rice bran mixed substrate following fermentation using Rhizopus oryzae. The fermented substrate obtained had its true protein content increased from 1.95% to 23.16%. After analyses using ultra-performance liquid chromatography quadrupole time of flight mass spectrometry, the following amino acids, namely: total and free glutamates, total and free valine, total proline, as well as free alanine underwent increase, while the others decreased. The concentration of the antinutritional factor theobromine was below the limit detectable by HPLC.Keywords: Rhizopus oryzae, Theobroma cacao, theobromine, fermentation, amino acidsABSTRAKSebagai penghasil kakao (Theobroma cacao) terbesar ketiga di dunia, Indonesia mempunyai hasil samping melimpah berupa kulit cangkang kakao. Meskipun kandungan bahan biologisnya tinggi, penggunaan produk samping ini sebagai pakan ternak masih terbatas karena nilai gizi yang rendah serta kandungan zat antinutrisi yang tinggi. Oleh karenanya, penelitian ini bertujuan mengetahui perubahan kandungan asam amino glutamat, aspartat, valin, alanin, dan prolin, serta senyawa antinutrisi teobromin dalam campuran hasil samping coklat-dedak padi pasca fermentasi menggunakan Rhizopus oryzae. Substrat hasil fermentasi mengalami peningkatan kandungan protein sejati dari 1,95% menjadi 23,16%. Hasil analisis menggunakan ultra-performance liquid chromatography quadrupole time of flight mass spectrometry, menunjukkan bahwa kandungan asam amino: glutamat total dan glutamat bebas, valin total dan valin bebas, prolin total, serta alanin bebas mengalami peningkatan, sementara asam amino selainnya mengalami penurunan. Kandungan antinutrisi teobromin berada di bawah ambang batas deteksi oleh HPLC.Kata kunci: Rhizopus oryzae, Theobroma cacao, teobromin, fermentasi, asam amino ]]>
