<![CDATA[Abstract. Palm kernel cake is a byproduct of the palm oil industry that remains underutilized despite its high content of non-starch polysaccharides and carbohydrate-bound proteins with potential as plant-based biomaterials. This study aimed to extract protein from palm kernel cake and identify its functional groups and protein content using Fourier Transform Infrared (FTIR) spectroscopy and the Kjeldahl method. Protein extraction was carried out using an alkali–acid process involving solubilization with NaOH followed by isoelectric precipitation with HCl. The dried protein extract was analyzed using FTIR to detect characteristic protein absorption bands, while protein content was quantified using the Kjeldahl method. The extraction produced a yield of 9.6%. FTIR spectra showed the presence of Amide I (1650 cm⁻¹), Amide II (1540 cm⁻¹), and Amide III (1230 cm⁻¹) bands, confirming the protein structure within the extract. The Kjeldahl analysis revealed a protein content of 49.27%, which is higher than previously reported values and exceeds the minimum protein requirement of 13% set by the Indonesian National Standard (SNI). These findings demonstrate that palm kernel cake is a promising raw material for the development of plant-derived protein suitable for pharmaceutical and biomaterial applications. Abstrak. Bungkil sawit merupakan produk samping industri minyak sawit yang masih belum dimanfaatkan secara optimal, meskipun mengandung polisakarida bukan pati dan protein terikat yang berpotensi sebagai sumber biomaterial nabati. Penelitian ini bertujuan untuk mengekstraksi protein dari bungkil sawit serta mengidentifikasi struktur fungsional dan kadarnya menggunakan spektroskopi Fourier Transform Infrared (FTIR) dan metode Kjeldahl. Proses ekstraksi dilakukan menggunakan metode alkali–asid dengan pelarutan NaOH dan presipitasi isoelektrik menggunakan HCl. Sampel protein kering dianalisis menggunakan FTIR untuk mendeteksi pita-pita karakteristik protein, sedangkan kadar protein ditentukan secara kuantitatif dengan metode Kjeldahl. Hasil penelitian menunjukkan rendemen protein sebesar 9,6%. Spektrum FTIR memperlihatkan pita Amida I pada 1650 cm⁻¹, Amida II pada 1540 cm⁻¹, dan Amida III pada 1230 cm⁻¹ yang mengonfirmasi keberadaan struktur protein. Uji Kjeldahl menunjukkan kadar protein sebesar 49,27%, lebih tinggi daripada nilai yang dilaporkan pada penelitian sebelumnya dan telah memenuhi standar SNI minimal 13%. Temuan ini menunjukkan bahwa bungkil sawit berpotensi sebagai sumber protein nabati untuk pengembangan aplikasi farmasi dan biomaterial.]]>
