Electronic Theses and Dissertation

Daun kelor (moringa oleifera l.) merupakan tanaman tropis yang dikenal sebagai miracle tree karena kekayaan kandungan nutrisi dan senyawa bioaktifnya yang tinggi, dua parameter penting yang menentukan kualitas bioaktif daun kelor adalah total phenolic content (tpc) dan aktivitas antioksidan, yang menggambarkan kemampuan daun kelor dalam menetralisir radikal bebas dan mencegah kerusakan oksidatif. metode analisis konvensional seperti folin-ciocalteu untuk tpc dan dpph untuk aktivitas antioksidan memiliki akurasi yang baik, namun memerlukan waktu analisis yang lama (4–6 jam), konsumsi reagen kimia tinggi, dan menghasilkan limbah berbahaya. sebagai alternatif yang lebih efisien, teknologi spektroskopi fourier transform infrared (ftir) menawarkan analisis non-destruktif yang cepat (2–3 menit per sampel), tanpa preparasi sampel yang kompleks, dan tidak menghasilkan limbah kimia. penelitian ini bertujuan untuk mengkaji kemampuan teknologi ftir yang dikombinasikan dengan metode kemometrik partial least square (pls) dalam memprediksi nilai tpc dan aktivitas antioksidan bubuk daun kelor secara cepat dan akurat, serta menentukan metode pretreatment spektrum yang paling optimal. prosedur penelitian diawali dengan pengumpulan sampel bubuk daun kelor dari 12 lokasi yang berbeda. pengukuran tpc dilakukan menggunakan metode folin-ciocalteu, sedangkan aktivitas antioksidan diukur menggunakan metode dpph (1,1-difenil-2-pikrilhidrazil), yang hasilnya dijadikan data referensi. pengukuran spektrum ftir dilakukan menggunakan instrumen spektrometer ftir pada rentang bilangan gelombang 4000–400 cm⁻¹. data spektral kemudian diolah menggunakan perangkat lunak the unscrambler® x versi 10.4 melalui dua metode pretreatment, yaitu standard normal variate dan detrending. model kalibrasi kemudian dikembangkan menggunakan metode pls, kinerja model dievaluasi menggunakan parameter statistik meliputi koefisien korelasi (r), koefisien determinasi (r²), root mean square error of calibration (rmsec), dan residual predictive deviation (rpd). hasil penelitian menunjukkan bahwa teknologi ftir yang dikombinasikan dengan metode pls berhasil memprediksi kandungan tpc dan aktivitas antioksidan bubuk daun kelor dengan tingkat akurasi yang sangat baik. penerapan pretreatment snv terbukti memberikan performa terbaik untuk prediksi tpc dengan nilai r = 0,9968, r² = 0,9936, rmsec = 0,0920458, dan rpd = 13,071. sementara itu, model snv juga menghasilkan performa terbaik untuk prediksi aktivitas antioksidan (ic₅₀) dengan nilai r = 0,9994, r² = 0,9987, rmsec = 0,1174718, dan rpd = 29,305. kedua model memiliki nilai rpd > 3 yang termasuk dalam kategori excellent prediction accuracy menurut nicolai et al. (2007), menunjukkan bahwa ftir-pls merupakan metode yang valid dan andal sebagai alternatif analisis cepat kandungan bioaktif bubuk daun kelor.

Moringa leaf (Moringa oleifera L.) is a tropical plant known as the miracle tree due to its rich nutritional content and high concentration of bioactive compounds. Two important parameters that determine the bioactive quality of moringa leaves are Total Phenolic Content (TPC) and antioxidant activity, which describe the leaf's capacity to neutralize free radicals and prevent oxidative damage. Conventional analytical methods such as Folin-Ciocalteu for TPC and DPPH for antioxidant activity offer good accuracy but require lengthy analysis time (4–6 hours), high consumption of chemical reagents, and generate hazardous waste. As a more efficient alternative, Fourier Transform Infrared (FTIR) Spectroscopy technology offers rapid, non-destructive analysis (2–3 minutes per sample), requires no complex sample preparation, and produces no chemical waste. This study aims to examine the capability of FTIR technology combined with the Partial Least Squares (PLS) chemometric method in rapidly and accurately predicting the TPC and antioxidant activity values of moringa leaf powder, as well as to determine the most optimal spectral pretreatment method. The research procedure began with the collection of moringa leaf powder samples from 12 different locations. TPC measurement was performed using the Folin-Ciocalteu method, while antioxidant activity was measured using the DPPH (1,1-diphenyl-2-picrylhydrazyl) method, with the results serving as reference data. FTIR spectral measurements were performed using an FTIR spectrometer instrument over the wavenumber range of 4000–400 cm⁻¹. The spectral data were then processed using The Unscrambler® X software version 10.4 through two pretreatment methods, namely Standard Normal Variate (SNV) and Detrending. Calibration models were then developed using the PLS method, and model performance was evaluated using statistical parameters including the correlation coefficient (r), coefficient of determination (R²), Root Mean Square Error of Calibration (RMSEC), and Residual Predictive Deviation (RPD). The results showed that FTIR technology combined with the PLS method successfully predicted the TPC and antioxidant activity of moringa leaf powder with a very high level of accuracy. The application of SNV pretreatment was shown to provide the best performance for TPC prediction, with values of r = 0.9968, R² = 0.9936, RMSEC = 0.0920458, and RPD = 13.071. Meanwhile, the SNV model also produced the best performance for predicting antioxidant activity (IC₅₀), with values of r = 0.9994, R² = 0.9987, RMSEC = 0.1174718, and RPD = 29.305. Both models had RPD values > 3, which fall into the excellent prediction accuracy category according to Nicolai et al. (2007), indicating that FTIR-PLS is a valid and reliable method as a rapid alternative for analyzing the bioactive content of moringa leaf powder.