PendahuluanPenentuan kematangan Tandan Buah Segar (TBS) sawit di perkebunan sangat mempengaruhi rendemen dalam produksi minyak sawit. Apabila minyak pada buah mentah atau lewat matang ikut diekstraksi, maka dapat menurunkan hasil rendemen. Salah satu upaya peningkatan rendemen minyak yaitu dengan dengan mengoptimalkan kegiatan penentuan kematangan buah, karena sampai saat ini masih menggunakan metode konvensional yaitu dengan melihat secara visual. TBS dikatakan layak panen apabila sudah menjatuhkan brondol (buah kecil) sebanyak 10-15 butir. Kenyataan di lapangan, terdapat TBS yang sulit menjatuhkan brondol atau brondol tersangkut di sela pelepah. Penentuan secara konvensional ini juga sangat bergantung pada pengalaman, kondisi psikis serta pengetahuan pemanen saat menentukan kematangan buah. Technical Paper Pendugaan Kadar Air dan Total Karoten Tandan Buah Segar (TBS) Kelapa Sawit Menggunakan NIR Spektroskopi Keywords: Fresh Fruit Bunch (FFB) maturity, NIR spectra, calibration model, water content, total carotene AbstrakTujuan dari penelitian ini adalah untuk membangun model kalibrasi dari kadar air dan total karotenyang dapat dijadikan standar kematangan buah. Terdapat tiga tahapan pada penelitian ini, pertama akuisisi spektrum Near Infrared (NIR) pada 60 sampel menggunakan NIRFlex N-500. Langkah selanjutnya adalah pengujiankadar air dan total karoten tiap sampel secara destruktif. Langkah terakhir adalah pembuatan model kalibrasi menggunakan metode (Partial Least Square) PLS dan menerapkan pretreatment data Standard Normal Variate (SNV), normalisasi (N01), dan First Derivative Savitzky-Golay 9 titik (DG1). Hasil menunjukkan bahwa kadar air dapat diprediksi dengan baik menggunakan SNV dengan R 2 (kalibrasi) = 0.89 dan R 2 (validasi) = 0.88 dan RPD = 2.84. Total karoten juga dapat diprediksi dengan baik menggunakan DG1 dengan R 2 (kalibrasi) = 0.84 dan R 2 (validasi) = 0.77 dan RPD = 2.06.

Sheet-pipe is a sort of perforated mole drain placed horizontally between 30–50 cm below the land surface commonly having a water-logged problem. The sheet-pipe can be installed with a heavy machine mole drainer. The primary purpose of installing sheet-pipe is to maintain or control the expected water table in farmlands. Sheet-pipe having a diameter of 5 mm has been installed at a depth of 40 cm with a drain spacing of 4 m and length of 100 m covering a paddy field of 1 hectare located in Sukamandi District, Subang Regency, West Java, Indonesia. Field investigation and numerical studies were undertaken to figure out water head profiles surrounding the sheet-pipe. The paddy field installed with sheet-pipe can be drained faster (2 times), and in consequence, its water level can be managed easier. Right after an effective rainfall event (34 mm), the rainwater immediately infiltrates downward resulting in a parabolic curve of infiltration rate (maximum rate 0.94 cm/h) which differs with a standard infiltration curve (steady state 0.121 cm/h). Water level profile is horizontally flat except at the points closer to the sheet-pipe, which is showing the presence of outward gradients of the water head. The electrical conductivity was low (0.33 Ms/cm) due to the leaching effect.

In current practice, appearance was used to determine ripeness for oil palm fresh fruits bunch (FFB), that accompanied by detachment of fruit-lets from the bunch. The FFB from marihat clone harvested at five ripeness stages, under ripeness (F0), ripeness (F1, F2, F3), and over ripeness (F4). At every ripeness stages, differences of oil content and pigment accumulation were observed on the bunch. All samples recorded using a digital camera (10 MPixels) from 2, 7, 10, and 15 meter distance, simulating variation of light intensity upon recording. During image recording, three lighting were used, namely ultraviolet lamp (320-380 nm), visible light lamp (400-700 nm) and infrared lamp (720-1100 nm), all have similar power output of 600watt. Camera point of view was set to cover a square area of 12,5cm by 12,5cm of the frontal area of FFB, each picture produced has 3888 by 2952 pixel. Image processing software created to extract digital RGB information from the images, and displayed the information in histogram. From the experiment, it was observed that the changes of intensity influence the RGB value of recorded image with reverse correlation, and longer wave light spectrum produce smaller RGB value. The correlation model among image recording distance and RGB of the image display similar nature. From three color channels, G_mean represents better correlation for sample's oil content determination. Using UV and visible lighting, the FFB samples may be determined for harvest decision, up to seven meter observation distance.

Kadar Asam Lemak Bebas (ALB) yang rendah merupakan salah satu indikator kualitas Crude Palm Oil (CPO) yang baik. Apabila Tandan Buah Segar (TBS) kelapa sawit yang lewat matang ikut diolah menjadi CPO, maka kadar ALB selama produksi dapat meningkat. Proses pemanenan menjadi titik krusial yang sangat mempengaruhi tingkat kematangan buah. Selama ini penentuan kematangan TBS kelapa sawit masih dilakukan secara visual yang bergantung kepada kemampuan dan kondisi pemanen buah sawit. Oleh karena itu, perlu dikembangkan suatu metode secara kuantitatif yang dapat memprediksi kadar ALB secara objektif. Pada penelitian ini, akan dikembangankan metode non-destruktif berbasis NIR spectroscopy yang akan dikaji sebagai metode untuk menentukan tingkat kematangan TBS berdasarkan kandungan ALB. Penelitian ini dibagi menjadi tiga tahapan, yaitu akuisisi data reflektansi spektrum TBS dengan NIR Flex N-500, pengukuran kadar ALB, dan pembangunan model kalibrasi dengan menggunakan kemometrik. Dari hasil pengembangan model didapatkan nilai R2 tanpa preprocessing sebesar 0.236, RPD sebesar 1.27 dan PC sebesar 2. Proprocessing First Derivative Savitzky Golay (DG1) memberikan nilai koefisien determinasi tertinggi yaitu sebesar 0.243, dengan nilai RPD sebesar 1.17 dan PC sebesar 2. Akan tetapi kualitas model kalibrasi yang dibangun tetap belum mampu menunjukkan kehandalan dalam memprediksi kandungan ALB tandan buah segar kelapa sawit.

In order to develop a model for predicting the oil palm Fresh Fruit Bunch (FFB) ripeness, a rapid and non-destructive method such as NIR spectroscopy is utilized. This method has shown its capability to determine the quality of some crops by predicting their internal chemical contents. The objective of the research is to investigate the feasibility of NIR spectroscopy to predict water and oil content in FFB by developing a calibration model. Sixty samples of FFB were scanned by using NIRFlex N-500 spectrometer ranging from 1000 to 2500nm. Water and oil content of samples were measured after scanned. To develop a calibration model, Partial Least Square (PLS) Regression and pre-processing were conducted using Unscrambler X 10.3. The results showed that PLS performs well to establish a calibration model to predict water content using MSC pre-processing with r2, factor, RSMECV, and RPD are 0.93, 3, 5.24, and 2, respectively. On the other hand, PLS could not be used well for establishing oil content calibration model because the result did not meet statistic parameters. For laboratory measurement, the model could predict water content of FFB; but it was limited to samples taken from the same variety and plantation. However, NIR Spectroscopy proposed a promising method to detect the ripeness of oil palm FFB.