Pendugaan Kandungan Kimia Jambu Air Citra Menggunakan Near Infrared Spectroscopy (NIRS)

Abstract

Jambu air citra termasuk salah satu buah lokal yang menjadi unggulan dan memiliki nilai komersial tertinggi dibandingkan dengan jenis jambu air lainnya. Penentuan kualitas jambu air citra didasarkan pada permintaan pasar dengan pertimbangan kualitas internal dan eksternal buah. Kandungan buah seperti kadar air, kandungan gula, dan total asam menjadi kriteria mutu internal yang penting. Pada umumnya untuk mengetahui kandungan internal di dalam buah dilakukan pengukuran secara destruktif yang bersifat merusak buah. Dengan kemajuan teknologi, penentuan kandungan kimia internal suatu bahan dapat dilakukan secara non-destruktif menggunakan teknologi Near Infrared Spectroscopy (NIRS). Penelitian ini bertujuan untuk menduga kadar air, total padatan terlarut dan total asam buah jambu air citra secara non-destruktif menggunakan NIRS. Bahan yang digunakan adalah buah jambu air citra dengan tiga umur panen yang berbeda. Alat yang digunakan adalah NIR spektrometer tipe NIRFlex N-500 fiber optik solid yang bekerja pada panjang gelombang 1000-2500 nm. Metode pengolahan data yang digunakan dalam kalibrasi dan validasi data spektra NIR dengan data referensi adalah metode kemometrik Partial Least Squares (PLS) dengan pre-treatment data spektra Normalisasi, Standard Normal Variate (SNV), De-Trending (DT), Multiplicative Scatter Correction (MSC), dan Smoothing Savitzky-Golay (SSG). Perlakuan terbaik dalam menduga kadar air diperoleh dengan pre-treatment data SSG pada faktor PLS 16 dengan nilai r = 0,90; SEC = 0,86%; SEP = 1,00%; CV = 1,11%; RPD = 1,83; dan konsistensi = 85,73%. Pengolahan data spektra terbaik dalam menduga total padatan terlarut diperoleh dengan pre-treatment data SSG pada faktor PLS 16 dengan nilai r = 0,94; SEC = 0,72 °Brix; SEP = 0,75 °Brix; CV = 8,44%; RPD = 2,57; dan konsistensi = 95,69%. Perlakuan terbaik dalam menduga total asam diperoleh dengan pre-treatment data De-Trending pada faktor PLS 8, dengan nilai r = 0,70; SEC = 0,10%; SEP = 0,11%; CV = 24,15%; RPD = 1,21; dan konsistensi = 94,86%. Hasil ini menunjukkan bahwa NIRS dapat digunakan untuk menduga kadar air dan total padatan terlarut buah jambu air citra, namun belum mampu menduga secara akurat kandungan total asam pada buah jambu air citra.

Citra water apple is one of the leading local fruits and has the highest commercial value compared to other types of water apple. The quality of citra water apple determined based on market demand with consideration of the internal and external quality of the fruit. The content of the fruit such as moisture content, sugar content, and total acid are important criteria for internal quality. In general, to determine the internal content in the fruit, destructive measurements are made which damage the fruit. With technological advances, determination of the internal chemical content of a material can be done non-destructively using Near Infrared Spectroscopy (NIRS) technology. This study aims to estimate the water content, total soluble solids and total acid of water apple fruit non-destructively using NIRS. The materials used were citra water apple fruits with three different harvest ages. The tool used is NIR spectrometer type NIRFlex N-500 solid optical fiber that works at a wavelength of 1000-2500 nm. The method used in the calibration and validation of NIR spectra data with reference data is the Partial Least Squares (PLS) chemometric method with pre-treatment of spectra data Normalization, Standard Normal Variate (SNV), De-Trending (DT), Multiplicative Scatter Correction (MSC), and Smoothing Savitzky-Golay (SSG). The best spectra data processing to estimate water content was obtained by using SSG data pre-treatment on PLS factor 16, with r = 0.90; SEC = 0.86%; SEP = 1.00%; CV = 1.11%; RPD = 1.83; and consistency = 85.73%. The best spectra data processing to estimate total soluble solids was obtained by SSG data pre-treatment on PLS factor 16, with r = 0.94; SEC = 0.72 °Brix; SEP = 0.75 °Brix; CV = 8.44%; RPD = 2.57; and consistency = 95.69%. The best spectra data processing to estimate total acid was obtained by De-Trending data pre-treatment on PLS factor 8, with r = 0.70; SEC = 0.10%; SEP = 0.11%; CV = 24.15%; RPD = 1.21; and consistency = 94.86%. These results indicate that NIRS can be used to estimate water content and total soluble solids, but is not yet able to accurately estimate the total acid content of citra water apple.