Prediksi Sifat Fisikokimia Nenas Varietas Queen secara Nondestruktif Menggunakan Near Infrared Spectroscopy (NIRS)

Abstract

Nenas Queen banyak digemari orang karena selain memiliki rasa yang enak, segar dan mengandung sedikit asam juga mengandung berbagai nutrisi yang baik untuk kesehatan. Penentuan sifat fisikokimia pada buah nenas selama ini masih dilakukan secara visual dan manual, metode lain adalah dengan pengukuran obyektif menggunakan alat namun bersifat destruktif. Oleh karena itu perlu dilakukan penentuan sifat fisikokimia secara nondestruktif menggunakan Near Infrared Spectroscopy. Penelitian bertujuan menghasilkan metode prediksi sifat fisikokimia secara nondestruktif buah nenas Queen meliputi kekerasan, total padatan terlarut (TPT), total asam dan rasio gula asam menggunakan NIRS. Sampel yang digunakan yakni buah nenas varietas Queen dengan tingkat kematangan yang berbeda (n=60). Pengukuran NIRS dilakukan dengan NIRFlex spectrometer pada panjang gelombang 1000-2500 nm dilanjutkan dengan penentuan kekerasan, TPT, dan total asam secara destruktif. Kalibrasi dan validasi dilakukan dengan menggunakan metode Partial Least Square (PLS) menggunakan 2 region panjang gelombang yaitu 1000-1500 nm dan 1000-2500 nm. Peningkatan hasil prediksi dilakukan dengan beberapa metode pre-treatment yaitu normalisasi, SNV, de-trending, dan smoothing savitzky golay. Evaluasi hasil kalibrasi dan validasi dilakukan berdasarkan nilai r, SEC, SEP, CV, RPD, dan konsistensi. Hasil terbaik untuk prediksi kekerasan nenas Queen adalah menggunakan pre-treatment de-trending dan faktor 9 dengan nilai r = 0,76, SEC = 5,43 N, SEP = 6,34 N, CV = 22,98%, RPD = 1,32 dan konsistensi = 85,65%. Prediksi terbaik untuk TPT dengan pre-treatment normalisasi faktor 9 dengan nilai r = 0,77, SEC = 0,95 °brix, SEP = 1,14 °brix, CV = 8,89%, RPD = 1,38 dan konsistensi = 82,91%. Untuk total asam prediksi terbaik dengan pre-treatment smoothing savitzky golay faktor 9 dengan nilai r = 0,56, SEC = 0,26%, SEP = 0,32%, CV = 28,57%, RPD = 1,07 dan konsistensi = 80,25%. Sedangkan untuk rasio gula asam, prediksi terbaik dengan pre-treatment SNV faktor 8 dengan nilai r = 0,64, SEC = 4,35 °brix/%asam SEP = 4,35 °brix/%asam, CV = 35,96%, RPD = 1,20 dan konsistensi = 99,99%. Hasil penelitian menunjukkan metoda masih kurang akurat dalam memprediksi kekerasan, TPT, total asam, dan rasio gula asam nenas Queen secara nondestruktif. Meskipun demikian, model yang dibangun memiliki potensi untuk menggolongkan mutu nenas ke dalam 3 kelompok kematangan berdasarkan rasio kadar gula asam dengan ketepatan penggolongan 90%.

Queen pineapple is favored by many people because in addition to having a good, fresh taste and containing a little acid, it also contains various nutrients that are good for health. Determination of physicochemical properties in pineapple fruit has been done visually and manually, another method is by objective measurement using tools but is destructive. Therefore, it is necessary to determine physicochemical properties nondestructively using Near Infrared Spectroscopy. The research aims to produce a method of predicting physicochemical properties nondestructively of Queen pineapple fruit including hardness, total soluble solids (TPT), total acid and acid sugar ratio using NIRS. The samples used were Queen variety pineapple fruits with different maturity levels (n=60). NIRS measurements were carried out with a NIRFlex spectrometer at a wavelength of 1000-2500 nm followed by destructive determination of hardness, TPT, and total acid. Calibration and validation were carried out using the Partial Least Square (PLS) method using 2 wavelength regions, namely 1000-1500 nm and 1000-2500 nm. Improvement of prediction results is done with several pre-treatment methods, namely normalization, SNV, de-trending, and Savitzky Golay smoothing. Evaluation of calibration and validation results is carried out based on the value of r, SEC, SEP, CV, RPD, and consistency. The best result for Queen pineapple hardness prediction is using de-trending pre-treatment and factor 9 with r value = 0,76, SEC = 5,43 N, SEP = 6,34 N, CV = 22,98%, RPD = 1,32 and consistency = 85,65%. Best prediction for TPT with factor 9 normalization pre-treatment with r = 0.77, SEC = 0,95 °brix, SEP = 1.14 °brix, CV = 8,89%, RPD = 1,38 and consistency = 82,91%. For total acid, the best prediction with pre-treatment smoothing Savitzky Golay factor 9 with r = 0,56, SEC = 0,26%, SEP = 0,32%, CV = 28,57%, RPD = 1,07 and consistency = 80,25%. As for the acid sugar ratio, the best prediction was with SNV pre-treatment factor 8 with r = 0,64, SEC = 4,35 °brix/% acid SEP = 4,35 °brix/% acid, CV = 35,96%, RPD = 1,20 and consistency = 99,99%. The results showed that the method was still inaccurate in nondestructively predicting the hardness, TPT, total acid, and sour sugar ratio of Queen pineapple. However, the model has the potential to classify the quality of pineapple into 3 maturity groups based on the acid sugar ratio with 90% classification accuracy.