Identifikasi Perubahan Mutu Selama Penyimpanan Buah Manggis Menggunakan Near Infra Red Spectroscopy
 
(Identification of Quality Changes of Mangosteen During Storage Using Near Infra Red Spectroscopy)

Sutrisno, Yohanes Aris Purwanto, Emmy Darmawati, Enrico Syaefullah
 
ABSTRAK
 
Salah satu perubahan kualitas pada buah manggis utuh selama penyimpanan adalah pengerasan kulit buah yang diduga berkaitan dengan kadar air kulit buah. Tujuan penelitian adalah menentukan korelasi antara kadar air dengan kekerasan, dan memprediksi perubahan kadar air berdasarkan reflektan near infrared (NIR). Hubungan kadar air dan kekerasan kulit buah manggis pada penyimpanan 13 °C dapat ditentukan dengan persamaan y = 0,07972x 2 9.833x + 305,9 dan pada suhu ruang y = 0,1207x 2 14,89x + 460,8; dimana nilai y adalah kekerasan kulit dan x adalah kadar air kulit buah. Evaluasi hasil kalibrasi dan validasi hasil pengukuran NIR dan metode oven menggunakan partial least square (PLS) menunjukkan nilai r sebesar 0,758 0,882; RMSEC dan RMSEP sebesar 0,09 0,39% dan CV<5% yaitu 2,5 3,3%. Prediksi kadar air kulit buah manggis berdasarkan reflektan NIR adalah y (suhu:8°C) = -0,057x + 65,14; y (suhu 13 C)
 = -0,253x + 64,96; y  = -0,421x + 64,76.  (suhu ruang)

Kata kunci: chilling injury, manggis, mutu simpan, near infra red, partial least square

ABSTRACT
 
One of quality changes during storage of intact mangosteen fruit is firmness. This occurrence was predicted to have associate with moisture content in the pericarp. The objective of this  research was to determine the correlation between moisture content and firmness, and to predict moisture content changes based on reflectance  spectrum of near infra red (NIR). The correlation between moisture content and firmness at 13 C is y = 0.07972x 9.833x + 305.9 while at room temperature showed y = 0.1207x 2 14.89x + 460.8; in which y refers to firmness and x refers to moisture content in pericarp. The calibration and validation evaluation using partial least square of  moisture content resulted in NIR and oven method showed that the magnitude of r is 0.758 0.882; RMSEC and RMSEP is 0.09 0.39%; CV<5% is at 2.5 3.3%. Moisture content prediction using NIR reflectant spektrum is y  (temperature:8 C) = -0.057x + 65.14; y  (temperature 13 C) = -0.253x + 64.96; y  = -0.421x + 64.76. 

Keywords: chilling injury, mangosteen, near infra red, partial least square, storage quality (room temperature)