Near Infrared Spectroscopy (NIRS): Fast and Non-destructive Metohd to Determination of Chemical Compositions of Modified Cassava Flour (Mocaf)

Abstract

Mocaf is one of the local food commodities which is expected to succeed in the food diversification program to reduce dependence on wheat flour in Indonesia. Mocaf's chemical composition can be identified by time-consuming and destructive laboratory testing. Near-infrared spectoscopy (NIRS) is a new method that predicts the chemical compositions of Mocaf, since this method is fast, and non-destructive. This study aims to determine the best spectrum data processing and multivariate calibration methods (partial least squares regression (PLSR) method and principal component regression (PCR) method) from the NIRS method which can be used to determine the chemical compositions (water content, ash content, pH, and amylose content) of Mocaf in a non-destructive and fast. The wavelength ranges to predicting Mocaf chemical compositions, from 1000 to 2500 nm. Data treatment on the reflectance and absorbance spectrum curve estimation Mocaf chemical compositions, among others: smooth average 3 points, second derivative Savitzky-Golay 9 points, and combination both of them. A number of 70 Mocaf were used as samples. Samples were divided into two phases: 2/3 of total samples for developing calibration equation and 1/3 of total samples for performing validation. NIRS data analysis result shows that PLSR method with NIRS reflectance data and the smooth average 3 points is the best method of calibration to predicting water content of Mocaf. Prediction of ash content, pH, and amylose content of Mocaf best obtained with the PLSR method, the NIRS absorbance data, and combination data treatment. The standard error of prediction (SEP) and coefficient of variability (CV) respectively were 0.49% and 4.2% for moisture contents; 0.02% and 2.8% for ash contents; 0.02% and 0.4% for pH contents; and 0.39% and 1.3% for amylose contents. This study shows that the NIRS method can be used to determine the chemical compositions of Mocaf.

Keywords:   NIRS, Mocaf, PLSR, PCR