Development of a Universal Algorithm for Use of Nir in Estimation of Soluble Solids in Fruit Juices

The protocol to identify and confirm effective soluble solids absorption wavelengths and to develop universalcalibration equations for many kinds of fresh fruit juices was discussed and conducted. Near infrared transmittance ofsugar solutions (glucose, fructose, and sucrose), ready-to-serve, and fresh fruit juices (orange, apple, grapefruit, grape,pear, pineapple, and sugarcane) was analyzed in the range from 1000 nm to 2500 nm. Absorbance at 2270 nm was foundto be a dominant factor in estimating Brix values in fruit juices. The single-wavelength (2270 nm) universal calibrationequation with r2 = 0.982, SEC = 0.518, SEP = 0.621, bias = 0.025 was developed for fresh fruit juices. The validationof developed calibration equations by cantaloupe, papaya, and peach fresh juices enhanced the applicability to other fruitjuices and confirmed the reliability of universality.