Abstract
Near infrared spectroscopy (NIRS) is being practically used for measuring sugar and acid contents in intact fruits because NIRS has advantages of easy handling, and quick and nondestructive measurement. However, NIRS involves many problems which should be considered. Regarding samples for calibration and validation, there are many factors affecting the measurement accuracy such as variety, producing place, harvesting season and year, maturity level, sample temperature, and the distribution of constituents interested. To make a robust calibration equation, proper selection of samples for calibration and validation, and suitable wavelength selection should be needed. As for sample selection, calibration samples should be representative of samples which will be measured in the future. As for wavelength selection, the main wavelength of the calibration equation should be absorption band of constituents interested. It is also important to clarify the measurement accuracy needed for practical use.
