Abstract:

A nondestructive measurement model predicting quality of apple fruit was developed at room temperature by near infrared (NIR) spectroscopy. The effects of testing position and temperature on NIR model accuracy of evaluating apple qualities was studied, and the minimal quantity of samples used to compensate temperature fluctuations was discussed. Results showed that the accuracy of model constructed by averaging over spectra gained from two positions of each side (sun-expose side and shaded side) is the highest. One minus variance ratios of moisture and color model reach to 0.8274 and 0.8005, respectively. Samples of different temperatures (twenty percent of calibration sets) are needed to add in room temperature model to compensate temperature fluctuations. Hybrid calibration model accuracies of soluble solid content, moisture and color (°Hue) after temperature compensation are much higher than those of model at room temperature. Standard errors of the prediction of hybrid calibration model of soluble solid content, moisture and color are lower than those of model at room temperature by 15.52% to 29.77%, 13.68% to 31.68% and 45.9% to 88.46%, respectively.

Key words: apple, near infrared spectroscopy, testing position, temperature, quality