Abstract:

In order to quest an approach to measure sugar content of kiwifruit rapidly and nondestructively, wavelet denoising was used to preprocess the near infrared (NIR) spectra (1000 to 2500 nm) of kiwifruit. Partial least square (PLS), interval partial least square (iPLS) and synergy interval partial least square (siPLS) methods were used to establish the calibration models of sugar content. Experimental results showed that the optimal siPLS model is obtained with 16 intervals and the optimal combinations of intervals are number 9, 11 and 13. The model is achieved with correlation coefficient 0.9414 and root mean square error of cross validation (RMSECV) 0.3788 in calibration set and correlation coefficient 0.9295 and RMSEP 0.3904 in prediction set, and its factor number is 7. This study demonstrated that NIR spectroscopy with siPLS model could not only diminish run time and select the optimal intervals, but also improve precision.

Key words: NIR spectroscopy, kiwifruit, sugar content, synergy interval partial least square