Quality Prediction of Kiwifruit Based on Near Infrared Spectroscopy

Abstract

To establish the standard of ripe kiwifruit sorting, near infrared (NIR) spectroscopy was performed on kiwifruit sampled from three farms. Destructive measurements of flesh firmness, soluble solids content (SSC), and acidity were performed and compared to measurement using NIR reflectance spectrums from 408 to 2,492 nm. NIR predictions of those quality factors were calculated using the modified partial least square regression method. Flesh firmness was predicted with a standard error of prediction (SEP) of 3.32 N and with a correlation coefficient (<TEX>$R^2$</TEX>) of 0.88. SSC was predicted with SEP of <TEX>$0.49^{\circ}Brix$</TEX> and with <TEX>$R^2$</TEX> of 0.98. Acidity was predicted with SEP of 0.28% and with <TEX>$R^2$</TEX> of 0.91. Kiwifruit ripened at <TEX>$20^{\circ}C$</TEX> for 15 days showed uneven qualities with normal distribution. Considering the SEP of each parameter, kiwifruit after ripening treatment could be non-destructively predicted their qualities and sorted by flesh firmness or soluble solids content through NIR prediction.