Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2001
Publication Date: 9/1/2001
Citation: LU, R. PREDICTING FIRMNESS AND SUGAR CONTENT OF SWEET CHERRIES USING NEAR-INFRARED DIFFUSE REFLECTANCE SPECTROSCOPY. TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. 2001. v. 44(5). p. 1265-1271. Interpretive Summary: The U.S. fruit industry needs technologies that can enhance and/or insure the postharvest quality of fresh fruit and increase its competitiveness in both domestic and international markets. Firmness and sugar content are two important fruit traits that not only determine the overall quality and consumer acceptance of sweet cherries, but also influence their shelf life and susceptibility to bruising and the subsequent pathogenic invasion by pathogens. Currently, no technologies are available for grading or sorting sweet cherries based on firmness or sugar content. Experiments were conducted that investigated the potential of a light-based sensing technique, namely near-infrared (NIR) diffuse reflectance, for nondestructive measurement of the firmness and sugar content of sweet cherries. We found that the proposed NIR technique gave good predictions of the firmness and sugar content of intact sweet cherries. The NIR technique and mathematical methods developed in this study can be used to grade or sort sweet cherries into different classes of firmness and sweetness. The findings of this research are important to the development of new sensing technology, which will allow the fruit industry to sort individual cherries based on their internal quality, thus increasing its competitiveness and profitability. Consumers will also benefit from this research because there will be an assurance of consistent, superior quality fruit for them to purchase.
Technical Abstract: The objective of this research was to study the potential of near-infrared (NIR) reflectance spectroscopy as a means for nondestructive measurement of the firmness and sugar content of sweet cherries. NIR spectral data were collected from 'Hedelfinger' and 'Sam' sweet cherries in the spectral region between 800 nm and 1700 nm. Statistical models were developed using the partial least square method to predict the firmness and sugar content of sweet cherries. The models gave relatively good predictions of the firmness of both 'Hedelfinger' and 'Sam' cherries with the corresponding r- values being 0.80 and 0.65 and the standard errors of prediction (SEP) of 0.55 N and 0.44 N. The NIR models gave excellent predictions of the sugar content of the sweet cherries, with the SEP of 0.71 deg and 0.65 deg Brix for Hedelfinger and Sam, respectively. NIR reflectance spectroscopy can be used to predict the firmness and sugar content of sweet cherries.