Submitted to: Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: June 23, 2001
Publication Date: N/A
Technical Abstract: Firmness and sugar content are two important quality attributes that not only determine the consumer acceptance and shelf life of sweet cherries but also influence their susceptibility to bruising pathogenic invasion by pathogens. 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 diffuse reflectance data were collected from 'Hedelfinger' and 'Sam' sweet cherry varieties in the spectral region between 800 and 1700 nm. The firmness and sugar content of cherry fruit were measured using the standard compression and Brix refractometry methods. Calibration models were developed using the partial least square (PLS) method for both cherry varieties. Results showed that firm cherries had a higher reflectance (or lower absorption) than the softer ones over the entire spectral region. Between the 800 and 1400 nm spectral region, cherries with high sugar contents had a higher absorption than those with a lower sugar content. With the PLS models, good predictions of the firmness of the two cherry cultivars resulted with r values of 0.80 and 0.65 and standard errors of prediction of 0.55 N and 0.44 N for 'Hedelfinger' and 'Sam', respectively. The PLS models gave excellent predictions of the sugar content of the sweet cherries, with r=0.95 and 0.89, and SEP=0.71 and 0.65 Brix for 'Hedelfinger' and 'Sam', respectively. This research showed that NIR reflectance spectroscopy is useful to predict the firmness and sugar content of sweet cherries. A nondestructive grading system based on NIR reflectance spectroscopy can be developed, which would allow sweet cherries to be sorted into different firmness and sweetness classes.