Submitted to: Apple Research Review
Publication Type: Other
Publication Acceptance Date: January 22, 2007
Publication Date: January 22, 2007
Citation: Lu, R. 2007. Hyperspectral reflectance and fluorescence for assessing apple maturity. In: Apple Research Review. 2007 Washington Tree Fruit Research Commission Annual Research Review, January 23, 2007, Wenatchee, Washington. p. 80-88. Technical Abstract: Apple maturity encompasses multiple quality attributes, including skin and flesh color, flesh firmness, soluble solids, starch, acid, and ethylene production. Nondestructive measurement of these quality attributes is needed for better determining optimal harvest time and implementing appropriate postharvest handling and storage practices. Visible and near-infrared reflectance and fluorescence are two different techniques that are promising for measuring selected fruit quality attributes. We investigated both reflectance and fluorescence for measuring multiple maturity attributes of freshly-harvested apples and proposed an integrated method for better measurement of apple maturity. This report summarizes the results from the two-and-one-half year research on using reflectance, fluorescence, and the integrated data to measure fruit maturity. Overall, reflectance (or interactance) is better than fluorescence in measuring individual quality attributes. The integration of reflectance (or interactance) and fluorescence led to improved results for measuring fruit maturity parameters, especially for firmness, starch and acid. The integrated technique resulted in good to excellent results for the measurement of fruit skin and flesh color, soluble solids content, firmness, and starch. The integrated technique provided more consistent and accurate measurement of fruit maturity. A prototype was designed and assembled using miniature spectrometer, which could facilitate further development of a portable device for field applications.