Reflectance spectral features and non-destructive estimation of chlorophyll, carotenoid and anthocyanin content in apple fruit Mark N. Merzlyak a , Alexei E. Solovchenko a , Anatoly A. Gitelson b,  a Department of Cell Physiology and Immunology, Faculty of Biology, Moscow State University, 119899 GSP, Moscow W-234, Russia b CALMIT, School of Natural Resource Sciences, University of Nebraska-Lincoln, 113 Nebraska Hall, Lincoln, NE 68588-0517, USA Received 28 August 2001; accepted 5 May 2002 Abstract Fruit reflectance spectra of five apple (Malus domestica Borkh.) cultivars (Zhigulevskoe, Antonovka, Granny Smith, Golden Delicious and Renet Simirenko) with a wide range of peel pigment (chlorophylls a and b , carotenoids and anthocyanins) content have been studied to develop non-destructive techniques for pigment assessment. In addition to chlorophylls, positions of in vivo absorption maxima were established for carotenoids (480, 455 and a shoulder at 425 nm) and for anthocyanins (near 550 nm). In anthocyanin-free fruit, a close relationship between reflectance at 550 nm (R 550 ) and 700 nm (R 700 ) has been found (r 2 /0.95). In fruit with chlorophyll content more than 5 nmol/cm 2 , the reflectance near 678 nm was insensitive to a variation in chlorophylls, whereas, reflectance in the bands 550  /650 nm and 690  /705 nm remained sensitive to chlorophyll content in a wide range of its variation. The reflectance ratios, R 800 / R 700 and R 800 /R 640 , were directly proportional to total chlorophyll content ranging from 0.4 to 11 nmol/cm 2 (r 2 /0.93). The reflectance in the band 520  /530 nm was found to be dependent mostly on carotenoids absorption. The index R 800 (1/R 520  /1/R 700 ) was suggested for estimation of carotenoid content in the range 0.6  /4.5 nmol/cm 2 . The index for assessment of a carotenoid/chlorophyll ratio was proposed in the form, (R 480  /R 678 )/R 800 . Reflectance in the green region of the spectrum proved to be sensitive to anthocyanin content. The index R 800 (1/R 550  /1/R 700 ) was developed to estimate anthocyanin content in peel ranging from 2.5 to 50 nmol/cm 2 ; the determination coefficient of the index with anthocyanin content was higher than 0.93. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Anthocyanins; Apple fruit; Carotenoids; Chlorophyll; Non-destructive determination; Reflectance 1. Introduction The content of chlorophylls, carotenoids and anthocyanins as well as their proportions deter- mine fruit color and appearance (Saure, 1990; Abbott, 1999) and serve as markers of quality. Pigment changes occur during ripening, storage and as a result of various stresses (Knee, 1972, 1988; Chuma et al., 1981; Merzlyak et al., 1997, 1999; Abbott, 1999; Merzlyak and Chivkunova, 2000; Merzlyak et al., 2002). The pigments in fruit fulfil several important roles. In apples, peel  Corresponding author. Tel.:  /1-402-472-8386; fax:  /1- 402-472-4608 E-mail address: gitelson@calmit.unl.edu (A.A. Gitelson). Postharvest Biology and Technology 27 (2003) 197  /211 www.elsevier.com/locate/postharvbio 0925-5214/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0925-5214(02)00066-2