ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Reflectance spectral features and non-destructive estimation of chlorophyll, carotenoid and anthocyanin content in apple fruit

Mark N. Merzlyak, Alexei E. Solovchenko and Anatoly A. Gitelson

Postharvest Biology and Technology Volume 27, Issue 2 , February 2003, Pages 197-211

2003

บทคัดย่อ

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 (R₅₅₀) and 700 nm (R₇₀₀) has been found (r²>0.95). In fruit with chlorophyll content more than 5 nmol/cm², 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, R₈₀₀/R₇₀₀ and R₈₀₀/R₆₄₀, were directly proportional to total chlorophyll content ranging from 0.4 to 11 nmol/cm² (r²>0.93). The reflectance in the band 520–530 nm was found to be dependent mostly o­n carotenoids absorption. The index R₈₀₀(1/R₅₂₀-1/R₇₀₀) was suggested for estimation of carotenoid content in the range 0.6–4.5 nmol/cm². The index for assessment of a carotenoid/chlorophyll ratio was proposed in the form, (R₄₈₀- R₆₇₈)/R₈₀₀. Reflectance in the green region of the spectrum proved to be sensitive to anthocyanin content. The index R₈₀₀(1/R₅₅₀- 1/R₇₀₀) was developed to estimate anthocyanin content in peel ranging from 2.5 to 50 nmol/cm²; the determination coefficient of the index with anthocyanin content was higher than 0.93.