Pectic composition, optical properties measured by time-resolved reflectance spectroscopy and quality in 'Jonagored' apples

'Jonagored' apples, picked on 30 August and 13 September 2002, were measured by TRS at 630 nm for absorption coefficient (μ a 630) and at 750 nm for transport scattering coefficient (μ s '750) and stored for six months in NA or CA in order to study the relationships among TRS optical properties, quality and pectic composition. Apples were analysed for fruit mass, skin color, firmness, soluble solids (SS), titratable acidity, relative internal space volume (RISV) and pectic substances. All data were processed by Principal Component Analysis. Both at harvest and after storage, μ a 630 was associated with colour characteristics, while μ s '750 was associated with RISV and firmness at harvest and with firmness and SS at the end of storage. Furthermore, μ s '750 was inversely related to oxalate fraction and residual insoluble pectin (RI) at harvest and to protopectin index, RI and firmness after storage. Our results confirmed that, using the absorption coefficient, fruits with different maturity degrees could be separated, and suggested that the transport scattering coefficient is more related to fruit structure and texture, especially to pectin composition.

[1]  J. V. Buren,et al.  Function of Pectin in Plant Tissue Structure and Firmness , 1991 .

[2]  P. Zerbini,et al.  A model for the softening of nectarines based on sorting fruit at harvest by time-resolved reflectance spectroscopy , 2006 .

[3]  Alessandro Torricelli,et al.  Time-Resolved Reflectance Spectroscopy as a Non Destructive Tool to Assess the Maturity at Harvest and to Model the Softening of Nectarines , 2004 .

[4]  Prodotti Agricoli,et al.  CHANGES IN SUGAR AND ACID COMPOSITION OF 'AMBRA' NECTARINES DURING SHELF LIFE BASED ON NON-DESTRUCTIVE ASSESSMENT OF MATURITY BY TIME-RESOLVED REFLECTANCE SPECTROSCOPY , 2006 .

[5]  Alessandro Torricelli,et al.  The quality and storability of apples cv. 'Jonagored' selected at- harvest by time-resolved reflectance spectroscopy , 2004 .

[6]  D. Torreggiani,et al.  Research into changes of pectic substances in apricots and peaches processed by osmotic dehydration , 1986 .

[7]  Alessandro Torricelli,et al.  Selection Models for the Internal Quality of Fruit, based on Time Domain Laser Reflectance Spectroscopy , 2004 .

[8]  H. Baumann,et al.  INTERCELLULAR SPACE VOLUME OF FRUIT , 1983 .

[9]  A. Polesello,et al.  A preliminary characterization of some pectins from quince fruit (Cydonia oblonga Mill.) and prickly pear (Opuntia ficus indica) peel , 1994 .

[10]  R. Cubeddu,et al.  Nondestructive quantification of chemical and physical properties of fruits by time-resolved reflectance spectroscopy in the wavelength range 650-1000 nm. , 2001, Applied optics.

[11]  Alessandro Torricelli,et al.  Time-Resolved Reflectance Spectroscopy , 2006 .