Time-resolved reflectance spectroscopy (TRS), allows for the complete optical characterization (in terms of the absorption and scattering coefficients) of diffusive media such as fruit, in the spectral range 600-1100 nm, probing a volume to a depth of about 2 cm. The hypothesis was made that the absorption coefficient at 670 nm (mu(a)), near the chlorophyll peak, could be an index of fruit maturity at harvest. The aim of this research was to model nectarine softening for fruit of different maturity at harvest, as assessed by mu(a). Nectarine fruit of two sizes (A and B) were picked in 2002, 2003 (cv 'Spring Bright') and 2004 (cv 'Ambra'), measured by TRS at harvest on two opposite sides and ranked by decreasing mu(a) averaged per fruit (increasing maturity). Fruit were stored at 0 degrees C for 3, 10 and 6 days, then at 20 degrees C for 79, 120 and 117 h in 2002. 2003 and 2004, respectively. Firmness was measured by pressure test (8 mm tip) during shelf life, on two sides of each fruit, and then averaged. Softening at 20 degrees C followed a logistic model as a function of mu(a) at harvest and of time at 20 degrees C (adjusted R-2 = 0.85 in 'Spring Bright' and 0.75 in 'Ambra'). The effects of fruit size and cold storage were negligible. The absorption coefficient mu(a) explained 13-34% of the variation of firmness. Fruit with different mu(a) at harvest softened with the same sigmoidal pattern in time, which was shifted earlier in low mu(a) fruit and later in high mu(a) fruit. mu(a) accounted for the time shift in softening of individual fruit within the same batch. The value of mu(a) can be regarded as an index of the biological age of fruit. By using this model, it is possible to predict individual fruit softening rates at 20 degrees C. (c) 2005 Elsevier B.V. All rights reserved.
A model for the softening of nectarines based on sorting fruit at harvest by time-resolved reflectance spectroscopy
Cubeddu R;Pifferi A;Spinelli L;
2006
Abstract
Time-resolved reflectance spectroscopy (TRS), allows for the complete optical characterization (in terms of the absorption and scattering coefficients) of diffusive media such as fruit, in the spectral range 600-1100 nm, probing a volume to a depth of about 2 cm. The hypothesis was made that the absorption coefficient at 670 nm (mu(a)), near the chlorophyll peak, could be an index of fruit maturity at harvest. The aim of this research was to model nectarine softening for fruit of different maturity at harvest, as assessed by mu(a). Nectarine fruit of two sizes (A and B) were picked in 2002, 2003 (cv 'Spring Bright') and 2004 (cv 'Ambra'), measured by TRS at harvest on two opposite sides and ranked by decreasing mu(a) averaged per fruit (increasing maturity). Fruit were stored at 0 degrees C for 3, 10 and 6 days, then at 20 degrees C for 79, 120 and 117 h in 2002. 2003 and 2004, respectively. Firmness was measured by pressure test (8 mm tip) during shelf life, on two sides of each fruit, and then averaged. Softening at 20 degrees C followed a logistic model as a function of mu(a) at harvest and of time at 20 degrees C (adjusted R-2 = 0.85 in 'Spring Bright' and 0.75 in 'Ambra'). The effects of fruit size and cold storage were negligible. The absorption coefficient mu(a) explained 13-34% of the variation of firmness. Fruit with different mu(a) at harvest softened with the same sigmoidal pattern in time, which was shifted earlier in low mu(a) fruit and later in high mu(a) fruit. mu(a) accounted for the time shift in softening of individual fruit within the same batch. The value of mu(a) can be regarded as an index of the biological age of fruit. By using this model, it is possible to predict individual fruit softening rates at 20 degrees C. (c) 2005 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
