Internal quality evaluation of apples using spectral absorption and scattering properties

The objective of this research was to measure the absorption and reduced scattering coefficients (μa and μs', respectively) of apples via a spatially-resolved hyperspectral imaging technique and relate them to fruit firmness and soluble solids content (SSC). Spatially-resolved hyperspectral images were acquired from 600 'Golden Delicious' apples, and values for μa and μs' were determined using an inverse algorithm to fit the diffusion theory model to the spectral scattering profiles over 500-1000 nm. There were two predominant peaks in the absorption spectra around 675 nm and 970 nm due to the presence of chlorophyll and water in the fruit, respectively. Spectra of μs' decreased monotonically with the increasing wavelength. Both μa and μs' were correlated with fruit firmness, with the correlation coefficient (r) of 0.82 and 0.80, respectively. Values of μa were also correlated with the SSC with r = 0.70. The combined data of μa and μs' were able to predict fruit firmness with r = 0.88 and the standard error of prediction (SEP) of 5.66 N, and SSC with r = 0.82 and SEP = 0.75%. This research demonstrated the potential of using spectral absorption and scattering properties to evaluate internal quality attributes of horticultural products.

[1]  E. Berg,et al.  Characterizing beef muscles with optical scattering and absorption coefficients in VIS-NIR region. , 2007, Meat science.

[2]  Tuan Vo-Dinh,et al.  Biomedical Photonics Handbook , 2003 .

[3]  B. Wilson,et al.  Time resolved reflectance and transmittance for the non-invasive measurement of tissue optical properties. , 1989, Applied optics.

[4]  V. Mcglone,et al.  Vis/NIR estimation at harvest of pre- and post-storage quality indices for 'Royal Gala' apple , 2002 .

[5]  Renfu Lu,et al.  Nondestructive measurement of firmness and soluble solids content for apple fruit using hyperspectral scattering images , 2007 .

[6]  B. Wilson,et al.  Frequency-domain reflectance for the determination of the scattering and absorption properties of tissue. , 1991, Applied optics.

[7]  Renfu Lu,et al.  NIR Measurement of Apple Fruit Soluble Solids Content and Firmness as Affected by Postharvest Storage , 2005 .

[8]  Jianwei Qin,et al.  Measurement of the Absorption and Scattering Properties of Turbid Liquid Foods Using Hyperspectral Imaging , 2007, Applied spectroscopy.

[9]  A. Gitelson,et al.  Reflectance spectral features and non-destructive estimation of chlorophyll, carotenoid and anthocyanin content in apple fruit , 2003 .

[10]  B. Wilson,et al.  A diffusion theory model of spatially resolved, steady-state diffuse reflectance for the noninvasive determination of tissue optical properties in vivo. , 1992, Medical physics.

[11]  V. Tuchin.  Tissue Optics: Light Scattering Methods and Instruments for Medical Diagnosis , 2000 .

[12]  Renfu Lu,et al.  AN LCTF-BASED MULTISPECTRAL IMAGING SYSTEM FOR ESTIMATION OF APPLE FRUIT FIRMNESS: PART II. SELECTION OF OPTIMAL WAVELENGTHS AND DEVELOPMENT OF PREDICTION MODELS , 2006 .

[13]  Randolph M. Beaudry,et al.  Determination of firmness and sugar content of apples using near-infrared diffuse reflectance , 2000 .

[14]  R. Steiner,et al.  Spatially resolved absolute diffuse reflectance measurements for noninvasive determination of the optical scattering and absorption coefficients of biological tissue. , 1996, Applied optics.

[15]  Yankun Peng,et al.  Measurement of the Optical Properties of Apples by Hyperspectral Imaging for Assessing Fruit Quality , 2006 .

[16]  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.

[17]  Alessandro Torricelli,et al.  Time-Resolved Reflectance Spectroscopy Applied to the Nondestructive Monitoring of the Internal Optical Properties in Apples , 2001 .

[18]  Yud-Ren Chen,et al.  Hyperspectral imaging for safety inspection of food and agricultural products , 1999, Other Conferences.

[19]  J. Abbott,et al.  NEAR-INFRARED DIFFUSE REFLECTANCE FOR QUANTITATIVE AND QUALITATIVE MEASUREMENT OF SOLUBLE SOLIDS AND FIRMNESS OF DELICIOUS AND GALA APPLES , 2003 .