Laser light backscattering to monitor moisture content, soluble solid content and hardness of apple tissue during drying

Abstract Continuous monitoring of food properties during drying is of stark relevance for the food processing industry. The main task of this research is to apply laser backscattering technology to simultaneously predict variations in hardness, moisture content and soluble solids content (SSC) of apples during drying. A laser diode with a wavelength of 635 nm was used to non-destructively analyze photon migration in the apple tissue. The backscattering area in pixel numbers, representing the illuminated area after laser light injection, and light luminescence measured by grey values were used for estimating changes in internal quality parameters during drying. A decrease in moisture content caused a reduction in photon scattering determined by diminished light propagation in the fruit tissue. Additionally, scattering images showed less photon migration as the SSC increased due to the light absorption of light at 635 nm by fruit compounds. To estimate moisture content, calibration models gave the highest coefficients of determination ( R 2  = 0.8 and 0.89) with standard errors of cross validation (SECV) of 11.6 and 9.8 for backscattering area and light luminescence, respectively. However, predictions obtained for SSC were slightly lower. Laser light measurement at 635 nm was found to be adequate for predicting changes in moisture content and SSC of apple during drying over different stages. On the contrary, photon scattering at 635 nm is not recommended as estimator of change in hardness during apple drying, based on the results.

[1]  Jianwei Qin,et al.  Monte Carlo simulation for quantification of light transport features in apples , 2009 .

[2]  R. Lu,et al.  Analysis of spatially resolved hyperspectral scattering images for assessing apple fruit firmness and soluble solids content , 2008 .

[3]  José Miguel Aguilera,et al.  Drying and Dried Products Under the Microscope , 2003 .

[4]  P Jancsók,et al.  Preliminary study on the influence of turgor pressure on body reflectance of red laser light as a ripeness indicator for apples , 1999 .

[5]  Renfu Lu,et al.  A NEAR–INFRARED SENSING TECHNIQUE FOR MEASURING INTERNAL QUALITY OF APPLE FRUIT , 2002 .

[6]  Yande Liu,et al.  Nondestructive determination of pear internal quality indices by visible and near-infrared spectrometry , 2008 .

[7]  Yankun Peng,et al.  Prediction of apple fruit firmness and soluble solids content using characteristics of multispectral scattering images , 2007 .

[8]  Manuela Zude,et al.  Non-destructive analyses of apple quality parameters by means of laser-induced light backscattering imaging , 2008 .

[9]  Wahbi Jomaa,et al.  Shrinkage and density evolution during drying of tropical fruits: application to banana , 2004 .

[10]  Klaus Gottschalk,et al.  An Approach for Monitoring the Moisture Content Changes of Drying Banana Slices with Laser Light Backscattering Imaging , 2008 .

[11]  Gerald S. Birth,et al.  THE LIGHT SCATTERING PROPERTIES OF FOODS , 1978 .

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

[13]  R. Lu.  Multispectral imaging for predicting firmness and soluble solids content of apple fruit , 2004 .

[14]  Manuela Zude,et al.  Analysis of Laser Light Migration in Apple Tissue by Monte Carlo Simulation , 2008 .

[15]  Manuela Zude,et al.  Predicting soluble solid content and firmness in apple fruit by means of laser light backscattering image analysis , 2007 .

[16]  Tormod Næs,et al.  A user-friendly guide to multivariate calibration and classification , 2002 .

[17]  Yan Bai,et al.  Structural changes in apple rings during convection air-drying with controlled temperature and humidity. , 2002, Journal of agricultural and food chemistry.

[18]  Marvin R Paulsen,et al.  Optical methods for nondestructive quality evaluation of agricultural and biological materials , 1985 .

[19]  Emanuele Cerruto,et al.  Influence of colour changes and moisture content during banana drying on laser backscattering , 2010 .

[20]  Piotr P. Lewicki,et al.  Effect of hot air temperature on mechanical properties of dried apples , 2004 .

[21]  Jianwei Qin,et al.  Measurement of the Optical Properties of Apples Using Hyperspectral Diffuse Reflectance Imaging , 2006 .

[22]  Zacharias B. Maroulis,et al.  The effect of the method of drying on the colour of dehydrated products , 2001 .

[23]  Alessandro Torricelli,et al.  Approach for non-destructive pigment analysis in model liquids and carrots by means of time-of-flight and multi-wavelength remittance readings. , 2008, Analytica chimica acta.

[24]  L. Rodriguez-Saona,et al.  Application of NIR and MIR spectroscopy in quality control of potato chips. , 2009 .

[25]  Yibin Ying,et al.  FOURIER TRANSFORM NEAR-INFRARED DETERMINATION OF TOTAL SOLUBLE SOLIDS AND AVAILABLE ACID IN INTACT PEACHES , 2005 .

[26]  B. Nicolai,et al.  Postharvest quality of apple predicted by NIR-spectroscopy: Study of the effect of biological variability on spectra and model performance , 2010 .

[27]  R. Lu,et al.  Hyperspectral Scattering for assessing Peach Fruit Firmness , 2006 .

[28]  Manuela Zude.  Non-destructive prediction of banana fruit quality using VIS/NIR spectroscopy , 2003 .