Visible/Near Infrared Spectroscopic Method for the Prediction of Lycopene in Tomato (Lycopersicon esculentum, Mill.) Fruits

Abstract

The aim of the present study was to predict the potential of visible and near infrared (Vis/NIR) Spectroscopy in estimating the amount of lycopene in intact tomato. Eight tomato varieties from loose and cluster type were selected and harvested at commercial ripening stage for the study. The tomato cultivars were prepared after 3 days storage at 18°C and 80% Relative Humidity (RH) before they were subjected to visible and near
infrared (Vis/NIR) spectroscopy measurements. For the visible and near infrared (Vis/NIR) spectroscopy measurements four tomato fruits from each variety were prepared as appropriate by separating of clusters,  removal of attached stems and assigning a number to each of the tomato fruits. Accordingly, the spectral measurements were done on intact tomato fruits. The visible and near infrared (Vis/NIR) spectroscopy combined with
multivariate calibration method such as principal component analysis (PCA) and partial least-squares (PLS) has showed a reasonable prediction performance. The established PLS model at full spectral range (380 –  1700 nm) was with correlation coefficient (r) =0.90 and standard error of prediction (SEP) = 0.65 mg/100g for lycopene. However, the best model for prediction was obtained when the spectral range was limited to the visible range (380 – 950 nm), correlation coefficient (r) = 0.92 and  standard error of prediction (SEP) = 0.58 mg/100g. Although HPLC is the most accepted method of analysis, Vis/NIR spectroscopy measurement combined with multivariate techniques has the potential to estimate  lycopene in intact tomato fruits.