Prediction of Soluble Solids and Lycopene Content of Processing Tomato Cultivars by Vis-NIR Spectroscopy

Abstract

Tomato-based products are significant components of vegetable consumption. The processing tomato industry is unquestionably in need of a rapid definition method for measuring soluble solids content (SSC) and lycopene content. The objective was to find the best chemometric method for the estimation of SSC and lycopene content from visible and near-infrared (Vis-NIR) absorbance and reflectance data so that they could be determined without the use of chemicals in the process. A total of 326 Vis-NIR absorbance and reflectance spectra and reference measurements were available to calibrate and validate prediction models. The obtained spectra can be manipulated using different preprocessing methods and multivariate data analysis techniques to develop prediction models for these two main quality attributes of tomato fruits. Eight different method combinations were compared in homogenized and intact fruit samples. For SSC prediction, the results showed that the best root mean squared error of cross-validation (RMSECV) originated from raw absorbance (0.58) data and with multiplicative scatter correction (MSC) (0.59) of intact fruit in Vis-NIR, and first derivatives of reflectance (R2 = 0.41) for homogenate in the short-wave infrared (SWIR) region. The best predictive ability for lycopene content of homogenate in the SWIR range (R2 = 0.47; RMSECV = 17.95 mg kg–1) was slightly lower than that of Vis-NIR (R2 = 0.68; 15.07 mg kg–1). This study reports the suitability of two Vis-NIR spectrometers, absorbance/reflectance spectra, preprocessing methods, and partial least square (PLS) regression to predict SSC and lycopene content of intact tomato fruit and its homogenate.

Daily Monitoring of Ripening Processes of a Tomato Using an Original Handheld Visible–Near-Infrared Spectrometer

“…In Vis-NIR spectroscopic measurements of tomatoes, several spectral analyses including chemometrics have been conducted to obtain good indicators having good correlations to contents of representative chemical components such as chlorophylls, carotenoids, lycopene, sugars, and soluble solids (Brix). [5][6][7][8][9][10][11][12][17][18][19][20][21][22]25 However, in this study, it is impossible to conduct conventional chemical analyses of the same mini tomato sample at the different ripening stages. Therefore, the absolute contents of chemical components cannot be evaluated.…”

“…[1][2][3][4] Nondestructive Vis-NIR spectroscopy with color measurements has been conducted to evaluate the lycopene contents and soluble solid contents (Brix). 5,8,9,11 However, quantitative changes of chemical components with small time intervals were lacking. Therefore, the present study provides the detailed daily changes of chlorophyll, lycopene, and carotenoids and their relations to color values.…”

“…Near-infrared (NIR) spectroscopy has also been performed for fruits/vegetable ripening processes, especially for evaluating water and soluble solids such as sugars. 10,11 For tomatoes, the Vis-NIR region was analyzed by chemometrics to evaluate the contents of chemical components with their sensory qualities, 12 and soluble solids and lycopene. 11 However, for farmers working at cultivation sites, the decision of harvesting and shipping of fruits and vegetables needs detailed data on quantitative daily changes of main chemical components in response to different ripening stages.…”

“…10,11 For tomatoes, the Vis-NIR region was analyzed by chemometrics to evaluate the contents of chemical components with their sensory qualities, 12 and soluble solids and lycopene. 11 However, for farmers working at cultivation sites, the decision of harvesting and shipping of fruits and vegetables needs detailed data on quantitative daily changes of main chemical components in response to different ripening stages. Conventional analytical chemical methods are timeconsuming and cannot be applied to the same samples.…”

“…Near-infrared (NIR) spectroscopy has also been performed for fruits/vegetable ripening processes, especially for evaluating water and soluble solids such as sugars. 10,11 For tomatoes, the Vis-NIR region was analyzed by chemometrics to evaluate the contents of chemical components with their sensory qualities, 12 and soluble solids and lycopene. 11…”