Rapid profiling of tomatoes using infrared spectroscopy and chemometerics

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Tomatoes are the second most produced and consumed vegetable in the United States according to the USDA. The value of tomato production in the US totals over $2 billion since 2005. Current methods to analyze sugars and carotenoids in tomatoes are time and labor intensive and utilize harmful solvents making efficient assays for detection and quantification desirable. Our objective was to develop simple accurate and economical protocols to determine sugars and carotenoids by Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy and multivariate analysis. Samples were obtained from genetically diverse tomato varieties that encompassed commercial hybrids and elite parents used in tomato processing and fresh market industry. Fresh tomatoes were blended, aliquots (5 mL) centrifuged and infrared spectra collected using ATR-IR microspectroscopy from vacuum dried supernatant or paste applied directly to a handheld IR. Reference methods included HPLC for carotenoids and enzymatic kits for sugars. Partial least squares regression (PLSR) was used to create calibration models that correlated the chemical components in tomatoes with infrared spectra. Multivariate models accurately predicted sugars (glucose, fructose), using the supernatant with R-values > 0.94 and SECV <0.02 g/100g using the infrared region of 1200-900cm-1. By using infrared spectra collected from tomato paste, PLSR models predicted carotenoids content with R-value >0.95 and SECV of 0.5 for lycopene. ATR-IR could provide the tomato industry with a simple and high throughput method for chemical profiling of tomatoes that could lead to improved varieties with enhanced characteristics for industry and consumer demands.



Tomatoes, Infrared