The interest in antioxidant compounds like lycopene and β-carotene has significantly increased over the past few years. The red flesh of watermelons is a great source of them, and of lycopene in particular.
Mini-watermelons were used due to their high carotenoid content, small size (100-150 mm diameter) and very thin rind (<0,5 mm). The research was commissioned by "La Diamantina" PO and led to an industrial patented deposited with the Ministry of Economic Development. The research was successfully applied to "Cuore Dolce" mini-watermelons.
800 spectra collected from 100 samples were used to calibrate the reading between 900-1700 nm. Calibration models were performed using partial least square (PLS) regression on pre-treated spectra with the following intervals: 2.65-151.75 mg/kg for lycopene, 0.19-9.39 mg/kg for β-carotene and 3.5-13.7% for total soluble solids. PLS models showed a good predictive capacity to assess lycopene, β-carotene and total soluble solid contents with R2 > 0,8.
"The method developed was used to predict carotenoid and total soluble solid concentration in fruit in real time. NIR tools have already been successfully implemented both in fields and on processing lines."
"Implementing NIR systems on watermelon post-harvesting processing lines represent a step forward to improve product quality, help producers promote the nutritional value of their fruit and increase consumer awareness."
Source: Elena Tamburini, Stefania Costa, Irene Rugiero, Paola Pedrini, Maria Gabriella Marchetti, 'Quantification of Lycopene, β-Carotene, and Total Soluble Solids in Intact Red-Flesh Watermelon (Citrullus lanatus) Using On-Line Near-Infrared Spectroscopy', 2017, Sensors, 17(4), 746; doi:10.3390/s17040746.