Infrared Spectroscopy Analysis
Mid-infrared spectra were collected at room temperature (20±5°C) for each tomato juice sample using a portable Fourier Transform Mid-infrared (FT-IR) spectrometer Cary 630 (Agilent Technologies Inc., Santa Clara, CA) equipped with a dial-path transmittance accessory at 50 μm path length. The unit was coupled with a Zinc Selenide (ZnSe) beam splitter and a deuterated triglycine sulfate (DTGS) detector. Spectra were collected between 4000 and 700 cm-1 with a resolution of 4 cm-1. Interferograms of 64 scans were co-added during each spectrum collection to improve the signal to noise ratio. A background spectrum was acquired before measuring each sample to account for environmental variations. Spectra were collected by applying approximately 50 μL of tomato juice directly on the crystal and ensuring a full coverage of the crystal with the sample. After each sample spectrum collection, the crystal was wiped, cleaned with 70% ethanol and dried using a 100% cotton cloth. Duplicate independent spectral measurements were taken for each sample and the collected spectra were recorded using Agilent MicroLab PC software (Agilent Technologies Inc., Danbury, CT, USA