Total and individual carotenoids and phenolic acids content in fresh, refrigerated and processed spinach (Spinacia oleracea L.)

The carotenoid and phenolic acid contents in fresh, stored and processed (blanched, frozen and boiled) spinach were comparatively determined by spectrophotometric and HPLC analyses. The major carotenoids identified after HPLC analysis in saponified samples were lutein (37–53 μg/kg), β-carotene (18–31 μg/kg), violaxanthin (9–23 μg/kg) and neoxanthin (10–22 μg/kg). These carotenoids were all affected by storage and/or heating. The content of carotenoids was best preserved after storage for one day at 4 °C.The total phenolic content in the fresh spinach was 2088 mg GAE/kg FW. After LC–MS analysis three phenolic acids were identified and quantified. These being ortho-coumaric acid (28–60 mg/kg FW), ferulic acid (10–35 mg/kg) and para-coumaric acid (1–30 mg/kg) depending on the sample type. After storage of spinach at different temperatures (4 °C or −18 °C) the amount of total phenolic compounds decreased by around 20%, while the amount of individual phenolic acids increased by four times on average.