Effect of processing on polyphenols in butternut pumpkin (Cucurbita moschata)

Abstract

Pumpkin (Cucurbita moschata) is consumed worldwide with a diverse array of phytochemicals, including phenolics, that have therapeutic properties such as anti-inflammatory, antibacterial, antioxidant, and neuroprotective effects. Nevertheless, detailed information on polyphenol content in pumpkin processing is still limited. Therefore, the present work aimed to investigate the changes in polyphenol content and their antioxidant potential during pumpkin processing, followed by their comprehensive characterization and quantification using liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS) and high-performance liquid chromatography–photodiode array (HPLC-PDA). The antioxidant results showed that pumpkins’ seeds and skins (PSS) contained the highest total phenolic content (TPC, 0.39 mg gallic acid equivalent mg/g) and total antioxidant capacity (TAC, 0.35 mg ascorbic acid equivalent mg/g), respectively. However, separated pumpkin puree (SPP) had a higher total condensed tannins content (TCT, 0.15 mg catechin equivalent mg/g). The LC-ESI-QTOF-MS/MS tentatively identified a total of 23 phenolic compounds present in the five pumpkin samples. Through HPLC-PDA quantification, the most abundant phenolic compounds were epicatechin (6.645 μg/g) and catechin (6.146 μg/g) detected in PSS. The comprehensive characterization and quantification of phenolics in processed pumpkins indicate the importance of pumpkins as a promising source of polyphenols with antioxidant properties. This study provides supportive information on the utilization of pumpkin phenolics in the food, pharmacological, and nutraceutical industries.