Pulsed electric field processing of green tea-infused chardonnay wine: Effects on physicochemical properties, antioxidant activities, phenolic and volatile compounds

Pulsed electric field (PEF) was used to develop a novel Chardonnay wine infused with green tea, where the physicochemical characteristics (pH, titratable acidity, color) were modulated. The PEF processing conditions were optimized via response surface methodology by evaluating antioxidant activity (assessed by DPPH, FRAP and ABTS assays), total free phenolic content (TPC), total free flavonoid content (TFC), and volatile content. The optimum conditions were determined as electric field strength 1.3 kV/cm and pulse number 10. The PEF-processed green tea-infused wines were also analyzed for the phenolic and volatile profiles. A total of 178 phenolics and non-phenolics were identified by HPLC-DAD-ESI-QTOF-MS/MS in the PEF-treated wines. The application of PEF resulted in additional 20 phenolic compounds and 14 non-phenolic compounds absent in either Chardonnay or green tea. Catechin was the most abundant phenolic compound, while the enhanced antioxidant power was mainly driven by epigallocatechin. There were 49 volatiles detected by HS-SPME-GC-MS in the PEF-treated wines, with 15 volatiles as odor-active compounds. Under both artificial saliva spiked and non-spiked conditions, green tea infusion diminished fruity, floral and spicy odors, and intensified citrus and green odors. The PEF treatment (0.1 and 0.5 kV/cm) could impart more intense citrus and green aromas from tea to wine. Saliva addition decreased the release of volatile acids, alcohols, esters and aldehydes, and increased the release of benzenoids and terpenes. This study forecasted a promising future of PEF as a time and energy efficient technique in the production of flavored wine with enhanced functionalities and desired aromas.