Effects of pulsed electric fields on bioactive components, colour and flavour of green tea infusions

Abstract

SummaryGreen tea is an unfermented tea containing a higher quantity of bioactive components. In this paper, the effects of pulsed electric field (PEF) treatments on the bioactive components (polyphenols, catechins and free amino acids), colour and flavour of green tea infusions were studied. PEF as a promising non‐thermal sterilisation technology could efficiently retain polyphenols, catechins and original colour of green tea infusions with electric field strength from 20 to 40 kV cm−1 for 200 μs. PEF treatments caused a significant increase in the total free amino acids of green tea infusions. The total free amino acids increased by 7.5% after PEF treatment at 40 kV cm−1. The increase in total amino acids induced by PEF treatment, especially to theanine, is beneficial for the quality of commercial ready‐to‐drink green tea infusion products. There was no significant effect of PEF treatment at 20 or 30 kV cm−1 on flavour compounds of green tea infusions. However, PEF treatment caused losses of volatiles in green tea infusions to different extents when PEF dosage was higher than a critical level. The total concentration of volatiles lost was approximately 10% after PEF treatment at 40 kV cm−1 for 200 μs.