THE EFFECT OF FERMENTATION DURATION ON THE QUALITY OF FIREWEED LEAVES GROWN USING DIFFERENT METHODS

Abstract

The quality analysis of fireweed leaves was conducted in 2023–2024 at the Bio-Fermentation of Secondary Food Raw Materials Laboratory of Vytautas Magnus University Agriculture Academy (VDU ŽŪA) and the Biochemical Research Laboratory of the Warsaw University of Life Sciences (Poland). To determine the effects of solid-phase fermentation on the quality of fireweed leaves grown using different methods, a two-factor experiment was carried out:

• Factor A – Different cultivation methods:
  • A1) Naturally grown fireweed leaves
  • A2) Organically cultivated fireweed leaves
• Factor B – Different durations of solid-phase fermentation:
  • B1) Non-fermented leaves (control)
  • B2) Leaves fermented for 24 hours
  • B3) Leaves fermented for 48 hours

The fermentation of fireweed leaves was conducted in a dark chamber at a temperature of 30 °C for 24 and 48 hours. The levels of oenothein B, chlorophyll a, and chlorophyll b in non-fermented and fermented leaves were determined using the high-performance liquid chromatography (HPLC) method. The antioxidant activity of the leaves was assessed using the spectrophotometric ABTS radical cation binding method.

The study results indicated that the levels of oenothein B, chlorophyll a, and chlorophyll b in fireweed leaves were influenced by both the cultivation method and the duration of solid-phase fermentation. The statistically highest levels of oenothein B were found in non-fermented leaves of fireweed cultivated organically. The highest levels of chlorophylls a and b were observed in non-fermented leaves of fireweed grown naturally. Non-fermented leaves of fireweed cultivated organically exhibited the significantly highest antioxidant activity.