# Screening of Four Microbes for Solid-State Fermentation of Hawk Tea to Improve Its Flavor: Electronic Nose/GC-MS/GC-IMS-Guided Selection

## TL;DR

This study identifies a microbe that improves the flavor of hawk tea by reducing its strong camphor smell and enhancing floral and fruity aromas.

## Contribution

The study introduces a novel microbial strain, Blastobotrys adeninivorans, as a promising starter culture for enhancing hawk tea flavor through fermentation.

## Key findings

- Fermentation with Blastobotrys adeninivorans significantly reduced camphoraceous and oil oxidation odors in hawk tea.
- The fermented tea showed elevated floral and fruity aromas, with perillaldehyde and linalool as key contributors.
- Sensory evaluation confirmed improved aroma complexity and consumer acceptability in the fermented samples.

## Abstract

Hawk tea (Litsea coreana Levl. var. lanuginosa), a naturally caffeine-free herbal beverage widely consumed in Southwest China, is characterized by a pronounced camphoraceous note that often deters first-time consumers. In this study, hawk tea leaves were subjected to solid-state fermentation with four microbial strains—Monascus purpureus, Aspergillus cristatus, Bacillus subtilis, and Blastobotrys adeninivorans. The volatile compounds of unfermented and fermented hawk teas were identified by ultra-fast gas chromatography electronic nose (ultra-fast GC e-nose), gas chromatography–mass spectrometry (GC-MS) and gas chromatography–ion mobility spectrometry (GC-IMS) analyses, respectively. Furthermore, the calculation of odor activity values (OAVs) and relative odor activity value (ROAV) revealed that 6 and 25 volatile chemicals, including perillaldehyde (OAV 3.692) and linalool (ROAV 100), were the main contributors to the floral, fruity, and woody aroma of fermented hawk tea. Sensory evaluation confirmed that fermentation generally enhanced woody notes while significantly reducing the characteristic camphoraceous and oil oxidation odors. Notably, the Blastobotrys adeninivorans-fermented sample exhibited the most pronounced floral and fruity nuances, accompanied by significantly elevated aroma complexity and acceptability. Consequently, Blastobotrys adeninivorans represents a promising starter culture for the improvement of hawk tea flavor.