# Natural Strategies to Preserve Alcohol-Free Beer: Phenolamide Dimers with Anti-Yeast Potential

## TL;DR

Researchers found that certain natural compounds, called phenolamide dimers, can inhibit yeast growth in alcohol-free beer, offering a natural preservative solution.

## Contribution

The study demonstrates that amidation and oxidative coupling enhance anti-yeast activity of hydroxycinnamic acid derivatives.

## Key findings

- Hydroxycinnamic acid dimers and HCAgms did not inhibit yeast, but HCAgm dimers did.
- Specific HCAgm dimers like CouAgm-4-O-7′/3-8′-DCouAgm and FerAgm-4-O-7′/3-8′-DFerAgm showed anti-yeast activity in beer.
- A new agmatine amide of poacic acid had increased antiyeast activity compared to its monomeric precursors.

## Abstract

Trends in clean label food and the growing popularity
of alcohol-free
beers have led to a demand for natural compounds to prevent microbial
spoilage. Oxidative coupling products of hydroxycinnamic acids and
their amides, i.e. phenolamides, obtained via chemo-enzymatic synthesis
and from barley rootlets, a beer brewing byproduct, were tested for
their inhibitory activity against the beer spoilage yeast Saccharomyces cerevisiae subsp. diastaticus. Hydroxycinnamic acids, their dimers, and hydroxycinnamoylagmatines
(HCAgms) did not inhibit the yeast. However, inhibitory activity was
observed with HCAgm dimers. In particular, CouAgm-4-O-7′/3-8′-DCouAgm and FerAgm-4-O-7′/3-8′-DFerAgm
were active at 46–255 μg/mL in beer. Notably, the newly
synthesized agmatine amide of poacic acid, a stilbenoid dimer of ferulic
acid, showed increased antiyeast activity compared to its monomeric
precursors. These results demonstrate that amidation and oxidative
coupling can increase the antiyeast activity of hydroxycinnamic acid
derivatives, and that hydroxycinnamoylagmatine dimers possess potential
as preservatives against wild yeast spoilage in beer.