Vernonia amygdalina as a hop substitute in red sorghum beer: Effects on fermentation performance and physicochemical properties

TL;DR

This study explores using Vernonia amygdalina as a hop substitute in red sorghum beer, finding it improves fermentation and beer quality.

Contribution

The novel use of Vernonia amygdalina as a sustainable hop substitute in sorghum beer production is evaluated for its impact on fermentation and beer properties.

Findings

Using Vernonia amygdalina increased alcohol content by up to 6.3% v/v compared to hop-only beer.

Higher substitution levels improved apparent attenuation and lowered final pH during fermentation.

V. amygdalina did not inhibit yeast activity and supported efficient fermentation without contamination.

Abstract

The substitution of imported hops with locally available botanical alternatives offers a sustainable strategy for sorghum-based beer production. This study evaluated partial and total replacement of hops with Vernonia amygdalina as a bittering agent on fermentation performance and physicochemical properties of red sorghum malt beer. Five formulations were prepared with 0, 25, 50, 75, and 100% (w/w) substitution and fermented for 192 h using Saccharomyces cerevisiae (brewer's yeast strain ANGEL BF-16) under controlled laboratory conditions.

V. amygdalina was added at the end of the 60-min boil, immediately before cooling, to maximize extraction of bitter compounds while preserving heat-sensitive aromatic molecules. Fermentation kinetics and final beer characteristics were assessed via extract content, density, alcohol concentration, pH, color (EBC), and apparent attenuation. Increasing proportions of V. amygdalina significantly enhanced fermentation, yielding higher alcohol content (5.2–6.3% v/v), increased apparent attenuation (61.6–75.5%), and lower final pH values compared to the hop-only control. Higher substitution levels also increased color intensity, reflecting contributions of plant-derived pigments and polyphenols.

Microbiological analyses confirmed the absence of detectable contaminants, indicating that V. amygdalina did not inhibit yeast activity. Statistical analysis showed that fermentation duration and bitter extract formulation significantly affected all measured variables (p < 0.05). Although sensory evaluation and detailed phytochemical profiling were not performed, results indicate that V. amygdalina is a viable hop substitute with measurable effects on fermentation efficiency and beer quality. Future studies should investigate sensory acceptance and optimize substitution levels for industrial application.

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•Hop substitution with a local natural resource (Vernonia amygdalina)•Alcohol yield improved by 21% thanks to the use of V. amygdalina•Improved apparent attenuation and alcohol production were observed with increasing V. amygdalina substitution.

Hop substitution with a local natural resource (Vernonia amygdalina)

Alcohol yield improved by 21% thanks to the use of V. amygdalina

Improved apparent attenuation and alcohol production were observed with increasing V. amygdalina substitution.

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