The Role of Non-Traditional Yeasts in the Flavor Profile of Non-Alcoholic Beers

This post is also available in:

The growing demand for non-alcoholic beers (Non-Alcoholic Beer, NAB) has highlighted a significant challenge: the perception that these beverages lack the aromatic complexity that characterizes their alcoholic counterparts.

To address this problem, a pioneering study published in ACS Food Science & Technology (2025) by Maust, Sen and Lafontaine evaluates the impact of 11 non-traditional yeast strains on NAB quality.

These yeasts, unable to metabolize maltose or maltotriose (the predominant sugars in barley wort), generate a minimal ethanol residual while producing secondary metabolites that define beer character.

From fermentation to sensory analysis

This study employs a multidisciplinary approach to evaluate how yeasts affect the sensory and chemical profile of NABs.

A base wort made from American pale ale malt was used, at two nutrient levels: 4.5°P (low gravity) and 9°P (high gravity).

Fermentation was standardized at 20°C for 108 hours (4.5 days), using a constant inoculation rate of 10 million cells/mL to ensure comparability across strains, disregarding variable manufacturer recommendations.

Fermentation and quality control

The production process included critical steps such as differential mashing at 75°C for most samples, except for yeasts G and I-HM, which were subjected to mashing at 80°C to reduce fermentable sugars.

After fermentation, pasteurization was applied at 400 Pasteur units (15 min at 100°C) to ensure microbiological safety — an essential step in NABs due to the absence of ethanol as a natural preservative.

In addition, pH was adjusted with lactic acid if it did not drop to ≤4.2, a necessary control to inhibit pathogens such as Clostridium botulinum.

Sensory and chemical analysis

The study included a detailed sensory analysis conducted by a trained panel of 10 tasters, who evaluated 24 orthonasal (ON-A), retronasal (RN-A), taste and mouthfeel attributes.

Alcoholic beers were used as style references (lager, wheat, pale ale).

Volatile compounds were quantified using headspace solid-phase microextraction (HS-SPME) and mass spectrometry (GC-MS/MS), combining untargeted (full-scan mode) and targeted (multiple reaction monitoring, MRM) approaches.

A total of 169 compounds were analyzed using deuterated internal standards to ensure measurement precision.

The concentration of volatile compounds was calculated using the following formula:

[math]C = \frac{A_{\text{comp}}}{A_{\text{IS}}} \times C_{\text{IS}} \times \frac{V_{\text{IS}}}{V_{\text{muestra}}}[/math]

Where:

C = Compound concentration
A_comp = Peak area of the compound
A_IS = Peak area of the internal standard (IS)
C_IS = Concentration of the internal standard
V_IS = Volume of the internal standard
V_muestra = Volume of the analyzed sample

Differentiation by strain and nutrient level

The results showed how yeasts influence the sensory and chemical profile of NABs, with significant implications for reproducing specific beer styles.

1. Fermentation performance

Only maltose-negative yeasts — unable to metabolize maltose — produced valid NABs (<0.5% ABV) in 4.5°P wort.

Maltose-positive strains (G, I-CM, I-HM) exceeded this limit even when mashing at 80°C was used.

Among the maltose-negative yeasts, two distinct groups were observed.

1. Fast-acting yeasts such as modified Saccharomyces or Pichia, which consumed simple sugars within 48 hours.
2. Slower-acting yeasts such as Hanseniaspora uvarum or Torulaspora delbrueckii, which showed a more pronounced extract drop between 48 and 72 hours.

The Real Degree of Fermentation (RDF), which measures the percentage of fermented extract, ranged from 1.28% to 51.20%, correlating directly with ethanol production.

2. Profiles and metabolites

Through Principal Component Analysis (PCA) and Multiple Factor Analysis (MFA), unique profiles linked to specific beer styles were identified.

Yeasts J (Saccharomycodes ludwigii) and K generated a lager-type profile with cereal and dried fruit notes, linked to aldehydes such as 3-methylbutanal (malty aroma) and furfural (toasty).

Strains A and B (genetically modified) produced a pale ale-type profile with tropical and citrus notes, driven by terpenes such as geraniol (floral) and linalyl acetate (citrus).

Yeast D stood out for wheat-style character due to 4-vinylguaiacol (4-VG), a phenol derived from the decarboxylation of ferulic acid that imparts clove notes.

Aromatic intensity was higher in 9°P worts, although in strains such as Hanseniaspora uvarum (C), 4.5°P worts favored the production of key esters such as phenylethyl acetate (fruity aromas).

3. Wort gravity

9°P worts generated a greater mouthfeel body, attributed to a higher residual extract and ethanol.

This finding is crucial, as the perception of “thin mouthfeel” in NABs reduces consumer acceptance.

The correlation between bitterness and ABV (r=0.801) suggests that ethanol enhances this sensation, which represents a challenge for NABs.

As a strategy, increasing the concentration of non-fermentable dextrins through mashing profiles could improve viscosity without excessively increasing sweetness.

Future perspectives

Non-traditional yeasts have great potential to improve the sensory profile of non-alcoholic beers, bringing them closer to the complexity of alcoholic beers.

Strains such as Torulaspora delbrueckii (K) offer fruity complexity suited to lager-type beers, while modified yeasts such as NA Cabana (A) enable the targeted production of terpenes associated with pale ale-type beers.

However, technical limitations exist: maltose-positive strains do not comply with legal ABV limits, and pasteurization can alter heat-labile volatile compounds such as esters.

Future research should optimize nutritional stress to modulate the production of specific metabolites and validate key compounds using techniques such as AEDA (Aroma Extract Dilution Analysis).

For the industry, yeast selection must align with the target beer style and regional preferences, considering that North American consumers prefer fruity profiles over malt-dominated ones.

Frequently Asked Questions (FAQ)

How are most non-alcoholic beers (NAB) currently produced?

Most commercially available non-alcoholic beers are produced using one of three main methods: arrested fermentation (cooling the mixture before it reaches the alcohol limit), alcohol removal after fermentation (typically by vacuum distillation or reverse osmosis), or the use of low-fermentability worts. These methods tend to compromise the aromatic profile and body, which explains the search for alternatives such as maltose-negative yeasts.

What impact does high-temperature mashing (75–80°C) have on non-alcoholic beer quality?

High-temperature mashing — specifically between 75 and 80°C — is used strategically to deactivate enzymes (such as beta-amylase) that convert starch into simple fermentable sugars (maltose). This maximizes the production of non-fermentable dextrins, which are complex sugars. The result is a wort with more residual extract that the yeast cannot consume, translating into greater body and better mouthfeel, counteracting the “thin mouthfeel” typical of NABs — without exceeding the legal alcohol limit.

What is the difference between “maltose-negative” and “maltose-positive” yeasts in NAB production?

The key difference lies in their capacity to metabolize maltose and maltotriose, the predominant sugars in barley wort. Maltose-negative strains (used in the study) lack the genes needed to consume these sugars, ensuring minimal ethanol production of <0.5% ABV. Maltose-positive strains (such as traditional S. cerevisiae) do metabolize these sugars and therefore exceed the legal alcohol limit for NABs, even with adjustments to the mashing process.

Why is pasteurization an essential step in non-alcoholic beers, and what risks does it involve?

Pasteurization is essential in NABs because, with very low ethanol content (which acts as a natural preservative), they are far more susceptible to microbial contamination and spoilage. The most relevant risk it mitigates is the inhibition of pathogens. However, the main technical risk of pasteurization (15 min at 100°C in this study) is that it can degrade or alter heat-labile volatile compounds — especially esters and terpenes — that are crucial for the complex aromatic profile sought through non-traditional yeasts.

What are terpenes and why are they important in the sensory profile of a non-alcoholic Pale Ale?

Terpenes are a large class of aromatic organic compounds found naturally in hops, fruits and spices. In the context of non-alcoholic Pale Ale-type beers (such as those produced by strains A and B in the study), terpenes are fundamental because they deliver the desired tropical and citrus notes (such as geraniol and linalyl acetate). As high-impact aroma compounds, they help compensate for the loss of flavor complexity that occurs when alcohol content is drastically reduced — making them a key factor in acceptance among consumers seeking these fruity profiles.

Reference

Maust, A., Sen, R., & Lafontaine, S. (2025). Exploring non-traditional yeast for flavor innovation in non-alcoholic beer. ACS Food Science & Technology, 5(8), 2007-2020. https://doi.org/10.1021/acsfoodscitech.5c00291

Recommended

• What is beer and how is it made? Definition, ingredients and basic processes
• The kykeon and the Eleusinian Mysteries: an ancestral psychedelic beer?