Research

Upcycling vineyard by-products as natural sulphite alternatives

June 17, 2025

Upcycling of viticultural by-products as natural alternatives to sulphites represents one of the most promising innovations for the contemporary wine industry, which is called upon to reduce sulphur dioxide (SO₂) both due to concerns relating to allergies and individual sensitivities, and because of growing consumer interest in natural wines.

The circular bioeconomy, on the other hand, can enable the valorisation of grape pomace as well (20-30% of processed grapes) — being rich in bioactive polyphenols such as anthocyanins, flavonols, flavanols, phenolic acids and resveratrol (Peixoto et al., 2018) — within the same viticultural supply chain. Thus transforming the related food loss and waste into valuable resources, also for nutraceutical purposes (Fernandes et al., 2025).

Bioma SA (Quartino, Switzerland) has developed pioneering technology to convert this waste into functional additives for winemaking (Mercanti et al., 2024), offering an effective alternative to sulphites that supports sustainable, hopefully organic viticulture. The research is distinguished by rigorous scientific validation that demonstrates the maintenance of the wine’s organoleptic quality and its characterisation (Mercanti et al., 2025).

Table of Contents

Sulphites: health concerns and wine quality

Sulphite sensitivity affects approximately 1% of the general population, but occurs in 3-10% of people with asthma (Vally & Misso, 2012). Clinical studies confirm that sulphite-sensitive subjects with asthma may react to the ingestion of foods and beverages containing sulphites, with the likelihood of reaction dependent upon the nature of the food, the level of residual sulphites, and the patient’s sensitivity (Taylor et al., 1988).

In the context of wine production, the use of excessive doses of SO₂ must be avoided not only because of adverse reactions in sensitive subjects, but also because from an oenological standpoint it can cause organoleptic alterations in the final product, neutralise the aroma and even produce characteristic aromatic defects (Santos et al., 2015).

European regulations have progressively reduced permitted SO₂ levels through a comprehensive regulatory framework. Commission Delegated Regulation (EU) 2019/934 currently establishes maximum total sulphur dioxide content limits of 150 mg/L for red wines and 200 mg/L for white and rosé wines. These limits may be raised to 200 mg/L for red wines and 250 mg/L for white and rosé wines when sugar content (expressed as the sum of glucose and fructose) exceeds 5 g/L. For specific protected designations of origin and wines with particular characteristics, the regulation provides for elevated limits up to 400 mg/L under defined conditions.

The EU regulation acknowledges that ‘in the light of current scientific studies into the reduction and replacement of sulphites in wine and the sulphite intake from wine in the human diet, the maximum limits could be re-examined at a later date with a view to further reducing them’, whilst consumer demand increasingly tends to favour beverages without or with minimal quantities of added sulphites.

The Bioma innovation: upcycling grape pomace into natural alternatives to sulphytes

The Bioma technology represents a paradigm shift in winemaking by addressing multiple challenges simultaneously: reducing SO₂ use, valorising food loss and waste, and improving wine quality. The company’s Epyca line of additives derives from carefully processed grape pomace, rich in phenolic compounds that provide natural antimicrobial and antioxidant properties.

Bioactive phytochemicals present in winery by-products are mainly represented by (poly)phenols, which arise biogenetically from two main primary biosynthetic pathways: the shikimate and acetate pathways (Teixeira et al., 2014). These compounds include:

anthocyanins, providing colour stability and antioxidant protection;
flavanols, contributing to structure and astringency whilst offering antimicrobial properties;
phenolic acids, exhibiting strong antioxidant capacity;
resveratrol and stilbenes, offering both preservation and health-promoting properties.

The upcycling process transforms what would otherwise be food loss and waste (FLW) into high-value functional ingredients. The present study established that the winemaking process provides an excellent source of raw materials for the recovery of ingredients rich in valuable phenolic compounds, thus contributing to the circular bioeconomy (Fraga-Corral et al., 2021). This approach aligns with sustainable development goals whilst creating economic value from vineyard by-products.

Methodology for comparative analysis

To validate the efficacy of Bioma additives, Mercanti et al. (2025) conducted a comprehensive comparative study examining the elemental profiles of wines produced through traditional and alternative vinification methods. The study employed Sangiovese grapes, with identical musts divided between traditional sulphite-based protocol and Bioma-based vinification.

The analytical approach utilised triple quadrupole ICP-MS (Thermo Fischer iCAP TQe) to quantify 23 elements representing soil markers, agricultural inputs, and potential contaminants. This sophisticated instrumentation enabled simultaneous multi-elemental analysis with superior sensitivity and reduced spectral interferences. Sample preparation involved mineralisation with nitric acid and hydrogen peroxide, followed by controlled digestion at 85°C.

Both vinification protocols were tested with wines aged in either oak barrels or stainless steel tanks, allowing assessment of the interaction between preservation method and ageing technique. Statistical analysis employed one-way and two-way ANOVA (Analysis of Variance), with principal component analysis (PCA) providing multivariate discrimination between production methods.

Elemental profile results: safety and quality indicators

The multi-elemental fingerprinting revealed that Bioma-produced wines maintained elemental compositions comparable to traditional wines whilst exhibiting distinct characteristics. Critically, all potentially toxic elements remained well below EU safety thresholds:

lead: ≤5.9 µg/L (EU limit: 150 µg/L)
cadmium: ≤0.3 µg/L (EU limit: 100 µg/L)
arsenic: ≤12.1 µg/L (well below safety concerns)

These results confirm that the alternative vinification process does not compromise wine safety regarding heavy metal contamination. The maintenance of these low levels is particularly significant given consumer concerns about cumulative exposure to toxic elements through dietary sources.

The study identified several trace elements that varied significantly between vinification methods, potentially serving as markers for authentication:

manganese showed unexpected sensitivity to production methods (1.38-1.86 mg/L range);
rubidium was higher in wood-aged wines, particularly Bioma samples (9.9 ± 0.58 mg/L)
strontium was consistently elevated in Bioma wines, suggesting method-specific signatures.

Sulphite reduction: regulatory implications and economic considerations

Food Information Regulation (EU) 1169/2011 prescribes the mandatory indication of sulphites on wine labels when the total SO₂ concentration exceeds 10 mg/L. The study by Mercanti et al. (2025) did not analyse SO₂ but rather the total sulphur content, to which free SO₂ (preservative additive), bound SO₂ (inactive, complexed with wine compounds), natural sulphur compounds from grapes and fermentation, sulphur from soil, water and amino acids, and other sulphur-containing molecules contribute. Finding that, in wines from Sangiovese grapes aged in wood produced with Bioma additives, compared to traditional ones, the total sulphur is almost halved: 107 ± 4.67 mg/L compared to 209 ± 11 mg/L. (Mercanti et al. 2025).

The dramatic reduction in sulphites therefore suggests that Bioma technology may also enable the production of wines with total SO₂ levels below the threshold (10 mg/L) that requires their mandatory indication on labels. This advancement could revolutionise market access for sulphite-sensitive consumers, whilst also meeting the growing demand for ‘clean label’ wines. Previous studies (Delmas et al., 2016) have moreover already found that consumers prefer red wines without added sulphites — due to the perception that they may cause headaches — and are willing to recognise their added value.

Microbiological and organoleptic stability

The phenolic compounds in Bioma additives provide multifaceted protection mechanisms that replicate and potentially exceed SO₂’s preservative functions. The compositional characteristics of the formulations of the Epyca line, developed by Bioma Company, were assessed (Mercanti et al., 2024), revealing that these additives maintain wine stability through:

Antioxidant activity. Polyphenols scavenge free radicals and chelate pro-oxidant metals;
Antimicrobial properties. Phenolic acids and tannins inhibit spoilage microorganisms;
Colour stabilisation. Anthocyanins and copigmentation cofactors preserve visual appeal;
Structural enhancement. Tannins contribute to mouthfeel and ageing potential.

The preservation of organoleptic qualities was confirmed through comprehensive volatile compound analysis. Bioma wines maintained characteristic aroma profiles whilst avoiding the sensory defects sometimes associated with excessive SO₂ use. The alternative additives contributed minimal amounts (approximately 1 mg/L of phenols), ensuring no significant alteration of wine composition or flavour.

Principal component analysis: distinguishing production methods

The principal component analysis (PCA) results provided compelling evidence for the discriminatory power of elemental profiling between vinification protocols:

with the first two principal components explaining 90.5% of total variance, clear separation emerged between Bioma and traditional wines;
this distinction suggests that multi-elemental fingerprinting could serve as an authentication tool for verifying production methods and supporting traceability initiatives.

Elements contributing most strongly to the separation included manganese, rubidium, strontium, arsenic, and zinc along PC1, whilst sodium, calcium, and potassium showed inverse correlations.

Broader implications for sustainable winemaking

The Bioma innovation exemplifies the potential of circular economy principles in traditional industries. By upcycling waste streams into valuable inputs, this approach addresses multiple sustainability challenges:

food loss and waste (FLW) reduction, valorising 20-30% of grape mass typically discarded;
chemical reduction, eliminating or minimising synthetic preservative use
energy efficiency, utilising locally available materials without extensive processing
economic value, creating new revenue streams from by-products.

Large amounts of pomace are produced during a short period of harvesting, which increases the concentration per area (Zacharof, 2017). The environmental benefits extend beyond waste diversion, as grape pomace disposal often involves energy-intensive processes or creates pollution through decomposition.

Future perspectives and research directions

The successful demonstration of this innovation opens numerous avenues for further development:

Source material safety and organic certification. Prioritising organic vineyard by-products to eliminate pesticide contamination risks
Optimisation studies. Refining extraction and application methods for maximum efficacy
Varietal expansion. Testing effectiveness across different grape cultivars and wine styles
Shelf-life assessment. Long-term stability studies comparing traditional and alternative preservation
Sensory profiling. Consumer acceptance studies and trained panel evaluations
Economic analysis. Cost-benefit assessments for commercial implementation

Future research should prioritise precise SO₂ quantification using aspiration or flow injection methods to definitively establish whether Bioma wines consistently maintain levels below 10 mg/L. Additionally, investigating the bioavailability of phenolic compounds from these additives could reveal potential health benefits beyond allergen avoidance.

Ensuring safety through organic vineyard selection

A critical consideration for future implementation involves the source selection of vineyard by-products. Given that quantifiable pesticide residues were observed in more than 86% of grapes from conventional agriculture (Stávková et al., 2021), the use of organic vineyard streams becomes imperative for ensuring the safety of these additives. Research demonstrates that the pesticide transfer rate in pomace ranged from 17.76% to 51.55% (Martín-García et al., 2024), with lipophilic pesticides particularly prone to accumulation in solid by-products. Furthermore, heavy metals and pesticide residues may be present in winery wastes (Zacharof, 2018), necessitating careful source selection and monitoring.

The adoption of organic vineyard by-products would eliminate these contamination risks whilst aligning with the sustainability ethos of the circular economy approach. Studies confirm that organic production systems result in substantially lower pesticide residues, with 23 samples were free of quantifiable residues/detected metabolites or contained residues approved for organic production (Stávková et al., 2021). This strategy would ensure that these kind of additives remain free from synthetic pesticide contamination, maintaining product integrity and consumer safety.

Conclusions

The comprehensive investigation of Bioma’s innovative technology demonstrates a transformative approach to winemaking that successfully addresses health, environmental, and quality challenges simultaneously. By upcycling vineyard by-products rich in bioactive phenolic compounds, this method provides natural alternatives to sulphur dioxide whilst maintaining the microbiological stability and organoleptic qualities essential for wine preservation.

The elemental profiling analysis confirms that wines produced with Bioma additives meet all EU safety standards for toxic elements whilst exhibiting distinctive signatures that could support authentication and traceability. The substantial reduction in total sulphur content suggests potential for producing wines below the 10 mg/L SO₂ threshold, eliminating mandatory allergen labelling and expanding accessibility for sensitive consumers.

Beyond addressing sulphite sensitivity, this innovation responds to broader health concerns about SO₂ exposure, including respiratory, cardiovascular, and metabolic effects documented in epidemiological studies. The circular economy approach transforms environmental liabilities into valuable resources, contributing to sustainable viticulture whilst creating economic opportunities.

The distinct elemental fingerprints identified through multivariate analysis establish that alternative vinification methods can be scientifically verified, providing tools for regulatory compliance and consumer protection. As the wine industry continues evolving toward sustainable practices, the Bioma model demonstrates that innovation rooted in circular economy principles can deliver superior outcomes for human health, environmental protection, and product quality.

The future of truly sustainable and responsible winemaking undoubtedly hinges on prioritizing organic viticulture to guarantee the cleanest possible inputs for these valuable upcycled products, thereby eliminating concerns about pesticide residues and further elevating product integrity.

This pioneering work establishes a foundation for the next generation of sustainable oenological practices, where food loss and waste becomes resource, tradition embraces innovation, and wine production aligns with contemporary health and environmental imperatives. The success of this approach suggests that similar strategies could transform other sectors of the food and beverage industry, contributing to a more sustainable and health-conscious future.

#Wasteless

Dario Dongo

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