Low sulfur dioxide sped oxidation in Peruvian Negra Criolla wine within a year of bottling

A study published in OENO One found that bottle aging changed the sensory profile of Peruvian Negra Criolla red wine within the first year after bottling, with lower sulfur dioxide levels linked to faster oxidation, weaker fruit aromas and less stable color.

The research, published June 25, examined wines from two Peruvian growing areas, Tacna and Moquegua, to track how free sulfur dioxide, dissolved oxygen and carbon dioxide evolved during storage and how those changes related to consumer acceptance. The authors said the work addresses a gap in research on Negra Criolla, a heritage grape widely grown in Peru for both wine and pisco.

Peru’s wine production rose from 15.1 million liters in 2019 to 19.2 million liters in 2024, according to figures cited from the International Organisation of Vine and Wine. Negra Criolla, also known in other countries as País, Mission or Criolla Chica, is one of the country’s most widely cultivated grapes.

The study used a 2021 Tacna wine and a 2022 Moquegua wine made with spontaneous fermentation and no oak contact. Before bottling, researchers adjusted free SO2 to target levels of 15mg/L, 30mg/L and 45mg/L. The wines were then bottled in 0.75-liter green Bordeaux bottles, purged briefly with CO2 before filling, sealed with natural cork and stored horizontally at 16°C in darkness.

Chemical analyses ran for 259 days for the Tacna wine and 244 days for the Moquegua wine. Sensory tests ran slightly longer, to 265 days and 251 days. At each point, three bottles per treatment were analyzed. Sensory sessions were held five times for each wine with about 50 participants per session, using a nine-point hedonic scale and a Check-All-That-Apply method covering 29 visual, aroma, taste and retronasal descriptors.

The clearest pattern appeared in wines bottled with 15mg/L free SO2. According to the paper, those wines showed faster depletion of free SO2, higher dissolved oxygen concentrations, loss of fruity aromas and color shifts toward garnet and brick-red tones. Wines bottled at 30mg/L and 45mg/L kept lower oxygen levels and retained more desirable sensory traits.

Overall acceptance declined slightly from the fourth month onward. The authors said storage time influenced SO2 and oxygen levels and, through them, affected both sensory profile and liking. They also cautioned that the findings should not be generalized too broadly because the initial condition of the wines may have been affected by factors before bottling that were not controlled as experimental variables.

The wines came from different vineyard settings. The Tacna sample was made from grapes harvested from 10-year-old vines trained on a Spanish pergola system, with potential alcohol of about 14.15% and titratable acidity of 5.5g/L. The Moquegua sample came from vines more than 30 years old trained on a vertical trellis system, with potential alcohol of about 13.11% and titratable acidity of 5.3g/L.

Researchers noted that maintaining the balance between oxygen exposure and sulfur dioxide is central to preserving red wine quality during bottle storage. They cited guidance that a free SO2 range of 20mg/L to 40mg/L is generally adequate for red wines, with about 30mg/L often considered optimal.

For producers, especially smaller wineries that may struggle with SO2 management, the findings could help refine bottling targets and oxygen control during storage. That may reduce oxidation risk and better protect aroma, freshness and color stability as wines age in bottle.

The authors concluded that, under the conditions tested, tracking both sensory evolution and the behavior of free SO2 and dissolved oxygen during the first year after bottling is necessary to judge the aging potential of Negra Criolla red wine.