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Oxygen and its influence on wine aging

When selecting a wine closure, consideration should be given to oxygen transmission rates, their long-term affect on a wine's style and the style consumers prefer

Maurizio Ugliano Nomacorc

During a wine’s life in the bottle, the aroma can change dramatically as a result of the aging process. Due to the complexity of this phenomenon, one of the main challenges of the modern wine industry is to be able to deliver to consumers wines with consistent and enjoyable sensory characteristics. To help achieve this, winemakers should consider the importance of oxygen and its influence in wine bottle aging.

Although it is generally accepted that wine aging should take place without excessive exposure to oxygen, there is a risk for a wine to develop reduced or off-odors if conditions become too reductive, as often observed with tightly-sealed closures like screw caps.

Research on closures’ impact on wine composition has clearly shown that the selection of closures with the appropriate oxygen transfer rate (OTR) can effectively assist winemakers in their efforts to address reduction and/or oxidation issues. More recently, the wine trade has taken interest in the idea that wine packaging, including closures, could not only be an inert container but an active component of the winemaking process. However, one main question that continued to remain unanswered was whether consumers were able to perceive differences created by different closure OTRs. And, if perceived, how can a consumers’ preference be affected by the closure.

The data in the illustration, obtained from a trial carried out at the Australian Wine Research Institute (AWRI), focused on Semillon wines aged for two years under different closures. This data provides an interesting insight into the question of consumer preference. Participating consumers, 102 in total, were presented the wines in a series of blind tastings where no information was given regarding the type of closures used for each sample. The closures were selected based on differences in their OTR. Following the tasting, they were asked to express a preference on the sensory quality of the wine.

The results obtained clearly showed that after an aging period of two years, consumers are able to distinguish among wines aged under different closures, and their preference is affected by the sensory characteristics that are linked to the use of different closures. Given that at the moment of tasting, consumers did not know which sample was stored under which closure, the results from the AWRI study clearly show that the chemical changes that are introduced by the use of different closure OTRs have the potential to drive consumer preference.

Additionally, the study found that not all consumers responded in the same way. Based on their sensory responses, the study was also able to identify three different groups showing different preferences to different wine styles. In this respect, the results suggests that from the point-of-view of the sensory characteristics that are determined by the different closures, there is no one single closure that will consistently meet consumers’ preference. The types of consumer belonging to the three clusters are distinctively different, indicating that there are segments of consumers that, being attracted by a particular style of wine, tend to direct their choice toward the sensory profile displayed by that wine.

Another finding from the study indicates that by using different closures it is possible to generate sensory profiles that are attractive to specific types of consumers. Personal background, social conditions, and other factors all play a role in shaping consumers’ preferences.

A major conclusion from this study is that the choice of closure, and in particular of the OTR, plays a key role in the achievement of sensory characteristics that are important to the consumer. Additionally, these results reinforce the importance of consistency of closures’ OTRs to ensure proper development from bottle-to-bottle. Engineered closures, like Nomacorc co-extruded wine closures, help ensure a consistent oxygen ingress rate into the wine while other closures may vary in oxygen permeability.

The choice of closure does not only have marketing implications linked to consumer’s acceptance of different closure types. It also represents an additional step in the process of delivering wines that can meet consumer’s demands for sensory enjoyment.

Illustrated: Preference segmentation of sample of 102 Australian consumers (adapted from Nygard et a. Australian, New Zealand grapegrower winemaker, 55-60, 2010)

Maurizio Ugliano joined Nomacorc in September 2010 as its enological research manager. Based out of Nomacorc’s enology headquarters in Nimes, France, he is responsible for coordinating research initiatives and overseeing academic research partnerships.

Before joining Nomacorc, Maurizio was the lead scientist for an oxygen management research program at the Australian Wine Research Institute (AWRI) in Adelaide, Australia. He pioneered numerous studies on wine aroma chemistry, microbiology and oxygen management. Maurizio has also served as a research assistant in the department of food science at the University of Naples in Italy.

Maurizio has an extensive research background in food science, with a focus on flavor biochemistry. In addition, he is the co-author of more than 30 scientific publications in the areas of food processing, yeast metabolism, wine aroma and chemistry of oxygen in wine.

Maurizio earned his Ph.D. in food biotechnology from the University of Foggia in Italy.

10 March 2014