Local wine drinkers’ love affair with premium bag-in-box (BiB) wine is rapidly gathering momentum. Yet, new research reveals how the bag’s inherent headspace – or air bubble – could affect sensory and aromatic composition, and potentially smother the baby in its crib.
Globally, there’s been a surge in consumer demand for BiB wines, partially caused by changing behaviours due to the Covid-19 pandemic. Research by Smurfit Kappa and Wine Intelligence found that BiB wine attracted 3.7 million new consumers in France and the United Kingdom during the past six months as wine drinkers have increasingly moved to drinking and entertaining at home.
Closer to home, BiB has become a fast-growing segment of the South African wine marketplace, and the wine quality standard has been rising just as rapidly. During lockdown, producers and retailers latched on to this trend by offering a range of premium BiB wines on the domestic shelf. Producers such as Kleine Zalze and Beyerskloof, and major retailers such as Woolworths, have released impressive examples of this format.
Designed for quick convenient consumption, consumers laud BiB’s ability to preserve wine for up to 6-8 weeks after opening compared to 2-3 days in a glass bottle. However, one of South Africa’s leading oenologists and founder of Basic Wine, Dr Carien Coetzee, says this is a common misconception as the shelf-life of BiB wine depends on many factors.
Carien has been studying the effect of oxygen on oenological parameters and volatile compounds of dry white wine for several years. “The biggest contributor to this loss in wine quality is the ‘headspace bubble’ found in most BiB wines,” she says. The headspace bubble refers to the air or oxygen ‘space’ that remains in the bag once filling is complete. “In my opinion, the bubble is often far too big for the amount of wine in the bag.”
Upon further investigation Carien discovered that wine in BiB packaging can contain up to 30 ml of air headspace. “Some filling companies manage to lower the bubble volume considerably, yet it’s still unclear whether this could effectively solve the oxidation problem. We often see inconsistent bubble volumes from one BiB to the next. Some BiBs possess 40 ml of headspace while others contain less than 8 ml.”
She says the oxygen bubble remains roughly the same despite the size of the packaging. “Potential headspace oxygen problems become more acute with smaller BiBs as the size of the bubble remains constant regardless of the bag size. We’ve seen shelf-life issues occur especially in the 1.5-litre, and two-litre formats, with notably larger and uneven headspace oxygen to wine-volume ratios.”
Problems for producers
Oxidation poses a serious dilemma for producers of premium BiB wines. Despite being reasonably priced in South Africa, discerning wine buyers have high expectations of quality levels in this category. Carien believes the headspace bubble shortens the wine’s shelf life considerably.
Producers recommend drinking BiB wines within 8-12 months from the fill date (which some display on the packaging). But Carien says her studies have shown significant losses in quality and sensory composition within six months for certain wines. “Retailers packing 1.5-litre and two-litre BiB should accept that shelf-life is likely to be shortened. Those packing smaller BiB sizes must manage oxygen even more conservatively and ensure the wine is protected as much as possible through the addition of antioxidants.”
Carien goes on to say producers risk their own reputation when BiB wine becomes oxidised. “We’ve seen an increase in consumer complaints who feel BiB doesn’t taste the same as in the bottle. It’s not sub-standard wine, but the oxygen bubble in the bag affects the wine’s sensory and aromatic composition. The extent of the loss, in some cases, is much higher than we initially thought”.
A carbon dioxide conundrum
Alarmingly low levels of carbon dioxide (CO2) in BiB wines raise additional concerns for BiB producers. Carien says maximum allowed CO2 levels are specified by the bag producer, however it’s usually around 0.4 to 0.5 g per litre of wine. “This is very low, and, depending on the wine style, can cause the wines to taste flat. It also diminishes a lot of the wine’s freshness and vibrancy.”
Carien suggests producers insist on proper quality control (QC) during the filling process. “The quality of packaging and filling plays an all-important role in preserving the wine effectively. It’s important to ensure that the oxygen level in the tank is low to begin with. Straight after filling, oxygen must be monitored constantly to determine how much oxygen concentration has increased in the sealed bag.”
It doesn’t pay to put to the finest wine in BiB when the quality is ultimately affected by the packaging, or the filling process is sub-standard. “Some wines are unable to handle large amounts of oxygen,” says Carien, “and once exposed, the wine eventually deteriorates.” She adds that fruit-driven wines are often more susceptible to oxidation.
Avoiding exposure to air and preventing the solubilisation of oxygen in wine is the first step to prevent oxidation. In addition to inerting the bag with gas, there’s the possibility of doing a chemical inertisation. Ascorbic acid, tannins and yeast hulls work rapidly in consuming oxygen before oxidation starts with wine compounds.
Lida Malandra, general manager at Enartis says EnartisStab SLI is a viable solution for BiB producers who experience problems with oxidation in the bag. The EnartisStab SLI is special blend of yeast derivative, PVPP and untoasted oak tannin and is effective in preventing the degradation and oxidation of wine aromas during storage. “It’s recommended for the protection of wines that have already been clarified, filtered and eventually stabilised, especially wines that are sensitive to oxidation.”
While the EnartisStab SLI product is designed to protect wine – stored over an extended period of time before being packaged – from oxidation, the EnartisTan SLI is a pre-bottling tannin for extending the shelf life of wine.
EnartisTan SLI is produced from untoasted American oak with a unique process that avoids the use of high temperature. “It has an extraordinary capability to scavenge oxygen and radicals, chelating metals and slightly reducing wine redox potential,” says Lida. She adds EnartisTan SLI can be used in synergy or as an alternative to sulphur, “to protect wine from oxidation and to improve its shelf life.”
Enartis also has a pre-bottling adjunct called Citrostab rH (made of citric acid, potassium metabisulphite and gallic tannins) to protect wine against atypical ageing, oxidation, pinking and white haze.
She adds that EnartisStab SLI will protect wine from oxidation by providing solids capable of consuming accumulated oxygen while lowering the redox potential. For more information, visit www.enartis.com/en-za/