"Did Someone Take a Sip?"... We Measured Sparkling Water Ourselves [Taste Guru X-Files]

'Headspace' Is Minimal in Bottled Water and Sports Drinks
Helps Prevent Container Damage from Carbonation
"The Empty Space Depends on the Container's Shape, Volume, and Other Factors"

Sparkling water products on sale at a retail outlet in Seoul. Photo by Jeong Hyeonjin.

Jang, an office worker who recently tried to buy sparkling water at a convenience store, was surprised by what they saw on the shelf. When they reached for a bottle, they noticed a sizable empty space directly below the cap. They said it looked "as if someone had taken a sip" and hesitated before paying. Have you ever had a similar experience when buying sparkling water?

These days, quite a few consumers choose sparkling water instead of regular water. Some enjoy it on its own, while others buy it to make drinks such as highballs. According to market research firm Euromonitor, South Korea's sparkling water market was worth around KRW 190.6 billion last year. A wide variety of products are available, including basic sparkling water and flavored options such as lemon. The empty space inside the bottles is also visible in these products.

Coca-Cola's Seagram label-free sparkling water, pictured before opening. Photo by Jung Hyunjin.

So do sparkling water products contain less than the labeled volume, compared with other beverages? Or are their packages made larger to make the products look bigger? In this installment of Taste Guru X-Files, we investigate the truth behind the empty space in sparkling water bottles.

According to industry sources on Nov. 1, the space inside a plastic bottle is called "headspace." It refers to the space left between the surface of the contents and the inner edge of the cap after a sealed container is filled. It is a necessary buffer left empty during food processing to prevent the product from spoiling or the container from being damaged.

One company says the empty space in sparkling water bottles looks particularly large compared with that in bottles of regular water, tea, or sports drinks because of the carbonation. Sparkling water is a drink in which carbon dioxide is either naturally dissolved in water or injected into it. Carbonated soft drinks, including cola and lemon-lime soda, are made by adding sugar, flavorings, and food additives to this base.

Because carbonation is formed when carbon dioxide dissolves in water, leaving no empty space at the top of the product could increase the risk of the plastic bottle deforming as internal pressure rises with changes in the outside temperature. In other words, headspace is needed to prevent this. It also provides a buffer so the drink does not suddenly gush out when the cap is opened.

At this point, the question consumers are most curious about is how much product is actually inside. They may wonder whether the bottle contains less than the amount printed on the package, or whether it is effectively overpackaged. We bought four types of sparkling water sold at convenience stores and used a scale to check whether the actual volume of their contents differed from the amount stated on the package.

Four carbonated water products purchased on the market. Reporter Jung Hyunjin.

Lotte Chilsung Beverage's Trevi contained 499.0 mL against a labeled volume of 500 mL. Coca-Cola's Seagram contained 350.7 mL against a labeled volume of 350 mL, slightly exceeding the stated amount. Minemaine Sparkling, launched by Dongwon F&B last August, contained 499.1 mL against a labeled volume of 500 mL, while Woongjin Foods' The Big Victoria Lemon contained 497.1 mL against a labeled volume of 500 mL. Although there were slight differences, the products contained amounts close to their labeled volumes.

The permissible tolerance for a shortfall in net contents is set by law. According to the Ministry of Food and Drug Safety's "Standards for Labeling of Foods, etc.," for products labeled as containing more than 300 mL and up to 500 mL, the tolerance is 3% of the stated amount. This means that if a product is labeled as containing 500 mL, a volume of 485 mL is permitted. The contents of the four products we checked with a scale were all very close to their labeled volumes and fell within the permitted tolerance.

In fact, headspace is not found only in sparkling water. The same applies to carbonated soft drinks, including cola and lemon-lime soda. Sparkling water also comes in a variety of flavored options containing ingredients such as flavorings. As a result, some of these products may be classified on their labels under the same food type as cola and lemon-lime soda: "carbonated beverages."

Lotte Chilsung Beverage, which makes Trevi, the leading brand in South Korea's sparkling water market, explained: "The size of the empty space depends on a combination of factors, including the shape and capacity of the container and the level of carbonation added to the product, rather than simply on whether it is sparkling water or another carbonated beverage." In other words, adding sugar or flavorings to carbonated water does not, by itself, significantly change the size of the headspace; the factors need to be considered together.

Notice of packaging changes for Lotte Chilsung Beverage's Trevi. Screenshot of the product description on an online sales channel.

Sparkling water is also sold in aluminum cans and glass bottles, not just plastic bottles. The company said that packaging conditions can vary depending on the material and shape of the container. Headspace is inevitably affected as well.

Trevi products have used three different container shapes, introduced in 2007, 2019, and 2021, and the amount of empty space has varied along with those changes. Lotte Chilsung Beverage explained: "Changes to the container's shape, material, and structure can affect how the product is filled. A difference in the visible size of the empty space does not, by itself, indicate a difference in carbonation levels."

This year, Dongwon F&B and Jeju Samdasoo entered the sparkling water market, leading to an increase in related product launches. Beyond diversifying flavors to reflect consumer preferences, companies appear to be differentiating their products by offering more varied carbonation levels and ways of drinking them.

This weekend, as chilly winds blow enough to make your nose tingle, many of you may be enjoying classic winter snacks such as roasted sweet potatoes, bungeoppang, or hoppang. Pick up a bottle of sparkling water or a carbonated soft drink, check out the empty space for yourself, and enjoy a relaxing weekend.

This content was produced with the assistance of AI translation services.