Starbucks (NASDAQ:SBUX) has expanded its test markets for a carbonated- beverage machine called Fizzio. The carbonation aspect invites instant comparison to SodaStream's (NASDAQ:SODA) line of consumer machines. But does SodaStream need to worry about Starbucks' Fizzio -- or keep looking over its shoulder for the impending competition from Keurig Green Mountain (UNKNOWN:GMCR.DL)?

Which company stands the greater chance of popping SodaStream's bubble? 

Fizzio vs. SodaStream 
Fizzio machines will only exist inside Starbucks stores, which differentiates the product from SodaStream's at-home beverage makers. But the differences don't end there. Starbucks' machine "brews" the drink as it adds bubbles, while SodaStream adds the carbonation to water, which is then flavored with syrup. Introductory Fizzio flavors include Spiced Root Beer and Golden Ginger Ale, but customers can also choose to add fizz to Teavana or Refreshers flavors for an additional charge.

Starbucks' marketing positions Fizzio drinks as a healthy alternative to regular soft drinks, noting that the drinks don't contain preservatives or high fructose corn syrup. 

Starbucks hasn't announced any plans to eventually bring versions of the Fizzio to store shelves and kitchen counters. The release of that type of Fizzio machine would stand a chance at constricting SodaStream's market since the preparation method would seem easier -- as it doesn't involve the user adding syrup -- and Starbucks has built-in brand loyalty. 

But SodaStream's immediate threat remains the forthcoming Keurig Cold from Keurig Green Mountain. 

Coke pushes the Cold 
Keurig Green Mountain share prices have risen more than 61% year to date largely due to a multi-year, exclusive deal with Coca-Cola (NYSE:KO) concerning the forthcoming Cold machine. Coca-Cola was originally given a 10% stake in the brewing company but later upped that amount to 16%. The depth of the partnership was further highlighted when the Vermont-based Keurig recently picked a manufacturing facility for its Cold pods that's not far from the Atlanta-based soft-drink giant.

Source: SodaStream

The partnership makes sense from Keurig's end because licensing agreements keep the big names locked into Keurig Green Mountain's brewing systems -- and keep little things like K-Cup patent expirations from torpedoing revenue. Coca-Cola's appearance in the cold machine market will likely cause other drink makers to sign on with Keurig to remain competitive and the brand name presence will help differentiate the Cold from SodaStream, which only has off-brand soda flavors.

What's the appeal for Coca-Cola? The company receives an ownership stake in a thriving company about to enter a new market. Coca-Cola also stays a step ahead of PepsiCo, which has joined Starbucks in offering an in-business individual drink maker called the Pepsi Spire.

Coca-Cola has a vested interest in making the Keurig Cold succeed, and the combination of brand-name recognition and the easier pod-based design could make the Cold push SodaStream off the shelf.

SodaStream feels the Cold
SodaStream investors seem wary of the Cold's potential. Check out the share prices of both companies for the past year, noting that the Coca-Cola announcement was made in February:

SODA Total Return Price Chart

SodaStream Total Return Price data by YCharts

SodaStream had a rough year in general, with questions about its West Bank facility and poor product sales, but the chart shows that investors mostly reacted to the announced Coca-Cola-Keurig deal. 

Foolish final thoughts 
Starbucks' Fizzio would remain more of a niche market even if a consumer version came to pass.  Should that happen, Fizzio could put a dent in SodaStream's wounded market share, but its the Keurig Cold that really has SodaStream investors worried. The Cold's release next year will show whether or not the cold brewing market is large enough for both machines.