​Can Keurig Green Mountain get its buzz back?

Keurig Green Mountain (GMCR) is learning that investors are a lot like a cup of coffee: They can grow cold and bitter in a matter of minutes.

Shares of the coffee-machine maker fell as much as 30 percent in trading on Thursday, after the company reported a hit to its second-quarter sales and plans to cut about 5 percent of its workforce. In the meantime, pressure is on the company to successfully debut a new soda-making machine called Kold, which Keurig Green Mountain is slated to roll out later this year.

The stakes couldn't be higher for Keurig Green Mountain, which stumbled with Keurig 2.0 coffee machines after consumers discovered the devices use a scanner to lock out coffee pods made by other brands. Late last year, Keurig also recalled its Mini Plus brewer because of a burn hazard. The company's dismal earnings report comes after an earlier guidance cut this year.

Now, analysts and investors are asking whether Keurig Green Mountain can ever get its buzz back.

"We underestimated the magnitude and duration of the negative sales and profit impact stemming from weaker brewer sales during the holiday season and we find it difficult to defend the stock after a third guidance cut," wrote Goldman Sachs analysts Judy Hong and Freda Zhuo in a research note today. They downgraded the stock to "neutral" and removed the stock from Goldman's "Americas Buy List."

The negative consumer reception to Keurig 2.0 and the Mini recall created a "negative feedback loop," the Goldman analysts noted. That has created a continuing impact on its business so far in 2015, which could continue to impact the company through 2016.

Keurig Green Mountain also lowered its earnings outlook to a level that was even lower than Goldman had expected. In a conference call Wednesday, the retailer's chief financial officer said the company expects a "low teens decline" in its earnings per share for the year, compared with Goldman's estimate for a mid-single digit dip. The company also forecast a sales decline for the year.

With many Americans already owning Keurig machines or rival coffee makers, one question facing the company is whether the market is saturated. Consumers don't rush out to buy new coffee machines each time a new version is rolled out, unlike tech status symbols such as Apple's (AAPL) iPhone. Rivals have also elbowed into the coffee-pod business, offering similar coffee-brewing packs at lower prices.

That's why so much is riding on the Kold machine, a counter-top soda maker that some investors and analysts hope could put the fizz back into Keurig Green Mountain's shares. That won't be easy. The new machine must show strong sales in order to reassure Wall Street, even while boasting a $300 price tag that many families may consider too expensive.

On top of that, rival SodaStream (SODA) already has a share of the counter-top soda maker market, and it's also struggling with slowing consumer demand. The company on Wednesday said second-quarter revenue slipped by 28 percent.

Keurig also has beverage giant Coca-Cola at its back. The soda maker holds a 16 percent equity stake in Keurig, stemming from a February 2014 agreement to supply brands such as Coke and Sprite for the Kold machine.

The Kold machine so far has proved costly for Keurig, with chief executive Brian Kelley telling analysts on a conference call on Tuesday that the company will invest more than $100 million in its development this fiscal year. The rollout of the appliance this holiday season remains one of the company's biggest risks, along with declining sales of brewing machines and profitability of its coffee pods, Goldman noted.

Keurig's Kelley defended the investment in Kold as necessary to ensure a successful debut later this year. "There is a desire to get it out there and get the system started," he said on the call. "And so we believe the investment has been prudent." He added, "We need to have perfect execution."

That could help get some juice back into Keurig Green Mountain's operations, although its recent track record suggest investors may be lukewarm on the coffee seller.