Greg Guidotti, senior director of ready-to-drink beverages at Capri Sun marketer Kraft Foods, said its resarch found 14% of moms are aware that common food mold has been found from time to time in the brand's pouches. But while that seems like a small number, the conversation around the incidents has changed dramatically in recent years. "The level to which things are accentuated in social media, it really changed the way we wanted to engage with moms," Guidotti said. "We've spent a lot of time speaking to the consumer-response groups. We want to offer empathy and offer it with transparency."

The clear-panel packaging was a year in development and will be available nationally this month. But it's also a springboard for a broader brand rethink. A new ad carries the line, "See the goodness before it's gulped."

The mold problem also presented Capri Sun with an opportunity. The growth occurred because Capri Sun has no preservatives — but the brand's lack of artificial preservatives, colors and flavors was also an overlooked selling point. The brand has been free of those things for decades, but 70% of consumers are unaware of that fact, which Kraft sees as a big miss.

"The amplification of mold [issues] initiated some of our thinking, but as we did our deep dive, we saw a much broader trend around health and wellness," said Guidotti.

Capri Sun has devoted millions to the development of the clear panel and will be pouring $45 million into marketing this year. That's a big jump for a brand that spent $20 million on measured media in 2013, according to Kantar Media.

Saatchi & Saatchi and Razorfish are handling marketing efforts.

Guidotti expects the investment will pay off, citing a goal of adding 2 million customers to the franchise, which today stands at about 10 million. "It's a material investment for Kraft," said Guidotti, who characterized Capri Sun as a "tentpole" brand for the company. Capri Sun recorded $713 million in sales in 2013, down 8% from the year prior, according to IRI.