Probiotic juice is one of the biggest untapped opportunities in the functional beverage business worldwide, according to food and beverage industry expert Julian Mellentin, reports New Nutrition Business. Mellentin points out that Danone took a 51 percent stake in ProViva, the world's first probiotic fruit drink for digestive health, and secured a 10-year global licence agreement with its inventors.Mellentin has tracked the brand since 1998, and Danone's interest shows the massive potential in probiotic fruit and vegetable juices. "It is likely that this move is connected to Danone's recent announcement of a global joint venture with Chiquita, one of the world's biggest fruit companies," said Mellentin. "It makes sense that Danone should partner with someone who has access to fruits from around the world and expertise in the area. Danone's expertise lies primarily in dairy." ProViva, with the active ingredient Lactobacillus plantarum 299v, and developed by Swedish science company Probi AB, was launched in Sweden in 1994 by Swedish dairy group Skånemejerier, and has grown to become one of the world's most successful innovations in juice drinks with annual retail sales of more than $50 million a year, and still growing at around 8 percent per year. Sweden has a population of just nine million people. If ProViva's sales in Sweden were pro rated to the U.S., with a population of 300 million, it could become a $1.5 billion brand.