Can alcohol sales and an expanded array of food choices provide the boost White Castle is seeking?

QSR chain White Castle, a 90-year-old hamburger chain that sells square “slider” burgers, has begun serving beer and wine in an Indiana location as part of a test program, the Chicago Tribune reported.

And White Castle is not alone. Earlier this year Burger King opened the Whopper Bar South Beach, a restaurant in Miami Beach offering beer, and Starbucks is also testing beer and wine sales in Chicago.

Companies are recognizing the sale of alcoholic beverages as a growth opportunity after years of flat sales, David Henkes, a vice president with the Chicago-based food research firm Technomic told the Chicago Tribune. “Alcohol is one of those things that is extremely profitable to the operator,” he said.

White Castle’s beer and wine tryout is part of a larger test plan that includes three new concepts the company has been studying for more than a year. In addition to the usual Blaze Modern BBQ concept, the chain is also experimenting with an Asian food brand, Laughing Noodle, at a White Castle in Springfield, Ohio, and a triple-decker sandwich concept, Deckers, in Lebanon, Tenn.

While customer response to beer and wine sales at the Indiana location has been strong, for now White Castle is only considering expanding the option to two other co-branded locations.

White Castle would face challenges trying to roll out beer and wine on a wider scale, Henkes told the Chicago Tribune. “What we find with fast-food places is, there’s very strict regulations around training. Typically, a lot of the employees in fast food are under 21, so you get into some service issues,” he said. “You get into some inventory issues. You get into whether distributors are willing to deliver to you because you’re generally not doing a whole lot of volume in these categories.”