Buy a package of Kona coffee, and by Hawaii law what you get must show on the label — 100 percent of the pricey beans or at least 10 percent in a blend. But for brewed Kona coffee, similar disclosures are often absent.

Kona coffee farmers say that’s not fair. And so they want the Legislature to expand a more than 25-year-old state law that helps protect the industry from unscrupulous companies passing off cheaper foreign coffees as the much more expensive variety grown in Kona, mainly on small farms.

Nineteen representatives in the state House sponsored a bill to do this, and the measure passed the House Committee on Agriculture on Wednesday.

The bill would expand a law that requires disclosing the origin and quantity of Hawaii-grown coffee beans, including instant coffee, so that it also applies to brewed coffees advertised as being of Hawaii origin.

House Bill 1757 was prompted partly by a Kona Coffee Farmers Association complaint to the state Department of Agriculture in October about bottles of KonaRed cold-brew coffees labeled to suggest Kona coffee makes up at least half the product.

The association also expressed concern about other ready-to-drink coffees using the Kona name but not disclosing how much, if any, Kona coffee is present, such as cans of Royal Mills Hawaiian Kona Premium Coffee.

KonaRed said it was adjusting its labeling, and major retailer Costco quickly added the disclosure on price tags for the product stating that it contains 10 percent Kona coffee.

Yet the issue, farmers say, is widespread from store shelves to cups of coffee sold in cafes, and that the harm includes Kona farmers getting paid less while consumers get a false and bad impression of Kona coffee.

Suzanne Shriner, operator of the family-run Lions Gate Farms, told lawmakers in written testimony that she recently picked up a can of cold-brew coffee using the Kona name in a convenience store and had no idea how much Kona coffee might be inside.

“The state does not currently regulate such products, so vendors are free to use and misuse the trademark at will,” she said of the Kona name. “Our island farmers do not earn any money from mainland coffee that is mislabeled as ‘Kona’ or ‘Hawaiian.’ And consumers now associate Kona coffee with some bitter brew they drank at a convenience store. This is very bad for my gourmet brand. For the same reason that Louis Vuitton fights the cheap ripoffs sold out of back alleys, we Kona farmers are trying to protect our name.”

Kona coffee commands a premium. A medium cup of 100 percent Kona at the Morning Brew cafe in Kakaako sells for $4.15, compared with $2.60 for the house coffee. At Starbucks an 8.8-ounce package of 100 percent Kona retails for $24, compared with 16-ounce packages of other varieties for $13.

About a dozen other Kona coffee farmers and supporters submitted written testimony in favor of the bill.

The Hawaii Food Industry Association, representing food retailers, distributors, producers and suppliers, opposed the bill. Lauren Zirbel, association executive director, said in written testimony that labeling guidelines should be determined at the national level, as most ready-to-drink coffee is distributed nationally.

“Placing stricter requirements on Hawaii coffee beverages unfairly places certain companies at a disadvantage,” she said. “This law would make it harder for businesses selling Hawaii coffee to create labels that best suit their brand and promote local coffee to consumers.”

The state Department of Agriculture said in testimony that it supports Hawaii’s coffee industry but that it can’t determine the content or origin(s) of coffee after roasting. Department Director Scott Enright also added that the agency lacks jurisdiction to enforce such a rule, if it were law, for coffee beverages produced out of state.

Kona coffee farmer Bruce Corker took issue with Enright’s concerns. He said the state should do what it can to prevent misleading or fraudulent labeling of products sold in Hawaii, and that most marketers would obey the law that protects local farmers and lets consumers know what they are buying.

Corker, who operates Rancho Aloha, also said testing can be done on brewed coffee to determine origin. He cited a 2009 study by University of Hawaii researchers published in the Journal of Food Science.

One of the authors, Qing X. Li, a professor in the Department of Molecular Biosciences and Bioengineering at the College of Tropical Agriculture and Human Resources, said the team’s analysis showed that the presence of chemical profiles of Kona coffee can be determined in brewed coffee through a procedure called Fourier transform infrared spectroscopy.

“It provides a fingerprint,” Li said, adding that the equipment and procedure are quite affordable, quick and easy to use.

Shriner of Lions Gate said amending the law will make a difference in the lives of hundreds of small farmers.

“Our coffee is more than just a cup of coffee,” she said. “It is an excellent cup of coffee, and it represents a way of life that is under threat.”