Mister Donut - the iconic franchise launched in the United States in 1955 and brought to Japan in 1970 - served "Fruity Milk" drinks made from expired melon- and strawberry-flavored syrups at shops across Japan, its operator Duskin Co. said.
The syrups, some almost 30 days past their expiry date, were used to prepare 1,075 servings of Fruity Milk sold at 181 Mister Donut outlets, according to Duskin spokesman Akira Kita. The drink was pulled from stores Wednesday.
"We're extremely sorry for causing our customers concern and trouble," Kita told reporters.
Duskin said in a statement it did not think the expired syrup posed a health risk, and that it had not received any complaints from customers.
Mister Donut has gained a following among mostly younger Japanese for its American-style doughnuts, decor and music, becoming the country's biggest donut chain.
Duskin, whose main business involves renting cleaning equipment, also operates almost 1,500 Mister Donut stores across Asia, including the Philippines, Thailand, Taiwan, China and South Korea.
But stores in their native United States have changed their name to Dunkin' Donuts after Allied-Lyons acquired Mister Donut in 1990.
The scandal at Mister Donut follows a slew of food companies in Japan that have admitted using outdated ingredients or falsely labeling their products, threatening Japan's reputation for impeccable sanitation.
Earlier this month, a respected maker of traditional Japanese sweets, Akafuku Co., was found to have recycled the red bean filling in its rice cakes, collecting old filling from leftover boxes and shipping them out as new. That came after another famous confectioner, Fujiya Co., admitted using old milk in its cream puffs.
Two meat companies were also raided this month for falsely labeling products. In one case, a meat processor falsely labeled pork, chicken and beef mixture as pure ground beef.
"I've stopped being surprised. There are scandals everywhere," said Mami Igarashi, 21, a frequent Mister Donut customer who was strolling near an outlet in central Tokyo.
"I liked Mister Donut because their donuts are good and cheap. But now I'm worried about eating there," Igarashi said.
Analysts say price wars in Japan's food industry have squeezed profits and spurred companies to cut corners.
They also worry that the scandals have hurt the image of Japanese food overseas at a time when companies are looking to expand internationally.
No old syrup was used in drinks sold overseas, according to Duskin.