A popular restaurant in Tokyo, Japan, sparked controversy for claiming to dip its delicious pork skewers in a sauce jar that has not been cleaned in over half a century.

Abe-chan, a famous pork skewer eatery in Tokyo’s Azabu Juban shopping district, was recently featured on a popular Japanese television show where it was revealed that one of the secrets to its success was a rather dubious-looking jar covered in a gelatinous mass. Apparently, this was the same sauce jar that pork skewers have been dipped in for the last sixty years, and the dark brown mass around the jar is the sauce that spilled over and hardened over the decades. According to the third-generation owner of Abe-chan, the jar has never been cleaned in the last six decades, which apparently contributes to the rich taste of the sauce.

Instead of cleaning the sauce jar every day, after closing, the staff at Abe-chan simply pours more sauce over the leftovers of the day, which only amplifies its aroma. The congealed mass around the earthen pot of sauce isn’t the most appetizing sight when ordering street food, but for the owners of Abe-chan it is a valuable treasure put on display right next to the charcoal grill.

Abe-chan was reportedly founded in 1933 by the grandfather of the current owner, and the sauce jar has been around since those early days. The tradition of adding to the sauce without actually cleaning the container has been respected by all three generations, and the current owner is convinced that it contributed to the success of the family business.

During the television show, experts were asked about the potential hygiene hazards of simply adding new sauce in a container that hasn’t been cleaned in several decades and one of them said that if the sauce is heat-treated long enough, there shouldn’t be any danger of bacterial contamination. Also, an experiment where clean water was added to a container full of black water 365 times showed that most of the original contents didn’t even exist by the end. So it’s not like the sauce jar actually contains sauce from 60 years ago.

The television program caused quite a stir online, and while some Abe-chan patrons defended the eatery, claiming they had been eating there for years and had never experienced any health problems because of the food, others claimed that the deformed-looking sauce jar posed some serious hygiene concerns.

At the time of this writing, it’s unclear how Abe-chan is handling the criticism of its decades-old tradition. Some sources claim that the owner decided to go on with business as usual despite the controversy, while others say that he cleaned the jar for the first time in 60 years.

Interestingly, Abe-chan isn’t alone in its controversial practice. A few years ago, we featured another Japanese restaurant that had been using the same broth for 65 years, and earlier than that we had featured the noodle soup at Wattana Panich, in Thailand, which had been cooked in the same uncleaned pot for 45 years.