Environment health officers inspect and grade establishments on overall standards, conduct and maintenance, process control, cleaning and sanitising and staff training.
Barilla joined 28 others to hold a D grade in Auckland after an inspection in May, out of more than 3600 establishments in the city, a council spokesperson said.
It previously held a B grade.
Spokesman for the family business Peng Li told the Herald food safety had improved since the inspection, and they were expecting to pass the next review.
"We already do everything that we had made mistakes before, and made it better," he said. "We stored some stuff, like condiments that we didn't use, out the back and they asked me to pack away, and also we made the dumplings on the cage out the back but they said it's not pretty safe and so we moved to inside now."
When the Herald visited last night, a sign advertising the grade that was displayed in the window earlier in the day had been removed.
Mr Li said he did not know why it had been removed from the window, or why it was not displayed anywhere in the store.
Regular diners, Auckland men Simon Campbell, 26, Jack Merridew, 23, and Bill Walsh, 22, said they were surprised such a popular restaurant would have a low grade, but kept eating their meals as they spoke to a reporter.
"We have eaten here before and never had any problems," said Mr Merridew. "To not display [the grade] is not really fair. Our food ratings must be really high in New Zealand."
As part of its grading, Barilla will be inspected by council officers three times in the next year.
D is for dumplings
The 12 reasons Barilla Dumpling was graded D for food safety by Auckland City Council:
1. Licence and grade not visible to public.
2. Shed in backyard used to store and prepare food.
3. Food stored in a toilet isolation lobby.
4. Hot water supply to taps disrupted by dishwasher.
5. Cloth towel to wipe surfaces after sanitising.
6. Food handlers wear dirty aprons and do not use hair restraints.
7. Food stored uncovered inside fridge/freezer.
8. Overcrowding in kitchen.
9. Food stored and prepared next to a wastewater drain.
10. Backyard full of clutter.
11. Poor general cleaning practices.
12. Stove with no exhaust used.
Auckland's Food Grades
A - 3401
B - 192
D - 29
E - 10
There are four grades: A, B, D and E. There is no C grade as establishments are either above or below "average" safety standards.