It means that of Preston's 245 restaurants, cafes and canteens with ratings, 187 (76%) have ratings of five and none have zero ratings.
The rating comes as it was revealed that the city council is considering introducing a fee for businesses which want their score re-assessed quickly after carrying out improvements.
Food places are rated from 0 to 5 by council inspectors who make unannounced visits every 12 to 18 months.
At present those who score low can apply for one free re-grading if they complete recommendations made by the assessors.
But council chiefs are now looking to bring in a £165 charge, insisting the taxpayer should not be footing the bill for food businesses to improve their score and thus their turnover.