Environmental health officers inspected Fairway Premier on The Fairway in Banbury and awarded the convenience store a one-out-of-five food hygiene rating.
The visit, carried out by Cherwell District Council in August this year, identified several concerns.
Inspectors discovered a packet of ready-to-eat ham in a refrigerated display that was well beyond its use-by date.
Problems were also identified around the store’s slush puppy machine.
A nearby sink, intended for washing equipment, could not be accessed and was dirty, while the area surrounding the machine was described as dirty and cluttered.
Inspectors additionally found dust on the shop’s shelving and discarded packaging among the products.
The rear stockroom was overcrowded, with goods placed both on the floor and on shelving in what inspectors described as a very chaotic arrangement.
Council inspectors said the shop’s owners had not taken sufficient steps to ensure that food remained safe.
They also found that staff possessed insufficient knowledge of food hygiene standards.
Despite the low overall rating, officers judged the business’s hygienic food handling to be generally satisfactory at the time of the inspection.
This assessment covered the preparation, cooking, reheating, cooling and storage of food.
The cleanliness and condition of the premises, including its layout, ventilation, hand-washing facilities and pest-control arrangements, were also considered generally satisfactory.
However, the inspection identified a need for major improvement in the management of food safety.
Fairway Premier is part of Premier convenience stores, a nationwide chain operating more than 5,000 outlets across the UK.
The chain also operates several locations in Oxford, including The Oval in Rose Hill and Oxford Supermarket in Blackbird Leys.