Heads have rolled, staff retrained and investigations launched following a BBC Whistleblower documentary - but Tesco and Sainsbury's were insisting this week that the shocking practices were isolated incidents. Falsified records, serious breaches of hygiene and flouting of strict food safety procedures at Tesco's Woodford Green store in Essex, and Sainsbury's Didcot store were exposed by the BBC1 programme on Tuesday. Sainsbury's said it had launched an immediate investigation at the store and identified "some instances where our procedures had not been followed correctly, and we have already taken the necessary action". But any local breakdown in procedure was "entirely unrepresentative of the hard work and commitment to high standards displayed every day by employees". Speaking on a video-link from the store posted on the Tesco website less than 48 hours after the programme was aired, Tesco trading director Richard Brasher said: "It is disappointing for staff and customers to see our business portrayed in a way that frankly didn't represent the emphasis we put on hygiene, quality and safety in our stores. The UK is the envy of the world in terms of food safety enforcement." The store's compliance officer said: "If these incidents had been reported to me, I would have taken immediate action." Store checkout operations manager Rohin added: "It took four months of working in this store to find three or four things that were negative, which says everything about the programme." The Food Standards Agency is meeting local authorities to discuss preliminary findings following visits made to the businesses. A spokesman said it was very disappointed to see such practices occurring at these supermarkets. "We would normally expect them to set high standards, and indeed, have no evidence that such practices are widespread among retailers," it added. Trading Standards is also meeting with environmental health officers to investigate. Ian Marriott, group manager of Oxfordshire Trading Standards, said: "There are issues that need to be addressed. We will review our processes in order to establish whether this was a one-off situation that has slipped through the net or - God forbid - it is happening elsewhere. We would be daft not to learn from what has happened." An internal investigation is ongoing at Tesco but staff on the fresh food counters had been retrained, said a spokesman. Referring to an employee who had falsified records, made up sell-by dates for fish, and ordered defrosted prawns to be refrozen, he added. "It's fair to say Kelly will not be working on the fresh food counter." But Kelly and two other employees at Woodford Green had not been at the store in the two days following the programme, our investigations showed. The Grocer also discovered that three Sainsbury's employees implicated in the scandal, including the store manager, were no longer working at Didcot. A new store manager, Scott Dykes, was appointed a few weeks ago, said a source at the store. The documentary was watched by 4.5 million people but Richard Hyman, chairman of Verdict, said it would have minimal impact. "Some people will be put off but the impact of will be minimal for Tesco and Sainsbury's."