Not loving it: McDonald's faces safety investigation after serving stomach-churning RAW Big Mac Sue Bennett opened her bun and saw one of her burgers was raw A quick test showed it was half the minimum temperature for cooking Health inspectors are testing the product and investigating the branch McDonald's said it had retrained staff after this 'isolated incident' McDonald's has apologised to a customer who was served this stomach-churning burger - which was raw in the middle. Sue Bennett, 43, choked in disgust as she took the top of the bun off the burger to remove the gherkins. One of the meat patties was pink and uncooked so she took it to the manageress, who tested it with a temperature probe. Disgusted: Sue Bennett has handed her raw McDonald's burger over to public health inspectors after she realised it was raw in the middle It gave a reading of 39 degrees C - nearly half the minimum temperature for cooking the burger. Ms Bennett, a social services worker, was given a full refund for the Big Mac and a Fillet-o-Fish her husband Carl had bought at the branch in Dalton, Rotherham. She went home and alerted her local environmental services department who have now taken the burger away for examination. Ms Bennett, a mother-of-two, said: 'I was mortified. I took the burger apart to take off the gherkins and saw how red the burger was. It was so raw it was falling apart. I took it straight back to the manageress and asked her to test it. 'I know what the minimum core temperature of food should be as I've learnt about it as part of my job. 'I asked the manageress if she knew and she thought it may be 70C - it's actually a minimum of 75C. She put the probe in it and it showed 39C and I took it away. Evidence: When she opened up the bun, Ms Bennet saw one of her burgers was so uncooked it was falling apart, right. A test found it was only 39C McDonald's said it had retrained staff at its Dalton, Rotherham branch after this 'isolated incident' Ms Bennett, of Rotherham, said one of the patties in the Big Mac was properly cooked but the other was raw. She put the burger in a bag and stored it in her fridge until it was taken away by the environmental health officer on Wednesday. 'I'm not expecting any compensation - not that I was offered any, apart from my money back,' she said. 'But I don't think I'll be able to go back to McDonald's because I don't feel I can trust them any more. 'It's a shame because I did enjoy going there every now and then.' Rotherham Borough Council confirmed their Environmental Health department was investigating the complaint. McDonald's said: 'At McDonald's food quality and safety is of paramount importance. This isolated incident was investigated as soon as it occurred and staff have been retrained to prevent any recurrence. We apologise to Miss Bennett for this isolated lapse in our usual high standards of quality and customer service.