Tesco's Group Technical Director Tim Smith said the supermarket was "appalled" over the burgers that contained 29% horsemeat and they took "full responsibility" for the error.
Mr Smith told the Commons Environment Committee that the supermarket would "continue to investigate as though Tesco and not the supplier was responsible."
More top news
The Defence Secretary Michael Fallon repeatedly refused to confirm details of the test when he was summoned to the Commons.
Mrs Bush was hospitalised after experiencing fatigue and coughing and was admitted just days after her husband George H.W. Bush.
The Football Association has charged Arsenal manager Arsene Wenger with misconduct in the wake of Sunday's game with Burnley.