The majority of substantiated claims against Wallace related to inappropriate sexual language and humour, but also culturally insensitive or racist comments.
In his first interview since being sacked, the presenter acknowledged that he had said things that "offended people, that weren't socially acceptable and perhaps they felt too intimidated or nervous to say anything at the time.
"I understand that now - and to anyone I have hurt, I am so sorry."
He indicated his background was to blame for those comments, as a former greengrocer from Peckham working in an environment that was "jovial and crude".
But he added: "I'm not a groper. People think I've been taking my trousers down and exposing myself - I am not a flasher.
"People think I'm a sex pest. I am not."
Wallace said that one of the upheld claims against him related to a widely reported incident in which he had allegedly walked around MasterChef's set naked with a sock on his penis.
Addressing that incident, he said that there were no contestants on set, and just four of his friends from the show outside his dressing room door.
"I was getting changed to go to a black tie event, a charity event. I put my bow tie on and my shirt. It's only them outside the door. I put the sock on, opened the door, went, 'Wahey!' and shut the door again.
"The people interviewed were either amused or bemused. Nobody was distressed," he claimed.