This was despite undercover footage from the investigation showing that chicken drumsticks returned by Lidl were repackaged under Willow Farms.
The investigation also found workers at 2 Sisters’ plant in West Bromwich had been altering the slaughter dates of poultry processed at the plant. Tesco joined other supermarkets in boycotting the plant, and 2 Sisters has now suspended operations there.
Lewis, speaking on a conference call for Tesco’s half-year results, said that he and other top executives had visited 2 Sisters plants in the past year and that Tesco had carried out six separate audits of the business.
Food safety was "absolutely our priority", Lewis said, adding that Tesco had immediately investigated following the news coming out. He added that he wanted to re-emphasise there was no suggestion that unsafe food had reached Tesco.
Tesco at the weekend removed a claim from its website that the Willow Farms brand was "reared exclusively" for Tesco, with a spokesman confirming that this was mistaken.
But Lewis said consumers understood more about the realities of food production than they were given credit for.
"Willow Farms is exclusively a Tesco brand," Lewis said. "It has a quality specification for the chicken brought to market under that brand, and that will be maintained, as will the brand.
"When we created the brand, we did an awful lot of work with customer involvement. More credit should be given to customers – they understand that a single farming entity is not possible to supply a business the size of Tesco."
He added that the seven farm brands, which include meat, poultry and both British and imported fruit and veg, were now appearing in 70% of baskets. "They give customers a value and quality they appreciate," Lewis said.
Tesco reported group sales up 3.3%to £25.2bn in the first half of its financial year – the 26 weeks ending 26 August. With inflation having gradually risen since the Brexit vote, this represents a real increase of 0.7%.
UK like-for-like sales were up 2.2% – less than the current rate of inflation, which is 2.9%.
But operating profit grew more handsomely across the business to £759m, up 27.3% year on year.