Revealing the secret to her success in preparing meals for Madiba, his family and many guests who have visited the Mandela residence, Ndoyiya, who regards Madiba as her parent and leader said: "The food that I have been feeding Tata does not have any secrets.

"The reason that I have had to come up with this book is because whenever the children or guests come to the house they always accuse me of having a secret," said Ndoyiya, whose first job was peeling potatoes and washing dishes.

"Now I am saying YES there is a secret – it's love. I cook food with love."

The cookbook contains a collection of more than 60 recipes that Ndoyiya has prepared over the last 19 years.

Unable to attend the event Mr Mandela's granddaughter, Ndileka Mandela read out a letter from him and his wife Graca Machel which said: "Your love and devotion to Madiba and I is beyond words."

Various family members spoke in praise of Ndoyiya. Mandela's grandson Luvuyo Mandela said: "uMam'Xoli has been the family's best kept secret. She is more than someone who prepared meals ... she was a parent to us."

He thanked an emotional Ndoyiya for her "many sacrifices" including spending more time with his family than with her own family in the Eastern Cape.

"Thank you for everything, we love you," said Luvuyo.

Also in attendance at the launch, held at the Nelson Mandela Centre of Memory, was Mrs Paulette Rothstein, who employed Ndoyiya when she first came to Johannesburg in the 1980s.