One prominent theory is that word came to English from the Cantonese name for tomato sauce which is "kei zap" (茄汁 which is a shorterned version of 蕃茄汁).
One prominent theory is that word came to English via Hong Kong. The Cantonese word for tomato sauce is "kei zap" (茄汁 which is a shorterned version of 蕃茄汁).