Histamine Production in Soy Extended Tuna Salads

Abstract

ABSTRACTHistamine production in tuna salads extended with textured soy protein (TSP) was evaluated. Salads were inoculated with five known histamine‐producing bacteria and held at 8°C, 24°C, and 37°C for up to 48 hr. Addition of 30% TSP to tuna salads resulted in higher initial pH and favorable growth conditions for microorganisms and histidine decarboxylase activity. Addition of 15% TSP provided an initial pH for maximal enzyme and histamine production but somewhat slower microbial growth. Tuna salad extended with either 15% or 30% TSP developed toxic levels of histamine (>50 mg/l00 g) when held at either 24° or 37°C for 6 hr. Nonextended tuna salads did not develop toxic levels of histamine even when inoculated with known histamine‐producing bacteria and held at 24° or 37°C for 48 hr.