Evaluation of sensory and bacterial content of frigate tuna raw material preserved by oligochitin combined with ice
Abstract
This study was conducted to evaluate the sensory and bacterial content in frigate tuna raw material caught in Khanh Hoa sea, Vietnam and then preserved by oligochitin (1÷3kDa) of 1,0% combined with ice (2±1ºC). Bacterial content evaluation included TPC, Shewanella putrefaciens and Pseudomonas spp of frigate tuna raw material (1000±50 gr/fish). The result showed that sensory quality satisfactory was for 21 days, starting to deteriorate on day 22; TPC was over the standard limit from day 16; Pseudomonas spp exceeded the threshold causing rot, about 2.1x109 cfu/g from day 22; Shewanella putrefaciens exceeded the threshold causing rot, about 1,5x109 cfu/g from day 18. Compared to the samples that was only used ice for preservation: Sensory quality lasted 1.9 times longer; TPC was 1.67; Pseudomonas spp was 1.65; and Shewanella putrefaciens was 1.59 times lower respectively.
