Effects of bioactive substances to prolong the shelf-life and inhibit the formation of black spots in black tiger shrimp (Penaeus monodon) preserved at 0 degree C

The objective of this study was to extend the shelf-life and inhibit the process of black spots formation in giant black tiger shrimp (Penaeus monodon) by using 1.5 % solutions of the bioactives including: gallic acid, caffelic acid and cinnamaldehyde. Shrimp samples were dipped in the solutions for ten minutes, at 4 degrees C and stored at 0 degrees C for 15 days. Total viable count (TVC), melanosis evaluation method, chemical quality indexes including total volatile base nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), pH and hypoxanthine values were used to evaluate the effectiveness of the treatments. TVC values, melanosis score of shrimp samples treated with bioactive compounds appeared more slowly, TVB-N and TMA-N values changed exponentially, hypoxanthine values increased linearly with storage time, and pH decreased on day 2, then increased gradually. Shelf life of treated samples were found to be longer than that of the control sample (8 days), and had a better ability to inhibit melanosis, in particular, the samples treated with a solution of cinnamaldehyde had the longest shelf life of 14 days, compared with 13 days of samples treated with caffelic acid and 12 days of the ones treated with gallic acid.