Storage experiments
In fresh condition B. pterotum has firm flesh and a strong and very typical smell which is difficult to describe.
(i) No cooling, no draining.
A quantity of 10 kg fish caught 3/8 in the Gulf of Oman (trawl station 202, N 24°03' E 58°07') with an initial temperature of 25 C and a pH 6.6 was held in a container at ambient temperature. Changes during storage are recorded in Table 16. Samples were prepared during the experiment for later analysis in Tromsø: 40 grams minced fish was mixed with 40 ml of 10% TCA (Trichloracetic acid) and subsequently frozen; also 1 kg was taken from the batch and frozen as well.
Table 16. Storage experiment with B. pterotum.
|
Day |
time |
temp.(°C) |
pH |
Appearance and smell |
|
3/8 |
12.30 |
24.8 |
6.6 |
fresh |
|
14.30 |
31.0 |
6.6 |
fresh |
|
|
16.45 |
31.4 |
6.7 |
not fresh |
|
|
18.45 |
31.6 |
6.7 |
not fresh |
|
|
21.00 |
33.8 |
6.6 |
slightly spoiled |
|
|
4/8 |
03.00 |
30.2 |
6.5 |
spoiled |
A quality of 20 liters of fish caught 2/8 in the Gulf of Oman at trawl station 199 (N 24°03' E 58°07') was mixed with 10 liters crushed freshwater ice and stored in the chill room of the ship which is normally kept at -10°C. Changes are seen in Table 17. Samples were taken during the experiment for further analysis in Tromsø.
Table 17. Storage experiment with B. pterotum.
|
Day |
time |
temp. |
(°C) |
pH |
Appearance and smell |
|
2/8 |
23.00 |
25.0 |
6.6 |
fresh, bright, typical smell |
|
|
24.00 |
8.4 |
7.3 |
fresh; paler |
||
|
3/8 |
24/00 |
-1.0 |
7.4 |
fresh; pale |
|
|
4/8 |
|
0 |
7.2 |
|
|
|
5/8 |
|
1 |
7.0 |
|
|
|
7/8 |
|
8 |
7.3 |
fresh; pale |
|
|
8/8 |
|
5 |
7.8 |
|
|
|
9/8 |
|
6 |
7.0 |
not fresh; paler; softening; sweet smell |
|
|
10/8 |
|
3 |
7.4 |
not fresh; paler; softening; sweet smell |
|
|
11/8 |
|
|
|
not fresh; paler; softening; sweet smell |
|
|
12/8 |
|
|
|
slightly spoiled |
|
|
13/8 |
|
|
|
spoiled |
|
Silage was prepared from 5 liters minced fish and 85 ml of a mixture of propionic and formic acid (1:1) both of 85% concentration. After mixing the pH was 4.5. The fish had been caught 3/8 at trawl station 202 (N 24°03' E 58°07') in the Gulf of Oman. The initial temperature was 24.8°C. Daily samples were taken for analysis in Tromsø.
Autolysis
A quantity of 10 liters fish caught 3/8 in the Gulf of Oman at trawl station 202 was stored at 45°C in the engine room of the ship. After 6 hours the fish was spoiled. It appears that the initial temperature of 25°C is too low and warming up too slow to obtain any positive preserving effects of the high ambient temperature.
