RESUMO
Spotted shrimp ( Pandalus platyceros ) were stored head on and head off on melting ice in air and controlled atmosphere for 14 d to test effects of controlled atmosphere on storage life of the shrimp. Pure carbon dioxide was allowed to flow through the controlled atmosphere chamber at the rate of 0.5 L/min maintaining a 100% CO2 atmosphere. Aerobic bacteria counts, ammonia, weight loss and sensory analyses were determined initially and after 7 and 14 d. Bacterial counts increased more rapidly and to higher levels in air pack than controlled atmosphere samples. The levels of ammonia were very low in the fresh shrimp and increased to 21 and 16 mg% in head-on and head-off air-pack samples, respectively. The levels reached only 12 and 6 mg% in similar samples stored in CO2. Weight loss was greater for shrimp stored in CO2 than in air. Sensory evaluation showed air-pack head-off samples to be unacceptable after 14 d of storage but CO2-packed samples had only moderate discoloration and no detectable off-odors. These data show that spotted shrimp could be shipped on ice under controlled atmosphere to fresh fish markets.
RESUMO
Shrimp ( Pandalus platyceros ) were packed head-on and head-off in pouches with air or 50 or 100% CO2 and stored at 0 to 2°C for up to 23 d. Carbon dioxide in modified atmosphere pouches dissolved in the liquid phase and the pH decreased. As storage progressed, the pH increased. Only 100% CO2 was effective in extending the lag in bacterial growth, but the greatest weight or drip was also obtained with this atmosphere. The bacterial flora changed from mixed gram-negative and gram-positive organisms to a predominantly gram-positive flora. Ammonia was produced throughout storage in all atmospheres, but was delayed longer in head-off than in head-on shrimp. Indole was produced readily in air packs but only at low levels in CO2 packs.
