The effects of some plant extracts on the melanosis inhibition and quality changes in shrimp

In this study, the effect of some plant extracts with high antioxidant activity on melanosis formation and shelf life in shrimp was investigated. Aristeus antennatus (Risso,1816) was used as the research material. Dried rosemary and green tea were extracted in ethanol. Dipping solutions were prepared using distilled water. Treatment groups were green tea and rosemary extracts, sodium metabsulphite and sodium metabisulphite based combinations with plant extracts. After catching, the shrimps were divided immediately into 8 groups and dipped into solutions. The treatment groups were stored at 4 °C. Melanosis and quality changes were evaluated daily during the storage.There were significant differences in phenolic content and antioxidant activity between green tea and rosemary extracts. Green tea extract had higher level of total phenolic content and antioxidant activity than rosemary extract.Total volatile bases (TVB-N), Trimethyl amine nitrogen (TMA-N) and pH increased during the storage. Rosemary extract was more effective than green tea extract for preserving the quality. The combinations of sodium metabisulphite and plant extracts treatment showed the best results. The combinations of sodium metabisulphite and plant extracts were the most effective treatment for delaying melanosis. Green tea was more effective than rosemary extract. The combinations of sodium metabisulphite and plant extracts had high L and a values. Sodium metabisulphite was effective for keeping the red colour of shrimps, whereas rosemary and green tea extract treatment groups had lower values. The results of L and a values were correlated with sensory melanosis scores in all treatments