Changes in biogenic amines, biochemical and microbial attributes of three spotted crab (Portunus sanguinolentus) during iced and refrigerated storage.

Three spotted crab (Portunus sanguinolentus) is a preferred variety of crab among seafood consumers. Biochemical, microbial and sensory characters along with formation of biogenic amines of whole crabs stored under iced and refrigerated condition was evaluated. Cadaverine, putrescine and spermidine were the major amines formed during spoilage and a strong correlation between cadaverine and psychrotrophs was observed in refrigerated (0.92) and iced storage (0.86) respectively. Histamine was at lower level and not likely to cause any toxicological problems to consumers. Although TVB-N and TMA-N increased significantly (p < 0.01), TVBN was observed as a good indicator of spoilage than TMA-N. Mesophilic and psychrotrophic bacteria crossed 7 log CFU/g on 8th day, rejection day of refrigeration, while it was below spoilage limit in iced storage. A shelf life of 6 and 10 days were observed in storage under refrigeration and icing respectively based on microbiological, biochemical and sensory attributes.

Identification of allergic proteins of Flower tail shrimp (Metapenaeus dobsonii).

Allergy to seafood mainly fish and shellfish has been reported. Tropomyosin is recognized as a major allergen in many crustaceans especially shrimps. A study was carried out to identify the IgE reactive proteins of allergic nature in Flower tail shrimp (Metapenaeus dobsonii), a frequently consumed shrimp in India mainly in dried form. Protein profiling and identification of IgE reactive proteins in raw and cooked extracts of Flower tail shrimp was carried out by SDS-PAGE and immunoblotting using sera of 13 patients having allergic reactions on consumption of shrimp and positive to skin prick test. The IgE binding ability was determined by ELISA and it was found higher in the case of cooked extracts ranging from 0.244 to 0.440 at 490 nm. The SDS-PAGE of raw extract revealed many protein bands between 205 and 6.5 KDa, while in the case of cooked extracts bands of 36, 20, 29 and 70 KDa were prominent. Heat resistant protein of 37 KDa, tropomyosin was showing a clear immune reaction both in the case of raw and cooked extracts was identified as the major allergen by all the patient sera. The minor proteins of raw extract identified by immune reaction are 50, 75 and 100 KDa. The identified allergen can be used for the diagnosis and management of shrimp allergy.