In this article we will discuss about the Processing of Shrimps: - A. Preservation on Board B. Shrimp Handling on Shore.
On sea, shrimps are frozen in cold brine or a solution of sugar and salt. This is done by air blast freezing or by plate freezing. Cooked as well as raw, whole shrimp can be frozen in a plate freezer, but immersion freezing of cooked shrimp cannot be done as the thawed shrimp are difficult to peel. Improved glaze on the shrimp can be obtained by freezing in sugar and salt solution.
The frozen shrimp can be stored at sea at -30°C and transferred to shore cold storage on arrival at the port, or thawed immediately for further processing.
Immediately after catching, cooking helps to retain the best flavour and texture. However, if the product gets contaminated after cooking, food poisoning bacteria can grow rapidly on it. To reduce such risk of poisoning, the cooked shrimp should be frozen on board immediately.
The whole shrimp, after sorting and washing, are packed in ice in shallow boxes. In the box successive layers of crushed ice and shrimps are placed till it is fully packed. Subsequently, for best result the iced shrimp should be processed on shore within 2 days of capture.
Whole raw shrimps on landing should be processed in factories without wasting much time.
(a) Thawing of Frozen Whole Shrimp:
Blocks of whole shrimp frozen at sea, when brought to shore are thawed in air or water. The thawed strimps can then be processed further.
(b) Size Grading:
Whole raw shrimp in the factory are first graded for size. The bigger sized shrimps are mechanically peeled. Small shrimps are uneconomical to peel and are discarded. They are chopped and used as raw material for various products.
The shells of the shrimps are normally peeled by hand. Peeling machines are now available commercially which can handle deep water shrimp. The shrimps are beheaded the shell is split along the back and then pulled out from the meats. A small incision is done on the dorsal side to remove the digestive tract.
Particular attention is to be paid to hygiene and sanitation. Regular bacteriological control is essential for this type of product. Care should be taken at the time of peeling process, particularly hand peeling.
Workers should clean their hand frequently and all working surfaces must be kept clean. To keep down contamination, chlorinated water should be used and the shrimp should be kept cool throughout the process. Machine peeling, however, results in far less re-contamination.
Cooking of shrimp provides a product that is ready to eat. Cooking, prior to peeling, is also done to loosen the meat in the shell, so that peeling becomes easy.
Water containing 3-5 per cent salt is used with a ratio of 1 kg shrimp to 20 litres of water. Use of stronger brines can cause discolouration. The boiling time should be such so as to develop fully the flavour and texture of the shrimp meat. Overcooking would destroy the flavour and result in loss of weight.