The weight of the blocks are generally maintained at 2 Ibs, 4 Ibs, 1 kg, 1.8 kg or 2 kg, as dictated by the buyers. Prawn is also weighted in kg, if the buyer wants. Grade 2/4 means that there are two to four prawns in each pound in the packet. Items to be frozen through contact freezer are packed in small paper boxes according to export grade such as 2/4, 4/6, 6/8, 8/12, 12/15, 15/18, etc. Prepared items are washed again followed by pressure washing through strong water jet by a motor. as shown in Table 10.3 are generally prepared. Products of different categories, like tail on, tail off, peeled undeveined (PUD), peeled and deveined (P & D), shell on (S/O), etc. Prawn mixed with ice is taken on the panning table for dressing and preparing for the product as per the buyer's demand. Prawns are washed again with chilled water and re-iced with the flake ice or crushed block ice produced by the factory itself. Factory grading is done on the basis of the size of prawn, ranging from U5 to U16. The prawns are washed with potable chilled water, graded, called the factory grading and then weighed. The raw material prawn, either headless on head on, is received through the receiving window (temperature 4 to 5☌) of the processing factory. The storage of frozen fish is ideal at -30☌ to have minimum quality changes and many countries have adopted -30☌ as recommended storage temperature for frozen shrimp. The products are packed in master cartons and kept stored at - 20☌. Addition of citric acid, sugar and chloride are permissible in glaze water at the levels 0.2, 0.5 and 0.5% respectively. In block freezing glaze water can be added prior to freezing to produce uniform glaze. The glaze water should contain 5 to 10 mg/kg available chlorine. In order to prevent freeze drying of the body surface, glazing is done with cold water. The contact time may vary from 5 to 15 min depending on the thickness of the shrimp. A common equipment for value-added IQF products of shrimp is spiral freezer. Either spiral, tunnel or belt freezer can be used for individual quick freezing of shrimp. The anterior core of the block should attain a temperature of about - 15☌ to - 20☌.įor individual quick freezing (IQF), the blanched or graded shrimps are individually loaded into the conveyer of the IQF machine and frozen rapidly in the freezing chamber. Thickness of the block should be around 5 cm. The quicker the freezing, the better the quality. The time taken for the freezing operation varies from 1.5 to 3 h depending on the cooling efficiency of the freezer and the thickness of the slab. They are then quick frozen in contact plate freezer at - 40☌. For block freezing, the graded shrimps are weighed and packed in wax laminated cartons with a lining of water-proof material. The material is then processed further for freezing either as blocks or individuals. They are washed in potable water containing 10 mg/kg available chlorine. After blanching, the shrimps are graded into different sizes. Best result can be obtained by immediate cooling in chilled water subsequent to blanching. Blanching gives a good color to the meat but care should be taken that the product is not cooked. The material should be stored in stainless steel or polypropylene/plastic containers in crushed ice- water maintained at 2 to 3☌.įor blanched products, the materials should be blanched in stainless steel container, heated electrically or by steam by holding the products in water with or without additives or exposing to steam. The recommended storage temperature is 3☌ till it is processed in the factory. Hence, it is imperative that the shrimp should be iced immediately after capture. Quality of frozen shrimp depends on the freshness of raw materials. Chill storage: The iced shrimp is kept in a chilled room maintained at an operational temperature of 4☌ ± 2☌ until further processing for freezing.Īll these types of pre-processed shrimps are frozen either as block or individual quick frozen (IQF) product depending on foreign buyer's requirements. Icing: The graded and weighed shrimp is iced again to maintain the temperature around 0☌.Ħ. Weighing: The desired quality is weighed in bulk for processing.ĥ. Grading: grading is done as per the size of shrimp.Ĥ. At no stage should the temperature of shrimp be above 5☌ to maintain top quality of the final product.ģ. Icing: The shrimps are iced immediately after capture and re-iced after coming to the factory. If any black spots are seen, it should be discarded.Ģ. There should not be any black spot formed. Inspection for quality: The shrimps are inspected for freshness visually. General freezing steps and methods are described below.ġ. Shrimp freezing is the most vital of all freezing plants operating for processing of seafood.
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