Quality Control 



Quality control must start immediately after the net is 

 hauled aboard the boat. Exposure to heat, trawling too long, allow- 

 ing oil slick to settle on the deck, failure to wash or ice the shrimp 

 properly, and negligent handling in unloading and transferring are 

 among the many causes of spoilage over which vessel personnel have 

 some degree of control. Other known factors are delays caused hy 

 stomy weather, prolonged heat spells, exhaustion of the vessel's 

 ice supply or a mechanical breakdown in refrigeration equipment. 

 Quality control during production and processing are described in 

 the following sections. 



Aboard Ship 



Proper methods of icing shrimp and insulating storage bins 

 aboard ship have been described In Chapter III - Pishing Operations. 

 When shrimp are held too long In Ice, softening, "black- spot" dis- 

 coloration, and loss of flavor vlll occur. Melanogenesls or "black- 

 spot" formation in the shell of the shrimp does not necessarily 

 Indicate spoilage of product. It Is caused by oxidization rather 

 than by bacteria. As experiments described below have shown. It can 

 be combated by dipping the shrimp In sodlxim bisulfite solutions. 

 SodltDB bisulfite Is a cheap chemical irtilch has been used for years 

 In the processing of dried fruits to prevent darkening. The en- 

 couraging results obtained by the research staff of the Marine 

 Laboratory of the University of Mlsml, Florida, In their tests with 

 shrliBp samples have brought about the approval by the United States 

 Food and Drug Administration of this chemical for use In controlling 

 "black-spot" fomatlon. Ibe user of the antl-oxldant must be cau- 

 tioned that overexposure of shrimp to sodium bisulfite may cause 

 yellowish discoloration as well as a slight off -taste. 



O^ough not Indicative of spoilage, "black-spot" will account 

 for a down-grading of quality and lowered receipts for the catch, llius, 

 shrimp which normally would be graded as "pearls" 9/ (top quality) could 

 be sold only as "good" 9/, the next lower classification. Where quality 

 deterioration has proceeded to the point i^ere the color on the belly 

 of the shrimp appears gray (as the result of the progressive leaching 

 by the melting Ice water), the catch would be rated as "culls" 9/^ the 

 lowest standard for xmbroken shrimp. 



Signs of quality deterioration other than "black- spot" are 

 Increased bacterial loads and olefactory sensations Imparted by the 

 so-called "Iodoform", "sulfide", and "stinker" shrimp. Interesting 

 to note In this connection are the cdJLeged Increased deterioration 

 rates of shrimp caught at night as ccnpared to those of shrimp caught 

 during day-time , a phenomenon i^hlch some flshexmen ascribe to moon- 

 light. 



9/ Grade classifications used in Florida ports, 



81 



