35-2

C. WANG¹, B. Wang, Y. Zhang, and J. Tidwell⁴. (1) Human Nutrition Program, Kentucky State University, 213 Atwood Building, Frankfort, KY 40601, (2) Aquaculture Research Center, Kentucky State University, Frankfort, KY 40601

JUSTIFICATION: Refrigeration and freezing are two important methods for preserving meat, fish, and shrimps. For fish and land animal meat, freezing is usually applied post rigor mortis because texture and overall quality of the meat are adversely affected by freezing prior to rigor mortis. However, there is no report on the texture of freshwater prawns related to rigor mortis with refrigeration and freezing storage.

OBJECTIVES: The objectives of this study were to examine the changes in the texture of freshwater prawns stored refrigerated and frozen before and after rigor mortis so that proper procedures could be established to preserve the shrimps.

METHODS: Twenty male and twenty female shrimps were de-headed and put on ice for 0, 2, 4, 6, 8, 16, 24, 48, 96, and 192 hours. At each designated time, ten shrimps each from the male and female groups were analyzed for textural changes and the other ten shrimps were frozen in a -20 C freezer. One month later, the frozen shrimps were thawed, cooked, shelled, and analyzed for their textural changes.

RESULTS: The results indicated that the fracture force of male shrimps increased from 15 to 20 N with 16 hours of refrigeration. The fracture force of female shrimps increased from 18 N to 23 N with two hour refrigeration. After one month of frozen storage, these shrimps also exhibited higher fracture force and cooking yield than the control(P<0.05). Shrimps refrigerated for longer periods before frozen had slightly lower fracture force but higher cooking yield.

SIGNIFICANCE: Rigor mortis appeared to occur after 16 hours and 2 hours of refrigeration for male and female shrimps, respectively. To enhance texture and increase the cooking yield, freshwater prawns need to be frozen after rigor mortis.