Effect of pre-cooking times on enzymes, properties, and melanosis of Pacific white shrimp during refrigerated storage

Authors

• Kusaimah Manheem ¹
• Soottawat Benjakul ¹
• Kongkarn Kijroongrojana ¹
• Nandhsha Faithong ¹
• Wonnop Visessanguan ²

¹ Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand

² National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Phaholyothin Rd., Klong 1, Klong Luang, Pathumthani 12120, Thailand.

10.1186/2008-6970-5-1

Abstract

Pre-cooked shrimp have gained interest due to their attractive color and flavor. However, shrimp without sufficient pre-cooking have faced melanosis, particularly during the extended storage. This leads to the rejection by consumers and the market. Therefore, pre-cooking with appropriate time would be a means to tackle such a problem. The objective of this study was to investigate the effect of pre-cooking times on enzyme activities, properties, microstructure, and melanosis of Pacific white shrimp (Litopenaeus vannamei). Pacific white shrimp were subjected to pre-cooking at 80°C for various times (0 to 120 s). The residual activities of polyphenoloxidase (PPO) and protease decreased with increasing pre-cooking times (p < 0.05). Nevertheless, the increasing pre-cooking time resulted in more cooking loss. With cooking time above 60 s, a cooking loss of 9.85% was obtained (p < 0.05). Marked decreases in the relative PPO and protease activities were observed within the first 30 s of pre-cooking, and negligible activities were detected after 120 s. The microstructure study revealed that the muscle fibers of pre-cooked shrimps were less attached with concomitantly higher shrinkage of the sarcomere, compared with those of the raw counterpart. Shrimps pre-cooked with longer time showed a lower development of black spots as evidenced by a lower melanosis score throughout storage of 7 days at 4°C. Therefore, a pre-cooking time of 30 s at 80°C was sufficient to lower PPO and protease activities with the minimized cooking loss and melanosis during refrigerated storage.

Keywords

• Pre-cooking time
• Pacific white shrimp
• Melanosis
• Polyphenoloxidase
• Protease
• Cooking loss
• Microstructure

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