Fresh white shrimp (Litopenaeus vannamei) shells were obtained from a frozen shrimp processing plant in Samut-Sakorn province, Thailand. The samples were covered with ice and transported to the laboratory within 2 h. Upon arrival at the laboratory, samples were divided into several portions with the weight approximately 1 kg. Each portion was packed into plastic food storage bags and frozen at −20 °C for up to 2 months. Prior to use, samples were thawed by submerging the bag under cool running tap water.