Whole fresh farmed striped catfish (P. hypophthalmus) (approximately
2 years old) weighing 1 ± 0.5 kg/fish stored on ice were
procured from the fish market of Hat Yai, Songhkla, Thailand. Fish
were stored in ice with a fish/ice ratio of 1:2 (w/w) and transported
within 1 h to the Department of Food Technology, Prince of Songkla
University, Hat Yai, Thailand. Upon arrival, fish were washed
using tap water and deskinned. The skin was washed with cold
water (5–8 C) and cut into small pieces (0.5 0.5 cm2). The prepared
skin samples were packed in polyethylene bags and kept
at 20 C until used. The storage time was not longer than
1 month.