Tuna meat was purchased from Xiangshan blue whale aquatic products co. LTD. Alkaline protease was purchased from Novozymes Biotechnology Co., Ltd, China. Sodium selenite (Na2SeO3) was purchased from Shanghai Sinopharm Co., Ltd. Kunming mice were obtained from Guangzhou University of Chinese Medicine. Interleukin-1 (IL-1), interleukin-2 (IL-2), interferon-γ (IFN-γ), tumor necrosis factor-α (TNF- α), immunoglobulin A (Ig A), immunoglobulin G (Ig G), immunoglobulin M (Ig M), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) kits were purchased from Shanghai Hengyuan biological technology co., LTD. All of the chemicals used were of analytical grade or better.