Exploratory screening of wild-game tissues in Japan toward value-added utilization: estimated soluble protein/peptide yields and DPPH radical-scavenging and ACE-inhibitory activities after in vitro digestion

Abstract This exploratory study aimed to compare estimated soluble protein/peptide yields and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging and angiotensin-converting enzyme (ACE)-inhibitory activities after in vitro digestion of eight tissues from wild-caught sika deer and wild boar and corresponding cattle and pig tissues, with relevance to value-added utilization in Japan. Eight tissues were obtained from sika deer and wild boar (n = 5 each) and commercially sourced cattle and pigs (n = 3 per tissue per species). Heated samples underwent gastric and intestinal digestion. DPPH and ACE activities were expressed as IC₅₀ values and analyzed using Kruskal–Wallis tests followed by Dunn’s tests with Holm adjustment. Estimated soluble protein/peptide yields differed among species groups in six tissues. Wild boar had higher yields in the stomach than sika deer, in the liver than sika deer and cattle, and in the round than pigs, but a lower yield in the small intestine than pigs. Sika deer spleen had a lower yield than wild boar and cattle spleens. DPPH IC₅₀ values were lower in wild boar liver than cattle liver and in wild boar loin than sika deer and cattle loin. ACE IC₅₀ was lower in sika deer spleen than wild boar spleen. Differences were tissue dependent, and estimated soluble protein/peptide yield did not consistently correspond to either activity. Wild boar liver and loin and sika deer spleen may warrant further characterization as candidates for value-added utilization in Japan.