2025 Volume 33 Issue 4 Pages 508-514
Marine product processing companies often discard processing by-products, such as fish heads, skins, bones, and entrails; however, there is a growing demand for their effective utilization. In the present study, we prepared horse mackerel by-products (HMBP) and HMBP hydrolysates (HMBP-H) from the head, abdomen, mesosoma, and fins of horse mackerel (Trachurus japonicus) using protease. The effects of HMBP and HMBP-H on serum lipid concentrations were then examined in vivo. Four-week-old male C57BL/6J mice were fed a high-fat diet (Control, casein 23 wt%) and the control diet supplemented with HMBP and HMBP-H, respectively. HMBP and HMBP-H diets were formulated to comprise that the protein sourced from HMBP and HMBP-H constituted 3.2 wt% of the diets, respectively. After four weeks, blood and organs were collected. Serum triglyceride contents were lower in the HMBP and HMBP-H groups than in the control group. These decreases were partly attributed to reductions in the mRNA expression levels of liver fatty acid synthase and acetyl-CoA carboxylase, which are rate-limiting enzymes for fatty acid synthesis. Furthermore, serum total cholesterol contents were reduced in the HMBP-H group, but not in the HMBP group. This decrease may be related to the increased mRNA expression level of liver cholesterol 7 alpha-hydroxylase, which is the rate-limiting enzyme for cholesterol catabolism. These results suggest the potential of HMBP-H as a functional food material to attenuate hyperlipidemia.
