Introduction: Hypertension is a chronic cardiovascular disease, which can trigger some disease such as heart failure, loss of vision or kidney. There were various peptides derived from food that are recognized for their ability to inhibit ACE activity, potentially leading to a reduction in blood pressure levels in vivo. The primary objective of this research is to discover ACE inhibitory peptides from protein hydrolysates of eel bone collagen (EBCHs).Methods: To begin, EBCHs were created and then divided through the process of ultrafiltration. The second step involved screening of peptides capable of inhibiting ACE by combining peptidomics and molecular docking. And the mechanism by which ACE interacts with peptides has been studied. Finally, the hypotensive mechanism of identified peptide through cell experiments with HUVEC (Human Umbilical Vein Endothelial Cells).Results: Eel (Anguilla japonica) bone collagen was hydrolyzed by alcalase and the hydrolysate was separated into three fractions, among which the F2 displayed a higher level of ACE inhibitory activity. According to molecular docking calculations, a total of 615 peptides were identified through nano-HPLC-MS/MS, with the prediction of seven newly discovered ACE inhibitory peptides (PMGPR, GPMGPR, GPAGPR, GPPGPPGL, GGPGPSGPR, GPIGPPGPR, GPSGAPGPR). Notably, GPPGPPGL had the lowest IC₅₀ value of 535.84 μM among the identified peptides, indicating its potency as an ACE inhibitor. The ACE S2 pocket formed hydrogen and hydrophobic interactions with GPPGPPGL. Lineweaver-Burk plots revealed that GPPGPPGL competitively bound to ACE’s active site residues. Treatment with GPPGPPGL significantly increased nitric oxide secretion (p < 0.01) and decreased endothelin-1 (ET-1) production in HUVECs.Discussion: Our findings suggest that combining peptidomics with molecular docking is effective for rapidly screening ACE inhibitory peptides. Future studies should assess the bioavailability and in vivo activity of the identified peptide GPPGPPGL from EBCHs.

Fermentation is an effective method for ameliorating the gelation properties of freshwater fish surimi, but the formation of biogenic amines (BAs) during fermentation should also be controlled. In this study, the BAs in fermented tilapia surimi were inhibited by the collaborative fermentation of Latilactobacillus sakei and Pediococcus acidilactici, followed by the revelation of the BA inhibition mechanism. Most of the BAs, and the total BA, as well as their precusor free amino acids (FAAs), were significantly reduced, while the umami FAAs, including glutamic acid and aspartic acid, were significantly enhanced after cooperative fermentation with starters. The high-throughput sequencing found that the spoilage microorganisms such as Acinetobacter, Micrococcus, and Streptococcus as well as Pediococcus were significantly inhibited, while Latilactobacillus rapidly became the dominant genus after cooperative fermentation, suggesting the better environment adaptability of L. sakei than P. acidilactici. The group-dimension correlation analysis suggested that Lactiplantibacillus had the greatest influence on the decrease in BAss. The quick acidification of starters, especially L. sakei, could inhibit the growth and metabolism of spoilage microorganisms to reduce BAs. L. sakei and P. acidilactici can be developed as the special starters to control the BA production in the fermented tilapia surimi through collaborative fermentation.

Air frying as a new roasting technology has potential for roasted fish production. In this study, the changes in volatile compounds (VCs) during air frying of tilapia were studied by quantitative gas chromatography–ion mobility spectrometry, followed by the identification of key VCs based on their odor activity value (OAV). There were 34 verified VCs, of which 16 VCs were identified as the key VCs with OAV ≥ 1. Most of the VCs were improved by air frying and peaked at 20 min. During the air frying, the total sulfhydryl content markedly decreased, while the protein carbonyl and MDA content significantly increased, suggesting the enhancement in the oxidation of lipids and proteins. The correlation network among the chemical properties and key VCs was constructed. The change in total sulfhydryl, protein carbonyl, and MDA showed significant correlation with most of the key VCs, especially 2-methyl butanal, ethyl acetate, and propanal. The results indicated that the oxidation of lipids and proteins contributed the most to the flavor improvement in air-fried tilapia. This study provides a crucial reference for the volatile flavor improvement and pre-cooked product development of roasted tilapia.