Bioactive peptides can be obtained from plant, animal or marine sources. Bioactive peptides possess diverse biological activities such as antihypertension, antioxidant, antithrombosis, cholesterol-lowering, blood pressure-lowering, antibacterial, immune regulation, cell regulation, and mineral-binding properties. How to improve the conversion rate of proteins to peptides is always one of the difficulties in the research field of peptide. Ultra-high pressure technology is a novel non-thermal physical processing technology suitable for large-scale production, which has been widely used to the structural and functional characteristics of proteins, as well as the extraction and production efficiency of bioactive peptides. This review paper mainly focuses on the application of ultra-high pressure technology in protein modification and peptide preparation. The types, sources and biological activities of bioactive peptides prepared by ultra-high pressure technology are also summarized.

Konjac glucomannan (KGM) was degraded by β-glucanase. The structural characteristics of KGM and its hydrolysate were identified by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and their molecular masses were determined by gel permeation chromatography with multiple angle laser light scattering. The chemical characteristics of the hydrolysate were evaluated by measuring their intrinsic viscosity, deacetylation degree, soluble polysaccharide content and electrical characteristics. The results showed that the major chain structure of the hydrolysate did not change compared with KGM. After 120 min of treatment with a five-fold excess of the enzyme, a weak crystalline region may appear. SEM results showed that the surface of the hydrolysate gradually became lamellated, and its molecular weight decreased to (36.48 ± 1.23) kDa. The characteristic viscosity decreased by 98%, the degree of deacetylation increased significantly (P < 0.05), and the content of total soluble sugar decreased significantly (P < 0.05). This study can provide a reference for the enzymatic modification of KGM to promote the high-value utilization of KGM hydrolysate resources.

Chitosan nanoparticle is becoming an excellent carrier for the delivery of bioactive components due to the advantages of simple preparation, low cost and high biocompatibility. Previous studies have shown that chitosan/sodium tripolyphosphate (CS/TPP) and chitosan/flaxseed gum (CS/FG) nanoparticles loaded with bighead carp peptides (BCP) have the advantages of small particle size, high encapsulation rate and significant slow-release effect. This study explored the effects of ionic strength, pH, simulated digestion and storage time on the preparation of chitosan/sodium tripolyphosphate (CS/TPP-BCP) and chitosan/flaxseed gum (CS/FG-BCP) nanoparticles, and evaluated the extracellular lactate dehydrogenase content and antioxidant capacity in vivo of Caco-2 cells treated with the chitosan nanoparticles and their cellular uptake. The results showed that the two kinds of chitosan nanoparticles were stable under acidic conditions and sensitive to a solution with opposite charges. The stability of the nanoparticles loaded with bighead peptides was higher than that of free peptides and both nanoparticles showed higher biocompatibility and cell uptake.