Hydrolysis Conditions of Porcine Blood Proteins and Antimicrobial Effects of Their Hydrolysates

Can proteins, protein hydrolysates and peptides cooperate with probiotics to inhibit pathogens?

Studies have shown that probiotics can effectively inhibit pathogens in the presence of proteins, protein hydrolysates and peptides (protein derivates). However, it is still unclear the modes of probiotics to inhibit pathogens regulated by protein derivates. Therefore, we summarized the possible effects of protein derivates from different sources on probiotics and pathogens. There is abundant evidence that proteins and peptides from different sources can significantly promote the proliferation of probiotics and increase their secretion of antibacterial substances. Such proteins and peptides can also stimulate the adhesion of probiotics to intestinal epithelial cells and contribute to regulating intestinal immunity, but they seem to have the negative effects on pathogens. Moreover, a direct effect of proteins on intestinal cells is summarized. Whether or not they can cooperate with probiotics to inhibit pathogens using above possible mechanisms were discussed. Furthermore, there seems to be no consistent conclusions that protein derivates have synergistic effects with probiotics, and there is still limited evidence on the inhibiting patterns. Therefore, the existing problems and shortcomings are noted, and future research direction is proposed.

Effects of Physicochemical Characteristics and Storage Stability of Porcine Albumin Protein Hydrolysates in Pork Sausage

In this study, the physicochemical characteristics and storage stability of porcine albumin protein hydrolysates (PAPH) in sausage were evaluated. Four concentrations of PAPH were added to pork emulsion sausage (T1, 0.3%; T2, 0.6%; T3, 0.9%; T4, 1.2%) and compared to the control (CON, 0%). On day 0, proximate composition, cooking loss, and sensory evaluation were compared. Purge loss, color, texture profile analysis, shear force, free amino acids, lipid oxidation, microbial counts, and volatile basic nitrogen (VBN) were compared on day 0 and after 4 weeks of refrigeration. The content of essential amino acids and redness(a*) increased as the level of PAPH added increased (p<0.05). Also, the cooking loss was improved (p<0.05). However, lipid oxidation, microbial counts, and VBN were increased significantly during storage for 4 weeks (p<0.05). The findings indicated that the addition of PAPH improved cooking loss and the protein composition of sausages, but negatively affected storage stability.

Effect of Porcine Whole Blood Protein Hydrolysate on Slow-Twitch Muscle Fiber Expression and Mitochondrial Biogenesis via the AMPK/SIRT1 Pathway

Skeletal muscle is a heterogeneous tissue composed of a variety of functionally different fiber types. Slow-twitch type I muscle fibers are rich with mitochondria, and mitochondrial biogenesis promotes a shift towards more slow fibers. Leucine, a branched-chain amino acid (BCAA), regulates slow-twitch muscle fiber expression and mitochondrial function. The BCAA content is increased in porcine whole-blood protein hydrolysates (PWBPH) but the effect of PWBPH on muscle fiber type conversion is unknown. Supplementation with PWBPH (250 and 500 mg/kg for 5 weeks) increased time to exhaustion in the forced swimming test and the mass of the quadriceps femoris muscle but decreased the levels of blood markers of exercise-induced fatigue. PWBPH also promoted fast-twitch to slow-twitch muscle fiber conversion, elevated the levels of mitochondrial biogenesis markers (SIRT1, p-AMPK, PGC-1α, NRF1 and TFAM) and increased succinate dehydrogenase and malate dehydrogenase activities in ICR mice. Similarly, PWBPH induced markers of slow-twitch muscle fibers and mitochondrial biogenesis in C2C12 myotubes. Moreover, AMPK and SIRT1 inhibition blocked the PWBPH-induced muscle fiber type conversion in C2C12 myotubes. These results indicate that PWBPH enhances exercise performance by promoting slow-twitch muscle fiber expression and mitochondrial function via the AMPK/SIRT1 signaling pathway.

Optimization of chemical and enzymatic hydrolysis for production of chicken blood protein hydrolysate rich in angiotensin-I converting enzyme inhibitory and antioxidant activity

Response surface methodology was adopted to optimize hydrolysis conditions for the production of antioxidant and angiotensin-I converting enzyme (ACE) inhibitory peptides from chicken red blood cells by both enzymatic and acid hydrolysis. During acid hydrolysis, temperature (P < 0.001) and acid concentration (P < 0.001) influenced the degree of hydrolysis (DH%) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of the hydrolysate while ACE inhibitory activity of the hydrolysate was strongly influenced by acid concentration (P < 0.001). Temperature and time of hydrolysis had no effect (P > 0.05) on the ACE inhibitory activity of the hydrolysate. Acid hydrolysis conditions of 50°C, 32 h, and 0.03 N hydrochloric acid resulted in optimum DH% (33.1%), optimum DPPH scavenging activity (46%), and optimum ACE inhibitory activity (43.7%) of the hydrolysate. During enzymatic hydrolysis of chicken red blood cells, DH% was influenced by the temperature of hydrolysis (P < 0.001) and enzyme concentration (P < 0.001). DPPH scavenging of the hydrolysate was marginally (P < 0.05) influenced by the temperature of hydrolysis and ACE inhibitory activity of the hydrolysate was highly influenced by temperature (P < 0.001) and enzyme concentration (P < 0.001). Enzyme hydrolysis conditions of 60°C, 150 min, and 2.5% alcalase resulted in maximum DH% of 63.9%, while the highest DPPH scavenging activity (75%) of hydrolysate was observed under the hydrolysis conditions of 60°C, 30 min, and 2.5% of the enzyme. Optimum ACE inhibitory activity (45%) of the hydrolysate was achieved at hydrolysis conditions of 2.5% alcalase, 120 min of hydrolysis at 60°C. ACE inhibitory activity of the enzymatically hydrolyzed product was directly proportional to DH%, while DPPH activity was inversely proportional to DH%. DPPH scavenging activity of the acid hydrolysate was recorded at a lower range (34.8-56.9%) compared to the enzyme hydrolysate (40.4-77.4%), while ACE inhibitory activity of both the hydrolysates was observed in the same range (18.7-49.4 and 14.2-47.7% for acid and enzyme hydrolysate, respectively). This study indicated that chicken red blood cells could be successfully hydrolyzed by both chemical and enzymatic methods to obtain hydrolysates having antioxidant and ACE inhibitory activity.