Sun Jin Hur

Antihypertensive peptides from animal products, marine organisms, and plants

Bioactive peptides from food proteins exert beneficial effects on human health, such as angiotensin-converting enzyme (ACE) inhibition and antihypertensive activity. Several studies have reported that ACE-inhibitory peptides can come from animal products, marine organisms, and plants-derived by hydrolyzing enzymes such as pepsin, chymotrypsin, and trypsin-and microbial enzymes such as alcalase, thermolysin, flavourzyme, and proteinase K. Different ACE-inhibitory effects are closely related with different peptide sequences and molecular weights. Sequences of ACE-inhibitory peptides are composed of hydrophobic (proline) and aliphatic amino acids (isoleucine and leucine) at the N-terminus. As result of this review, we assume that low molecular weight peptides have a greater ACE inhibition because lower molecular weight peptides have a higher absorbency in the body. Therefore, the ACE-inhibitory effect is closely related with the degree of enzymatic hydrolysis and the composition of the peptide sequence.

Development of Sausages Containing Mechanically Deboned Chicken Meat Hydrolysates

UNLABELLEDnPork meat sausages were prepared using protein hydrolysates from mechanically deboned chicken meat (MDCM). In terms of the color, compared to the controls before and after storage, the redness (a*) was significantly higher in sausages containing MDCM hydrolysates, ascorbate, and sodium erythorbate. After storage, compared to the other sausage samples, the yellowness (b*) was lower in the sausages containing ascorbate and sodium erythorbate. TBARS was not significantly different among the sausage samples before storage, whereas TBARS and DPPH radical scavenging activities were significantly higher in the sausagescontainingascorbate and sodium erythorbate, compared to the other sausage samples after 4 wk of storage. In terms of sensory evaluation, the color was significantly higher in the sausages containing MDCM hydrolysates, ascorbate, and sodium erythorbate, compared to the other sausage samples after 4 wk of storage. The off-flavor and overall acceptability were significantly lower in the sausages containing MDCM hydrolysates than in the other sausage samples.nnnPRACTICAL APPLICATIONnIn most of the developed countries, meat from spent laying hens is not consumed, leading toan urgent need for effectively utilization or disposal methods. In this study, sausages were prepared using spent laying hens and protein hydrolysates from mechanically deboned chicken meat. Sausage can be made by spent laying hens hydrolysates, although overall acceptability was lower than those of other sausage samples.

Changes of sodium nitrate, nitrite, and N-nitrosodiethylamine during in vitro human digestion

This study aimed to determine the changes in sodium nitrate, sodium nitrite, and N-nitrosodiethylamine (NDEA) during in vitro human digestion, and the effect of enterobacteria on the changes in these compounds. The concentrations of nitrate, nitrite, and NDEA were significantly reduced from 150, 150, and 1ppm to 42.8, 63.2, and 0.85ppm, respectively, during in vitro human digestion (p<0.05). The enterobacteria Escherichia coli and Lactobacillus casei reduced the amount of these compounds present during in vitro human digestion. This study is the first to report that E. coli can dramatically reduce the amount of nitrite during in vitro human digestion and this may be due to the effect of nitrite reductase present in E. coli. We therefore conclude that the amounts of potentially harmful substances and their toxicity can be decreased during human digestion.

Effect of six different starter cultures on the concentration of residual nitrite in fermented sausages during in vitro human digestion

The objective of this study was to determine the effect of six different starter cultures of enterobacteria on the concentration of residual nitrite in fermented sausages during in vitro human digestion. Before digestion, the concentration of residual nitrite was dependent on starter culture in fermented sausage and ranged from 25.2 to 33.2mg/kg. Among the six starter cultures of enterobacteria, Pediococcus acidilactici, Pediococcus pentosaceus, and Staphylococcus carnosus showed higher nitrite depletion ability than the other three strains in fermented sausages. The concentration of residual nitrite in fermented sausages was significantly (p<0.05) decreased after stomach digestion and ranged from 17.4 to 21.6mg/kg. Enterobacteria Escherichia coli (E. coli) and/or Lactobacillus casei (L. casei) effectively increased the degree of depletion of residual nitrite in large intestine digestion. In conclusion, starter cultures could influence the concentration of residual nitrite during in vitro human digestion. They could deplete residual nitrite in fermented sausages.

A systematic study of nuclear interactome of C-terminal domain small phosphatase-like 2 using inducible expression system and shotgun proteomics

RNA polymerase II C-terminal domain phosphatases are newly emerging family of phosphatases that contain FCPH domain with Mg+2-binding DXDX(T/V) signature motif. Its subfamily includes small CTD phosphatases (SCPs). Recently, we identified several interacting partners of human SCP1 with appearance of dephosphorylation and O-GlcNAcylation. In this study, using an established cell line with inducible CTDSPL2 protein (a member of the new phosphatase family), proteomic screening was conducted to identify binding partners of CTDSPL2 in nuclear extract through immunoprecipitation of CTDSPL2 with its associated. This approach led to the identification of several interacting partners of CTDSPL2. This will provide a better understanding on CTDSPL2. [BMB Reports 2016; 49(6): 319-324]

Angiotensin Converting Enzyme Inhibitory and Antioxidant Activities of Enzymatic Hydrolysates of Korean Native Cattle (Hanwoo) Myofibrillar Protein

The purpose of this study was to determine the angiotensin converting enzyme (ACE) inhibitory and antioxidant activities of myofibrillar protein hydrolysates (HMPHs) of different molecular weights (<3 and <10u2009kDa) derived from Korean native cattle (Hanwoo breed) using a commercially available and inexpensive enzyme (Alkaline-AK). HMPH of both tested molecular weights had ACE inhibitory activity. Among the antioxidant activities, iron chelation and nitrite scavenging activities were higher in low-molecular-weight peptide of HMPH (<3u2009kDa), whereas 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was higher in high-molecular-weight peptide of HMPH (<10u2009kDa). HMPH did not induce cytotoxicity in RAW 264.7 cells at concentrations of 5–20u2009mg/mL. These results indicate that HMPH can be cheaply produced using Alkaline-AK and applied as a potential ACE inhibitor and antioxidant.

Effect of Thyme and Rosemary on The Quality Characteristics, Shelf-life, and Residual Nitrite Content of Sausages During Cold Storage.

The effects of thyme and rosemary on the quality characteristics of sausages during cold storage were investigated. Sausages were prepared with thyme and rosemary powder (1 and 2%) and stored for 6 weeks at 10℃. The pH was significantly decreased in sausages by addition of thyme and rosemary compared to that observed in the control before and after storage. At 4 weeks of storage, the residual nitrite content was decreased by thyme and rosemary compared to the control. Lightness (L*) and yellowness (b*) were increased during storage, whereas redness (a*) and whiteness (W) were decreased before and after storage by addition of thyme and rosemary. The amount of TPC and lactic acid bacteria was lower at the end of storage in sausage containing thyme and rosemary. The 2, 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging capacity of sausages was increased by addition of thyme and rosemary compared to that in the control before and after storage. In particular, T2 (0.2% thyme addition) showed the highest DPPH radical scavenging capacity during storage. In a sensory evaluation, flavor and overall acceptability were lower in sausages containing thyme and rosemary than in the control. However, at the end of storage (6 wk), aroma, flavor and overall acceptability were not significantly different among the sausage samples.

Changes in resistance to and antimicrobial activity of antibiotics during in vitro human digestion

OBJECTIVESnThis study was performed to determine changes in (i) the antimicrobial activity of antibiotics (tetracycline, ofloxacin and penicillin) and (ii) the resistance of Staphylococcus aureus RN4220 (SA RN4220) and methicillin-resistant S. aureus (MRSA) to these antibiotics during in vitro human digestion.nnnMETHODSnA human gastrointestinal digestion model simulating the conditions of the mouth, stomach, small intestine and large intestine (with intestinal microbial application) was used in this study. Antimicrobial susceptibility testing was performed by the disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) guidelines.nnnRESULTSnConcentrations of the three antibiotics decreased during digestion. In particular, the three antibiotics were unstable under conditions of stomach to large intestine digestion, and thus a decrease in antibiotic concentration could cause a reduction in antimicrobial activity during in vitro human digestion. The resistance of SA RN4220 and MRSA to the three antibiotics increased after in vitro human digestion. SA RN4220 and MRSA showed less resistance to ofloxacin compared with tetracycline and penicillin during in vitro human digestion.nnnCONCLUSIONSnThese results may help to explain the factors affecting antimicrobial activity and resistance to antibiotics during digestion in the human alimentary canal.

Effects of in vitro Human Digestion on the Antioxidant Activity and Stability of Lycopene and Phenolic Compounds in Pork Patties Containing Dried Tomato Prepared at Different Temperatures: Antioxidant activity of tomato powder…

The antioxidant activity can be changed during digestion. The effects of in vitro human digestion on the antioxidant activity and stability of tomato powders (TPs), dried at three different temperatures (60, 80, and 100 °C) and added to pork patties (1% TP by weight), were investigated. The pork patties with three TPs underwent in vitro human digestion with enterobacteria. Lycopene and individual phenolic compounds were analyzed by using HPLC. The highest total phenolic compounds (6.96 g/100 g) and lycopene concentrations (2.68 mg/100 g) were observed in pork patties with TP dried at 100 °C. In addition, antioxidant activity of pork patties containing TPs were measured during in vitro human digestion. Gallic acid (23.8 to 41.6 g/100 g), chlorogenic acid (11.2 to 25.7 g/100 g), and caffeic acid (11.1 to 21.7 g/100 g) were detected as the main phenolic compounds in the TPs. Lycopene, and total and individual phenolic compound contents increased with increasing drying temperatures. Moreover, in vitro human digestion increased the antioxidant activity of TP-containing pork patties. The lycopene and total phenolics contents were increased during in vitro human digestion with enterobacteria by 146% to 220% and 1549% to 2095%, respectively as compared to the samples of before digestion. Hence, we hypothesized that the antioxidant activity of each TP increased during in vitro human digestion and depended on the amount of lycopene and phenolic compounds released. The TP dried at the highest temperature (100 °C) had the highest antioxidant activity in pork patties during in vitro human digestion.nnnPRACTICAL APPLICATIONnIn this study, we revealed that in vitro human digestion increases the antioxidant activities of tomato powder. In addition, tomato powder dried at the highest temperature (100 °C) showed the highest antioxidant activity. Therefore, tomato powder at 100 °C could be used as strong antioxidants in meat products.

Development of Sausage with Inhibition of 60% Sodium Intake, Using Biopolymer Encapsulation Technology and Sodium Replacers

To develop sausage with inhibition of 60% sodium intake, using biopolymer encapsulation technology and sodium replacer, the sausages were subdivided into five treatment groups: control was the normal sodium amount without sodium substitution and biopolymers; and four treatments involved encapsulation with four different biopolymers (T1: pectin, T2: chitosan, T3: cellulose, T4: dextrin), with sodium substituted by 55% with sodium replacers (a mixture of potassium, magnesium, and calcium chlorides). The experimental sausages were fed to mice for 48xa0h, and sodium absorption and its inhibition were measured. T2 sausage (3% chitosan with a sodium replacer) and T3 sausage (3% cellulose with a sodium replacer) showed the highest rates of inhibition of sodium absorption: 69.65 and 67.34%, respectively. These results indicated that the final goal of 60% inhibition of sodium intake was accomplished by 55% sodium replacement and more than 15% inhibition of sodium absorption with minimal deterioration of sausage quality.