Sun Hee Moon

Addition of garlic or onion before irradiation on lipid oxidation, volatiles and sensory characteristics of cooked ground beef

Addition of 0.5% onion was effective in reducing lipid oxidation in irradiated cooked ground beef after 7 day storage. Addition of garlic or onion greatly increased the amounts of sulfur volatiles from cooked ground beef. Irradiation and storage both changed the amounts and compositions of sulfur compounds in both garlic- and onion-added cooked ground beef significantly. Although, addition of garlic and onion produced large amounts of sulfur compounds, the intensity of irradiation odor and irradiation flavor in irradiated cooked ground beef was similar to that of the nonirradiated control. Addition of garlic (0.1%) or onion (0.5%) to ground beef produced a garlic/onion aroma and flavor after cooking, and the intensity was stronger with 0.1% garlic than 0.5% onion treatment. Considering the sensory results and the amounts of sulfur compounds produced in cooked ground beef with added garlic or onion, 0.5% of onion or less than 0.1% of garlic is recommended to mask or change irradiation off-odor and off-flavor.

Antimicrobial Effect of 7-O-Butylnaringenin, a Novel Flavonoid, and Various Natural Flavonoids against Helicobacter pylori Strains

The antimicrobial effect of a novel flavonoid (7-O-butylnaringenin) on Helicobacter pylori 26695, 51, and SS1 strains and its inhibitory effect on the urease activity of the strains were evaluated and compared with those of several natural flavonoids. First, various flavonoids were screened for antimicrobial activities using the paper disc diffusion method. Hesperetin and naringenin showed the strongest antimicrobial effects among the natural flavonoids tested, and thus hesperetin and naringenin were selected for comparison with 7-O-butylnaringenin. The antimicrobial effect of 7-O-butylnaringenin was greater than that of the hesperetin and naringenin. H. pylori 51 was more sensitive to 7-O-butylnaringenin (2 log reduction of colony forming units, p < 0.05) than the other two strains at 200 μM. 7-O-Butylnaringenin also showed the highest inhibitory effect against urease activity of H. pylori. Morphological changes of H. pylori 26695 treated with these flavonoids indicated that both hesperetin and 7-O-butylnaringenin at 200 μM damaged the cell membranes.

Effect of garlic, onion, and their combination on the quality and sensory characteristics of irradiated raw ground beef.

Irradiated raw ground beef had lower a*- and b*-values than nonirradiated ones regardless of garlic or onion treatment at 0 d. Irradiation increased TBARS values of control ground beef, but addition of 0.5% onion or 0.1% garlic+0.5% onion reduced oxidative changes during storage. Addition of garlic or onion greatly increased the amounts of sulfur compounds, but the increase was greater with garlic. With irradiation, the profiles and amounts of S-volatiles in raw ground beef changed significantly. However, the intensity of irradiation aroma in irradiated raw ground beef with garlic or onion was similar to that of the nonirradiated control. This indicated that some of the sulfur compounds unique to garlic or onion interacted with common sulfur compounds detected in irradiated meat and masked or changed the odor characteristics of irradiated raw ground beef. It was concluded that >0.5% onion or <0.01% garlic would be needed to mask or prevent irradiation aroma in irradiated raw ground beef.

In vitro antioxidant and mineral-chelating properties of natural and autocleaved ovotransferrin

BACKGROUNDnEgg white proteins can be excellent substrates for the development of functional foods and nutraceuticals. In this study, several in vitro antioxidant methods, namely the β-carotene linoleate model system, the ferric thiocyanate method, the 2-thiobarbituric acid-reactive substances (TBARS) method and copper/calcium ion chelation, were used to determine the antioxidant capacity of natural and autocleaved ovotransferrin.nnnRESULTSnAutocleaved ovotransferrin was prepared by reducing natural ovotransferrin with tris(2-carboxyethyl)phosphine (TCEP) for 6 h at 37 °C. Autocleaved ovotransferrin suppressed the discoloration of β-carotene effectively and prevented the oxidation of linoleic acid during 5 days of storage at 4 °C. However, the concentration of autocleaved ovotransferrin had no influence on its antioxidant effect. Similarly, the highest TBARS values were obtained from autocleaved ovotransferrin (>90%) and the lowest value in natural ovotransferrin (24%) during incubation at 37 °C for 48 h. The hydrolysates obtained from autocleaved ovotranferrin showed better copper/calcium-solublilizing activity than those from natural ovotransferrin.nnnCONCLUSIONnThe results indicated that autocleaved ovotransferrin has the potential to be used as a natural antioxidant in foods.

Cytotoxic and antigenotoxic activities of phosvitin from egg yolk

Egg yolk phosvitin is one of the most phosphorylated proteins in nature, and thus has a strong metal-binding ability. The objective of this study was to evaluate the cytotoxic and antigenotoxic activities of phosvitin in vitro. Using the 3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of phosvitin was evaluated in human cancer cell lines of various tissue origins, including the cervix (HeLa), breast (MCF-7), stomach (AGS), lung (A549 and SK-MES-1), liver (HepG2), and larynx (Hep-2). The growth of all cancer cell lines was inhibited in a dose-dependent manner by phosvitin. Among the cancer cell lines tested, MCF-7 and SK-MES-1 were the least sensitive and HeLa, AGS, and HepG2 were the most sensitive to phosvitin. The 50% inhibition of cell viability values of phosvitin were 5.38, 11.57, 4.78, 6.98, 11.82, 3.93, and 9.97 mg/mL for HeLa, MCF-7, AGS, A549, SK-MES-1, HepG2, and Hep-2, respectively. The protective effects of phosvitin against DNA damage in human leukocytes indicated that phosvitin showed protective effects against the oxidative stress-induced DNA damages in human leukocytes. These results suggested that phosvitin has a high potential to be used as an anticancer agent for humans.

Characterisation of phosvitin phosphopeptides using MALDI-TOF mass spectrometry.

Putative phosphopeptides produced from enzyme hydrolysis of phosvitin were identified and characterised using MALDI-TOF/MS. Phosvitin was heat-pretreated and then hydrolysed using pepsin, thermolysin, and trypsin at their optimal pH and temperature conditions with or without partial dephosphorylation. Pepsin and thermolysin were not effective in producing phosphopeptides, but trypsin hydrolysis produced many peptides from phosvitin: 12 peptides, 10 of which were phosphopeptides, were identified from the trypsin hydrolysate. Twelve peptides were also identified from the trypsin hydrolysate of partially dephosphorylated phosvitin, but the phosphate groups remaining with the peptides were much smaller than those from the trypsin hydrolysate of intact phosvitin. This suggested that the phosphopeptides produced from the partially dephosphorylated phosvitin lost most of their phosphate groups during the dephosphorylation step. Therefore, partial dephosphorylation of phosvitin before trypsin hydrolysis may not be always recommendable in producing functional phosphopeptides if the phosphate groups play important roles for their functionalities.

Antioxidant and anticancer effects of functional peptides from ovotransferrin hydrolysates: Antioxidant and anticancer effects of ovotransferrin hydrolysates

BACKGROUNDnEgg white is a good source for making functional peptides that can be used in the food industry. Ovotransferrin (OTF) is one of the major egg white proteins, with many functional properties, including antioxidant, antimicrobial and antiviral activities. However, enzymatic hydrolysis of ovotransferrin is known to further improve the functional activities of OTF. The aim of this study was to investigate the antioxidant and anticancer activities of functional peptides produced by two-step enzyme hydrolysis of OTF.nnnRESULTSnOTF hydrolysates were prepared using promod 278P, thermolysin and a combination of the two enzymes. OTF and OTF hydrolysates showed strong antioxidant activities when analyzed using the DPPH assay. However, only OTF hydrolysates showed a strong free radical scavenging activity when NO- or ABTS-scavenging activity was measured. OTF hydrolysates showed stronger cytotoxic activities than the natural OTF against human cancer cell lines. Furthermore, OTF hydrolysates prepared with promod 278P + thermolysin combination showed the strongest cytotoxic activity, and their IC50 values were 0.79, 0.78, 0.92 and 0.78 mg mL-1 against AGS, LoVo, HT-29 and HeLa, respectively.nnnCONCLUSIONnThese results indicated that the two-step enzyme hydrolysates of OTF have great potential for use as a food ingredient with antioxidant and anticancer activities.

Characterization of Phosvitin Phosphopeptides using MALDI-TOF Mass Spectrometry

Putative phosphopeptides produced from enzyme hydrolysis of phosvitin were identified and characterised using MALDI-TOF/MS. Phosvitin was heat-pretreated and then hydrolysed using pepsin, thermolysin, and trypsin at their optimal pH and temperature conditions with or without partial dephosphorylation. Pepsin and thermolysin were not effective in producing phosphopeptides, but trypsin hydrolysis produced many peptides from phosvitin: 12 peptides, 10 of which were phosphopeptides, were identified from the trypsin hydrolysate. Twelve peptides were also identified from the trypsin hydrolysate of partially dephosphorylated phosvitin, but the phosphate groups remaining with the peptides were much smaller than those from the trypsin hydrolysate of intact phosvitin. This suggested that the phosphopeptides produced from the partially dephosphorylated phosvitin lost most of their phosphate groups during the dephosphorylation step. Therefore, partial dephosphorylation of phosvitin before trypsin hydrolysis may not be always recommendable in producing functional phosphopeptides if the phosphate groups play important roles for their functionalities.