Subzero saline chilling with or without prechilling in icy water improved chilling efficiency and meat tenderness of broiler carcasses.

Freshly slaughtered carcasses need to be chilled to improve product quality, meat safety, and processing efficiency. This research investigated the effect of subzero saline chilling (SSC) on broiler carcasses with or without prechilling in icy water. Water immersion chilling at 0.5°C (WIC) or SSC at 4% NaCl/-2.41°C (SSC) was a major chilling step. For the combination of pre- and postchilling, the warm water immersion chilling (WWIC) at 10°C was used as prechilling and the WIC as postchilling (WWIC-WIC), and WIC was used as prechilling and the SSC as postchilling (WIC-SSC). The internal temperature of breast fillets was monitored during chilling. Carcasses in a prechiller were transported to a postchiller when their internal temperature reached 15°C. Chilling was completed when the carcass temperature reached 4.4°C or below, and breast fillets were harvested at 3-h postmortem to measure the pH and sarcomere length. Color (L*, a*, and b*) values were evaluated on both breast skin and skinless breast surfaces. Meat tenderness was evaluated using the breast fillets after overnight storage and cooking to an internal temperature of 76°C. The carcasses in the SSC and WIC-SSC showed shorter chilling times (85-91 min) than those (100-144 min) of WIC and WWIC-WIC. A higher chilling yield was observed for the carcasses in WIC-SSC, and a lower cooking yield was seen for the carcasses in WWIC-WIC than other chilling methods (P < 0.05). The breast fillets of broilers in the SSC and WIC-SSC showed lower shear forces and longer sarcomere length than the WIC and WWIC-WIC. No difference was found for L* and a* values, while lower b* value was observed in the SSC than the other chilling methods (P < 0.05). Based on these results, chilling of broiler carcasses in the SSC (4% NaCl/-2.41°C) with or without prechilling in WIC at 0.5°C significantly improved chilling efficiency and meat tenderness, with minor color changes on carcasses.

Anti-elastase and anti-hyaluronidase activity of phosvitin isolated from hen egg yolk.

1. Phosvitin, a major phosphoprotein found in egg yolk, has strong antioxidant activity. Activation of elastase, collagenase, and hyaluronidase by reactive oxygen species are related to the degradation of ECM and skin aging. The objective of this study was to determine the anti-elastase and anti-hyaluronidase activity of phosvitin.2. Elastase from porcine pancreas and hyaluronidase from bovine testes were used to study the inhibitory activity of phosvitin. To elucidate the mechanism of enzyme inhibition, a Lineweaver-Burk plot was constructed.3. Phosvitin inhibited elastase and hyaluronidase activity in a dose-dependent manner. The IC50 value of phosvitin was 31.6 µg/ml and 1,270 µg/ml against elastase and hyaluronidase, respectively. The analysis of elastase and hyaluronidase kinetics indicated that the apparent Michaelis constant (appKm) was increased by phosvitin but the Vmax value was not affected.4. In conclusion, phosvitin exhibited competitive inhibitory activity against elastase and hyaluronidase. Thus, phosvitin could be used as a natural anti-aging agent in the cosmetics industry.

Antioxidant, angiotensin-converting enzyme inhibitory activity and other functional properties of egg white proteins and their derived peptides - A review.

Egg white contains many functionally important proteins: ovalbumin (54%), ovotransferrin (12%), ovomucoid (11%), ovoglobulin (G2 and G3, 8%), ovomucin (3.5%), and lysozyme (3.5%) are major proteins, while ovoinhibitors, ovomacroglobulin, ovoglycoprotein, ovoflavoprotein, thiamine-binding proteins, and avidin are minor proteins present in egg white. These proteins, as well as the peptides derived from the proteins, have been recognized for their functional importance as antioxidant, antimicrobial, metal-chelating, anti-viral, anti-tumour, and angiotensin-converting enzyme (ACE)-inhibitory activities. Among the functional properties of the peptides, antioxidant and antimicrobial activities are important characteristics for food processing while other properties such as ACE-inhibitory activity of the peptides can have important health-related functionalities. Bioactive peptides can be produced from egg white proteins by enzyme hydrolysis, chemical treatments, or thermal treatments at different pH conditions. The effective functional peptides produced from egg white proteins are usually smaller than 2 kDa in molecular size. However, these peptides are known for their beneficial activities in vitro only, and little work has been done to prove their beneficial effects in vivo. Therefore, further studies are needed to see if the bioactive peptides derived from egg white proteins are helpful for humans in the future.

Effect of oregano oil and tannic acid combinations on the quality and sensory characteristics of cooked chicken meat.

The antioxidant effects of oregano essential oil and tannic acid combinations on ground chicken breast and thigh meats were studied. Six treatments, including: 1) control (none added), 2) 100 ppm oregano essential oil + 5 ppm tannic acid, 3) 100 ppm oregano essential oil + 10 ppm tannic acid, 4) 200 ppm oregano essential oil + 5 ppm tannic acid, 5) 200 ppm oregano essential oil + 10 ppm tannic acid, and 6) 5 ppm butylated hydroxyanisole (BHA) for breast or 14 ppm for thigh meat, were prepared. Cooked meat samples were individually vacuum-packaged in oxygen-impermeable vacuum bags and then cooked in-bag to an internal temperature of 75°C. After cooling to room temperature, the cooked meat was re-packaged in new oxygen-permeable bags and stored at 4°C for 7 days. Cooked ground chicken meats were analyzed for lipid and protein oxidation and volatiles at 0, 3, and 7 d of storage. The significant differences among the treatments were very clear in cooked meat samples: Thigh meat patties showed higher 2-thiobarbituric acid reactive substances (TBARS), total carbonyl, and volatiles content compared to the breast meat during storage. A combination of 200 ppm oregano oil with 10 ppm tannic acid showed the most significant effects (P < 0.05) on TBARS, total carbonyl, and off-odor volatile formation for both breast and thigh meats. Oregano oil (200 ppm) and 10 ppm tannic acid combination also showed positive effects on the sensory scores of chicken thigh meat. In conclusion, the combination of 200 ppm oregano oil and 10 ppm tannic acid could be a good replacement for the synthetic antioxidants in ground cooked chicken meat.

Immune-enhancing activity of phosvitin by stimulating the production of pro-inflammatory mediator.

Egg yolk phosvitin is one of the most phosphorylated proteins in nature, and the extraordinarily high concentration of phosphate groups in its structure provides a strong metal-binding ability. Phosvitin is known to possess various functional activities, including metal-chelating, antioxidant, emulsifying, antimicrobial, and cytotoxic activities. However, little is known about the immune-enhancing activity of phosvitin. The objective of this study was to evaluate the immune-enhancing activity of phosvitin in murine RAW 264.7 macrophages. Griess reagents and quantitative real-time PCR were used to determine the effect of phosvitin (at 12.5, 25, 50, and 100 µg/mL) on the levels of pro-inflammatory mediators NO and inducible nitric oxide synthase (iNOS), cytokines TNF-α and IL-1ß in RAW 264.7 macrophages. The effect of phosvitin on the phagocytic activity of RAW 264.7 macrophages was also measured using the Neutral-Red Uptake method. Lipopolysaccharides was used as a positive control. Phosvitin significantly (P < 0.05) increased the production of NO in RAW 264.7 macrophages in a dose-dependent manner, but did not show any cytotoxicity. The amounts of NO produced were 3.47, 7.12, 10.23, and 14.57 µM in 12.5 to 100 µg/mL range of phosvitin (control: 0.46 µM). Compared with the untreated group, phosvitin treatment at a 100 µg/mL level increased the production of NO by 31.67 times. Phosvitin also significantly increased the mRNA expression of the RAW 264.7 macrophages: 100 µg/mL of phosvitin treatment increased the expression of mRNA for iNOS, TNF-α, and IL-1ß by 46.25, 9.09, and 85.18 times of the control, respectively. The phagocytic activity of RAW 264.7 macrophages was also increased significantly by phosvitin treatment. These results demonstrated that phosvitin dramatically improved the immune functions RAW 264.7 macrophages by enhancing the production of immune mediators and increasing phagocytic activity. Therefore, phosvitin has a potential to be used as an immune-enhancing agent by food or nutraceutical industries.

In vitro cytotoxic and ACE-inhibitory activities of promod 278P hydrolysate of ovotransferrin from chicken egg white.

Peptides released from egg proteins via enzymatic hydrolysis show various bioactivities such as antimicrobial, antioxidant, antihypertensive, and immunomodulatory properties. The objective of this study was to investigate the cytotoxic and Angiotensin Converting Enzyme (ACE)-inhibitory activities of ovotransferrin and its promod 278P enzyme hydrolysate. Ovotransferrin from egg white was hydrolyzed using promod 278P at 45°C for 3 hours. Using the MTT assay, the cytotoxicity of ovotransferrin and promod 278P hydrolysate of ovotransferrin were evaluated in human cancer cell lines of various tissue origins. The ACE-inhibitory activity was determined using the cleavage of a chromogenic substrate -Hip-His-Leu. The promod 278P hydrolysate of ovotransferrin showed a potent cytotoxicity (>90%) at 20 mg/mL in all cancer cell lines tested, but ovotransferrin did not. The IC50 value of the promod 278P hydrolysate of ovotransferrin against 5 different cancer cells were 10.05 ± 1.55, 3.45 ± 0.94, 4.43 ± 1.87, 4.92 ± 0.63, and 10.43 ± 3.91 mg/mL for MCF-7, HeLa, HepG2, HT-29, and LoVo cells, respectively. The promod 278P hydrolysate of ovotransferrin showed a strong ACE-inhibiting activity: at 10 mg/mL level, the hydrolysate showed 76.82 ± 1.28% inhibition to ACE-inhibitory activity, and 73.33 ± 2.56%, 56.85 ± 1.84%, 50.32 ± 3.71%, 17.30 ± 0.13%, and 4.52 ± 6.83% inhibitory activity at 5, 2.5, 1.25, 0.625, and 0.3125 mg/mL level, respectively. The IC50 value of the promod 278P hydrolysate of ovotransferrin was 1.53 ± 0.20 mg/mL. However, ovotransferrin did not show any inhibitory effect to angiotensin-converting enzyme activity. This result indicated that the promod 278P hydrolysate of ovotransferrin has a great potential as an anticancer and antihypertension agent for humans, but the information on the peptides responsible for the functional activities is not available yet.

Enzymatic hydrolysis of ovomucin and the functional and structural characteristics of peptides in the hydrolysates.

Ovomucin was hydrolyzed using enzymes or by heating under alkaline conditions (pH 12.0), and the functional, structural and compositional characteristics of the peptides in the hydrolysates were determined. Among the treatments, heating at 100 °C for 15 min under alkaline conditions (OM) produced peptides with the highest iron-binding and antioxidant capacities. Ovomucin hydrolyzed with papain (OMPa) or alcalase (OMAl) produced peptides with high ACE-inhibitory activity. The mass spectrometry analysis indicated that most of the peptides from OMPa were <2 kDa, but peptides from OMTr and OM were >2 kDa. OMAl hydrolyzed ovomucin almost completely and no peptides within 700-5000 Da were found in the hydrolasate. The results indicated that the number and size of peptides were closely related to the functionality of the hydrolysates. Considering the time, cost and activities of the hydrolysates, OM was the best treatment for hydrolyzing ovomucin to produce functional peptides.

Influence of soy oil source and dietary supplementation of vitamins E and C on the oxidation status of serum and egg yolk, and the lipid profile of egg yolk.

An experiment was conducted to determine the effects of adding vitamins E and C to diets containing 3.5% refined soy oil (SO), recycled soy oil (RSO), or acidulated soy oil soapstocks (ASS) on 1) fatty acid (FA) profile, and cholesterol, triglyceride (TG) and α-tocopherol (α-T) concentrations of yolk, and 2) the oxidation status of serum and yolk. Twelve dietary treatments, using 3 oil sources, 2 levels of vitamin E (0 vs. 250 mg/kg), and 2 levels of vitamin C (0 vs. 250 mg/kg), were prepared. A total of 300 W36 Hy-line laying hens, from 44 to 56 weeks of age, were placed in 60 cages (5 birds/cage) and 5 cages were randomly assigned to one of the 12 diets. Blood samples and eggs were collected after 84 d on trial. No interactions among main effects were found for any of the traits studied. Oil sources had little effects on the FA profile of the yolk, except for C18:3 that was higher (P-value of < 0.01) in the hens fed SO than those fed RSO or ASS. Vitamin E supplementation significantly (P-value of < 0.05) increased the concentration of C16:0, C18:0, and C16:1 but decreased that of C18:2 and C22:6n3 in the yolk. Vitamin C supplementation significantly (P-value of < 0.05) increased C18:0 and C18:3 concentrations in the yolk but decreased the n6 to n3 FA ratio. The concentrations of cholesterol and triglyceride in serum and yolk were not affected by dietary treatment but α-tocopherol concentration increased (P-value of < 0.01) by the dietary vitamin E. Compared with the hens fed the SO diets, malondialdehyde (MDA) concentration in serum was higher with RSO diet but lower with ASS diet. Vitamin E and vitamin C supplementation decreased (P-value of < 0.05) serum MDA. Yolk FA profile was affected not only by the FA profile of the oil source used in diet, but also by the supplementation of vitamin E and C. The results showed that triglyceride profile, but not cholesterol content, of egg was affected by fatty acid profile of the supplemental oil and the vitamin C and E supplementations.

Enzymatic hydrolysis of ovomucoid and the functional properties of its hydrolysates.

Ovomucoid is well known as a "trypsin inhibitor" and is considered to be the main food allergen in egg. However, the negative functions of ovomucoid can be eliminated if the protein is cut into small peptides. The objectives of this study were to hydrolyze ovomucoid using various enzyme combinations, and compare the functional properties of the hydrolysates. Purified ovomucoid was dissolved in distilled water (20 mg/mL) and treated with 1% of pepsin, α-chymotrypsin, papain, and alcalase, singly or in combinations. Sodium sodium dodecyl sulfate-polyacrylamide (SDS-PAGE) results of the hydrolysates indicated that pepsin (OMP), alcalase (OMAl), alcalase+trypsin (OMAlTr), and alcalase+papain (OMAlPa) treatments best hydrolyzed the ovomucoid, and the 4 treatments were selected to determine their functional characteristics. Among the 4 enzyme treatments, hydrolysate from OMAlTr showed the highest iron-chelating and antioxidant activities, while OMP showed higher ACE-inhibitory activity, but lower Fe-chelating activity than the other treatments. However, no difference in the copper-chelating activity among the treatments was found. MS/MS analysis identified numerous peptides from the hydrolysates of OMAlPa and OMAlTr, and majority of the peptides produced were <2 kDa. Pepsin treatment (OMP), however, hydrolyzed ovomucoid almost completely and produced only amino acid monomers, di- and tri-peptides. The ACE-inhibitory, antioxidant and iron-chelating activities of the enzyme hydrolysates were not consistent with the number and size of peptides in the hydrolysates, but we do not have information about the quantity of each peptide present in the hydrolysates at this point.

Enzymatic hydrolysis of ovalbumin and the functional properties of the hydrolysates.

Ovalbumin is the predominant protein in egg white and is widely used in cell culture. However, it also can be used to produce peptides with various functional properties. The objectives of this study were to hydrolyze ovalbumin using various enzyme, incubation time, and temperature combinations, and to compare the functional properties of the hydrolysates. Ovalbumin (20 mg/mL) was hydrolyzed with 1% of pepsin, trypsin, α-chymotrypsin, papain, and alcalase, singly or in combination at 37°C, and then the enzymes were inactivated at 100°C for 15 min. Hydrolyzing ovalbumin with pepsin (OAPe), pepsin + papain (OAPePa), pepsin + alcalase (OAPeAl), alcalase + trypsin (OAAlTr), and α-chymotrypsin (OACh) was also effective in producing peptides from ovalbumin, and the peptides produced had strong iron- and copper-binding capacities and antioxidant capability. However, the best treatment of all was the OAAlTr treatment, which showed the highest iron-chelating and antioxidant activities among the enzyme treatments (P < 0.05). Electrospray-ionization mass spectrometry (MS/MS) analysis identified numerous peptides (<5 kDa) from the OAPe, OAPeAl, OACh, OAAlTr, and OAPePa hydrolysates of ovalbumin, but the number and size of peptides varied widely depending on the treatments. The enzymatic hydrolysis significantly increased the functionality of ovalbumin, and the improvement depended upon the composition of peptides produced rather than the number of the peptides produced.

Sequential separation of lysozyme, ovomucin, ovotransferrin, and ovalbumin from egg white.

Ovalbumin, ovotransferrin, ovomucin, and lysozyme are a few of the egg white proteins that can be used as functional components. The objective of this study was to develop a simple, sequential separation method for multiple proteins from egg white. Separated proteins are targeted for human use, and thus any toxic compounds were excluded. The methods for individual components and the sequential separation were practiced in laboratory scale first, and then tested for scale-up. Lysozyme was separated first using FPC3500 cation exchange resin and then ovomucin using isoelectric precipitation. Ovalbumin and ovotransferrin were separated from the lysozyme- and ovomucin-free egg white by precipitating ovotransferrin first using 5.0% (wt/vol) (NH4)2SO4 and 2.5% (wt/vol) citric acid combination. After centrifugation, the supernatant (S1) was used for ovalbumin separation and the precipitant was dissolved in water, and reprecipitated using 2.0% ammonium sulfate (wt/vol) and 1.5% citric acid (wt/vol) combination. The precipitant was used as ovotransferrin fraction, and the supernatant (S2) was pooled with the first supernatant (S1), desalted using ultrafiltration, and then heat-treated to remove impurities. The yield of ovomucin and ovalbumen was >98% and that of ovotransferrin and lysozyme was >82% for both laboratory and scale-up preparations. The SDS-PAGE and western blotting of the separated proteins, except for ovomucin, showed >90% purity. The ELISA results indicated that the activities of separated ovalbumin, ovotransferrin, and lysozyme were >96%. The protocol separated 4 major proteins in sequence, and the method was simple and easily scaled up.

Separation of ovotransferrin and ovomucoid from chicken egg white.

Ovotransferrin and ovomucoid were separated using 2 methods after extracting the ovotransferrin- and ovomucoid-containing fraction from egg white. Diluted egg white (2×) was added to Fe(3+) and treated with 43% ethanol (final concentration). After centrifugation, the supernatant was collected and treated with either a high-level ethanol (61% final concentration) or an acidic salt combination (2.5% ammonium sulfate and 2.5% citric acid) to separate ovotransferrin and ovomucoid. For the high-level of ethanol method, ovotransferrin was precipitated using 61% ethanol. After centrifugation, the precipitant was dissolved in 9 vol. of distilled water and the residual ethanol in the solution was removed using ultrafiltration. The supernatant, mainly containing ovomucoid, was diluted with 4 vol. of water, had ethanol removed, and was then concentrated and used as the ovomucoid fraction. For the acidic salt precipitation method, the ethanol in the supernatant was removed first. The ethanol-free solution was then concentrated and treated with a 2.5% ammonium sulfate and 2.5% citric acid combination. After centrifugation, the precipitant was used as the ovotransferrin and the supernatant as the ovomucoid fraction. The ovomucoid fraction from both of the protocols was further purified by heating at 65°C for 20 min and the impurities were removed by centrifugation. The yields of ovomucoid and ovotransferrin were >96 and >92%, respectively. The purity of ovomucoid was >89% and that of the ovotransferrin was >88%. The ELISA results confirmed that the activity of the separated ovotransferrin was >95%. Both of the protocols separated ovotransferrin and ovomucoid effectively and the methods were simple, fast, and easy to scale up.

Egg white proteins and their potential use in food processing or as nutraceutical and pharmaceutical agents--a review.

Egg white contains many functionally important proteins. Ovalbumin (54%), ovotransferrin (12%), ovomucoid (11%), ovomucin (3.5%), and lysozyme (3.5%) are among the major proteins that have high potentials for industrial applications if separated. The separation methods for these proteins from egg white have been developed since early 1900, but preparation methods of these proteins for commercial applications are still under development. Simplicity and scalability of the methods, use of nontoxic chemicals for the separation, and sequential separation for multiple proteins are very important criteria for the commercial production and application of these proteins. The separated proteins can be used in food and pharmaceutical industry as is or after modifications with enzymes. Ovotransferrin is used as a metal transporter, antimicrobial, or anticancer agent, whereas lysozyme is mainly used as a food preservative. Ovalbumin is widely used as a nutrient supplement and ovomucin as a tumor suppression agent. Ovomucoid is the major egg allergen but can inhibit the growth of tumors, and thus can be used as an anticancer agent. Hydrolyzed peptides from these proteins showed very good angiotensin I converting enzyme inhibitory, anticancer, metal binding, and antioxidant activities. Therefore, separation of egg white proteins and the productions of bioactive peptides from egg white proteins are emerging areas with many new applications.

Separation of ovotransferrin from chicken egg white without using organic solvents.

Ovotransferrin is one of the major egg white proteins that have antimicrobial activity as well as iron binding capability. The objective of this study was to develop a simple and easy method to separate ovotransferrin without using organic solvents. Egg white was separated from yolk, added in a 1:1 ratio to distilled water (DW), and then homogenized. The ovomucin in the diluted egg white was removed by centrifugation, adjusting the pH to 4.5 to 5.0. The resulting supernatant was added to different ratios of ammonium sulfate and citric acid, and then centrifuged after holding overnight at 4°C. The precipitant, which contains ovotransferrin, was dissolved in DW, and ovotransferrin was precipitated using different ratios of ammonium sulfate and citric acid. The precipitant collected after centrifugation was dissolved with DW and subjected to ultrafiltration to remove salts and concentrate the solution. The purity of the ovotransferrin was determined using SDS-PAGE, the protein identified using Western blot, and the estimated yield calculated by weighing the ovotransferrin after freeze drying. Over 85% purity and over 83% yield were obtained from the combinations of 5.0% (wt/vol) ammonium sulfate and 2.5% (wt/vol) citric acid followed by 2.0% (wt/vol) ammonium sulfate and 1.5% (wt/vol) citric acid. Activity of the ovotransferrin showed similar activity with previously separated ovotransferrin. However, this method is simpler and more cost effective than the previous method. The isolated ovotransferrin can be used as is or after modifications for various applications such as antimicrobial treatments, anticancer treatments, and iron-supplementing agents for humans.

Screening for cytotoxic activity of ovotransferrin and its enzyme hydrolysates.

The aim of this study was to investigate the cytotoxic activities of ovotransferrin (OTF) from egg white and its enzyme hydrolysates (OTH). The OTF was hydrolyzed at 45°C for 3 h using neutrase, alcalase, acid (0.03 N HCl, pH 2.5), protamex, protex 6L, flavorzyme, α-chymotrypsin, trypsin, and collupulin MG. The enzyme to substrate ratio was 1:25 (wt/wt) in all experiments. Using the 3-(4,5-dimethylthizol-2-yl)-2,5-diphenylatetetrazolium bromide (MTT) assay, the cytotoxicity of OTF and OTH was evaluated in human cancer cell lines of various tissue origins, including the lung (A549 and SK-MES-1), stomach (AGS), breast (MCF-7), larynx (Hep-2), cervix (HeLa), and liver (HepG2). The growth of all cancer cell lines was inhibited by both OTF and OTH in a dose-dependent manner. In particular, OTF displayed relatively high cytotoxicity (≤60% inhibition effects) at 40 mg/mL. At lower concentrations (≤5 mg/mL), however, OTF- and OTH-mediated cytotoxic effects were not significant in all cancer cell lines tested. The MCF-7 cells were the least sensitive to all treatments among all cancer cell lines tested. The OTH-trypsin and OTH-neutrase showed a potent cytotoxicity (over 90% cytotoxicity) to HeLa cells at the 10 mg/mL level. The OTH-trypsin, OTH-protamex, OTH-protex 6L, and OTH-collupulin MG caused 95, 96, 86, and 87% growth inhibition, respectively, in AGS cells. These results indicated there are possibilities that OTF and OTH can be used as natural growth inhibitors of human cancer cell lines.

Antioxidant effects of ovotransferrin and its hydrolysates.

Food protein-derived peptides are important components for nutraceuticals, with many biological functions as well as substantial nutritional benefits. The aim of this study was to investigate the antioxidant effects of ovotransferrin (OTF) derived from egg white and its hydrolysates (OH) prepared by hydrolyzing either with acid or enzymes (protamex, alkalase, trypsin, neutrase, flavorzyme, maxazyme, collupulin, protex, promod 278, and α-chymotrypsin). All OH showed approximately 3.2 to 13.5 times higher superoxide anion scavenging activity than OTF, with the maximum activity found in the OH-protamex. Similar results were obtained for oxygen radical absorbance capacity assay, with the highest value in OH-α-chymotrypsin [1.6 µM trolox equivalents (TE)] and the lowest value in OTF (0.2 µM TE). However, OTF showed the most powerful 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity, which reached 78.2% after 36 h of reaction. Both OTF and OH showed protective effects against the oxidative stress-induced DNA damages in human leukocytes. Overall, OTF possessed antioxidant abilities and hydrolyzation of OTF with acid or enzymes improved these abilities.

Irradiation of shell egg on the physicochemical and functional properties of liquid egg white.

This study was aimed at determining the effect of irradiation of shell eggs on the physiochemical and functional properties of liquid egg white during storage. Color and textural parameters of irradiated liquid egg white after cooking were also determined. Shell eggs were irradiated at 0, 2.5, 5, or 10 kGy using a linear accelerator. Egg white was separated from yolk and stored in at 4°C up to 14 d. Viscosity, pH, turbidity, foaming properties, color, and volatile profile of liquid egg white, and color and texture properties of cooked egg white were determined at 0, 7, and 14 d of storage. Irradiation increased the turbidity but decreased viscosity of liquid egg white. Foaming capacity and foam stability were not affected by irradiation at lower dose (2.5 kGy), but were deteriorated at higher doses (≥5.0 kGy) of irradiation. Sulfur-containing volatiles were generated by irradiation and their amounts increased as the irradiation dose increased. However, the sulfur volatiles disappeared during storage under aerobic conditions. Lightness (L* value) and yellowness (b* value) decreased, but greenness (-a* value) increased in cooked egg white in irradiation dose-dependent manners. All textural parameters (hardness, adhesiveness, cohesiveness, chewiness, and resilience) of cooked egg white increased as the irradiation dose increased, but those changes were marginal. Our results indicated that irradiation of shell egg at lower doses (up to 2.5 kGy) had little negative impact on the physiochemical and functional properties of liquid egg white, but can improve the efficiency of egg processing due to its viscosity-lowering effect. Therefore, irradiation of shell eggs at the lower doses has high potential to be used by the egg processing industry to improve the safety of liquid egg without compromising its quality.

Evaluation of radiation-induced compounds in irradiated raw or cooked chicken meat during storage.

The concentrations of hydrocarbons, 2-alkylcyclobutanones, and sulfur volatiles in irradiated (0 and 5 kGy) chicken meat samples (raw, precooked, and irradiated-cooked) were analyzed after 0 and 6 mo of frozen storage (-40°C) under oxygen-permeable packaging conditions. Two hydrocarbons [8-heptadecene (C(17:1)) and 6,9-heptadecadiene (C(17:2))], two 2-alkylcyclobutanones (2-dodecylcyclobutanone and 2-tetradecylcyclobutanone), and dimethyl disulfide were determined as radiation-induced detection markers in the irradiated raw and cooked chicken meats. Although irradiated-cooked samples produced fewer hydrocarbons and 2-alkylcyclobutanones than precooked irradiated samples, the number of individual hydrocarbons or 2-alkylcyclobutanones was still sufficient to detect radiation treatment even after 6 mo of storage at -40°C. Among sulfur volatiles, only dimethyl disulfide was found in meat after 6 mo of storage, indicating it has potential to be used an irradiation detection marker for frozen-stored meats under oxygen-permeable packaging conditions.

Influence of nisin and selected meat additives on the antimicrobial effect of ovotransferrin against Listeria monocytogenes.

The objective of this study was to determine the effect of nisin and selected meat additives (salt, lactate, lactate-diacetate combination, and polyphosphate) on the antimicrobial activities of ovotransferrin (OTF) against the growth of Listeria monocytogenes. A Bioscreen C turbidometer (Oy Growth Curves AB Ltd., Helsinki, Finland) was used to evaluate the effect of various concentrations of nisin and individual meat additives on the antilisterial activity of OTF in brain heart infusion (BHI) broth. The concentrations of OTF, meat additives, nisin, and their combinations that proved most inhibitory to L. monocytogenes were selected and their antilisterial effects were tested using frankfurters. Frankfurters were inoculated with L. monocytogenes (~6.0 log(10) cfu/frankfurter); treated with OTF, meat additives, and nisin singly or in combination; and held under vacuum at 4, 10, or 25°C. At 40 mg/mL, OTF strongly suppressed (3.46 log at 4 h and 2.59 log at 12 h) the growth of L. monocytogenes in BHI broth compared with the control. A combination of OTF (40 mg/mL) and nisin (1,000 IU) inhibited the growth of L. monocytogenes in BHI and in frankfurters held at 25°C below the detection limit (1 cfu/mL) at 12 h. However, the antimicrobial effect of OTF (40 mg/mL) alone was not observed in frankfurters at all temperatures used in this study. Nisin (1,000 IU), OTF (40 mg/mL), and nisin (1,000 IU) combination completely inhibited the growth of L. monocytogenes in frankfurters at all temperatures during 3 d. Salt at 0.5 and 1%, lactate at 0.78 and 1.56%, and lactate (1.56%) + diacetate (0.01%) did not alter the inhibitory effect of OTF against the pathogen in BHI, but salt at 2% or polyphosphate at 0.05% negated the growth inhibitory effect of OTF against L. monocytogenes. This study demonstrated that combination of OTF and nisin was effective in controlling L. monocytogenes.

Effects of diet, packaging, and irradiation on protein oxidation, lipid oxidation, and color of raw broiler thigh meat during refrigerated storage.

This study was designed to evaluate the effects of dietary treatment, packaging, and irradiation singly or in combination on the oxidative stability of broiler chicken thigh meat. A total of 120 four-week-old chickens were divided into 12 pens (10 birds/pen), and 4 pens of broilers were randomly assigned to a control oxidized diet (5% oxidized oil) or an antioxidant-added diet [500 IU of vitamin E + 200 mg/kg of butylated hydroxyanisole (BHA)] and fed for 2 wk. After slaughter, thigh meats were separated, ground, packaged in either oxygen-permeable or oxygen-impermeable vacuum bags, and irradiated at 0 or 3 kGy. Lipid oxidation (TBA-reactive substances), protein oxidation (carbonyl), and color of the meat were measured at 1, 4, and 7 d of refrigerated storage. The lipid and protein oxidation of thigh meats from birds fed the diet supplemented with antioxidants (vitamin E + BHA) was significantly lower than the lipid and protein oxidation of birds fed the control diet, whereas the lipid and protein oxidation of broilers fed the oxidized oil diet was higher than that of birds fed the control diet. Vacuum packaging slowed, but irradiation accelerated, the lipid and protein oxidation of thigh meat during storage. Dietary antioxidants (vitamin E + BHA) and irradiation treatments showed a stronger effect on lipid oxidation than on protein oxidation. A significant correlation between lipid and protein oxidation in meat was found during storage. Dietary supplementation of vitamin E + BHA and the irradiation treatment increased the lightness and redness of thigh meat, respectively. It is suggested that appropriate use of dietary antioxidants in combination with packaging could be effective in minimizing oxidative changes in irradiated raw chicken thigh meat.