Estimation of Genetic Parameters for Pork Belly Components in Yorkshire Pigs.

This study was conducted to estimate the genetic parameters for pork belly traits and muscles in Yorkshire pigs. Each pork belly was cut into nine parts perpendicular to the thoracic vertebrae (6th to 14th). Traits of belly muscles including the deep pectoral, latissimus dorsi, cutaneous trunci, rectus abdominis, external and internal abdominal oblique from 382 purebred pigs were recorded and analyzed using SAS Package (9.1) and Derivative-free restricted maximum likelihood methods. Heritability estimates for belly traits ranged from 0.27 to 0.49, while they were 0.12 to 0.66 for belly muscles. Moderate to high heritability estimates were noted in belly weight (0.33), belly length (0.28), and belly width (0.49). In belly muscles, the latissimus dorsi and deep pectoral, which are located only in the 6th to 9th vertebrae sections, were found to have heritability estimates ranging from 0.21 to 0.29 and 0.23 to 0.35, respectively. Strong heritability estimates were observed in the 7th to 13th sections of cutaneous trunci muscle ranging from 0.42 to 0.66. Genetic correlations of latissimus dorsi m. with belly length were positive (0.50), while cutaneous trunci m. with belly weight also revealed a positive relationship that ranged from 0.35 to 0.47. The estimated genetic parameters indicate that belly weight can be improved by genetic selection. Differences in the levels of heritability occurred among various parameters of Yorkshire pork belly, which should be considered when performing selection to improve pork belly quality. Moreover, these results can provide valuable information that can be used as the basis for further investigations to improve pork belly.

Estimation of Genetic Associations between Production and Meat Quality Traits in Duroc Pigs.

Data collected from 690 purebred Duroc pigs from 2009 to 2012 were used to estimate the heritability, and genetic and phenotypic correlations between production and meat quality traits. Variance components were obtained through the restricted maximum likelihood procedure using Wombat and SAS version 9.0. Animals were raised under the same management in five different breeding farms. The average daily gain, loin muscle area (LMA), backfat thickness (BF), and lean percent (LP) were measured as production traits. Meat quality traits included pH, cooking loss, lightness (L*), redness (a*), yellowness (b*), marbling score (MS), moisture content (MC), water holding capacity (WHC), and shear force. The results showed that the heritability estimates for meat quality traits varied largely from 0.19 to 0.79. Production traits were moderate to highly heritable from 0.41 to 0.73. Genotypically, the BF was positively correlated (p<0.05) with MC (0.786), WHC (0.904), and pH (0.328) but negatively correlated with shear force (-0.533). The results of genetic correlations indicated that selection for less BF could decrease pH, moisture content, and WHC and increase the shear force of meat. Additionally, a significant positive correlation was recorded between average daily gain and WHC, which indicates pork from faster-growing animals has higher WHC. Furthermore, selection for larger LMA and LP could increase MS and lightness color of meat. The meat quality and production traits could be improved simultaneously if desired. Hence, to avoid further deterioration of pork characteristics, appropriate selection of traits should be considered.

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.

A whole genome association study on meat palatability in hanwoo.

A whole genome association (WGA) study was carried out to find quantitative trait loci (QTL) for sensory evaluation traits in Hanwoo. Carcass samples of 250 Hanwoo steers were collected from National Agricultural Cooperative Livestock Research Institute, Ansung, Gyeonggi province, Korea, between 2011 and 2012 and genotyped with the Affymetrix Bovine Axiom Array 640K single nucleotide polymorphism (SNP) chip. Among the SNPs in the chip, a total of 322,160 SNPs were chosen after quality control tests. After adjusting for the effects of age, slaughter-year-season, and polygenic effects using genome relationship matrix, the corrected phenotypes for the sensory evaluation measurements were regressed on each SNP using a simple linear regression additive based model. A total of 1,631 SNPs were detected for color, aroma, tenderness, juiciness and palatability at 0.1% comparison-wise level. Among the significant SNPs, the best set of 52 SNP markers were chosen using a forward regression procedure at 0.05 level, among which the sets of 8, 14, 11, 10, and 9 SNPs were determined for the respectively sensory evaluation traits. The sets of significant SNPs explained 18% to 31% of phenotypic variance. Three SNPs were pleiotropic, i.e. AX-26703353 and AX-26742891 that were located at 101 and 110 Mb of BTA6, respectively, influencing tenderness, juiciness and palatability, while AX-18624743 at 3 Mb of BTA10 affected tenderness and palatability. Our results suggest that some QTL for sensory measures are segregating in a Hanwoo steer population. Additional WGA studies on fatty acid and nutritional components as well as the sensory panels are in process to characterize genetic architecture of meat quality and palatability in Hanwoo.

Evaluation of genome based estimated breeding values for meat quality in a berkshire population using high density single nucleotide polymorphism chips.

The accuracy of genomic estimated breeding values (GEBV) was evaluated for sixteen meat quality traits in a Berkshire population (n = 1,191) that was collected from Dasan breeding farm, Namwon, Korea. The animals were genotyped with the Illumina porcine 62 K single nucleotide polymorphism (SNP) bead chips, in which a set of 36,605 SNPs were available after quality control tests. Two methods were applied to evaluate GEBV accuracies, i.e. genome based linear unbiased prediction method (GBLUP) and Bayes B, using ASREML 3.0 and Gensel 4.0 software, respectively. The traits composed different sets of training (both genotypes and phenotypes) and testing (genotypes only) data. Under the GBLUP model, the GEBV accuracies for the training data ranged from 0.42±0.08 for collagen to 0.75±0.02 for water holding capacity with an average of 0.65±0.04 across all the traits. Under the Bayes B model, the GEBV accuracy ranged from 0.10±0.14 for National Pork Producers Council (NPCC) marbling score to 0.76±0.04 for drip loss, with an average of 0.49±0.10. For the testing samples, the GEBV accuracy had an average of 0.46±0.10 under the GBLUP model, ranging from 0.20±0.18 for protein to 0.65±0.06 for drip loss. Under the Bayes B model, the GEBV accuracy ranged from 0.04±0.09 for NPCC marbling score to 0.72±0.05 for drip loss with an average of 0.38±0.13. The GEBV accuracy increased with the size of the training data and heritability. In general, the GEBV accuracies under the Bayes B model were lower than under the GBLUP model, especially when the training sample size was small. Our results suggest that a much greater training sample size is needed to get better GEBV accuracies for the testing samples.

Comparison and correlation analysis of different Swine breeds meat quality.

This study was performed to determine the influence of pig breed and gender on the ultimate pH and physicochemical properties of pork. The correlations between pH and pork quality traits directly related to carcass grade, and consumer's preference were also evaluated. The pH and meat grading scores for cold carcasses of 215 purebred pigs (Duroc, Landrace, and Yorkshire) from four different farms were obtained. Meat quality parameters of the pork loin were analyzed. Duroc and female animals were more affected compared to other breeds and male pigs. Duroc animals had the highest ultimate pH, carcass back fat thickness, marbling scores, yellowness, and fat content (p<0.05). Landrace pigs had the highest color lightness and cooking loss values (p<0.05). Among all trait parameters, marbling scores showed the highest significant differences when evaluating the impact of breed and gender on meat quality characteristics (p<0.001). Ultimate pH was positively correlated with carcass weight (0.20), back fat thickness (0.19), marbling score (0.17), and color score (0.16) while negatively correlated with cooking loss (-0.24) and shear force (-0.20). Therefore, pork samples with lower ultimate pH had lower cooking loss, higher lightness, and higher shear force values irrespective of breed.

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.

Effects of chitosan coating and storage with dry ice on the freshness and quality of eggs.

To develop a method that can maintain egg freshness during practical storage conditions, eggs were coated with chitosan and stored with or without dry ice. The physicochemical and microbiological qualities of eggs were evaluated during 14 d of storage at 4 and 23°C without dry ice and at 23°C with dry ice. The combination of chitosan coating and dry ice significantly inhibited a Haugh unit decrease during storage at 23 °C. No difference in functional properties, such as foaming ability, foam stability, and viscosity, among treatments was observed, but chitosan coating and storage with dry ice decreased the rate of pH increase and moisture loss in albumen at d 7 and 14. The eggs treated with chitosan coating and storage with dry ice had a significantly lower number of Salmonella Typhimurium inoculated on the egg surface than did control eggs during storage at 23°C. Results revealed that the combination of chitosan coating and storage with dry ice limited the moisture loss, CO(2) emission, and pH increase, which helped maintaining the freshness of eggs. Microbial growth was also inhibited during storage at 23°C.

A simple and efficient method for preparing partially purified phosvitin from egg yolk using ethanol and salts.

The objective of this study was to develop a new protocol that could be used for large-scale separation of phosvitin from egg yolk using ethanol and salts. Yolk granules, which contain phosvitin, were precipitated after diluting egg yolk with 9 volumes of distilled water. The pH of the yolk solution was adjusted to pH 4.0 to 8.0 using 6 N HCl or NaOH, and then yolk granules containing phosvitin was separated by centrifugation at 3,220 × g for 30 min. Lipids and phospholipids were removed from the insoluble yolk granules using 85% ethanol. The optimal volumes and concentration of ethanol in removing lipids from the precipitants were determined. After centrifugation, the lipid-free precipitants were homogenized with 9 volumes of ammonium sulfate [(NH(4))(2)SO(4)] or NaCl to extract phosvitin. The optimal pH and concentration of (NH(4))(2)SO(4) or NaCl for the highest recovery rate and purity for phosvitin in final solution were determined. At pH 6.0, all the phosvitin in diluted egg yolk solution was precipitated. Among the (NH(4))(2)SO(4) and NaCl conditions tested, 10% (NH(4))(2)SO(4) or 10% NaCl at pH 4.0 yielded the greatest phosvitin extraction from the lipid-free precipitants. The recovery rates of phosvitin using (NH(4))(2)SO(4) and NaCl were 72 and 97%, respectively, and their purity was approximately 85%. Salt was removed from the extract using ultrafiltration. The salt-free phosvitin solution was concentrated using ultrafiltration, the impurities were removed by centrifugation, and the resulting solution was freeze-dried. The partially purified phosvitin was suitable for human use because ethanol was the only solvent used to remove lipids, (NH(4))(2)SO(4) or NaCl was used to extract phosvitin, and ultrafiltration was used to remove salt and concentrate the extract. The developed method was simple and suitable for a large-scale preparation of partially purified phosvitin.

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.

Effects of oleoresin-tocopherol combinations on lipid oxidation, off-odor, and color of irradiated raw and cooked pork patties.

Lipid oxidation, color, and volatiles of double-packaged pork loins with various oleoresin or oleoresin-tocopherol combinations were determined to establish the best oleoresin-tocopherol conditions that can improve the quality of irradiated raw and cooked pork loins. Rosemary and α-tocopherol combination at 0.05% and 0.02% of meat weight, respectively, showed the most potent antioxidant effects in reducing both TBARS values and the amounts of volatile aldehydes in irradiated raw and cooked pork loins. The antioxidant combination, however, did not affect the production of sulfur volatiles responsible for irradiation off-odor and showed little effects on color changes in irradiated raw and cooked pork loins. Exposing double-packaged irradiated pork to aerobic conditions for 3days during the 10-day storage was effective in controlling both lipid oxidation and irradiation off-odor, regardless of packaging sequences.

Influence of rosemary-tocopherol/packaging combination on meat quality and the survival of pathogens in restructured irradiated pork loins.

Irradiated restructured pork loins treated with rosemary-tocopherol/double-packaging had lower TBARS values than vacuum-packaged control after 10 days of refrigerated storage. The rosemary-tocopherol combination, however, had no effect on the production of sulfur volatiles responsible for the irradiation off-odor, and color changes in irradiated pork. V7/A3 double-packaging was effective in reducing the sulfur volatiles significantly. Rosemary-tocopherol combination was highly effective in reducing the volatile hexanal in irradiated restructure pork. Irradiation was effective in reducing Listeria monocytogenes and Salmonella typhimurium inoculated on the surface of restructured pork loin in dose-dependent manner. The irradiation D(10) values for L. monocytogenes and S. typhimurium were 0.58 and 0.55kGy, respectively. During the 20 days of refrigerated storage, L. monocytogenes in both nonirradiated and irradiated samples grew gradually, but the number of S. typhimurium decreased. The added rosemary-tocopherol, however, showed little bacteriocidal effects to L. monocytogenes and S. typhimurium.

Dietary functional ingredients: performance of animals and quality and storage stability of irradiated raw turkey breast.

The objective of this study was to evaluate the effect of dietary functional ingredients vitamin E (VE), Se, and conjugated linoleic acid (CLA), alone or in combination, on the quality of irradiated turkey breast meat. A total of 480 male turkeys (11-wk-old, raised on a cornsoybean basal diet) were randomly allotted to 32 pens and fed 1 of 8 experimental diets (4 pens/treatment) supplemented with none (control), 200 IU/kg of VE (VE), 0.3 ppm Se (Se), 2.5% CLA (CLA), 200 IU/kg of VE + 0.3 ppm Se (VE + Se), 200 IU/kg of VE + 2.5% CLA (VE + CLA), 2.5% CLA + 0.3 ppm Se (CLA + Se), 200 IU/kg of VE + 0.3 ppm Se + 2.5% CLA (VE + Se + CLA) for 4 wk. At 15 wk of age, all birds were slaughtered, and breast muscles of 8 birds from each pen were separated, pooled, and ground. Patties were prepared using the ground meat, aerobically packaged, and irradiated at 0 or 1.5 kGy absorbed dose. Lipid oxidation, color, and volatiles of the patties were measured after 0, 7, and 12 d of storage at 4 degrees C. The content of VE and Se and fatty acid composition of lipids were also determined. Dietary supplementation of VE and CLA increased their concentrations in turkey breast. Dietary CLA decreased monounsaturated and non-CLA polyunsaturated fatty acids content in meat. Irradiation increased (P < 0.05) Hunter color redness value of turkey breast and accelerated lipid oxidation, regardless of dietary treatments. However, dietary VE, Se, and CLA, alone and in combinations, decreased (P < 0.05) lipid oxidation in meat caused by both irradiation and storage. It was concluded that dietary supplementation of VE, Se, and CLA, alone and in combination, improved the storage stability of irradiated turkey breast meat.

Effects of dietary functional ingredients and packaging methods on sensory characteristics and consumer acceptance of irradiated turkey breast meat.

Raw and cooked breast patties from turkeys fed 8 different diets [control; 200 IU/kg of vitamin E (VE); 0.3 mg/kg of Se; 2.5% conjugated linoleic acids (CLA); 200 IU/kg of VE + 0.3 mg/kg of Se; 200 IU/kg of VE + 2.5% CLA; 0.3 mg/kg of Se + 2.5% CLA; and 200 IU/kg of VE + 0.3 mg/kg of Se + 2.5% CLA] were treated with 2 irradiation doses (0 and 1.5 kGy) and 2 packaging methods (vacuum and aerobic). Raw and cooked samples from 32 treatments were tested by 8 trained sensory panelists for turkey aroma and irradiation off-aroma. Based on the sensory scores, the 3 dietary treatments producing the most and the least off-aroma were selected and used for a consumer acceptance study. Sensory results of raw meat showed that turkey aroma was intense in aerobically packaged meat, whereas irradiation off-aroma was intense with vacuum packaging. Raw meats from dietary treatments containing CLA (CLA, VE + CLA, Se + CLA, VE + Se + CLA) had greater turkey aroma scores, whereas those containing VE (VE and VE + Se) had lower scores than the control. Dietary treatments containing VE (VE, VE + Se, VE + Se + CLA) significantly lowered (P < 0.05) irradiation off-aroma in raw turkey breast meat, whereas CLA increased it, especially when the meats were packaged aerobically. In cooked meat, however, irradiation and packaging had no effect on turkey meat aroma and irradiation off-aroma. Cooked meat from turkeys supplemented with VE (VE and VE + Se) had less (P < 0.05) irradiation off-odor than other dietary treatments. Dietary CLA increased the irradiation off-aroma in cooked meat, which could not be reduced, even when VE and Se were combined in the diet. Irradiation off-aroma of raw meat was not pleasant for most consumers, and dietary supplementation of VE and VE + Se improved consumer acceptance of irradiated raw meat. For cooked meat samples, consumers preferred both color and flavor of irradiated meat to nonirradiated meat.

Effect of far-infrared irradiation on the antioxidant activity of defatted sesame meal extracts.

To determine the effect of far-infrared (FIR) irradiation on the antioxidant activities of sesame meal, half of sesame seeds were FIR-irradiated and then oil was extracted from the seeds. The resulting defatted sesame meal (DSM) was extracted with methanol, and the antioxidant activities of methanolic extract were determined. FIR irradiation of sesame seeds for 30 min increased the total phenol content from 34.0 to 59.0 muM and radical scavenging activity of DSM extracts from 26.40 to 68.76%. The induction time of lipid oxidation of oil added to extracts was also retarded from 0.82 to 0.96 h. According to the gas chromatography-mass spectrometry analysis, several low molecular weight phenolic compounds, such as p-hydroxy benzoic acid, vanillic acid, p-coumaric acid, isoferulic acid, and o-coumaric acid, were frequently detected in FIR-irradiated DSM extracts as compared to unirradiated ones. These results indicated that FIR irradiation of sesame seeds increased the antioxidant activity of methanolic extracts of DSM.

Automatic stimulus breaker for electric dental pulp tester using pain response.

The pulp test provides a means of examining the vitality of dental pulp using physical or chemical stimulation. During electrical pulp testing, an electrical current stimulates the intradental nerve, which may be painful and stressful to patients. The study involved measurement of the electromyogram (EMG) from the anterior belly of the digastric muscle, finger movement and voice response during electrical pulp testing. The excessive stimulus time from the onset time of response (EMG, voice and finger movement) to the end of the stimulation was obtained. The results indicated that the responses occurred in the order: EMG, finger and voice. Based on these results, an automatic stimulus shut-off circuit was developed using the above-mentioned responses to stimulus during electric pulp testing. Excessive stimulus time was reduced by prompt switching-off of the pulp tester output, 64 ms on average after the first detected response (EMG). Consequently, excessive stimulus times were reduced by 284 and 152 ms on average for the subject and examiner disconnection, respectively, using the developed automatic shut-off circuit. Therefore it was possible to minimise pain and stress by reducing excessive pulp stimulation.

Effect of irradiating shell eggs on quality attributes and functional properties of yolk and white.

Shell eggs were irradiated and the physico-chemical, and functional properties of egg yolk and white were determined. The color of egg yolk was not affected, but the viscosity of egg white was dramatically lowered and became watery by irradiation. The foam capacity and foam stability of egg white were significantly decreased due to protein oxidation by irradiation. However, the texture characteristics of egg white were not changed by irradiation, indicating that irradiation may not alter the thermal characteristics of egg white proteins. Sulfur volatiles were generated by irradiation but disappeared during storage under aerobic conditions. Because egg white became watery, irradiation may not be advisable for table eggs but may be useful for pasteurizing liquid egg white or liquid whole egg without significant deterioration of their quality and functionality. In particular, the dramatic decrease in the viscosity of egg white by irradiation will improve flow of liquid egg white or liquid whole egg, which could be highly useful for egg processing.

Development of a frequency-dependent-type apex locator with automatic compensation.

Among apex locators, the frequency dependent type is more accurate and convenient to use than others. However, the accuracy of the apex locator is still influenced by the presence of various electrolytes used in root canal treatments. In this study, we developed a frequency-dependent electronic apex locator minimizing the influence of electrolytes on the measurement of root canal lengths. It was confirmed that the two frequencies of 0.5 and 10 kHz are better than the conventional ones of 0.4 and 8 kHz. The impedance ratio of the two different frequencies represents the position of the file in root canal, and the voltage difference of the two frequencies represents the status of the fluid in the root canal. As a result of compensation using the voltage differences of the two frequencies, the errors decreased significantly on average from +0.54 mm to +0.18 mm in H2O2 solution (p < 0.01), and from -0.33 mm to -0.01 mm in NaOCl solution (p < 0.01) in the tooth model experiments.

Far-infrared radiation increases the antioxidant properties of rice hull extract in cooked turkey meat.

To determine the antioxidant effects of rice hull extract exposed to far-infrared radiation, the added extracts were compared with sesamol in cooked turkey breast. Rice hull extract showed antioxidant properties in cooked turkey breast by reducing lipid oxidation and volatile aldehydes. Far-infrared radiation increased significantly the antioxidant activities of rice hull extracts. Rice hull extract irradiated by far-infrared (FRH) had lower TBARS values and fewer volatile aldehydes (hexanal, pentanal, and propanal) than a non-irradiated extract (IRH) during the 3 days of aerobic storage. Addition of FRH at 0.2% (w/w) in turkey meat could reduce the amounts of volatile hexanal to 18-47% of the control during the storage. However, the antioxidant activities of rice hull extracts did not last as long as those of pure sesamol due to the relatively low concentration of phenolics, and the extracts had some peculiar odor. Addition of rice hull extracts also increased both a and b values of the samples due to its brown intensity.

Effect of heat treatment on the antioxidant activity of extracts from citrus peels.

The effect of heat treatment on the antioxidant activity of extracts from Citrus unshiu peels was evaluated. Citrus peels (CP) (5 g) were placed in Pyrex Petri dishes (8.0 cm diameter) and heat-treated at 50, 100, or 150 degrees C for 10, 20, 30, 40, 50, and 60 min in an electric muffle furnace. After heat treatment, 70% ethanol extract (EE) and water extract (WE) (0.1 g/10 mL) of CP were prepared, and total phenol contents (TPC), radical scavenging activity (RSA), and reducing power of the extracts were determined. The antioxidant activities of CP extracts increased as heating temperature increased. For example, heat treatment of CP at 150 degrees C for 60 min increased the TPC, RSA, and reducing power of EE from 71.8 to 171.0 microM, from 29.64 to 64.25%, and from 0.45 to 0.82, respectively, compared to non-heat-treated control. In the case of WE from CP heat-treated at the same conditions (150 degrees C for 60 min), the TPC, RSA, and reducing power also increased from 84.4 to 204.9 microM, from 15.81 to 58.26%, and from 0.27 to 0.96, respectively. Several low molecular weight phenolic compounds such as 2,3-diacetyl-1-phenylnaphthalene, ferulic acid, p-hydroxybenzaldoxime, 5-hydroxyvaleric acid, 2,3-diacetyl-1-phenylnaphthalene, and vanillic acid were newly formed in the CP heated at 150 degrees C for 30 min. These results indicated that the antioxidant activity of CP extracts was significantly affected by heating temperature and duration of treatment on CP and that the heating process can be used as a tool for increasing the antioxidant activity of CP.