Effect of Dietary Sorghum Cultivars on the Storage Stability of Broiler Breast and Thigh Meat 1

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1 Effect of Dietary Sorghum Cultivars on the Storage Stability of Broiler Breast and Thigh Meat 1 M. Du,* G. Cherian, P. A. Stitt, and D. U. Ahn*,2 *Department of Animal Science, Iowa State University, Ames, Iowa 50011; Department of Animal Science, Oregon State University, Corvallis, Oregon ; and Essential Nutrient Research Corp. Manitowoc, Wisconsin ABSTRACT A total of d-old male broiler chicks tive change during 12-h holding time before analyses. were fed a corn-soy-flax meal-based diet (control), two cultivars of sorghum Ruby Red (low tannin content) Thigh meat from broilers fed the Valpo Red cultivar produced lower TBARS than that from control at Day 0. The and Valpo Red (high tannin content) were used at 10% amounts of aldehydes and sulfur compounds of cooked level. Birds were slaughtered at the end of 42-d feeding breast meats were lower from chickens fed the Valpo Red trial. Boneless, skinless breast and thigh muscles were cultivar than those fed the control or Ruby Red cultivar. Dietary Valpo Red cultivar improved the oxidative stability of breast meat 8 and 12 h after cooking. Dietary sor- separated and ground to make patties. Half of the breast and thigh meat patties were individually packaged in ghum slightly improved the color a* stability of raw thigh zipper bags, and 2-TBA-reactive substances (TBARS) and meat patties. This result indicated that feeding sorghum colors of the patties were determined after 0 and 7 d of to broilers could improve some measures of the storage storage at 4 C. The other half was cooked and vacuumpackaged. stability of broiler meat, but sorghum with high tannin The vacuum-packaged patties were used to determine time-dependent volatile production and oxidacontent was more effective than that with low tannin content. (Key words: sorghum, boiler meat, storage stability, volatiles, color) 2002 Poultry Science 81: INTRODUCTION Broiler diets can influence the oxidative stability of meat. Dietary vitamin E has been used to improve the oxidative stability of meat (Maraschiello et al., 1999). Garlic supplement (at 50g/kg of feed) is effective in improving oxidative stability of cooked chicken breast and thigh meats (Abdalla, 1999). Cave and Burrows (1993) reported that increasing naked oat in chicken diets decreases the oxidation in chicken thigh meat. Sorghum contains high levels of tannin and other phenolic compounds (El-Khalifa and El-Tinay, 1994). Tannin and related phenolic compounds have strong antioxidant effects. Yokozawa et al. (2000) reported that green tea extract and tannin mixtures protected cultured cells from oxidative stress, and tannin mixtures exhibit higher antioxidant activity than green tea extracts. Yokozawa et al. (2000) fed rats diets with tannin and found that lipid peroxidation 2002 Poultry Science Association, Inc. Received for publication July 30, Accepted for publication April 10, Journal Paper Number J of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA Project Number 3706; supported by the Hatch Act and Essential Nutrient Research Corp. 2 To whom correspondence should be addressed: duahn@iastate.edu. in plasma and tissues decreased significantly in the presence of supplemented polymeric tannins. They also found that the antioxidant effect of tannin was as effective as that of vitamin E. By using radioactive 14 C tracing, Jimenez et al. (1994) analyzed the absorption of condensed tannin and other phenolic compounds and suggested that radiolabeled condensed tannins from sorghum grain are not absorbed from the digestive tract of chickens, but nontannin phenolic compounds are absorbed and distributed in various tissues. This finding suggests that the absorbed phenolic compounds present in muscle could exhibit antioxidant effects and, thus, improve the oxidative stability of meat. The 2-TBA-reactive substances (TBARS) test measures malonaldhyde content in meat and is the most frequently used test to determine lipid oxidation. TBARS is positively related to warmed-over flavor and hexanal content in meat (Igene et al., 1985; Shu et al., 1995). The propanal, pentanal, hexanal, and total volatiles were also highly correlated with the TBARS values of meat (Ahn et al., 1998). Cooked meats are highly susceptible to oxidative changes upon exposure to air. Ahn et al. (1999a) showed that minced meat samples are quickly oxidized in sample vials during holding time for volatile analysis. The TBARS and hexanal Abbreviation Key: TBARS = 2-TBA-reactive substances. 1385

2 1386 DU ET AL. production of meat samples increase linearly with the duration of sample holding time, and their production rates differ depending on the susceptibility of meat samples to oxidation (Ahn et al., 1999b). Thus, this time-dependent volatile production on oxidative changes during sample holding provides a simple and quick model for assessing the oxidative stability of meat and was used in the current study for analyzing the oxidative stability of cooked broiler chicken meats. Lipid oxidation is also related to color stability. Greene (1969) first reported that lipid oxidation and metmyoglobin formation is well correlated. The rate of discoloration is closely related to the rate of myoglobin oxidation induced by lipid oxidation (Yin and Faustman, 1993). Schaefer et al. (1995) hypothesized that the products of lipid oxidation are more water-soluble than their parent compounds and can enter the cytoplasm where they interact with myoglobin to hasten its oxidation. Sorghum feeding may improve the color stability of meat by its antioxidant effects. The objective of the study reported here was to determine the effect of dietary sorghum on the oxidative stability of raw and cooked broiler chicken meats. MATERIALS AND METHODS Sample Preparation Day-old male Hubbard broiler chicks were obtained from a commercial hatchery and divided among nine pens (50 birds/pen). Three pens each were assigned to a diet containing 10% Ruby Red sorghum cultivar (high tannin content), 10% Valpo Red (low tannin content), or control (corn-soy basal diet) and were fed for 42 d. The diets were formulated to contain 21.5% crude protein and 3,050 kcal of energy/kg of diet. Four birds from each pen were randomly selected and slaughtered according to the USDA guidelines. Birds were killed by exsanguination, bled for 90 s, scalded at 54 C for 120 s, and mechanically defeathered for 30 s. Feet were removed manually by severing the intratarsal joint. Carcasses were manually eviscerated, washed, and allowed to drip for 5 min. Carcasses were chilled in ice slush for 30 min, allowed to drip for 5 min, and then stored overnight at 4 C. Breast and leg meats were separated from the selected carcasses, and the meats of four birds from the same pen were pooled and used as a replicate. After removing skin and visible fats, breast and thigh meats were ground separately through 9- and 3-mm plates. The ground breast and thigh meats were made into 100-g patties. Half of each patty was individually packaged an aerobic bag, stored at 4 C, and analyzed at 0 and 7 d for TBARS and color. The other half was vacuum-packaged and cooked in a 90 C water bath to an internal temperature of 74 C, drained, and then repackaged 3 Koch, Kansas City, MO. 4 Tekmar-Dohrmann, Cincinnati, OH. 5 Hewlett-Packard Co. Wilmington, DE. 6 Hunter Associated Labs Inc., Reston, VA. immediately in oxygen impermeable bags 3 (nylon/polyethylene, 9.3 ml O 2 /m 2 /24 h at 0 C) and used for volatiles and TBARS measurements within 3 d of cooking. Volatile Compound Analyses A purge-and-trap apparatus 4 (Precept II and purge-andtrap 3000) connected to a gas chromatograph/mass spectrometer 5 (GC/MS) was used to analyze volatiles. One gram of cooked meat patties was added into 40-mL sample vials, flushed with 99.99% helium for 5 s at 40 psi, and held for 0, 4, 8, or 12 h at 4 C before volatile analyses. The meat samples were purged with helium gas (40 ml/min) for 15 min. Volatiles were trapped at 20 C using a Tenax column, 4 desorbed for 2 min at 220 C, focused in a cryofocusing unit 4 at 90 C, and then thermally desorbed onto a column for 30 s at 220 C. A combined column (8-m HP- 624 column, µm i.d. with 1.4-µm nominal; a 52-m HP- 1 column, µm i.d. with 0.25 µm nominal; and an 8- m HP-wax column µm i.d. with 0.25-µm nominal combined using zero dead-volume column connectors) was used for volatile analysis. The oven temperature was kept at 0 C for 2.5 min, increased to 10 C at 2.5 C/min, increased to 45 C at 10 C/min, increased to 110 C at 20 C/min, increased to 180 C at 10 C/min, and held for 4.5 min. This procedure was used to improve volatile separation. Inlet temperature of the gas chromatograph oven was 180 C. Liquid nitrogen was used to cool oven below ambient temperature. Helium was the carrier gas at constant pressure of 20.5 psi. The ionization potential of the mass spectrometer was 70 ev, and scan range was 18.1 to 300 m/z. Identification of volatiles was achieved by comparing mass spectral data of samples with those of the Wiley Library 6 and standards when available. The area of each peak was integrated using the ChemStation software, 5 and the total peak area (pa s) 10 4 was reported as an indicator of volatiles generated from meat samples. The peaks produced by mass spectral data were grouped into five major volatile classes (alkanes, alkenes, ketones, aldehydes, and sulfur-containing compounds) and are reported. Color Measurement The color was determined on the packaged surface of meat samples using a Labscan Hunter color meter 6 that had been calibrated against white and black reference tiles packaged in the same bags as those used for meat packaging. Hunter values were obtained for L* (lightness), a* (redness), and b* (yellowness) (American Meat Science Association, 1991) using a setting of D65 (daylight, 65- degree light angle). An average value from two random locations on each sample surface was used for statistical analysis. TBARS Analyses For the raw meat, 3 g of meat was weighed into a 50- ml test tube and homogenized with 15 ml of deionized

3 DIETARY SORGHUM ON THE STABILITY OF BROILER MEAT 1387 TABLE 1. The 2-TBA-reactive substances (TBARS) values after storage (0 or 7 d) of raw broiler breast and thigh meat from birds fed a control diet or sorghum Dietary Breast meat Thigh meat treatment 0 d 7 d SEM 0 d 7 d SEM TBARS (mg MDA 1 /kg meat) Control b,x 2.04 a 0.15 Ruby Red b,x,y 1.82 a 0.22 Valpo Red b,y 1.43 a 0.06 SEM a,b Different letters within a row of the same category differed significantly (P < 0.05); n = 3. x-z Different letters within a column differed significantly (P < 0.05). 1 MDA = malondialdehyde. distilled water (DDW) using a Polytron homogenizer 7 (Type PT 10/35) for 10 s at highest speed. One milliliter of the meat homogenate was transferred to a disposable test tube (3 100 mm), and butylated hydroxyanisole (50 µl, 7.2%) and TBA-trichloroacetic acid (TCA) (2 ml) were added. The mixture was vortexed and then incubated in a boiling water bath for 15 min to develop color. The sample was then cooled in cold water for 10 min, vortexed again, and centrifuged for 15 min at 2,000 g. The absorbance of the resulting supernatant solution was determined at 531 nm against a blank containing 1 ml of DDW and 2 ml of TBA-TCA solution. For cooked meat, TBARS was analyzed at the same interval as in volatile analyses (every 4 h). If the absorbance of the solution after color development was greater than 1, the solution was diluted properly with water and TBA-TCA mixture (1:2) until the absorbance was less than 1.0. The amounts of TBARS were expressed as milligrams of malondialdehyde per kilogram of meat. Statistical Analyses The effect of dietary sorghum on the volatiles, TBARS, and color of chicken breast and thigh meat were analyzed statistically using the general linear models procedure of SAS software (SAS Institute, 1989). Student-Newman- Keuls multiple-range test was used to compare differences among mean values (P < 0.05). Means and SEM are reported. The interactions between sorghum treatments and storage for volatiles were also analyzed by general linear models. RESULTS AND DISCUSSION Table 1 shows the TBARS values of raw broiler chicken breast and thigh meat after 0 and 7 d of storage under aerobic conditions. The TBARS values of raw thigh meat from broilers fed the Valpo Red sorghum were lower than those fed the control diet at 0 d of storage but not 7 d of storage. The TBARS indicated that dietary Valpo Red cultivar sorghum slightly improved the oxidative stability 7 Brinkman Instruments Inc., Westbury, NY. of raw thigh meat. The ineffectiveness of dietary Valpo Red cultivar sorghum in improving raw breast meat oxidative stability could be due to few oxidative changes occurring in the breast meat, which could have masked the treatment effect. The stronger antioxidant effect of Valpo Red compared with Ruby Red could be due to its higher tannin content than Ruby Red cultivar. Yokozawa et al. (1998) suggested that dietary tannin had a protective action against oxidative stress in rats. A recent report indicated that specific polyphenols play a role as antioxidants inhibiting lipid peroxidation, low-density lipoprotein oxidation, and scavenging oxygen radicals (Sanchez et al., 2000). Tannin, like other polyphenols, is an effective reducing agent and may prevent diseases related to oxidative stress (Santos and Scalbert, 2000). There were no differences in L* and b* values of raw broiler meats by dietary sorghum treatments and storage (Table 2). At 0 d of storage, no difference in a* values was observed for raw breast and thigh meats among treatments. After 7dofstorage, the a* value of raw thigh meat from broilers fed with sorghum was higher than that of broilers on the control diet. The a* value of raw thigh meat from control broilers decreased significantly after 7 d of storage, but no significant reduction was observed for the meats from the sorghum treatments. Smaller changes in color a* for dietary sorghum than for control indicated that the color stability of raw thigh meat during storage was improved by the dietary sorghum. After 7 d of storage, however, there was a significant reduction in the a* value of raw breast meat from broilers fed Ruby Red. The reason for this reduction is not clear. Due to the structural damage to phospholipids during cooking, cooked meats tend to become oxidized and easily generate warmed-over flavor upon exposure to air (Ahn et al., 1992). Table 3 shows the TBARS of cooked meats at different durations of holding. At 0 h of holding, dietary sorghum reduced the TBARS of cooked breast meat. In cooked thigh meat, however, the TBARS of meat from broilers fed Valpo Red cultivar was higher than that of the control and Ruby Red. This result was somewhat unexpected. One possible reason for this finding could be that the phenolic compounds or tannins in thigh meat kept the iron in reduced state, which exhibited stronger prooxidative effects than ferric iron. Also, thigh meat is higher in iron content than breast meat, which could be another

4 1388 DU ET AL. TABLE 2. Color values after storage (0 or 7 d) of raw broiler breast and thigh meat from birds fed a control diet or sorghum Breast meat Thigh meat Control Ruby Red Valpo Red SEM Control Ruby Red Valpo Red SEM L* value 0 d d SEM a* value 0 d x x d y b,y a a 0.50 SEM b* value 0 d d SEM a,b Different letters within a row of the same category differed significantly (P < 0.05); n = 3. x,y Different letters within a column of the same category differed significantly (P < 0.05). reason for the difference in the antioxidant effect of sorghum between cooked breast and thigh meat. Ahn and Kim (1998) showed that reduced iron is a potent prooxidant. Cooked breast meats from sorghum treatments maintained lower TBARS than controls at 8 and 12 h of holding, showing the effectiveness of sorghum in improving the oxidative stability. For cooked thigh meat, the sorghum treatments were not effective in reducing TBARS values. The production of volatiles is closely related to the oxidative changes in meat. Table 4 shows that the volatile profiles of cooked breast meat at different durations of holding. The volatiles were grouped into aldehydes, alkanes, alkenes, ketones, and sulfur compounds and are reported. The amount of aldehydes was consistently the highest in control meat, followed by Ruby Red; Valpo Red had the least aldehydes (Table 4). The production of aldehydes is closely related to the oxidation of meat (Ahn et al., 1999a,b). This difference showed that the Valpo Red cultivar improved the oxidative stability of cooked breast meat, the but Ruby Red cultivar was less effective in improving oxidative stability. Among the aldehydes, hexanal, and pentanal increased greatly and contributed the majority of increment in alde- hydes during holding, and the increase of pentanal in breast meat from Valpo Red treatment was less than that of Ruby Red and control (Table 5). Pentane was the main alkanes detected, followed by heptane, octane, and hexane. After 12 h of holding, productions of pentane and heptane from cooked broiler meats of Valpo Red cultivar treatment were significantly lower than those from control (Table 5), as were total alkanes and alkenes after 4 h of holding (Table 4). This finding indicated that cooked breast meats from broilers fed Valpo Red cultivar had higher oxidative stability than those fed the control diet. The amounts of sulfur compound in cooked breast meat were also reduced by dietary sorghum treatments. Cooked breast meat from broilers fed Valpo Red produced significantly less sulfur compounds than those on control and Ruby Red treatments. Dimethyl disulfide was the main sulfur compounds in cooked broiler breast meat and increased greatly with sample holding time (Table 5). 2- Propanone was the major ketone detected, but the amounts of 2-propanone and total ketones were not changed significantly by dietary treatment and sample holding time. Dietary sorghum also influenced the volatiles of cooked thigh meat (Table 6). Dietary sorghum treatments had no TABLE 3. The 2-TBA-reactive substances (TBARS) after different durations of holding (0 to 12 h) of cooked broiler breast and thigh meat patties from birds fed a control diet or sorghum Dietary treatment 0 h 4 h 8 h 12 h SEM TBARS (mg MDA 1 /kg meat) Breast meat Control 1.69 c,x 2.15 c 6.49 b,x 8.79 a,x Ruby Red 1.02 d,y 2.49 c 4.26 b,y 7.78 a,y Valpo Red 1.01 d,y 2.29 c 3.78 b,z 6.56 a,z SEM Thigh meat Control 1.54 d,y 5.83 c,y 8.30 b,y a Ruby Red 1.77 d,y 6.60 c,x 9.99 b,x a Valpo Red 2.08 d,x 6.76 c,x 8.77 b,y a SEM a-d Different letters within a row differed significantly (P < 0.05); n = 3. x-z Different letters within a column of the same category differed significantly (P < 0.05). 1 MDA = malondialdehyde.

5 DIETARY SORGHUM ON THE STABILITY OF BROILER MEAT 1389 TABLE 4. Volatile profiles after different durations of holding (0 to 12 h) of cooked broiler breast from birds fed a control diet or sorghum Volatile 1 0h 4h 8h 12h SEM (total ion counts 10 4 ) Aldehydes Control 59,298 d,x 154,438 c,x 285,241 b,x 358,708 a,x 10,325 Ruby Red 50,941 d,x 130,327 c,y 244,734 b,y 349,656 a,x 9,410 Valpo Red 32,473 d,y 89,810 c,z 193,533 b,z 282,449 a,y 5,384 SEM 5,029 4,317 12,302 10,628 Alkanes Control 17,698 c 47,137 b,x 59,481 a 65,214 a 2,449 Ruby Red 14,498 c 42,908 b,x 58,673 a 59,329 a 3,221 Valpo Red 11,808 c 32,300 b,y 49,182 a 52,700 a 2,053 SEM 2,033 1,684 2,721 3,616 Alkenes Control 1,061 c 3,635 b,x 5,260 a 5,898 a 437 Ruby Red 625 c 2,695 b,xy 5,474 a 5,603 a 444 Valpo Red 670 c 1,945 b,y 4,207 a 4,830 a 304 SEM Ketones Control 62,821 61,714 77,495 78,270 5,619 Ruby Red 75,718 76,568 84,480 87,085 3,147 Valpo Red 64,313 68,696 75,929 75,767 3,572 SEM 4,890 4,978 3,268 3,603 Sulfur compounds Control 6,041 c 9,546 b 15,616 a,x 16,814 a,x 917 Ruby Red 6,252 c 10,726 b 15,172 a,x 16,312 a,x 672 Valpo Red 6,359 c 9,436 b 11,779 ab,y 12,562 a,y 755 SEM 683 1, a-d Different letters within a row differed significantly (P < 0.05); n = 3. x-z Different letters within a column of same category differed significantly (P < 0.05). 1 Aldehydes included acetaldehyde, propanal, butanal, pentanal, 2-methyl butanal, 3-methyl butanal, pentanal, and hexanal; alkanes included 2-methyl propane, butane, pentane, hexane, heptane, octane, 2,3-dimethylbutane, 2,3,3-trimethyl pentane, 2,3,4-trimethyl pentane, and 3-methyl-2-hepane; alkenes included 2-methyl-1-propene, 1-pentene, 2-pentene, 1-octene, and 2-octene; ketones included 2-propanone, 2-butanone, 2,3-dibutane dione, and 1,2-cyclohexadione; and sulfur compounds included dimethyl sulfide, thiourea, and dimethyl disulfide. significant effect on aldehydes or alkanes, the main volatiles associated with oxidation, but had significant effect on ketones, alkenes, and sulfur compounds of cooked thigh meats. The production of all groups of volatiles, except for ketones, increased during holding, with the increase in aldehydes being the greatest. The lack of differences in sorghum treatments on the production of aldehydes in cooked thigh meats was in agreement with the TBARS TABLE 5. Major volatiles of cooked breast and leg meats at 0 and 12 h of holding 0 h holding 12 h holding Volatile Control Ruby Red Valpo Red SEM Control Rudy Red Valpo Red SEM (total ion counts 10 4 ) Breast meats Acetaldehyde 40,192 a 39,056 a 24,225 b 3,510 75,123 a 73,777 a 52,870 b 2,317 Pentane 12,199 9,661 6,989 1,462 43,584 a 38,764 ab 33,947 b 2,301 Propanal 15,728 a 10,465 ab 7,422 b 2,005 97, ,032 87,903 3,761 2-Propanone 60,404 73,861 62,819 4,664 69,535 76,825 67,751 3,688 Heptane 1,562 1, ,119 a 5,144 ab 4,317 b 4,544 Pentanal 1,174 a 0 b 0 b 38 54,670 a 52,299 a 42,847 b 2,328 Dimethyl disulfide ,860 a 11,159 a 6,339 b 651 Octane 1,758 1,507 1, ,850 7,146 6, Hexanal , ,016 92,471 7,721 Thigh meats Acetaldehyde 34,518 a 35,028 a 12,166 b 4,103 60,656 76,673 56,706 18,671 Pentane 37,250 32,934 39,673 5,192 87,753 66,786 85,540 6,110 Propanal 24,039 26,532 22,756 3, , , ,467 43,713 2-Propanone 79,472 79,064 79,139 18,080 66, ,165 93,456 14,152 Heptane 7,081 6,273 6, ,802 9,377 11,394 1,051 Pentanal 8,703 6,329 3,638 2, , ,104 83,283 22,918 Dimethyl disulfide 2,912 a 2,892 a 754 b ,726 a 6,541 b 1,495 c 783 Octane 14,189 17,531 13,428 1,587 20,282 20,181 19,847 2,627 Hexanal , , ,795 45,854 a-c Means within a row of the same holding time with no common superscript differ significantly (P < 0.05); n = 3.

6 1390 DU ET AL. TABLE 6. Volatile profiles after different durations of holding (0 to 12 h) of cooked broiler thigh meat from birds fed control diet or sorghum Volatile 1 0h 4h 8h 12h SEM (total ion counts 10 4 Aldehydes Control 74,083 c 265,368 bc,y 420,844 ab 596,359 a 81,707 Ruby Red 74,436 b 447,899 a,x 561,853 a 629,755 a 78,476 Valpo Red 41,479 c 256,463 bc,y 391,774 b 625,398 a 75,704 SEM 9,401 26,052 77, ,893 Alkanes Control 71,647 b 93,628 b 109,113 ab 143,951 a 12,547 Ruby Red 75,427 b 141,203 a 116,738 ab 119,192 ab 14,263 Valpo Red 72,535 91, , ,607 17,314 SEM 8,110 15,563 20,698 12,021 Alkenes Control 6,270 b 8,088 b,y 10,391 ab 13,394 a 1,203 Ruby Red 7,551 b 17,777 a,x 14,161 ab 14,916 ab 2,285 Valpo Red 6,189 c 9,537 bc,y 12,295 ab 14,988 a 1,230 SEM 620 1,752 1,838 2,017 Ketones Control 84,772 77,108 38,231 y 75,831 14,388 Ruby Red 87, , ,116 x 111,231 21,248 Valpo Red 83,905 66,154 77,789 xy 102,212 14,493 SEM 18,339 16,118 17,546 15,942 Sulfur compounds Control 14,732 14,234 x 15,827 20,317 x 3,024 Ruby Red 10,028 b 15,610 a,x 16,427 a 15,835 a,y 730 Valpo Red 7,119 7,311 y 7,727 9,190 z 1,165 SEM 2,065 1,962 2,263 1,215 a-d Different letters within a row differed significantly (P < 0.05); n = 3. x-z Different letters within a column of same category differed significantly (P < 0.05). 1 Aldehydes included acetaldehyde, propanal, butanal, pentanal, 2-methyl butanal, 3-methyl butanal, pentanal and hexanal; alkanes included 2-methyl propane, butane, pentane, hexane, heptane, octane, 2,3-dimethylbutane, 2,3,3-trimethyl pentane, 2,3,4-trimethyl pentane, and 3-methyl-2-hepane; alkenes included 2-methyl-1-propene, 1-pentene, 2-pentene, 1-octene, and 2-octene; ketones included 2-propanone, 2-butanone, 2,3-dibutane dione, and 1,2-cyclohexadione; and sulfur compounds included dimethyl sulfide, thiourea, dimethyl disulfide, dimethyl trisulfide. values (Table 3). As in the volatiles of cooked breast meats, hexanal and pentanal were the major aldehydes, and they increased dramatically during sample holding. Pentane was the main alkane, dimethyl disulfide was the main sulfur compound, and 2-propanone was the main ketone in cooked thigh meat, as in breast meat (Table 5). Dietary Valpo Red sorghum significantly reduced the production of dimethyl disulfide but had no effect on the amounts of pentane and 2-propanone in cooked thigh meats. Overall, feeding sorghum generally improved the oxidative stability of cooked breast meats, with the Valpo Red cultivar being more effective than Ruby Red. Dietary Valpo red cultuvar sorghum improved the early oxidative stability of raw thigh meat but was not effective for cooked thigh meat. ACKNOWLEDGMENTS The assistance M. Goeger, T. Holsonbake, D. Weise and the staff of Poultry Farm, Oregon State University, for their assistance in feeding and taking care for the birds is acknowledged. The generous donation of chicks (Foster Farms, Northwest Division, Vancouver, WA), sorghum (Natural Ovens of Manitowoc, Manitowoc, WI) is appreciated. REFERENCES Abdalla, A. E. M Garlic supplementation and lipid oxidation in chicken breast and thigh meat after cooking and storage. Adv. Food Sci. 21: Ahn, D. U., C. Jo, and D. G. Olson. 1999a. Headspace oxygen in sample vials affects volatiles production of meat during the automated purge-and-trap/gc analyses. J. Agric. Food Chem. 47: Ahn, D. U., C. Jo, and D. G. Olson. 1999b. Volatile profiles of raw and cooked turkey thigh as affected by purge temperature and holding time before purge. J. Food Sci. 64: Ahn, D. U., and S. M. Kim Prooxidant effects of ferrous iron, hemoglobin, and ferritin in oil emulsion and cookedmeat homogenates are different from those in raw-meat homogenates. Poult. Sci. 77: Ahn, D. U., D. G. Olson, J. I., Lee, C. Jo, X. Chen, and C. Wu Packaging and irradiation effects on lipid oxidation and volatiles in pork patties. J. Food Sci. 63: Ahn, D. U., F. H. Wolfe, J. S. Sim, and D. H. Kim Packaging cooked turkey meat patties while hot reduces lipid oxidation. J. Food Sci. 57: , American Meat Science Association Guidelines for meat color evaluation. In Proc. 44th Recip. Meat Conf., Chicago, IL. National Livestock and Meat Board, Chicago. Cave, N. A., and V. D. Burrows Evaluation of naked oat (Avena nuda) in the broiler chicken diet. Can. J. Anim. Sci. 73: El-Khalifa, A. O., and A. H. El-Tinay Effect of fermentation on protein fractions and tannin content of low- and hightannin cultivars of sorghum. Food Chem. 49:

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