Meat lipid oxidation causes negative quality effects, especially in further processed products. Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and rosemary extract (RM) are common antioxidants, but plant-based tannin compounds have been shown to be effective antioxidants. The objective was to evaluate antioxidant effectiveness, pH, color, and sensory effects of several tannin sources. In study 1, 19 percent fat ground beef was mixed with no treatment (control), BHA/BHT (0.02percent), RM (0.2percent), or 0.25percent or 0.5percent powders of Chardonnay grapeseed (CG), Norton grapeseed (NG), CitruSmart (CS), or dried cherry (CP). Raw and cooked patties were aerobically stored for 0 to 5 days at 4 degrees C. Cooked patties were analyzed using the TBARS (thiobarbituric acid reactive substances) method. Raw patties were analyzed for pH, instrumental color, subjective color, and ingredient specks. Study 2 was similar, except the treatments were 0.25percent and 0.5percent powders of CG, chestnut (CN), mimosa (M), and quebracho (Q) tannins, as well as 0.5percent NG, 0.02percent BHA/BHT, 0.2percent RM, and a control. In study 1, only the NG and CG pre-cooked patties had similar or lower TBARS values compared to RM and BHA/BHT patties. All tannin treatments, except 0.25percent CG and 0.25percent CS, lowered pH compared to the control. Patties with NG and 0.5percent CG were darker, and tannin-treated patties were not redder than the control. Patties with CG and 0.5percent NG were less yellow. Subjectively, tannin-treated patties did not have less discoloration during storage, and the CG and NG patties had numerous visible ingredient specks. In study 2, CN, M, Q, and 0.5percent CG treated patties had low TBARS during storage. pH was slightly lower in CG and CN patties than the control. All tannin-treated patties were darker than the control patties, except patties containing 0.25percent CG and Q, and control patties had the highest red values. Tannin-treatments patties, except CN and Q patties, were less yellow. Subjectively, only 0.25percent M patties had less discoloration than control patties, while 0.5percent CN patties were more discolored. Norton and Chardonnay grapeseed flour and chesnut, mimosa, and quebracho powders would be recommended for pre-cooked ground beef patties based on their antioxidant effectiveness in these studies.

No description available.

Bottom rounds were shipped to the Rosenthal Meat Science and Technology Center, ground and enhanced with one of the following predetermined treatments: control; 0.4% sodium phosphates and 0.3% salt; 0.25% sorghum bran; 2.0% sorghum bran; 0.25% sorghum bran, 0.4% sodium phosphates and 0.3% salt; and 2.0% sorghum bran, 0.4% sodium phosphates, and 0.3% salt. The ground beef was formed into 226 g ground beef patties, packaged in an 80% O2 and 20% CO2 gaseous environment, and stored under retail display at 4 degrees for 0, 3, 6, or 9d. Measurements to determine rate and extent of oxidation, rate of discoloration, and sensory characteristics were taken to evaluate the effectiveness of sorghum bran. Patties containing the highest amount of sorghum bran had the lowest TBARS values over 9 days of storage, lower a* values, greater amounts of discoloration, darker lean color, and less cook loss (P<0.05) than control patties. Patties enhanced with the highest level of sorghum bran had lower beefy/brothy and bloody flavor aromatics, higher sorghum flavor, more bitter and burnt aftertaste, and more sandy/gritty textures (P<0.05) when compared to control patties. Patties containing the low amount of sorghum had lower TBARS values (P<0.05), but similar amounts of cook loss as the control patties. Patties containing a low sorghum level, 0.4% sodium phosphates (SP) and 0.3% salt (S) had lower (P<0.05) amounts of cook loss when compared to control patties. Patties containing low amounts of sorghum were similar to control patties in terms of redness while the addition of low sorghum, SP, and S decreased (P<0.05) the degree of redness. Patties containing low amounts of sorghum bran had similar amounts of discoloration compared to control (CONT) patties. Also, these had less bloody flavor aromatics (P<0.05), but were similar in sorghum flavor aromatics and bitter taste when compared to control patties. The addition of sorghum bran at low levels can retard oxidative rancidity in ground beef patties without causing detrimental color changes and negatively affecting sensory attributes, while patties enhanced with 2% sorghum bran have extensive discoloration and undesirable sensory attributes.

Lipid oxidation degrades the quality and decreases the shelf-stability of muscle foods. The depletion of phosphates prior to cooking may be a major factor in this undesirable reaction. Thus, the effects on lipid oxidation with the use of an encapsulate to protect the phosphates during raw storage was investigated. Unencapsulated and encapsulated sodium tripolyphosphate (STP) and sodium acid pyrophosphate (SAPP), at a level of 0.5%, were compared to control samples in cooked, ground beef patties at 0 and 6 days. The unencapsulated and encapsulated treated samples were different (P<0.05) from the controls with an 81.1% to 89.7% improvement in the reduction of lipid oxidation. However, encapsulated phosphates did not decrease the level of oxidation beyond the unencapsulated treatment. This observation was attributable to the lack of a storage time prior to evaluating rancidity. Therefore, with an increase of precooked storage time, the 0.10% active encapsulated STP was essentially as effective as 0.20% unencapsulated STP for both 3 and 11 days. Unencapsulated STP (0.3% or 0.5%), encapsulated STP (0.3% or 0.5% active), a blend of unencapsulated (0.3%) and encapsulated (0.2% active) STP, and a control treatment was incorporated in ground turkey breast and stored at 3°C for 0, 5, and 10 days. The treated samples were cooked to two different endpoint temperatures (74°C and 79°C) and stored at 3°C (4 and 24 hr) before cooking. An improvement of 77% and 80% was found in the reduction of Thiobarbituric Acid Reactive Substances (TBARS) with the 0.3% and 0.5% encapsulated STP, respectively, in comparison to the unencapsulated STP. The best results were seen with a shorter storage time (4 hr) prior to cooking and a higher endpoint temperature (79°C). The unencapsulated and encapsulated STP were compared to commercial antioxidant blends, Lemo-fos and Freez-Gard FP 15, at a level of 0.5%, to determine differences in their capabilities of lipid oxidation reduction. The encapsulated phosphate was lower (P<0.05) in TBARS (3.5 mg/kg) in comparison to the treatments which ranged from 15.6 to 20.4 mg/kg. However, the CIE a* values were higher in the encapsulated samples due to the decrease in lipid oxidation. The effect of liquid nitrogen on TBARS values was investigated to identify a means of analyzing a large quantity of samples. The use of cryogenic freezing was not significantly different in TBARS in comparison with a fresh, unfrozen control. Raw and cooked ground turkey samples were submerged into liquid nitrogen and stored intact or immediately reduced in particle size to compare particle reduction effects on TBARS. The different particle reduction methods were not significantly different, although, the immediately reduced sample was more efficient in TBARS determination. The samples stored in an ultralow freezer (-80°C) for 14 and 33 days were not different (P>0.05). Overall, when encapsulated STP is used with sufficient pre-cook storage time, lipid oxidation can be more effectively reduced than with the use of unencapsulated phosphates. The use of cryogenic freezing and ultralow temperature storage can also aid in the determination of lipid oxidation in large sample quantities due to the stability of TBARS values. / Master of Science

No description available.

In the poultry industry, further processed meat products have the highest share in the market, and because there is a growing demand of food products with enriched amounts of unsaturated fatty acids, the objectives of this research were to assess lipid oxidation development and quality characteristics of chicken meat as affected by dietary fat and vitamin E levels. Broilers were fed during six weeks with diets containing animal/vegetable, lard, palm kernel, soybean, conjugated linoleic acid, flaxseed, or menhaden oil. Each lipid diet was supplemented with either a control (33 or 42 mg/kg) or a supranutritional level (200-400 or 200 mg/kg) of vitamin E. Breast and thigh meat, or skin, were processed, packaged, and refrigerated as raw meat, cooked patties, or cooked sous vide meat. The results showed that the chicken meat fatty acid composition reflected those from the dietary fats. In the meat or skin there was a higher lipid oxidation susceptibility as the proportion of unsaturated fatty acids increased, shown as malonaldehyde values, particularly in the treatments with low supplemented level of vitamin E (P<0.05). The relative lipid oxidative stability of the meat decreased in consecutive order from raw, cooked sous vide, and cooked meat patties. Sous vide cooked meat developed lipid oxidation at a slow rate and showed not to be affected by nonheme iron values. Dietary fat and vitamin E level affected breast meat lightness (L* color space) values (P<0.05), but not muscle pH, Allo-Kramer shear force, or water holding capacity. In conclusion, the increment in the proportion of unsaturated fatty acids increases the susceptibility to lipid oxidation in the meat. Supranutritional supplementation levels of vitamin E are more effective at inhibiting the lipid oxidation development in chicken meat than some current levels used by the poultry industry. Neither dietary fat nor vitamin E level seems to affect the development of pale, soft, and exudative meat condition in chicken meat.

In the poultry industry, further processed meat products have the highest share in the market, and because there is a growing demand of food products with enriched amounts of unsaturated fatty acids, the objectives of this research were to assess lipid oxidation development and quality characteristics of chicken meat as affected by dietary fat and vitamin E levels. Broilers were fed during six weeks with diets containing animal/vegetable, lard, palm kernel, soybean, conjugated linoleic acid, flaxseed, or menhaden oil. Each lipid diet was supplemented with either a control (33 or 42 mg/kg) or a supranutritional level (200-400 or 200 mg/kg) of vitamin E. Breast and thigh meat, or skin, were processed, packaged, and refrigerated as raw meat, cooked patties, or cooked sous vide meat. The results showed that the chicken meat fatty acid composition reflected those from the dietary fats. In the meat or skin there was a higher lipid oxidation susceptibility as the proportion of unsaturated fatty acids increased, shown as malonaldehyde values, particularly in the treatments with low supplemented level of vitamin E (P<0.05). The relative lipid oxidative stability of the meat decreased in consecutive order from raw, cooked sous vide, and cooked meat patties. Sous vide cooked meat developed lipid oxidation at a slow rate and showed not to be affected by nonheme iron values. Dietary fat and vitamin E level affected breast meat lightness (L* color space) values (P<0.05), but not muscle pH, Allo-Kramer shear force, or water holding capacity. In conclusion, the increment in the proportion of unsaturated fatty acids increases the susceptibility to lipid oxidation in the meat. Supranutritional supplementation levels of vitamin E are more effective at inhibiting the lipid oxidation development in chicken meat than some current levels used by the poultry industry. Neither dietary fat nor vitamin E level seems to affect the development of pale, soft, and exudative meat condition in chicken meat.

Gas chromatography (GC) and gas chromatography olfactometry (GCO) was used to determine the effect of specific light wavelengths on light oxidation in milk. The most damaging wavelengths to milk quality appear to be the UV (200-400 and 395 nm) and short visible (463 nm) wavelengths. However, exposure to 610 nm also appears to be damaging. GC and GCO were also used to look at the efficacy of film over-wraps made from iridescent films. Single-layer over-wraps were not as effective in reducing light oxidation as multi-layer film over-wraps. Single-layer over-wrap treatments had higher numbers of odor-active compounds than multi-layer over-wrap treatments with a number of odor-active compounds detected consistently in single-layer over-wrap treatments but not in the multi-layer over-wrap treatments. Concentrations of volatile compounds were slightly lower in the multilayer treatments. Multi-layer film over-wrap treatments were tested for light oxidation flavor intensity with a balanced incomplete block multi-sample difference test using a ranking system and a trained panel. Packaging over-wraps limited the production of light oxidation flavor in milk over time but not to the same degree as the complete light block. Blocking all visible riboflavin excitation wavelengths was better at reducing light oxidation flavor than blocking only a single visible excitation wavelength. A method to determine light oxidation in oil using Fourier Transform Infrared (FTIR) spectroscopy was established and preliminary data is presented. / Ph. D.

The Hulver laboratory has recently found that the neuropeptide Y Y1 receptor (NPY Y1R) mRNA expression is elevated in skeletal muscle of obese humans (Hulver, unpublished). The goal of this research is to study the role of the NPY Y1R in skeletal muscle lipid metabolism. Rat L6, mouse C2C12, and human primary myotubes were incubated in 14C palmitate labeled fatty acid oxidation medium containing 80ng/mL, 250ng/mL, and 500ng/mL of NPY and for a three hour period. Experiments were repeated with the addition of 17mg/mL diprotin A to each NPY treatment. Fatty acid oxidation (FAO) and the percentage of lipids stored within the myotubes as diacylglyceride (DAG) and triaclyglyceride (TAG) were measured. Analyses were repeated in rat L6 and mouse C2C12 following a three hour incubation in 14C palmitate labeled fatty acid oxidation medium containing 1µg/mL, 10µg/mL, and 50µg/mL of the NPY Y1R ligand, [Leu31, Pro34] neuropeptide Y (Bachem, Torrance, CA). Incubation of human primary myotubes in NPY treatments with the addition of diprotin A significantly increased TAG accumulation (p< 0.05). Mouse C2C12 mytoube incubation in 500ng/mL NPY with diprotin A increased FAO (p 0.05). All other NPY and NPY Y1R ligand treatments in had no significant effect on FAO or the accumulation of TAG and DAG. / Master of Science

Efficient use of renewable feedstocks for production of chemicals and intermediates is necessary to reduce dependence upon petroleum. A large portion of these chemicals could be produced using lipids from renewable feedstocks such as vegetable oils, animal fats, and bacterial lipids. For example, many lipid sources contain unsaturated fatty acids, which can be oxidized to form a variety of products such as diacids and epoxides. These chemicals are used to formulate herbicides, detergents, plasticizers, lubricants, paints, and other useful products. One of the most common unsaturated fatty acids is oleic acid, and it can be oxidized with an ozone/oxygen mixture to produce azelaic acid and pelargonic acid. Since the ozone/oxygen mixture is a gas and oleic acid is a liquid under reaction conditions, mass transfer limitations exist. However, a reduction of the mass-transfer limitations can be achieved if the reactants coexist in a single phase. When supercritical carbon dioxide (SC-CO2) is used as the reaction medium, it is possible for both oleic acid and the ozone/oxygen mixture to both exist in the same phase at the same time. Use of supercritical carbon dioxide also provides the possibility of product fractionation, depending upon the solubility of the products in SC-CO2. The overall goal of this research was to determine if any advantages could be realized by conducting the oleic acid oxidation in a supercritical fluid medium. First, the solubility of azelaic acid and pelargonic acid in supercritical carbon dioxide was determined over a range of temperatures and pressures. Pelargonic acid was found to have a significantly higher solubility than azelaic acid, which indicated the potential for product separation with supercritical carbon dioxide. Second, the impact of the solvent medium on reaction kinetics and product formation was determined using two oxidizers: ozone and potassium permanganate. Due to experimental limitations, no reaction was observed in the case of ozone in supercritical carbon dioxide. However, oxidation of oleic acid with potassium permanganate in supercritical carbon dioxide resulted in higher oleic acid conversion and increased yields of azelaic acid and pelargonic acid compared to the oxidation without SC-CO2.