Browsing by Subject "lipid oxidation"
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Item Effect of sorghum bran addition on lipid oxidation and sensory properties of ground beef patties differing in fat levels(Texas A&M University, 2006-10-30) Hemphill, Susan PatriciaOxidation of lipids influences the color and sensory qualities of meat products. Meat with a high fat content, such as ground meat, is susceptible to lipid oxidation that leads to the development of negative flavor and color changes. Antioxidants, such as butylated hydroxanisole (BHA), butylated hydroxytolune (BHT) and extracts of rosemary, are used in meat products to control the effects of lipid oxidation. Awika (2000, 2003) found that sorghum bran phytochemicals have high antioxidant properties. Our objective is to evaluate the pH, color, sensory and antioxidant effect of 10, 20 and 30% ground beef patties containing rosemary, BHA/BHT, and three levels of sorghum bran during 5 d of aerobic storage at 4????C. Beef trimmings containing either 50% or 90% lean were formulated into three meat blocks containing either 10, 20 or 30% lipid. Within a fat content, ground beef was equally divided into one of six treatments: 1) control-no added ingredients; 2) BHA and BHT at .01% of the meat weight; 3) rosemary at 0.2% of the meat weight; 4) high level of sorghum at 1.0% of the meat weight; 5) medium level of sorghum at 0.5% of the meat weight; and, 6) a low level of sorghum at 0.25% of the meat weight. The ground beef was aerobically packaged and stored for 0, 1, 3, or 5 days at 4????C. pH, thiobarbituric acid reactive substances (TBARS), fatty acid methyl esters (FAME), sensory color, Minolta color space values and descriptive sensory evaluations were determined. Antioxidant addition reduced TBARS values and increased hardness (P<0.020) and springiness (P=0.002) over time compared to controls. The addition of the high sorghum bran level resulted in lower raw color scores (2.0 vs. 2.9) (P<0.0001) and slightly increased bitter basic taste (2.47 vs. 2.65) (P=0.0069) when compared to control patties. The high sorghum level slightly increased pH (6.33 vs. 6.41) (P<0.0001) and resulted in darker (P<0.0001) and less yellow colored (P<0.0001) patties. With storage, patties had higher pH (P<0.0001) and color space values decreased (P<0.0001). Sensory properties of the patties differed across fat levels (P<0.05); however, interactions between fat level and antioxidant treatment were not significant (P>0.05). Moreover, 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.Item Factors Influencing the Stability and Marketability of a Novel, Phytochemical-Rich Oil from the A?ai Palm Fruit (Euterpe oleracea Mart.)(2012-02-14) Duncan, Christopher EdwardThe a?ai palm fruit has recently become the focus of numerous research endeavors due to its extraordinary antioxidant content. However, little is known about the fruit?s phytochemical rich oil, which is a by-product of the a?ai pulp. Therefore, the aim of this study was to investigate the phytochemical content of a?ai oil and its relation to oxidative stability. A total of 206 mg/kg of chlorophylls, which included chlorophyll a as well as four chlorophyll derivatives were tentatively identified by HPLC in crude a?ai oil (CAO). Two predominant carotenoids (216 mg/kg ?-carotene and 177 mg/kg lutein) were also characterized in addition to ?-tocopherol (645 mg/kg). Initial investigations into oil stability focused upon the photooxidation of a?ai oil due to its significant chlorophyll content and findings demonstrated that the increases of nonanal were observed when phospholipids and polyphenolics were reduced. Subsequently, investigations into the interactions between phospholipids and lipophilic antioxidants and their contributions to the stability of a?ai oil were also assessed by isolating phytochemicals and selectively reconstituting the oil. Findings demonstrated a potential relationship between phospholipids and lipophilic antioxidants, but this was not conclusive. Advances in the processing of the a?ai pulp by-product created from the clarification process yielded a partially refined a?ai oil (RAO). The stability of both RAO and CAO as a result of autoxidation were compared to other common food oils (olive, canola, and soybean) and primary and secondary oxidation data suggested CAO was most stable. The difference in the stability of the two a?ai oils was also investigated by blending these oils and assessing oxidation. An increased stability was demonstrated in the blended RAO, which suggested a significant antioxidant contribution from the CAO. With such similar lipophilic compositions in CAO and RAO, it is theorized that the driving factor behind the stability of CAO can be attributed to its water soluble antioxidant content. While further investigations are required to fully comprehend the interactions of a?ai oil phytochemicals, these experiments provide insight into the phytochemical content and stability of a?ai oil. The understanding and information obtained in these studies is geared at increasing the marketability of a?ai oil as a food ingredient.Item Plant-Based Tannins as Antioxidants in Pre-Cooked Ground Beef Patties(2011-10-21) Cruzen, Shannon MichelleMeat 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.