Color Stability and Microbial Growth Relationships in Beef as Affected by Endogenous α-Tocopherol

Longissimus muscle from Holstein steers supplemented with vitamin E at 500 or 2000 mg/head/day showed less surface metmyoglobin accumulation than controls during 12 days storage at 4°C. Temperature abuse at 25°C for 24 hr increased metmyoglobin formation; vitamin E supplementation diminished the adverse effect of temperature abuse. No differences (P > 0.05) in bacterial load were observed among the 3 vitamin E treatments during storage. Sensory panelists preferred vitamin E-supplemented beef steaks in visual acceptance. Panelist assessment of discoloration correlated highly with a value and hue angle. In general, elevated α-tocopherol concentrations in beef steaks did not affect panelist assessment of meat spoilage.     

α-Tocopherol, β-Carotene and Ascorbic Acid as Antioxidants in Stored Poultry Muscle

Broilers were fed α-tocopherol or β-carotene for 3 wk or L-ascorbic acid for 24 hr prior to slaughter. α-Tocopherol maintained the redness of unheated meat stored for 8 wk (—20°C). Values for thiobarbituric acid reactive substances in ground, stored meat showed that L-ascorbic acid produced results similar to the control while a-tocopherol produced results lower than the control. Panelists rated meat with added α-tocopherol as different from the control for smell and flavor. β-Carotene was a pro-oxidant compared to the control and other additives. Meat from broilers fed β-carotene had lower α-tocopherol content than the control. Vitamin A in livers of birds fed β-carotene was 64% higher than that of the control.     

Stability of α-Tocopherol, Thiamin, Riboflavin and Retinol in Pork Muscle and Liver during Heating as Affected by Dietary Supplementation

The α-tocopherol (Vit E) and ascorbic acid (Vit C) supplementation of pig diets increased (P<0.05) liver α-tocopherol concentrations. After heating, the liver samples of both treated groups and the longissimus dorsi muscle samples of the vitamin C group showed increased riboflavin retention (P<0.05). The supplemented and control groups did not show differences regarding retention of α-tocopherol, retinol and thiamin in heated liver and longissimus dorsi. Dietary vitamin C resulted in higher liver vitamin E and was most effective in protecting riboflavin against loss during heating of liver or longissimus dorsi.     

Dietary Pigmentation and Deposition of α-Tocopherol and Carotenoids in Rainbow Trout Muscle and Liver Tissue

Rainbow trout (Oncorhynchus mykiss) were fed diets supplemented with canthaxanthin, oleoresin paprika and α-tocopherol. Canthaxanthin was more efficiently absorbed (3.8–7.9 mg/kg) in the flesh of rainbow trout than the paprika carotenoids (2.4–3.1 mg/kg). With increased pigmentation, decrease in lightness (L*) and hue angle, and increase in redness (a*) of the muscle were observed. Canthaxanthin produced more desirable reddish-pink color. Deposition of α-tocopherol in liver and muscle tissue increased with increase in dietary α-tocopheryl acetate. Fish receiving lower α-tocopheryl acetate reached maximum deposition levels earlier than those fed higher levels. There was no effect of α-tocopherol and carotenoid levels on muscle fatty acid composition.     

α-Tocopherol and Ascorbate Delay Oxymyoglobin and Phospholipid Oxidation In Vitro

An oxymyoglobin liposome model was used to study the effects of α-tocopherol and/or ascorbate upon oxymyoglobin and lipid oxidation. Both oxidations were delayed (P<0.05) by increased concentrations of α-tocopherol alone and α-tocopherol/ascorbate relative to controls. The 14 μ Mα-tocopherol/140 μM ascorbate treatment resulted in greatest delay in both oxymyoglobin and lipid oxidation. Ascorbate alone delayed oxymyoglobin oxidation; effectiveness diminished as ascorbate increased. Ascorbate showed a prooxidant effect toward lipid oxidation which was unchanged in the presence of EDTA. Results support the hypothesis that α-tocopherol retards lipid oxidation directly and OxyMb oxidation indirectly.     

Thiamin, Riboflavin and α-Tocopherol Retention in Processed and Stored Irradiated Pork

Combination treatments for preservation of irradiated pork were investigated with respect to vitamin loss. Ground pork was prepared under nitrogen and packaged in anaerobic foil. The samples were enzyme denatured by heating before and after irradiation, then cooked and stored. Irradiation resulted in thiamin loss, but neither riboflavin nor α-tocopherol was affected. Neither thiamin nor riboflavin was affected by heat denaturation, cooking or storage, but heating and cooking increased the measured α-tocopherol. The lack of loss of the vitamins was attributed to the exclusion of oxygen.     

Effects of Dietary Oils and α-Tocopherol Supplementation on Lipid Composition and Stability of Broiler Meat

Broilers were fed diets containing oils of varying degrees of unsaturation, namely coconut oil, olive oil, linseed oil and partially hydrogenated soybean oil (HSBO), with and without α-tocopherol supplementation. The different oils significantly (P<0.01) affected the fatty acid composition of the neutral lipids and, to a lesser extent, the fatty acid composition of the phopholipids. Fatty acid composition, in turn, influenced the oxidative stability of the meat during refrigerated and frozen storage. Meat from broilers fed olive oil or coconut oil was consistently more stable than meat from the linseed oil group. Dietary supplementation with α-tocopherol significantly (P<0.01) improved the oxidative stability of the dark and white broiler meat during refrigerated and frozen storage compared to meat from the broilers fed HSBO.     

Dietary α-Linolenic Acid and Mixed Tocopherols, and Packaging Influences on Lipid Stability in Broiler Chicken Breast and Leg Muscle

Addition of α-linolenic acid alone or plus mixed tocopherols, to the diet of broiler chickens had significant effects on composition of muscle fatty acids. Degree of unsaturation in both neutral lipids and phospholipids was increased. Both the tocopherols in the tissues and the storage stability of the meat were affected by the degree of polyunsaturation in fatty acids and dietary tocopherols. The amount of tocopherols in leg meat was higher than that of breast meat, and the antioxidant effect of dietary tocopherols was significant in cooked leg meat with hot- and cold-vacuum packaging. Dietary tocopherols were not effective in the control of lipid oxidation in loosely packaged cooked meat. Lipid oxidation in α-linolenic acid-enriched cooked broiler meat could be controlled by hot-vacuum packaging, but the antioxidant effect of hot packaging plus dietary tocopherol was greater than hot packaging or tocopherol alone.     

Specific Disulfide Bond in α-Lactalbumin Infiuences Heat- Induced Gelation of α-Lactalbumin-Ovalbumin-Mixed Gels

The gel strength of ovalbumin mixed with α-lactalbumin (α-La) was determined after heating at 80°C for 15 min at pH 7.0 Gel strength of the mixture of 4%α-La and 4% ovalbumin was two times that of 8% ovalbumin. Modified α-La at Cys6-Cys120 (3 SSα-La) had low enhancement effects on ovalbumin gelation. Competitive ELISA using monoclonal antibody to α-La showed decreased binding reactivities after heating α-La with ovalbumin at specific concentrations. The decrease of total SH groups in the gel mixed with 3SS α-La was much less than when mixed with α-La. A disulfide bond of Cys6-Cys120 in α-La contributed to interactions between ovalbumin and α-La in heat-induced gels.     

Oxidative Reactions of Model Maillard Reaction Products and α-Tocopherol in a Flour-Lipid Mixture

Nondialyzable model Maillard reaction products (MRPs) were prepared by heating 0.8M D-glucose or D-fructose with 0.8M L-lysine under different reaction conditions and times. The usefulness of derived MRPs, with highest melanoidin yields, in stabilizing oxidative deterioration in food was evaluated in a flour-lipid dough mixture with or without cupric ions. Glucose-lysine MRPs effectively reduced lipid oxidation both with and without cupric ions. In contrast, fructose-lysine MRPs lowered lipid oxidation only without cupric ions, and accelerated lipid oxidation with cupric ions. Application of MRPs in combination with α-tocopherol showed no synergistic or antagonistic effect. Conditions and type of reducing sugar in synthesis of MRPs can influence their anti- or pro-oxidant activity.     

Selective Solubilization of α- Lactalbumin and β-Lactoglobulin into Reversed Micelles from Their Mixtures

Phase transfer experiments were performed, involving contact between an aqueous 1:1 solution of α-lactalbumin and β-lactoglobulin and an AOT-in-isooctane reversed micellar phase. The resulting extraction and separation of the two proteins were analyzed as functions of pH, ionic strength and total protein concentration using SDS-PAGE, and compared with extractions from pure solutions. At low protein concentrations, the extent of reversed micellar solubilization of the two pure proteins predicted well the extraction from mixtures. However, at higher protein concentrations β-lactoglobulin appeared to be excluded from the micellar droplets. Because of the significantly different partitioning behavior of the two proteins, reversed micellar extraction from an initially equal weight mixture led to an effective separation of the proteins.     

精制核桃油生产工艺及其氧化稳定性的研究

研究了利用物理压榨法制备核桃油及其精炼工艺，然后取等重的9组样品，分别添加不同的抗氧化剂TBHQ、PG、BHT、VE及增效剂柠檬酸、抗坏血酸(Vc)，与空白样一起利用Schaal烘箱法每隔24h测一次过氧化值(POV)，比较它们的氧化稳定性。试验结果表明：焙炒、脱酸、脱胶是精制核桃油的关键工序，其工艺条件依次为：焙炒温度130℃、时间30min；碱法脱酸：碱液浓度11％、碱炼初温40℃。加碱量为理论碱量和超碱量之和；磷酸脱胶：油重0．2％的85％磷酸、3％的水、温度保持在60℃；添加0．02％TBHQ、0．01％PG和0．015％Vc复合抗氧化剂的油样(在60℃通风条件下贮藏408h的过氧化值最低为0．75meq／kg，国家标准规定过氧化值≤10nmeq／kg，经计算其在20℃存储保质期可达22个月以上。     

共轭亚油酸氧化稳定性及其影响因素的研究

研究了共轭亚油酸的氧化稳定性及其主要影响因素。共轭亚油酸氧化稳定性低于相应的油脂。变价金属离子（Fe∧3 能够促进共轭亚油酸氧化。考察了几种抗氧化剂对共轭亚油酸的抗氧化性能,BHT、BHA BHT（1：1）对共轭亚油酸的抗氧化效果优于实验的其他抗氧化剂,添加抗氧化剂可是明显改善共轭亚油酸的氧化稳定性。     

Effects of Dietary Oils and α-Tocopherol Supplementation on Membranal Lipid Oxidation in Broiler Meat

The effects of different dietary oils and α-tocopherol on the fatty acid composition of mitochondrial and microsomal lipids of broiler muscle and their lability to NADPH-induced peroxidation were investigated. Fatty acid composition of both neutral lipids and phospholipids of mitochondria and microsomes was influenced by dietary oil composition. Supplementation of the diet with α-tocopherol only appeared to increase the α-tocophcrol concentration in the microsomal membranes in the dark meat. The rate of NADPH-induced lipid peroxidation in microsomes and mitochondria was dependent primarily on the fatty acid composition of the membrane lipids, and, to a lesser extent, on the α-tocopherol content.     

Dietary α-Tocopheryl Acetate Contributes to Lipid Stability in Cooked Beef

Lipid oxidation was investigated in cooked gluteus medius from Holstein steers fed diets including four levels of α-tocopheryl acetate (0, 250, 500 and 2,000 mg/steer daily) for 42 or 126 days. Alpha-tocopherol (vitamin E) concentrations increased in fresh and cooked muscle due to level and duration of supplementation (P<0.01). Cooking did not affect α-tocopherol concentration in the muscle. Dietary α-tocopheryl acetate delayed (P<0.01) accumulation of lipid oxidation products in cooked muscle during 6 days of display at 4°. Daily supplementation of 500 mg α-tocopheryl acetate for 126 days resulted in 3.4 μg α-tocopherol/g cooked gluteus medius.     

Isolation of α-Terpineol Dehydratase from Pseudomonas gladioli

An enzyme which converts the citrus by-product limonene to α-terpineol was purified 13-fold. After cell disruption of P. gladioli, α-terpineol dehydratase (α-TD) remained associated with a heterogeneous group of particulate material. α-TD was partially solubilized by extraction with 10 mM HEPES buffer, pH 7.0 containing 2.0% (w/v) Triton X-100 and 0.5M sodium trichloroacetate. Two soluble forms existed in 1.0% (w/v) Triton X-100 with apparent molecular weights of 94,500 and 206,500 daltons.     

油脂氧化稳定性的研究

用Ｒａｎｃｉｍａｔ仪器测定了油脂氧化稳定性。结果表明,温度的高低,脂肪酸不饱和度,抗氧化剂和增效剂的使用,均与油脂氧化稳定性有着密切的关系。     

Effects of α-, γ-, and δ-Tocopherols on Oxidative Stability of Soybean Oil

The effectts of 0, 100, 250, 500 and 1000 ppm of α-, γ-, or δ-tocopherol on oxidative stability of purified soybean oil in the dark at 55°C were studied. We measured peroxide value and headspace oxygen consumption in the samples. Purified soybean oil was prepared by liquid column chromatography. Tocopherols acted as antioxidants or prooxidants depending on their concentration. Optimum concentrations of α -, γ -, and δ– tocopherols to increase oxidative stability was 100, 250 and 500 ppm, respectively. The tocopherols had significant prooxidant effect (P < 0.05) at higher concentrations above this.     

Germination and Debittering Lupin Seeds Reduce α-Galactoside and Intestinal Carbohydrate Fermentation in Humans

Subjects submitted to untreated and processed test meals of Lupinus albus and Lupinus angustifolius had decreases in breath-hydrogen concentrations (as maximum and cumulative changes), for processed samples compared to untreated samples. Maximum changes (means) in breath-hydrogen decreased from 56.7 and 66.7 Δppm in untreated L. albus and L_- angustifolius, respectively, to 8.4. and 5.9 Δppm in debittered samples (p <0.001). and to 29.6 Δppm in germinated L. albus (p<0.01). Results paralleled the decrease in α-gaiactoside contents of germinated and debittered samples which showed over 90% reduction. Germination and debittering were very effective but debittering was more efficient to decrease fermentation in the human colon.