Lipid Oxidation in Cooked Turkey as Affected by Added Antioxidant Enzymes

Catalase (CAT) and glutathione peroxidase (GSH-Px) were added to turkey which had been cooked (80°C) to provide minimal activity of both enzymes, to determine their effects in development of lipid oxidation. CAT (100–500 U/g muscle) decreased the formation of thiobarbituric acid reactive substances (TBARS) 4–28% during 2 days of storage. GSH-Px (4.0 U/g muscle) decreased TBARS 8–11%. CAT (170 U/g muscle) and GSH-Px (1.3 U/g muscle) in combination decreased TBARS formation 7–14%. Reduced glutathione concentrations in the turkey were unaffected by cooking. These data suggest that heat inactivation of CAT and GSH-Px was not the only factor involved in heat-induced lipid oxidation reactions in turkey thigh muscle.     

Oxidation Kinetics of Menhaden Oil with TBHQ

The oxidation kinetics of menhaden oil containing 0% to 0.02% tertbutylhydroquinone (TBHQ) were evaluated at 37°C. Induction periods, and monomolecular and bimolecular oxidation rates were determined from thiobarbituric acid analysis. The disappearance rates of several fatty acids were determined from GC analysis. Free fatty acid and viscosity changes were evaluated. Induction periods were directly related to TBHQ concentration. Monomolecular rates decreased with increasing TBHQ concentration, but bimolecular rates did not change. The rate of disappearance of unsaturated fatty acids was proportional to their degree of unsaturation, but not related to TBHQ concentration. Free fatty acid content and viscosity increased rapidly after the monomolecular period.     

Oxymyoglobin Oxidation as Affected by Oxidation Products of Phosphatidylcholine Liposomes

Supernatants (105,000 ×g) of oxidized phosphatidylcholine (PC) liposomes contained higher levels of thiobarbituric acid-reactive substances, and caused greater metmyoglobin formation when combined with oxymyoglobin than those of controls (C) or PC plus tocopherol (PCT) (P<0.05). Products of PC liposome oxidation crossed dialysis membranes (mol wt cut-off = 500 Dalton) and accelerated the oxidation of oxymyoglobin more than C or PCT (P<0.05). The addition of known oxidation products of oleic acid and linoleic acid, fatty acids typical of PC, accelerated oxymyoglobin oxidation relative to controls (P<0.05). Results demonstrated that oxidation products of PC were prooxidative towards oxymyoglobin.     

Lipid Oxidation, Volatiles and Color Changes of Irradiated Pork Patties Affected by Antioxidants

Changes were measured in TBARS, color, and volatiles of irradiated (4.5 kGy) pork patties with antioxidants (sesamol, quercetin, rutin, BHT, and rosemary oleoresin) during 7 days storage at 4°C. Irradiation accelerated lipid oxidation of raw pork during storage. However, irradiation before cooking did not influence lipid oxidation of cooked pork during storage. Sesamol, quercetin, and BHT were effective in both irradiated raw and cooked pork during 7-days storage. Rosemary oleoresin and rutin were effective only in irradiated raw pork for 3 days. Hexanal, propanal and higher boiling components were well correlated (P < 0.01) with TBARS in cooked pork. Generation of volatiles was reduced by sesamol and quercetin, but the effects of antioxidants on color changes of raw pork patties were minor and inconsistent.     

Inhibition of Lipid Oxidation during Processing of Washed, Minced Atlantic Mackerel

An antioxidative system that was designed to maintain heme iron reduced, nonheme iron as an inactive chelate, and provide free radical scavenging in the aqueous and lipid phases, was most effective when added early in the processing of washed, minced mackerel muscle. Mince prepared from mackerel dark muscle showed greater propensity to oxidize than did the mince from light muscle. Washed mince from light muscle in the presence of the antioxidative system showed no loss of odor quality during 24 wk at -20°C. Postmortem age of the mackerel muscle had little effect on initial odor quality of the washed mince.     

Lipid Peroxidation in Chicken Meat During Chilled Storage as Affected by Antioxidants Combined with Low-Dose Gamma Irradiation

TBA values and carbonyl content for irradiated samples of ground chicken meat were higher than for nonirradiated samples. Addition of antioxidants tocopherol (natural) or BHT (synthetic) resulted in retardation of oxidative rancidity (p<0.05). Meat treated with antioxidants prior to irradiation had lower TBA values as compared to untreated irradiated counterparts. Free fatty acid (FFA) values decreased after irradiation. Addition of antioxidants prior to irradiation showed a synergistic effect in decreasing FFA content. TLC of muscle lipids indicated a reduction in the triacylglcerols content with concomitant increases in FFA of all samples during storage. All irradiated meats were acceptable for consumption up to 4 wk of storage.     

Color Stability and Lipid Oxidation of Rockfish as Affected by Antioxidant from Shrimp Shell Waste

Crude and partially purified antioxidants from shrimp shell waste were obtained by ethanol extraction and silica gel column chromatography. Whole rockfish ( Sebastolobus alascanus, Sebastes ruberriumus ) samples were treated with crude antioxidant solution dips while another species of rockfish fillets ( Sebastes alutus ) was treated with various concentrations of partially purified antioxidant solution dips from column chromatography. Higher a* values were found in all rockfish samples treated with antioxidants compared to the control. The partially purified antioxidant from shrimp shell waste significantly lowered TBA values compared to the untreated water-dipped control rockfish fillets ( Sebastesalutus ).     

Lipid Oxidation in Cooked Pork as Affected by Vitamin E, Cooking and Storage Conditions

The individual and combined effects of muscle vitamin E level, cooking conditions (duration, temperature and rate) and packaging on lipid oxidation in refrigerated cooked pork were examined. Oxidative stability following cooking was higher in pork with a higher vitamin E level (p<0.01), cooked at a lower cooking temperature (p<0.01), cooked for a shorter time (p<0.01), cooked at a faster cooking rate (p<0.05) or stored in vacuum packs (p<0.01). Significant two-way and three-way interactions were observed between the effects of muscle vitamin E level, cooking conditions and packaging on lipid oxidation. Adopting more than one of these approaches to minimize lipid oxidation was more effective than adopting a single approach.     

Effects of Blueberry (Vaccinium corymbosum) Juice on Lipid Oxidation During Spray Drying of Microencapsulated Menhaden Oil

This study investigated the effect of blueberry juice on menhaden oil lipid oxidation during microencapsulation. Oil in water emulsions containing menhaden oil with 0, 5, or 10% blueberry juice were spray dried to produce control-M, 5% BJ-M, and 10% BJ-M microencapsulated powders, respectively. All microencapsulated powders had similar encapsulation efficiencies with low surface oil content. Peroxide value (meq/kg of oil) was 4.50, 4.31, and 3.38 for control-M, 5% BJ-M and 10% BJ-M, respectively. Ten percent BJ-M had lower (P < 0.05) anisidine value, and totox values than 5% BJ-M and control-M. This indicated that 10% blueberry juice reduced lipid oxidation in menhaden oil during microencapsulation to a greater extent than the other formulations.     

Decreasing Lipid Oxidation in Soybean Oil by a UV Absorber in the Packaging Material

The stability and effectiveness of Tinuvin 326^TM, a UV absorber, dispersed within the regrind layer of coextruded, multilayered, polypropylene-based containers to protect packaged, bleached soybean oil from photooxidation was investigated. The level of Tinuvin 326 in the containers was determined by using high pressure liquid chromatography (HPLC) and UV spectrophotometric methods. No loss of Tinuvin 326 from the containers was observed over a 42-day storage period at 21 and 35°C, respectively. The migration of Tinuvin 326 from the containers to the oil stored at 35°C was greater than at 21°C. Migration levels at both temperatures, however, were too low to notably reduce Tinuvin 326 levels in the containers. Bleached oil in containers with 0.3% Tinuvin 326 underwent less photooxidation than oil in containers with no Tinuvin 326 when exposed to fluorescent light at 21 and 35°C for 35 days.     

Evaluation of Antioxidant Activity of Rosemary Extracts,Carnosol and Carnosic Acid in Bulk Vegetable Oils and Fish Oil and Their Emulsions

The antioxidant effectiveness of two rosemary extracts, carnosol and carnosic acid, was significantly influenced by the type of system tested (bulk oils vs oil-in-water emulsions), by the oil substrates, the methods used to follow oxi-dation, and the concentrations of test compounds. The rosemary extracts and compounds effectively inhibited conjugated diene hydroperoxide formation in corn oil, soya bean oil, peanut oil and fish oil, when tested in bulk. Test compounds also inhibited hexanal formation in bulk vegetable oils, and propanal and pentenal formation in bulk fish oils. In contrast, these test compounds were either inactive or promoted oxidation in the corresponding vegetable oil-in-water emulsions. In fish oil emulsions, however, the rosemary compounds inhibited the formation of conjugated diene and pentenal but not that of propanal. Interfacial phenomena may explain why the hydrophilic rosemary antioxidants afford more protection in the bulk oil systems by being oriented in the air–oil interface, and less protection in the oil-in-water emulsion systems by partitioning into the water phase.     

Iron-Lactoferrin Complex Reduces Iron-Catalyzed Off-flavor Formation in Powdered Milk with Added Fish Oil

Abstract: The iron–lactoferrin complex (FeLf) is useful for dietary iron supplementation. However, the effects of FeLf on iron‐catalyzed off‐flavors in lipid‐containing food products have not been reported. In this study, we investigated the effects of FeLf on off‐flavors development during the production and storage of powdered milk with added fish oil. Powdered milk samples were formulated with FeLf or iron (II) sulfate, then stored at 37 °C for 5 mo. A sensory evaluation revealed that FeLf delayed the development of oxidized flavor and reduced metallic taste in the powdered milk compared with iron (II) sulfate. Headspace gas chromatography–mass spectrometry analysis showed that oxidized volatile compounds, such as pentanal, hexanal, heptanal, octanal, 1‐penten‐3‐one, (Z)‐4‐heptenal, (E, E)‐2,4‐heptadienal, and (E)‐2‐octenal, were less developed in the powdered milk containing FeLf than in that containing iron (II) sulfate. Iron and lactoferrin (Lf) were retained in the high‐molecular‐weight (>10000 Da) fraction of the reconstituted FeLf‐containing powdered milk after its manufacture and storage, whereas the antigenicity of Lf was lost after ultrahigh‐temperature processing at 120 °C for 5 s. These results suggest that FeLf reduces the iron‐catalyzed off‐flavors that develop during the production and storage of powdered milk. The stable iron‐holding property of FeLf contributes to the inhibition of oxidized and metallic volatile formation, although the loss of Lf antigenicity did not affect the stability of FeLf and the iron‐catalyzed formation of off‐flavors in the powdered milk. Consequently, FeLf is a suitable candidate for the simultaneous supplementation of a single food with iron and fish oil. Practical Application: The supplementation of food products with iron and fish oil is a useful approach to redressing their inadequate intake in many populations. The iron–lactoferrin complex can protect food products against the off‐flavors caused by iron‐catalyzed lipid oxidation. Our results show that the iron–lactoferrin complex is useful for the simultaneous fortification of foods and nutraceuticals with iron and fish oil because this complex also reduces the formation of iron‐catalyzed off‐flavors in powdered milk enriched with fish oil.     

Kinetic Studies of Oxygen Dependence During Initial Lipid Oxidation in Rapeseed Oil

Lipid oxidation was studied in rapeseed oil, stored at 35 or 50°C in 0.03, 0.3, 1.0 or 1.8% oxygen for 42 days. Peroxide value (PV), oxygen consumption, tocopherol consumption and production of volatile compounds were analyzed to follow the oxidation. At 50°C, lipid oxidation measured as oxygen consumption or PV was only slightly influenced by oxygen concentration ≥1%. Below 0.5% the influence was strongly enhanced. The production of volatiles showed different relationships to oxygen concentration and some compounds were produced in larger amounts at lower O₂, than at higher O₂, concentrations.     

Metal-Catalyzed Oxidation of Ascorbate, Deoxyribose and Linoleic Acid as Affected by Phytic Acid in a Model System

Antioxidant activity of phytate was investigated in metal-catalyzed model systems. In a dose-dependent manner, phytate facilitated oxidation of Fe (II) to Fe (III) and inhibited formation of thiobarbituric acid-reactive substances (TBARS) from Fe (II)- or hemeprotein-catalyzed deoxyribose degradation. In the presence of 100 μM Fe (III), phytate inhibited reduction of Fe (III) to Fe (II) by 100 μM ascorbic acid and it consequently inhibited ascorbate oxidation. Phytate inhibited hemeprotein- and H₂O₂-catalyzed TBARS formation from linoleic acid micelles. Inhibition by phytate of iron + ascorbate-dependent lipid peroxidation depended on the concentration of ascorbate. These results indicate that phytate may be a useful antioxidant in the protection against oxidative deterioration of foods.     

鱼类血红蛋白诱导脂质氧化及其控制的研究进展

脂质氧化不仅使食品的营养、风味、质构和外观发生变化,而且缩短了产品的货架期,降低其食用品质,是造成水产食品品质劣变的重要原因之一。血红蛋白是水产品脂质氧化的重要诱导因子,其自动氧化产生的高铁血红蛋白可以加速脂质氧化反应速率,同时释放的血红素和铁离子也可催化脂质氧化的发生。化学防腐剂在食品中的应用越来越受到限制,天然抗氧化剂的研究与应用已成为热点,了解血红蛋白促氧化的机理,找到适宜的抗氧化技术,有效地控制水产品在贮藏过程中血红蛋白诱导的脂质氧化的发生是非常必要的。因此,本文以血红蛋白诱导的脂质氧化为切入点,介绍了鱼类血红蛋白的结构、促氧化的反应机理和影响因素,以及天然酚类抗氧化物在控制血红蛋白促氧化方面的诸多应用与进展,并提出了目前急需解决的问题和未来的研究趋势。     

天然抗氧化剂抑制肉制品氧化研究进展

天然抗氧化剂具有较好的抗氧化活性,对易腐败变质的肉制品能发挥良好的抗氧化与抑菌作用,且安全性高.针对肉制品在贮藏期间脂质氧化等问题,文章通过从植物、蔬菜、水果等中提取的天然抗氧化剂在香肠、肉饼、腊肉和火腿等肉制品中的保鲜应用进行了综述,为其在肉制品防腐保鲜中的应用提供了理论依据,提高了天然抗氧化剂的附加值,能更有效地应...     

Gelation of Beef Heart Surimi as Affected by Antioxidants

Oxidation of proteins (carbonyls) and lipids (TBARS) in beef heart surimi-like materials during preparation and storage (2°C) was inhibited by propyl gallate (0.02%) or α-tocopherol (0.2%). Inhibition of oxidation did not affect surimi gel property (storage modulus, G'). Storage promoted oxidation of proteins in 0.2% ascorbate-washed mince, leading to increases in peak (～ 55°C) and final (70°C) G' of thermally induced surimi gel. Protein carbonyls in stored surimi and its sol (salted), as well as TBARS of the sol, strongly correlated with both peak and final G of gels. Incorporation of tripolyphosphate into washed mince promoted gelation whether the surimi-like material was oxidized or not.     

Stability of Mackerel Surimi Prepared under Lipid-Stabilizing Processing Conditions

Surimi from mackerel whole and light muscle was prepared under conditions designed to minimize oxidation and development of rancidity. The lipid-stabilizing procedure included early addition of both lipid-and water-soluble antioxidants, avoidance of added sodium chloride, and exclusion of oxygen. Surimi prepared from light muscle was stable to rancid odor development in both the raw and cooked form; gel strength was reasonably stable during frozen storage, although the color was somewhat dark. Surimi prepared from mackerel whole muscle was darker, its odor quality lower and less consistent, and its gel strength lessened more rapidly during frozen storage than surimi prepared from light muscle.     

脉冲强光及抗氧化剂对动物油脂的影响

研究了不同抗氧化剂对动物油脂的抗氧化作用,探讨了脉冲时间、贮藏温度以及抗氧化剂对经脉冲强光处理动物油脂氧化的影响。结果表明,VE、燕麦油、VC和杨梅多酚4种物质对动物油脂都有抗氧化作用,其添加的最佳质量分数分别为0.5%、0.5%、0.01%0、.07%。脉冲强光处理可加速动物油脂的过氧化,且随脉冲强光闪照时间的增加,动物油脂的氧化程度加剧。经脉冲强光处理的动物油脂其在不同温度下的贮藏稳定性均有所下降;随贮藏温度的升高和脉冲闪照时间的增加,油脂的氧化速度加快。脉冲强光处理前添加的VE、燕麦油和杨梅多酚仍具有降低脉冲强光诱导动物油脂的过氧化作用,而VC却产生促氧化作用。     

紫苏油的氧化与抗氧化研究

研究了抗氧化剂丁基羟基茴香醚(BHA)、二丁基羟基甲苯(BHT)和特丁基对苯二酚(TB—HQ)在紫苏油中的抗氧化作用，得出紫苏油的最适抗氧化剂、协同使用量及增效剂的用量；并通过测定氧化前后紫苏油的脂肪酸组成，表明紫苏油氧化反应过程中因α—亚麻酸被氧化，含量明显降低，从而使紫苏油失去原有的营养价值。