Effect of Antioxidants on Cholesterol Oxidation in Spray-dried Egg Yolk during Extended Ambient Storage

ABSTRACT: Equimolar amounts of butylated hydroxyanisole, ascorbyl palmitate or a tocopherol blend were added to liquid yolk and spray-dried. One-g samples were stored in the dark at ambient temperature for 36 mo, then evaluated using gas chromatography. The tocopherol blend and BHA inhibited 7-ketocholesterol production. No significant differences were observed between the control and the various antioxidant treatments for the production of other cholesterol oxides. In contrast to the results of a previously conducted accelerated study, the added antioxidant levels were insufficient to significantly reduce cholesterol oxidation in spray-dried egg yolk held for an extended period of time, and additional means of inhibition may be required.     

Further Investigation of Oxidized Cholesterol Derivatives in Heated Fats

The oxidation of cholesterol in tallow heated at various frying temperatures, 135°, 150°, 165°, and 180°C was studied by capillary gas chromatography. The linearity of formation of 7-ketocholesterol with heating time was confirmed. However, no significant differences in rate of formation of 7-ketocholesterol were noted among temperatures of 135°, 150°, and 165°C. Therefore, it was not possible to construct a kinetic equation. The possible efficacy of antioxidants at frying temperatures was demonstrated by incorporating ascorbyl palmitate plus dl-α-tocopherol into tallow at 135°C.     

3种抗氧化剂对菜籽油氧化稳定性的影响

为探究抗坏血酸棕榈酸酯、迷迭香提取物和茶多酚棕榈酸酯及其复合物对菜籽油氧化稳定性的影响,采用Schaal烘箱加速氧化实验法对菜籽油进行氧化稳定性评价,并采用响应面实验优化复配抗氧化剂的配方。结果表明：3种抗氧化剂均能显著提高菜籽油的氧化稳定性（P＜0.05）,其中茶多酚棕榈酸酯抗氧化效果最为理想,添加量为0.01%和0.05%时,菜籽油过氧化值比空白对照分别降低了61.76%和68.79%;响应面实验得到最优复配抗氧化剂配方为0.02%抗坏血酸棕榈酸酯、0.03%迷迭香提取物、0.03%茶多酚棕榈酸酯,在此配方下加速氧化13 d时菜籽油过氧化值为6.017 mmol/kg。该复配抗氧化剂能有效减缓菜籽油的氧化速度,且能够保护菜籽油不易受高浓度抗氧化剂的促氧化作用。     

Cholesterol Oxidation Products in Some Muscle Foods

Cholesterol oxidation products were estimated in some meat products by capillary gas chromatography after trimethylsilylation. Peak identities were confirmed by mass spectrometry. Freeze-dried pork, stored in contact with air at 22°C for ca. 3 yr, revealed 7α- and 7β-hydroxycholesterol, 7-ketocholesterol, α- and β-epoxide and cholestane-triol. The total concentration of oxidation products reached almost half of the remaining cholesterol content with 7-ketocholesterol as the predominant species. Some oxidation products were noted at a few ppm levels in broiled beef steaks, but not in precooked beef products. As rancidity development advanced in comminuted and cooked meats during storage, the oxidation of cholesterol became apparent.     

TBA Values and 7-Ketocholesterol in Refrigerated Raw and Cooked Ground Beef

Thiobarbituric acid (TBA) values and 7-ketocholesterol were determined on raw and cooked ground beef patties after 0, 2, and 4 days of storage at 4°C. The mean 7-ketocholesterol at days 0, 2, and 4 was 9.65, 23.8, and 42.3 μg for 100g raw patties and 6.33, 277.9, and 484.7 kg for 100g cooked patties. The TBA values increased after 2 and 4 days for the raw and cooked patties. TBA values and 7-ketocholesterol were correlated with each other for raw (r²= 0.82) and cooked (r²= 0.98) patties. The peak suspected to be 7-ketocholesterol was confirmed by mass spectral analysis. The 7-ketocholesterol in the cooked patties stored two days represented a 0.3% oxidation of the free cholesterol.     

Wide-Bore Capillary Gas Chromatographic Method for Quantification of Cholesterol Oxidation Products in Egg Yolk Powder

A wide-bore capillary gas chromatographic (GC) method was developed for quantification of cholesterol oxidation products in egg yolk powder. Baseline separations were achieved between 7α- and 7β-hydroxycholesterol, cholesterol, cholesterol-5α,6α-epoxide, cholesterol-5β,6β-epoxide and 7-ketocholesterol chromatographed as the trimethylsilylated sterols. Excellent response linearity was obtained for each cholesterol oxidation product, permitting reliable quantification. Recoveries from freeze-dried egg yolk spiked with various levels of cholesterol oxidation products ranged from 78.2 to 95.1%. The coefficients of variation compared favorably to those for packed column GC methods.     

The antioxidative activity of RRR-α-tocopherol vs RRR-δ-tocopherol in combination with ascorbyl palmitate in cooked,minced turkey

RRR-α-tocopherol and RRR-δ-tocopheroI (100 or 200 ppm) had similar and significantly better antioxidative effects compared to ascorbyl palmitate (200 ppm) in turkey meat balls during storage at 5 °C for up to 9 days, as determined by measurement of thiobarbituric acid reactive substances (TBARS) and by static head space detection of hexanal. The antioxidative effect of α-tocopherol at 100 ppm was, measured as a reduction of head space hexanal, significantly enhanced by ascorbyl palmitate (200 ppm), resulting in a further 50% reduction compared to δ-tocopherol. At the 200-ppm level, only the antioxidative activity of α-tocopherol was enhanced significantly by ascorbyl palmitate (200 ppm), in contrast to the effect on the antioxidative activity of δ-tocopherol (200 ppm). The antioxidative activity obtained by α-tocopherol at the 100-ppm level in combination with ascorbyl palmitate (200 ppm) was similar to the effect obtained by α-tocopherol at the 200-ppm level in combination with ascorbyl palmitate (200 ppm) measured as head space hexanal. Ascorbyl palmitate was in all storage experiments depleted in the product at a rate which appeared to be independent of the presence of tocopherols. Of the tocopherol homologues, α-tocopherol was most affected by the presence of ascorbyl palmitate, and the concentration of α-tocopherol was found to decrease during storage in the absence of ascorbyl palmitate, in contrast to when ascorbyl palmitate was present. A similar effect of ascorbyl palmitate was less evident for δ-tocopherol and for γ-tocopherol in a natural mixture of the tocopherol homologues added to turkey meat balls.     

Oxidation of cholesterol in mayonnaise during storage

The oxidative stability of cholesterol in commercial mayonnaise under different storage conditions was evaluated by measuring cholesterol oxides (COs), 7-ketocholesterol (7-Keto), 25-hydroxycholesterol (25-OH), 7α-hydroxycholesterol (7α-OH) and 7β-hydroxycholesterol (7β-OH) using HPLC. Oxidation of cholesterol was indicated within about 15 days after manufacture by the presence of 7-Keto. Oxidation increased during storage at 4 and 25 °C (being greater at 25 °C) for 165 days in darkness, as indicated by the presence of 7-Keto, 25-OH, 7α-OH and 7β-OH. There was a strong correlation between COs and PV (peroxide value) [r²=0.95 (4 °C) and r²=0.96 (25 °C)] during the process of oxidation. The pattern of fatty acids was not affected during the period of the experiment. Temperature and time were important factors in the oxidative stability of cholesterol. Total formation of COs during 165 days was 20.3 μg/g at 4 °C and 30.2 μg/g at 25 °C.     

Effect of Antioxidants on Lipid Stability in Restructured Beef Steaks

Two natural antioxidant formulations–containing mixed tocopherols, ascorbyl palmitate and citric acid–and TBHQ were evaluated in restructured beef steaks formulated to contain 18% fat and 0.75% NaCl. Lipid oxidation was monitored over 12 months of frozen storage. TBHQ significantly (p < 0.05) lowered TBA numbers in raw and freshly cooked samples and in samples that were cooked and held 4 hr at 4°C. Natural antioxidants provided significant (p <0.05) protection in freshly cooked meat and were as effective as TBHQ in retarding lipid oxidation. Sensory evaluation and GC quantitation of hexanal were also used to monitor oxidation but the correlation between the three methods was not significant.     

THE EFFECTS OF DIETARY α-TOCOPHEROL AND SURFACE APPLICATION OF OLEORESIN ROSEMARY ON LIPID OXIDATION AND CHOLESTEROL OXIDE FORMATION IN COOKED RAINBOW TROUT (Oncorhynchus mykiss) MUSCLE

The inhibitory effect of dietary α-tocopherol supplementation (100 and 500 mg α-tocopheryl acetate/kg diet) and an oleoresin rosemary dip on lipid and cholesterol oxidation in cooked rainbow trout ( Oncorhynchus mykiss ) during storage at 4C for 48 h was investigated. The 2-thiobarbituric acid-reactive substances (TBARS) values of cooked fish muscle increased during storage for all treatments. Dietary α-tocopherol supplementation partially inhibited lipid oxidation. Surface application of oleoresin rosemary further enhanced this protective effect. Cholesterol oxides were formed in all the samples following cooking and storage. The major cholesterol oxidation products (COPS) were identified as 7 β-hydroxycholesterol, α- and β-epoxides, and 7-ketocholesterol. Formation of COPS was reduced by dietary supplementation with α-tocopherol and surface application of oleoresin rosemary. Statistical analysis revealed a highly significant (p < 0.01) inhibitory effect of oleoresin rosemary on COPS formation.     

Effect of plant phenolics,tocopherol and ascorbic acid on oxidative stability of pork patties

BACKGROUND: There is great interest in the use of naturally occurring antioxidants to delay oxidation in meat products. The effect of rosemary extract (RE), green tea extract (TE), tocopherol, trolox, ascorbic acid (AA) and ascorbyl palmitate (AP), at levels of 50–200 ppm of antioxidant components, on colour (CIE L*a*b*), lipid (TBARS) and protein oxidation (thiol groups) in fresh, frozen and cooked pork patties during illuminated chill storage was investigated. Individual components of RE and TE were also tested. RESULTS: RE, TE, AP, tocopherol and trolox equally inhibited lipid oxidation in fresh and frozen patties, whereas for cooked patties RE was most effective. AA stimulated lipid oxidation. No dose effect in the range of 50–200 ppm was found for fresh and frozen patties, whereas for cooked patties higher doses of RE and TE more efficiently prevented lipid oxidation. Protein oxidation was hardly influenced by antioxidant treatment. Colour stability decreased as follows: tocopherol, AA and AP > RE and TE > trolox. Antioxidant properties of the extracts and their major antioxidant components were comparable. CONCLUSION: The relative effect of the antioxidants depends on the oxidation parameter assessed, the applied dose and the hydrophilic/lipophilic character. Copyright © 2009 Society of Chemical Industry     

Effects of antioxidants and gamma irradiation on the shelf life of beef patties.

To improve the storage safety of two types of ground beef patty popular in Korea (general beef patties and bulgogi patties), we added various antioxidants (200 ppm; including butylated hydroxyanisole, ascorbyl palmitate, alpha-tocopherol, and beta-carotene) to typical formulations of patties, cooked the patties to 70 degrees C, and irradiated them at a dose of 1.5 or 3 kGy. During 30 d of storage at 5 degrees C, the number of aerobic bacteria and lactic acid bacteria were determined using total aerobic plate count and phenyl ethyl alcohol-sucrose agar, respectively. The concentration of thiobarbituric acid was also determined in each type of patty. No colonies were observed in patties irradiated at 3 kGy regardless of which antioxidant was added. In control patties and patties with butylated hydroxyanisole that were irradiated at a dose of 1.5 kGy, growth of microorganisms appeared to be more rapid than in patties with natural antioxidants. The microbiological safety of nonirradiated patties could not be ensured for a period of 20 d. Lipid oxidation was retarded in both types of patty when an antioxidant was added. Ascorbyl palmitate had the strongest antioxidant effect among the natural antioxidants. However, butylated hydroxyanisole was more effective than ascorbyl palmitate when used in an equal amount.     

Lipid and cholesterol oxidation in Chinese-style sausage using vacuum and modified atmosphere packaging

The oxidation of lipid and cholesterol in Chinese-style sausage in vacuum packaging (VP) and modified atmosphere packaging (MAP) stored at 4°C and 15°C, respectively, for 5 months was investigated. The 2-thiobarbitaric acid reactive substance (TBARS) and peroxide value (POV) of sausage were variable with packaging treatments during storage. TBARS and POV in sausage stored at 15°C were significantly greater (p < 0·05) than at 4°C, and the MAP treatment was more stable than the VP treatment. In addition, the polyunsaturated fatty acids (PUFA) in sausage decreased with storage for both treatments. The content of cholesterol decreased significantly after 3 months of storage. 7-β-hydroxycholesterol, 7-ketocholesterol and 22-ketocholesterol were the major cholesterol oxidation products (COPs), but there was no detectable (< 1 μg/100 g) 25-hydroxycholesterol or cholestanetriol with either treatment.     

鸡蛋贮藏过程中蛋黄内源抗氧化组分与氧化进程的关系

为证实蛋黄内源抗氧化组分对鸡蛋氧化进程的调控作用,本研究将新鲜鸡蛋于22 ℃、相对湿度65%条件下贮藏50 d,通过对贮藏过程中蛋黄氧化的表征及亲脂抗氧化组分（lipophilic antioxidant component,LAC）、亲水抗氧化组分（hydrophilic antioxidant component,HAC）抗氧化能力的比较,探究抗氧化组分与蛋黄氧化进程的关系。结果表明,贮藏过程中蛋黄蛋白质发生氧化降解,总巯基含量平均值下降29.69%,羰基含量平均值上升1.2 倍,十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析表明,贮藏过程中蛋黄卵黄高磷蛋白、高密度脂蛋白等蛋白发生降解,双烯值、丙二醛含量显著增加（P＜0.05）。鸡蛋贮藏过程中LAC对自由基的清除能力大于HAC,与磷脂相比,类胡萝卜素具有相对较高的自由基清除率。相关性分析结果显示蛋黄氧化程度与磷脂、类胡萝卜素抗氧化能力呈显著负相关（P＜0.05）,磷脂抗氧化能力与类胡萝卜素抗氧化能力呈显著正相关（P＜0.05）,与蛋黄蛋白质相比,LAC对蛋黄脂质氧化的调控作用更显著。结论：在贮藏过程中LAC对蛋黄氧化具有潜在调控作用,抗氧化组分之间可能存在协同增效作用。     

Effects of Antioxidants and Packaging on Lipid and Cholesterol Oxidation and Color Changes of Irradiated Egg Yolk Powder

Electron-beam irradiation significantly increased the oxidation of docosahexaenoic, arachidonic and linolenic acids, and cholesterol in egg yolk powder. Arachidonic-acid content was reduced from 4.58% to 3.07%, and total cholesterol oxidation products increased from 11 μg/g to 467 μg/g after 5.0 kGy irradiation. Further oxidation occurred during storage. Vacuum-packaging significantly reduced, but the use of antioxidants had no effect on the fatty acids and cholesterol oxidation during irradiation and storage. Irradiation caused color change in egg yolk powder. The Hunter color a- (redness) values decreased from 3.89 to 2.48 and 1.94, respectively, after 2.5 and 5.0 kGy irradiation. Hunter color a- and b-values were also decreased during storage. Vacuum-packaging and antioxidants significantly reduced color changes.     

Lipid and cholesterol oxidation in chicken meat are inhibited by sage but not by garlic

The effects of the addition of sage and garlic in chicken meat on lipid and cholesterol oxidation, having as prooxidant factors the addition of salt, thermal treatment, and frozen storage, were evaluated. The content of unsaturated fatty acids did not change in the presence of sage; on the contrary, with garlic, the content of these fatty acids decreased after cooking and storage. Hexanal and pentanal contents were lower in patties containing sage, and higher in those with garlic. The 7-ketocholesterol was the cholesterol oxide found in higher amount in raw chicken on day 0, while the formation of 7β- and 7α-hydroxycholesterol was verified only from day 30 on. Cooking and storage resulted in increase of total cholesterol oxides and decrease of α- and γ-tocopherol. Sage was effective in controlling lipid and cholesterol oxidation, minimizing the prooxidant effects of salt, cooking, and storage. However, garlic presented no effect as antioxidant and accelerated lipid oxidation. PRACTICAL APPLICATION: The addition of sage to chicken meat (0.1 g/100 g) is a good alternative to prevent and delay the formation of compounds derived from lipid oxidation that are responsible for off-flavors and loss of nutritional quality during long-term frozen storage. Care must be taken when using garlic to seasoning chicken meat products, such as hamburgers and meatballs, especially cooked or precooked due to its potential to promote lipid oxidation and consequently raising the risk of having the product rejected by the consumer.     

DIETARY OILS AND TOCOPHEROL SUPPLEMENTATION ON CHOLESTEROL OXIDE FORMATION IN FREEZE-DRIED CHICKEN MEAT DURING STORAGE

The influence of dietary oils [fish (FO), flax (LO), palm (PO) and sunflower (SO) oil] and tocohperol supplementation on the oxidation of cholesterol and lipids of chicken meat was investigated. Lipid oxidation in chicken meat powders was determined by thiobarbituric acid reactive substances (TBARS) and cholesterol oxidation products were estimated by capillary gas chromatography (GC) after trimethylsilylation. Peak identities from GC were confirmed by mass spectrometry. Freeze-dried chicken meat powder, stored in contact with air at room temperature for four months showed the presence of 7α- and 7β-hydroxycholesterol, 7-ketocholesterol, α and β-epoxide, and cholestane-triol. Total cholesterol oxides contents significantly (P < 0.05) increased with storage. The amount of cholesterol oxides in the meat powder was the highest in FO and SO group, and lowest in PO group. Lipid and cholesterol oxidation were accelerated by the presence of long-chain PUFA. Lipid and cholesterol stability of chicken meat were improved by the dietary supplementation of tocopherol.     

Additions of caffeic acid,ascorbyl palmitate or γ-tocopherol to fish oil-enriched energy bars affect lipid oxidation differently

The objectives of the study were to investigate the effects of caffeic acid, ascorbyl palmitate and γ-tocopherol on protection of fish oil-enriched energy bars against lipid oxidation during storage for 10 weeks at room temperature. The lipophilic γ-tocopherol reduced lipid oxidation during storage when added at a concentration above 440 μg/g fish oil. However, the best antioxidative effect was observed when it was added at a concentration of 660 μg/g fish oil. In contrast, prooxidative effects were observed when using either γ-tocopherol at concentrations below 220 μg/g fish oil, or the hydrophilic caffeic acid, or the amphiphilic ascorbyl palmitate at concentrations of 75, 150 and 300 μg/g fish oil. Prooxidative effects were observed as an increase in the formation of lipid hydroperoxides and volatile secondary oxidation products, as well as the development of rancid off-flavours. The differences in the efficacies of the three antioxidants examined are expected to be related to their different localisations and mechanisms of action.     

Evaluation of cholesterol and lipid oxidation in raw and cooked minced beef stored under oxygen-enriched atmosphere

Oxygen-enriched modified atmosphere packaging (MAP) represents an important means to stabilize meat colour but may lead to an increase in lipid oxidation, influencing the acceptability and safety of the product. In this work, the effect on cholesterol and lipid susceptibility to oxidation was investigated in commercial minced beef held under MAP (80% O(2)/20% CO(2)). Cholesterol oxidation products (COPs), peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were determined, before and after pan frying, at 1, 8 and 15 days since packaging under refrigerated storage (3-4°C). 7α-Hydroxycholesterol, 7β-hydroxycholesterol and 7-ketocholesterol were the more abundant COPs identified. COPs significantly increased in raw beef during storage: after 1, 8 and 15 days since packaging COPs were at the levels of 10.4, 30.7 and 60.5μg/g of fat, respectively. Cooking did not affect cholesterol oxidation in freshly packaged minced beef but led to a rise in COPs amount with respect to raw muscle after 8 and 15 days of storage. The trend in cholesterol oxidation reflected the progressive increase in lipid peroxidation rate brought by MAP conditions.     

Effect of selected antioxidants on the stability of dehydrated mashed potatoes

The antioxidants TBHQ, alpha-tocopherol, Prolong P (rosemary, thyme, marjoram mixture) or ascorbyl palmitate were not found able to replace the antioxidant BHA in potato flakes production if stored for up to 24 months. Ascorbyl palmitate gave good antioxidative protection up to 16 months of storage, and also protected against carotenoid degradation better than the other antioxidants. The ascorbyl palmitate lost its antioxidative effect after longer storage.