4-Hydroxynonenal and cholesterol oxidation products in atherosclerosis

4-Hydroxynonenal (HNE) is by far the most investigated aldehydic end-product of oxidative breakdown of membrane n-6 polyunsaturated fatty acids. Its potential involvement in the pathogenesis of atherosclerosis has been corroborated by its consistent detection in both oxidized LDL and fibrotic plaque in humans. HNE has been shown to activate both macrophage and smooth muscle cells, i.e. the two key cell types in chronic inflammatory processes characterized by excessive fibrogenesis. By signalling to the nucleus, the aldehyde may up-regulate in these cells both expression and synthesis of monocyte chemotactic protein 1 (MCP-1) and transforming growth factor beta1 (TGFbeta1). Oxysterols, namely 27 carbon atoms oxidation products of cholesterol, are found in relatively high amount in LDL from hypercholesterolemic individuals and are consistently detectable in foam cells and necrotic core of human atherosclerotic lesion. As for HNE, the challenge of cells of the macrophage lineage with a mixture of oxysterols like that detectable in hypercholesterolemic individuals led to a marked overexpression of TGFbeta1 and MCP-1. Both HNE and oxysterols then appear to be candidates for a primary role in the progression of the atherosclerotic process.     

Olive Oil Phenolics Prevent Oxysterol‐Induced Proinflammatory Cytokine Secretion and Reactive Oxygen Species Production in Human Peripheral Blood Mononuclear Cells,Through Modulation of p38 and JNK Pathways

1 Scope

The aim of the present study was to investigate the ability of extra virgin olive oil (EVOO) polyphenols to counteract the proinflammatory effects induced by dietary and endogenous oxysterols in ex vivo immune cells.

2 Methods and results

Peripheral blood mononuclear cells (PBMCs), separated from the whole blood of healthy donors, were utilized and were stimulated with an oxysterols mixture, in the presence of physiologically relevant concentrations of the EVOO polyphenols, hydroxytyrosol, tyrosol, and homovanillic alcohol. Oxysterols significantly increased the production of proinflammatory cytokines, interleukin‐1β, regulated on activation, normal T‐cell expressed and secreted and macrophage migration inhibitory factor in ex vivo cultured PBMCs. Increased levels of reactive oxygen species (ROS) were also detected along with increased phosphorylation of the p38 and JNK. All phenolic compounds significantly reduced cytokine secretion induced by the oxysterols and inhibited ROS production and mitogen activated protein kinase phosphorylation.

3 Conclusions

These results suggest that extra virgin olive oil polyphenols modulate the immune response induced by dietary and endogenous cholesterol oxidation products in human immune cells and may hold benefit in controlling chronic immune and/or inflammatory processes.     

Determination of cholesterol oxidation products in milk powder and infant formulas by gas chromatography and mass spectrometry

In this paper a method for the cholesterol oxidation products (oxysterols) determination in milk powder and infant formulas has been presented. In the sample preparation step lipids transesterification has been performed. The recoveries of oxysterols have been determined and ranged from 94.2% to 99.9% for all but 20a-hydroxy cholesterol (74.2%). Detection limits were 0.018-0.034 ppm and the relative standard deviations (RSD) values were 4.6%-18.3%. The method has been utilized for the determination of oxysterols in milk-based infant formulas and milk powder available on the market. The concentration of oxysterols was between 0.04 and 4.20 ppm of a lipid extract fraction.     

Effects of storage and various intrinsic vitamin E concentrations on lipid oxidation in dried egg powders

Supplementing the diets of laying hens with 0, 25, 50, 75, 100, and 200 mg of all-rac-α-tocopheryl acetate (vitamin E) per kg of feed increased the concentration of this antioxidant in the eggs in a dose-dependent manner. Storage of spray-dried whole-egg powders at ambient temperature for up to 18 months resulted in gradual losses of vitamin E after 6 months, with the greatest losses occurring in those powders with the highest initial content. Marked changes in the concentration of products of lipid peroxidation (thiobarbituric acid reactive substances (TBARS), free fatty acids, oxidised fatty acids, peroxide values, oxysterols) occurred during the storage period which generally correlated inversely with the vitamin E content of the powder. The appearance, and sometimes disappearance, of the products with storage time varied with the individual product. Oxidised fatty acids appeared at 0–2 months, free fatty acids at 4–8 months and TBARS at 8–12 months. 25-Hydroxycholesterol and cholestan-3,5,6-triol appeared at 2 months, peaked between 4 and 6 months and disappeared by 8 months. 7β-Hydroxycholesterol, 7-ketocholesterol and cholesterol-5,6-epoxide appeared at 4 months, peaked at 8–12 months and markedly declined by 18 months. Ingestion of certain lipid peroxidation products, particularly oxysterols which are generally regarded as cytotoxic, could be detrimental to health. Methods for preventing oxysterol formation in commercially prepared and stored foods by simply increasing the intrinsic vitamin E concentration of eggs, which are a major source of cholesterol, would benefit the food industry and human health.     

PRODUCTION OF A LOW-CHOLESTEROL SHRIMP USING SUPERCRITICAL EXTRACTION

A low‐cholesterol shrimp was produced using supercritical extraction. The processing sequence included freeze drying, cholesterol extraction and rehydration. The shrimp was freeze dried, kept under vacuum until an experimental central composite rotatory design was applied using Response Surface Analysis for the supercritical extraction process. Three variables at five levels each were tested during the experiment (pressure, volume and temperature). After the extraction procedure, various rehydration and cooking conditions were applied to obtain a processed product with characteristics similar to those of the natural shrimp. Two sensory analyses were performed: one which compared the attributes of fresh shrimp with those of the freeze‐dried and rehydrated products, and another one which compared the acceptability between fresh shrimp and low‐cholesterol shrimp after freeze drying, supercritical extraction and rehydration. Under the conditions of 310 bar, 1875 L of carbon dioxide and 37C, it was possible to obtain a low‐cholesterol shrimp with acceptable organoleptic properties.     

Cholesterol Oxides in Commercial Dry Egg Products: Quantitation

Cholesterol α-oxide (5α-cholestan-5,6α-epoxy-3β-ol), a suspected carcinogen and/or atherogen, and its β-isomer are found in varying amounts in commercial dried egg products. The level of total cholesterol oxides in dried eggs ranges from undetectable to 311 parts per million of total lipids. The majority of the samples (64%) had total cholesterol oxides content between 6 – 49 ppm. The level of cholesterol α-oxide ranges from undetectable to 62 ppm. The ratio of α-oxide to its β-isomer is found consistantly to be 1 to 4. The formation of cholesterol oxides is greater in samples dried by hot air heated directly with gas burner than those dried by air heated indirectly with steam. Prolonged storage increases cholesterol oxides content in dried egg products.     

Current Knowledge about Oxysterols: A Review

For years food consumers have been warned that a cholesterol‐rich diet may result in atherosclerosis. It is also well known that consumption of large amounts of phytosterols decreases concentration of low‐density lipoproteins (LDLs) in blood (LDLs are regarded a key risk factor in development of cardiovascular diseases). However, no scientific evidence has unambiguously proved any direct connection between amount of consumed cholesterol and LDL level in blood. On the other hand, concentration of cholesterol oxidation products, oxysterols, seems to be indeed relevant; for example, they significantly impact appearance of atherosclerotic lesions (plaques). Phytosterols (like sitosterol or campasterol) decrease LDL level in blood, but on the other hand products of their oxidation are toxic. Therefore, it is worth to know influence of phytosterols on living organisms, processes which lead to their formation, and their levels in popular foodstuffs. This paper is an attempt to review literature data on the above aspects, as well as on impact on living organisms of oxidation products of popular sterols.     

Prevention of 7-ketocholesterol-induced side effects by natural compounds

Abstract

Cholesterol oxidation products, also named oxysterols, can be formed either by cholesterol auto-oxidation, enzymatically or both. Among these oxysterols, 7-ketocholesterol (7KC) is mainly formed during radical attacks that take place on the carbon 7 of cholesterol. As increased levels of 7KC have been found in the tissues, plasma and/or cerebrospinal fluid of patients with major diseases, especially age-related diseases (cardiovascular diseases, eye diseases, neurodegenerative diseases), some cancers, and chronic inflammatory diseases, it is suspected that 7KC, could contribute to their development. Since 7KC, provided by the diet or endogenously formed, is not or little efficiently metabolized, except in hepatic cells, its cellular accumulation can trigger numerous side effects including oxidative stress, inflammation and cell death. To counteract 7KC-induced side effects, it is necessary to characterize the metabolic pathways activated by this oxysterol to identify potential targets for cytoprotection and geroprotection. Currently, several natural compounds (tocopherols, fatty acids, polyphenols, etc) or mixtures of compounds (oils) used in traditional medicine are able to inhibit the deleterious effects of 7KC. The different molecules identified could be valued in different ways (functional foods, recombinant molecules, theranostic) to prevent or treat diseases associated with 7KC.     

Dietary lipids and their oxidized products in Alzheimer's disease

Alzheimer's disease (AD) is the commonest form of dementia in the elderly, characterized by memory dysfunction, loss of lexical access, spatial and temporal disorientation, and impaired judgment. A growing body of scientific literature addresses the implication of dietary habits in the pathogenesis of AD. This review reports recent findings concerning the modulation of AD development by dietary lipids, in animals and humans, focusing on the pathogenetic role of lipid oxidation products. Oxidative breakdown products of ω-6 polyunsaturated fatty acids (ω-6 PUFAs), and cholesterol oxidation products (oxysterols), might play a role in favoring β-amyloid deposition, a hallmark of AD's onset and progression. Conversely, ω-3 PUFAs appear to contribute to preventing and treating AD. However, high concentrations of ω-3 PUFAs can also produce oxidized derivatives reacting with important functions of nervous cells. Thus, altered balances between cholesterol and oxysterols, and between ω-3 and ω-6 PUFAs must be considered in AD's pathophysiology. The use of a diet with an appropriate ω-3/ω-6 PUFA ratio, rich in healthy oils, fish and antioxidants, such as flavonoids, but low in cholesterol-containing foods, can be a beneficial component in the clinical strategies of prevention of AD.     

Photosensitized oxidation of cholesterol and altered oxysterol levels in sour cream: Effects of addition of cucumber pickles

The aim of this research was to examine whether sour cream (18% fat) is an exogenous source of oxysterols and whether it is possible to improve its antioxidative properties and to modulate cholesterol transformation by adding cucumber. To determine whether cucumber modifies the properties of sour cream, fresh cucumber or cucumber pickle (pH 3.3; 1.5% lactic acid) was added in an amount of 20%. The sour cream samples were then stored under light (450 lx, 590 cd, 120 lm) for 3 wk. After storage, the addition of the cucumber pickle increased total mesophilic aerobic bacteria from 7.5 to 9.3 log cfu/g and increased the l-lactic acid content from 6.1 to 9.7 g/L. The total conjugated linoleic acid content in sour cream with cucumber pickle also increased to 4.5 mg/g fat after storage, whereas the cholesterol content decreased to 3.44 g/kg fat. Importantly, with the addition of cucumber pickle, the total content of cholesterol oxidization products (COP) did not change after storage (1.7 mg/kg fat). By contrast, the total COP content in the control sour cream sample increased from 1.7 to 7.3 mg/kg fat over 3 wk of storage. The dominant COP before and after storage was 7β-hydroxycholesterol. Thus, despite exposure to light, adding cucumber pickle to sour cream modulates cholesterol transformation and effectively inhibits the formation of oxysterols.     

Effect of cracklings hydrolysates on oxidative stability of pork meatballs fat

The aim of this work was to determine the effect of cracklings hydrolysates addition on the oxidative stability of fat and cholesterol in meatballs during 7 days of refrigerated storage.Changes in peroxide value (PV), anisidine value (AV), thiobarbituric acid reactive substances (TBARS) and cholesterol oxidation products (COPs) were determined. Cholesterol and oxysterols were analyzed as trimethylsilyl derivatives (TMS) by gas chromatography. Stability properties of antioxidants so employed were characterized by their inhibition activity.Analyzed enzymatic and acid hydrolysates of cracklings (EHC and AHC) obtained from meat industry by-product showed stability properties against fat and cholesterol. AHC exhibited a superior inhibition activity against fat oxidation than that of EHC because of smaller PV, AV and TBARS values. EHC showed a better inhibition activity against the formation of COPs in stored meatballs. After 7 days of storage, inhibition of formation of the oxysterols in samples with added hydrolysates was 29–54%. The antioxidative properties of EHC and AHC based on PV, AV and TBARS values were weaker than that of BHT. On the other hand, BHT was a poorer antioxidant than the hydrolysates against cholesterol oxidation in stored meatballs.     

水产加工制品中胆固醇氧化物的分布与由来

使用GLC和GC/MS对市售盐渍干燥 ,水煮后干燥和烤制的水产加工制品中的胆固醇氧化物进行了定性定量的测定。胆固醇氧化物的含量为 8 3～ 188 0 μg/g。其中检出了7β 羟基胆固醇 ( 2～ 5 5 μg/g) ,7 酮基胆固醇 ( 2～ 6 0 μg/g) ,环氧化胆固醇 ( 1～ 43μg/g) ,胆甾烷三醇 ( 1～ 8μg/g)和 2 5 羟基胆固醇 ( 0 2～ 1 8μg/g)。并且对油脂的过氧化物价 (POV)和胆固醇氧化物含量的相关性进行了探讨。认为水产品在加工和贮藏过程中 ,胆固醇氧化物的生成与高度不饱和脂肪酸的过氧化反应有关     

Phase solubility studies and stability of cholesterol/β-cyclodextrin inclusion complexes

BACKGROUND: Cyclodextrins (CDs) are able to enhance the solubility, stability and bioavailability of several bioactive hydrophobic compounds by complex formation. They can also be used for removal of undesired components (such as cholesterol, off‐flavors or bitter components) present in foods. Although many patents account for the use of cyclodextrins for removal of cholesterol from dairy foods, there is no available information on the effect of water on encapsulation efficiency and on the stability of sterols in CDs. The aim of this work was to study the inclusion properties and the factors affecting the encapsulation and stability of cholesterol in β‐cyclodextrin (BCD). The optimum encapsulation conditions (ligand–CD molar ratio, stirring time and temperature), and stability of the complexes as a function of storage time and water content were analyzed. RESULTS: Phase solubility study pointed out the formation of 1:1 stoichiometric complexes between cholesterol and β‐cyclodextrin, which was influenced by temperature variations. The process was shown to be exothermic and energetically favored. The presence of cholesterol greatly modified the BCD water sorption curves, being the amount of adsorbed water smaller in the combined systems. The principal ‘driving force’ for complex formation is the substitution of the high‐enthalpy water molecules by an appropriate hydrophobic ligand. The freeze‐dried complexes probed to be stable at different storage conditions. CONCLUSION: The phase solubility and stability data obtained could be essential for selecting the most suitable conditions when CDs are employed either for removing cholesterol or to incorporate functional ingredients (i.e. sitosterol) in the development of innovative food products. Copyright © 2011 Society of Chemical Industry     

Cholesterol Oxides in Foods of Animal Origin

The earliest discovery of an oxidation product of cholesterol from a natural source was reported in 1940. Additional discoveries of cholesterol oxidation products (COPS) in edible food products accelerated in the 1980s as gas chromatography and high performance liquid chromatography detection methods were improved. COPS have been found in several foods including liquid eggs and dried egg products, milk and milk products, meat and meat products, marine food products, and other processed foods. Compelling evidence demonstrates that several cholesterol oxides are cytotoxic, atherogenic, mutagenic, and carcinogenic. Therefore, the presence of COPS in foods raises questions about the safety of consumption of some products.     

牛肉肉糜类制品加工技术研究进展

随着经济的发展,人们对物质生活的需求不断提升,以低胆固醇、高蛋白含量为代表的牛肉产品逐渐受到大众青睐,牛肉肉糜类产品种类也日益增多,成为广大消费者日常饮食的重要组成部分。本文概述了当前牛肉肉糜制品的主要种类,对牛肉肠、牛肉脯、牛肉饼、牛肉馅、牛肉丸、牛肉发酵香肠和牛肉膨化食品等牛肉肉糜产品的生产技术、品质与保鲜技术等进行了比较系统的阐述,并对其发展前景进行了展望。     

Effects of food processing and fruit juices on in-vitro estimated iron availability from cereals,vegetables and fruits

Selected processed foods were digested in vitro under simulated physiological conditions. The proportion of iron diffusing across a semi-permeable membrane was used as an index of bioavailability. Certain food processing procedures appeared to greatly enhance the proportion of diffusible iron. Many of the foods that were canned, dried, pickled, fermented, refined, or which contained certain additives, displayed enhanced iron diffusibility compared with unprocessed foods. Iron diffusibility from wheat flour was found to be enhanced by the addition of fruit juices. The constituent organic acids in the fruit juices, namely citric, ascorbic and malic, were found to be potentially responsible for this enhancement. These three compounds are also important examples of a sequestrant, an antioxidant, and an acidulant. These and similar compounds are added to many processed foods in order to improve their quality and preservation. All such additives have the potential to influence the chemical form, and probably the bioavailability, of food iron.     

Fatty acids and cholesterol oxidation in salted and dried shrimp

The aim of this work was to evaluate the occurrence of cholesterol oxidation products and to analyze the lipidic profile in salted–dried shrimp. Fifty samples of salted–dried shrimp were evaluated, and the cholesterol oxides (7β-OH, 7α-OH, 7-Keto and 25-OH) were quantified by high-performance liquid chromatography. The cholesterol oxides: 7β-OH (34.63–72.56 μg/g), 7α-OH (5.02–12.12μg/g), 7-Keto (7.44–32.68 μg/g) and 25-OH (2.37–22.88 μg/g) were determined in all samples analyzed. Regarding to the total cholesterol content and the average thiobarbituric acid reactive substances (TBARS) content, the results ranged from 73.88 to 247.69 mg/100 g, and 0.02 to 1.30 mgMA/kg, respectively. The fatty acids profile was: 27.48% saturated, 43.90% monounsaturated and 28.61% polyunsaturated. The presence of cholesterol oxidation products and the values of TBARS indicate the degree of oxidation of this product, which was probably initiated by inadequate conditions of processing and storage.     

The significance of physico chemical properties of plant cell wall materials for the development of innovative food products

Cell wall materials (CWM) are natural constituents of fruits and vegetables. They are added in a growing extent to foods as health ingredients to create innovative products (functional food). CWM or dietary fibres, respectively, have both physiological and technological functional properties, which are considerably modified during the dietary fibre preparation, during the incorporation of the dietary fibre ingredients into foods and generally during processing. Process-dependent external stress and the influence of internal conditions induce changes of the physico-chemical properties of the food constituents (such as particle size and shape, porosity, water binding and structure-forming as well as texturization properties). These changes affect or determine the technological functional, the material and the physiological properties. To evaluate the alterations of structure and properties of plant cell walls during processing without disturbing influences CWM-water-model suspensions and cell wall preparations, carefully dried after a water-ethanol-exchange, can be used. Such model studies and investigations for the improved manufacture of dietary fibre preparations as well as dried fruit and vegetable products show that both the pre-drying treatments (addition of salt, sugar, polysaccharides and surfactants) and the drying step itself considerably influence the extent of shrinkage, cell wall stiffening as well as cell collapse and glass transition. In pre-drying treatments variations of the degree of methoxylation of the pectin component and/or cation charging can be made which cause a pre-formation of structures and/or states of matter that determine essentially the drying process. The ability of rehydration plays an important role for the application and utilization of dried CWM and dietary fibre preparations as well as of dried fruit and vegetable products. The rehydration process is achieved by the plasticizing effect of water, the temperature influence and the external stress, e.g. by stirring, and is supposed to reverse the state transitions, resulting from drying. By application in foods the rehydration of the CWM and dietary fibre preparations can contribute to the formation of texture (texturization). The texturization caused by CWM depends not only on processing and internal conditions but also essentially on the concentration, size, shape, stiffness and deformability of the particles as well as their water binding properties (amount and strength). The investigations show that improved technologies for the production of cell wall and dietary fibre preparations as well as innovative foods with selectively adjusted functional properties require a fundamental understanding of the changes in structure and properties, caused by processing. Furthermore, a well coordinated cooperation of different scientific disciplines using information technology is necessary for a successful development of innovative dietary fibre enriched products.     

平菇微波-真空冷冻联合干燥工艺优化及其品质分析

为得到平菇最优干燥工艺,提高其干燥制品品质,本试验利用设计专家(Design-expert)软件的Box-Benhnken design(BBD)方法设计,分别采用单因素和响应面试验方法,分析探讨微波功率、转换点含水率和真空冷冻干燥时间三个因素对产品干基含水率、干燥速率、复水比和感官得分的影响。根据试验数据得出4个指标的二次回归模型,并对其进行响应面分析,得出优化后的平菇干燥工艺,最后对最优工艺条件下的平菇干制品营养成分(蛋白质、粗脂肪和总糖含量)进行测定。平菇最佳微波-真空冷冻联合干燥工艺为:微波功率300 W、转换点含水率37%、真空冷冻干燥时间11 h,在该条件下得到的平菇干制品具有色泽良好、品质极佳、营养成分保留较高等优点,以上工艺条件可为平菇干制品的工业化生产提供一定的理论依据和指导。     

香椿芽热泵式冷风干燥模型及干燥品质

为获得干燥速率快、品质高的香椿芽制品,以新鲜香椿芽为原料对其进行冷风干燥处理,研究不同干燥条件下香椿芽的干燥特性;采用Weibull函数模型对干燥曲线进行拟合并分析干燥过程;以干燥时间、干燥能耗、叶绿素含量、VC含量以及复水率为指标对不同条件下香椿芽冷风干燥过程进行加权综合评价;以热风干燥和真空冷冻干燥为参照,对比研究较优冷风干燥参数下香椿芽干制品的品质。结果表明,提升干燥温度、进口风速以及减少装载厚度均能显著减少香椿芽冷风干燥耗时（P＜0.05）,不同干燥条件对干燥耗时的影响程度由大到小为：温度＞进口风速＞装载厚度;Weibull函数模型能够准确描述香椿芽冷风干燥过程中水分含量变化过程（R2＞0.9）,其形状参数均小于1,整个干燥过程为降速干燥,主要由内部水分扩散控制;香椿芽冷风干燥有效水分扩散系数在（6.272～9.637）×10－9 m2/s之间,均属于10－9数量级,且受温度的影响最大;当干燥温度、装载厚度和进口风速分别为20 ℃、3.0 mm、2 m/s时,香椿芽冷风干燥的综合评分值最高,实验范围内,该条件较适合应用于香椿芽的冷风干燥中;相对于热风干燥而言,冷风干燥产品的品质更接近真空冷冻干燥产品的品质。