Phytosterol Oxidation Products Research Articles

Lipolysis and Sterol Stability and Bioaccessibility of Wholemeal Rye Bread Enriched with Plant Sterols Subjected to Adult and Elderly Digestion Conditions.

This study evaluated the impact of different digestion conditions (adult and senior) on lipolysis and bioaccessibility of plant sterols (PS) and phytosterol oxidation products (POPs) in PS-enriched wholemeal rye bread. Under adult digestion conditions, the addition of gastric lipase (GL) reduced lipolysis products (by 6.1% for free fatty acids and 11.7% for monoacylglycerols) and the bioaccessibility of PS by 6.7%, compared to the control. In digestion with both GL and cholesterol esterase (CE), these reductions were 12.9, 20.1, and 11.3%, respectively. Both modifications (GL and GL + CE) increased the bioaccessibility of POPs by 4.5-4.0%. When simulating the elderly digestion, the modified gastric and intestinal phases did not alter PS bioaccessibility but decreased POPs bioaccessibility by 21.8% compared to control, along with reduced lipolysis. Incorporating GL and CE thus approached physiological conditions and influenced lipid digestion. Elderly simulated digestion conditions resulted in a positive outcome by maintaining PS bioaccessibility while reducing potentially harmful POPs.

Optimization and validation of an HPLC‐HRMS method through semipreparative HPLC system for determining phytosterol oxidation products during refining processing and storage of vegetable oils

AbstractA semi‐preparative liquid chromatographic system (LC‐Prep) has been used to isolate and collect the main oxidation products generated from β‐sitosterol, campesterol, and stigmasterol, which represent the main sterols detected in vegetable oils. In less than 50 min, 15 different phytosterol oxidation products (POPs) were separated with a satisfactory resolution (R >1) and collected. From each pure phytosterol standard the 5,6α‐epoxy (α‐E), 5,6β‐epoxy (β‐E), 7‐keto (7‐K), 7α‐hydroxy (7α‐H), and 7β‐hydroxy (7β‐H) isomers were obtained. The purity of POPs was >90%. Then, the obtained pure POPs were used to validate an HPLC‐Orbitrap‐HRMS analytical method. The LOD and LOQ determined in medium chain triacylglycerols were >0.012 and >0.039 ng/mL, respectively; whereas the recoveries ranged between 82% and 98%. The suitability of the analytical method was evaluated on palm oil (PO), palm olein (POL), and high oleic sunflower oil (HOSO) during the whole refining processing (crude oil, neutralization and degumming, bleaching and deodorization) and under storage conditions (45°C, 16 days). In the refining steps, the total POPs content significantly increased (p < 0.05) by 29%, 20%, and 13% in PO, POL, and HOSO, respectively. The highest amount was found in HOSO (15.046 mg/kg), followed by POL (1.067 mg/kg) and PO (0.538 mg/kg). Under storage conditions, the content of POPs did not significantly (p > 0.05) change and was lower than 8.965 mg/kg. The developed semi‐preparative liquid chromatographic system coupled to the LC‐Orbitrap‐HRMS method demonstrated to be a useful and valid tool for a robust, precise, accurate, and sensitive determination of POPs in refined and stored vegetable oils.

Effects of different deodorization methods on the oxidation of sterol components in rice bran oil

Rice bran oil contains a significant quantity of phytosterols that have various active functions and are natural active substances beneficial to humans. It is well known that deodorization during refining affects the quality of rice bran oil. However, changes in phytosterols fraction caused by stripping with nitrogen compared to water vapor remain unexplored. We measured phytosterols in rice bran oil after deodorization with nitrogen and water vapor. The variations in sitosterol fraction, which accounts for the highest percentage of phytosterols in rice bran oil, were analyzed by Gas chromatography (GC), Fourier transform infrared spectrometer (FTIR), and Nuclear magnetic resonance (NMR). Results showed that using nitrogen as the stripping gas was more suitable for deodorization. It promoted the formation of phytosterol esters, reduced the production of phytosterol oxidation products and improved the oil quality. This study provides a theoretical basis for improving the industrial production quality of rice bran oil.

Formation of Previously Undescribed Δ7-Phytosterol Oxidation Products and Tocopherylquinone Adducts in Pumpkin Seed Oil during Roasting, Screw-Pressing, and Simulated Culinary Processing at Elevated Temperatures.

The influence of pumpkin seed roasting conditions (110-140 °C) and screw-pressing on the formation of previously undescribed Δ7-phytosterol oxidation products and tocopherylquinone adducts with nucleophilic phosphatidylethanolamine species was investigated. The roasting process of pumpkin seed paste at a temperature above 120 °C for 30 min considerably enhanced the formation of Δ7-oxysterols. Targeted analysis [electron impact mass spectrometry (MS), 1D-nuclear magnetic resonance] led to the identification of five novel markers of pumpkin paste roasting, among which (3β,5α,22E,24S)-stigmasta-7,22-dien-6-one-3-ol (6-oxo-α-spinasterol), stereoisomers of (3β,5α,22E)-7,8-epoxystigmast-22-en-3-ol (7,8-epoxy-α-spinasterol), and (3β,5α)-22,23-epoxystigmast-7-en-3-ol (7,8-epoxy-α-spinasterol) were reported in edible oils for the first time. Simulated culinary processing provided novel stereoisomers of (3β,5α,22E)-stigmasta-7,22-dien-3,6-diol, unusual (3β,5α,22E)-stigmasta-7,22-dien-6,15-dione-3-ol, and (5α,22E)-stigmasta-7,22-dien-3-one accompanied by minor stereoisomers of (3β,5α)-7,8;22,23-diepoxystigmastan-3-ol. Moreover, a clear relationship between the pumpkin seed oil stability index and synergistic effect of glycerophospholipids with present tocochromanols was found. High-resolution atmospheric pressure chemical ionization-MS experiments clearly demonstrated the formation of various γ-tocopherylquinone adducts with primary amines, namely, octylamine. The mitigation strategy of potentially detrimental oxysterols from pumpkin seed oil included optimization of processing parameters while maintaining the formation of desirable sensory-active compounds.

Impact of photosensitizers and light wavelength on photooxidation of phytosterols in soymilk emulsions

The impact of photosensitizer and wavelength on photooxidation of phytosterols (PS) in soymilk and the oxidative stability of lipid and protein was determined. The oxidation of lipid and the consumption of dissolved oxygen showed a close relationship with PS oxidation. Riboflavin (Rb) leads to extra oxidation of both lipid and protein, and chlorophyll (Chl) prefer to absorb to and change the structure of protein. The influence of Rb and Chl on PS degradation under different wavelengths of light in the range of 365–665 nm was measured. Original soymilk emulsion placed under UVA (365–375 nm) and violet (400–410 nm) light underwent the most PS deterioration, whereas riboflavin was responsible for oxidation around blue (465–475 nm) region and extra formation of 6β-OH sterols, and chlorophyll enriched emulsion was vulnerable under red (645–665 nm) light. The wavelength of light (UVA > violet > blue > green > red > yellow) showed a great different effect in oxidation of PS and formation of phytosterol oxidation products (POPs). The UVA, violet, blue and red light gives rise to the prior five kind oxides of phytosterol: 6α-OH, 7α-OH, 7β-OH, 5,6β-epoxy and 7-keto.

Impact of Cold Atmospheric Plasma (CAP) Treatments on the Oxidation of Pistachio Kernel Lipids.

Cold atmospheric plasma (CAP) is a non-thermal technology that could be applied for food decontamination from both biological (microorganisms) and chemical (pesticides, food allergens, mycotoxins) contaminants, thanks to the production of reactive species (RS). However, RS could also promote the onset and the progress of food lipid oxidation, which may limit the quality and acceptability of the final products. The aim of this work was to assess the oxidation degree of pistachio kernels after treatment in a surface dielectric barrier discharge (SDBD). Two different operative conditions for CAP generation were investigated, resulting in the production of high (800 ppm) or low (300 ppm) concentrations of ozone. Limited amounts of hydroperoxides (3.00–4.22 mEq O2/kg), thiobarbituric acid reactive substances (TBARS, 0.072–0.600 mg TEP/g oil), and phytosterol oxidation products (POPs, 14.43–17.20 μg/g) were observed in lipids of both control and plasma processed pistachios. Plasma treatments did not significantly affect the total fatty acid composition and the amounts of identified unsaponifiable matter constituents (4-desmethylsterols, 4,4-dimethylsterols, 4-methylsterols), except for an unexpected significant increase of γ-tocopherol content in extracted oils. These findings contribute to gaining further knowledge for the scale-up of CAP technology to industrial processing.

Phytosterol oxidation products from coffee silverskin.

Coffee silverskin is a byproduct of the coffee roasting process contributing to organic waste burdens in urban areas. Silverskin is a potential source of dietary fiber, protein, carbohydrates, caffeine as well as vitamins and minerals. However, phytosterols present in the plant are susceptible to thermal oxidation resulting in the formation of phytosterol oxidation products (POPs) in the silverskin during roasting. In collaboration with a small roastery, the formation of POPs in three coffee varieties with roasting time was monitored by GC-MS. The objective was to evaluate the safety and potential benefits of incorporating coffee silverskin into value-added products. The qualitative profile of POPs in the silverskin from the three varieties was similar. Average total POPs were 0.32g POPs/kg silverskin. POPs from the dominant plant sterol, sitosterol, were present at the highest concentrations. Caffeine, total antioxidant capacity, and total flavonoids were measured in the silverskin of the three coffees. Average values were 1.3g caffeine/100g silverskin, TEAC of 11mmol Trolox/kg silverskin, and 1.94 to 8.60mg catechin equivalent (CE)/g silverskin, respectively. An analysis of the impact of consuming teas and baked goods containing silverskin was also performed. Using published formulations, a tea or cookie containing silverskin would contribute approximately 1 and 0.3mg POP per day, respectively. Consumption of these products would not substantially increase dietary exposure to POPs, while increasing fiber and antioxidants while reducing organic waste. PRACTICAL APPLICATION: Coffee silverskin has been studied as a possible source of fiber, antioxidants, and caffeine when incorporated in snack foods and used to make teas. To assess possible concerns about increasing dietary oxidized phytosterols, the formation of phytosterol oxidation products (POPs) was investigated in the silverskin fraction during the roasting process in three coffee varieties. In addition, caffeine, antioxidant capacity, and total flavonoids were determined. We found that silverskin can be safely used for value-added products including caffeinated teas, cookies, and bars with minimal impact on dietary POP exposures.

Determination of phytosterol oxidation products in pharmaceutical liposomal formulations and plant vegetable oil extracts using novel fast liquid chromatography - Tandem mass spectrometric methods

Phytosterol oxidation products (POPs) formed by the auto-oxidation of phytosterols can lead to negative health consequences. New liquid chromatography-tandem mass spectrometry (LC-MS/MS) quantitative and qualitative approaches were developed. For quantification, sixteen phytosterol oxidation products (POPs) in liposomal formulations; namely 7-keto, 7-hydroxy, 5,6-epoxy, and 5,6-dihydroxy derivatives of brassicasterol, campesterol, stigmasterol, and β-sitosterol were quantified. The method has a short run time of 5 min, achieved on a poroshell C18 column, using isocratic elution. To the best of our knowledge, this is the shortest run time among reported methods for the quantitative analysis of POPs. Atmospheric pressure chemical ionization (APCI) was used, and the mobile phase was composed of acetonitrile/methanol (99:1 v/v). The quantitative method was validated as per the FDA guidelines for linearity, accuracy, precision, selectivity, sensitivity, matrix effect, dilution integrity, and stability. The method was applied for the quantification of POPs in liposomal phytosterol formulations prepared with and without tocopherols, as antioxidants. The formulation process had little impact on the formation of POPs as only 7-ketobrassicasterol was quantified in tested samples. The quantified value of POPs in liposomal samples was insignificant to impart any toxicological effects. Other degradation products such as 7-hydroxy, 5,6-epoxy and 5,6-dihydroxy derivatives of brassicasterol, campesterol and β-sitosterol were below the lower limit of quantification. Phytosterol-containing formulations were then assessed for their oxidative stability after microwave exposure for 5 min. The incorporation of tocopherols significantly increased the stability of phytosterols in the liposomal formulations. Finally, LC-MS/MS qualitative identification of phytosterols obtained from extra virgin olive oil was performed. New POPs, namely 7-ketoavenasterol, and 7-ketomethylenecycloartenol were putatively identified, illustrating the applicability of the method to identify POPs with varying structures present in various phytosterol sources. In fact, it is the first time that 7-ketomethylenecycloartenol is reported as a POP.

Comparative analysis of free/combined phytosterols--degradation and differential formation of oxidation products during heating of sunflower seed oil

Sunflower seed oil was subjected to heating under 90, 180, and 220 °C for up to 180 min. A decrease in free phytosterols (FPS) and combined phytosterols (CPS) as well as a concurrent formation of individual free and combined phytosterol oxidation products (POPs) were determined and evaluated. During heating, the FPS decreased and were more susceptible to oxidation (a total of 22.8% of FPS vs. 19.2% of CPS was lost, respectively, after heating at 220 °C for 180 min), while lesser amount of the lost FPS (about 13.0% vs. 45.6%, after heating at 220 °C for 180 min) were transformed into typical oxidation derivatives compared to their corresponding combined forms. The absolute contents of individual POPs derived from FPS and CPS increased with heating temperature and time. We discovered that 7α-OH-, 7β-OH-, 5,6β-epoxy- and 5,6α-epoxy-PS derived from CPS were generated faster and at higher levels during heating at 180 °C and 220 °C for 180 min compared to those derived from the corresponding FPS, although the initial content of CPS (695.8 μg/g of oil) were far less than that (1545.5 μg/g of oil) of corresponding FPS.

Absolute configuration assignment of stigmasterol oxiranes.

Diastereoisomeric stigmasterol oxiranes 4, 5, 8, and 9 are known phytosterol oxidation products (POPs) that have been evaluated for their cytotoxicity, although the results are of limited significance since, in most cases, they were evaluated as mixtures. Consequently, to establish biological activity hierarchy of these oxides, it is critical to evaluate individual pure POPs. Therefore, we now describe the obtention of individual molecules and their absolute configuration (AC) determination. The two acetylated C-5-C-6 oxiranes 6 and 7; the two acetylated C-22-C-23 oxides 10 and 11, obtained by means of Δ5 double bond protection-deprotection; and the four C-5-C-6, C-22-C-23 diepoxystigmasteryl acetates 19-22 were now individually gained and their AC determined by vibrational circular dichroism. Vibrational modes associated with the C-5-C-6 and the C-22-C-23 bonds were identified in dioxiranes 19-22 and used to assign the AC of monoepoxides 6, 7, 10, and 11. The AC of biological active non-acetylated molecules follows immediately. Due to the scarce spectroscopic information available for these POPs, the 1 H and 13 C NMR chemical shifts of 3-22 were assigned using 1D- and 2D-NMR experiments.

Sterols and Sterol Oxidation Products: Effect of Dietary Intake on Tissue Distribution in ApoE-Deficient Mice.

Sterols and sterol oxidation products (SOPs) are well-known dietary factors influencing atherosclerosis; however, their distribution in vivo after dietary sterol/SOP intake is still unclear. Here, we investigated the tissue distribution of sterols and SOPs in ApoE-/- mice after dietary exposure to diets supplemented with phytosterols (PS), phytosterol oxidation products (POPs), or cholesterol oxidation products (COPs). The results showed that PS intake reduced cholesterol in serum and the liver but increased cholesterol in the brain. PS intake increased the levels of PS in vivo and the levels of 7-keto- and triol-POPs in serum and the liver. COP intake elevated the level of all COPs in serum but did not change the 7-keto-cholesterol level in the liver and brain. All POPs in serum and parts of POPs in the liver and brain increased after dietary POP exposure. Our study indicated that dietary PS and SOPs accumulated in vivo with varying degrees and influenced cerebral cholesterol metabolism.

Dietary Sterols and Sterol Oxidation Products on Atherosclerosis: An Insight Provided by Liver Proteomic and Lipidomic

The development of atherosclerosis is closely associated with disorder of lipid metabolism. Dietary sterols and their oxidation products play a role in the pathogenesis of atherosclerosis. However, their effects on liver lipid metabolism during the atherosclerosis remain unknown. Here, we apply lipidomic and proteomic analysis on liver of ApoE-/- mice feed with phytosterols, cholesterol oxidation products (COPs), or phytosterol oxidation products (POPs) to profile lipid species and reveal the underlying mechanism. Dietary exposure of phytosterols, COPs, and POPs all reduce the accumulation of liver triglyceride (TG), but COPs and POPs accelerate the fibrosis of liver. Lipidomic analysis reveals that phytosterols mainly decrease the levels of phosphatidylinositol (PI), while COPs and POPs both increase the level of digalactosyldiacylglycerol (DGDG) and reduce TG with long-chain polyunsaturated fatty acids. Besides, COPs up-regulated levels of lipids associate with atherosclerosis risk, such as phosphatidylcholines (PC), phosphatidylethanolamine (PE) and ceramides (Cer). POPs down-regulate the level of acyl carnitine (AcCa). Furthermore, proteomic analysis shows that COPs promote oxidative phosphorylation and POPs inhibit the beta oxidation of fatty acids. This study reveals that phytosterols, COPs, and POPs differently change the composition and metabolism of glycerophospholipids, sphingolipids, and glycerolipids in liver of ApoE-/- mice.

Analytical Strategies to Analyze the Oxidation Products of Phytosterols, and Formulation-Based Approaches to Reduce Their Generation.

Phytosterols are a class of lipid molecules present in plants that are structurally similar to cholesterol and have been widely utilized as cholesterol-lowering agents. However, the susceptibility of phytosterols to oxidation has led to concerns regarding their safety and tolerability. Phytosterol oxidation products (POPs) present in a variety of enriched and non-enriched foods can show pro-atherogenic and pro-inflammatory properties. Therefore, it is crucial to screen and analyze various phytosterol-containing products for the presence of POPs and ultimately design or modify phytosterols in such a way that prevents the generation of POPs and yet maintains their pharmacological activity. The main approaches for the analysis of POPs include the use of mass spectrometry (MS) linked to a suitable separation technique, notably gas chromatography (GC). However, liquid chromatography (LC)-MS has the potential to simplify the analysis due to the elimination of any derivatization step, usually required for GC-MS. To reduce the transformation of phytosterols to their oxidized counterparts, formulation strategies can theoretically be adopted, including the use of microemulsions, microcapsules, micelles, nanoparticles, and liposomes. In addition, co-formulation with antioxidants, such as tocopherols, may prove useful in substantially preventing POP generation. The main objectives of this review article are to evaluate the various analytical strategies that have been adopted for analyzing them. In addition, formulation approaches that can prevent the generation of these oxidation products are proposed.

Effects of stigmasterol on the thermal stability of soybean oil during heating

Phytosterols have been attached much attention for its thermal stability, but few research concerned the potential antioxidant activity of stigmasterol with two double bonds and the fate stigmasterol may experience through the whole process. The aim of this research was to comprehensively explore the realistic usage of soybean oil and the antioxidant role that stigmasterol may play. In this research, the degradation of stigmasterol added in soybean oil was evaluated with the treatments of 10-day heating at 60 °C, 9-h heating at 180 °C and 9-h frying at 180 °C. Phytosterol oxidation products and the proposed oxidation mechanisms of stigmasterol in soybean oil were investigated by GC–MS. The results showed that stigmasterol acted as a pro-oxidant at 60 °C but as an antioxidant at 180 °C. The decrease of phytosterol was usually accompanied by the increase amounts of oxidation products. After 10-day heating at 60 °C, the degradation of phytosterol was around 2.52–23.07% with 20.81–241.42 μg/g increase of oxidation products and 7-ketostigmasterol dominated. Heating at 180 °C underwent the most decreased phytosterol of 30.00–37.03% with the most rise of oxidation products 4.6–8.9 times higher than 60 °C. Differently, 5,6β-epoxy and 7β-hydroxy are the main products. According to the results of frying at 180 °C, stigmasterol literally presented excellent thermal stability in soybean oil. This indicated that stigmasterol exhibited antioxidant activity, and soybean oil with added stigmasterol could be suitable for home cooking or frying.

5α,6α-Epoxyphytosterols and 5α,6α-Epoxycholesterol Increase Oxidative Stress in Rats on Low-Cholesterol Diet.

Objective Cholesterol oxidation products have an established proatherogenic and cytotoxic effect. An increased exposure to these substances may be associated with the development of atherosclerosis and cancers. Relatively little, though, is known about the effect of phytosterol oxidation products, although phytosterols are present in commonly available and industrial food products. Thus, the aim of the research was to assess the effect of 5α,6α-epoxyphytosterols, which are important phytosterol oxidation products, on redox state in rats. Material and Methods The animals were divided into 3 groups and exposed to nutritional sterols by receiving feed containing 5α,6α-epoxyphytosterols (ES group) and 5α,6α-epoxycholesterol (Ech group) or sterol-free feed (C group). The levels of malondialdehyde (MDA), conjugated dienes (CD), and ferric reducing antioxidant potential (FRAP) were assayed in the plasma; anti-7-ketocholesterol antibodies and activity of paraoxonase-1 (PON1) were determined in serum, whereas the activity of catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), S-glutathione transferase (GST), and superoxide dismutase (SOD) were assayed in RBCs. Results During the experiment, the levels of lipid peroxidation products increased, such as CD and anti-7-ketocholesterol antibodies. At the same time, the plasma levels of FRAP and serum activity of PON1 decreased alongside the reduced activity of GPx, GR, and SOD in RBCs. There was no effect of the studied compounds on the plasma MDA levels or on the activity of CAT and GST in RBCs. Conclusions Both 5α,6α-epoxyphytosterols and 5α,6α-epoxycholesterols similarly dysregulate the redox state in experimental animal model and may significantly impact atherogenesis.

Phytosterols and their oxidative products in infant formula

AbstractInfant formulations are enriched with vegetable oils that confer not only calories, but also peculiar chemical attributes. Vegetable oils are particularly rich in phytosterols, a class of triterpene molecules analogous to cholesterol, but with different and largely unknown biological effects. The preparation and sterilization of infant formula provide opportune physicochemical conditions for oxidative reactions to occur. Oxidation of phytosterols during the preparation of infant formula can led to oxidized derivatives, known as phytosterol oxidation products [POPs], which harmful effects can be exacerbated given the wide variety of infant formulas characterized by their exclusivity of milk surrogates, required to fulfill specific needs in the nutritional development of a baby. In this review, the state‐of‐the‐art regarding phytosterols and their presence in infant formulation is revised, stressing the need of further investigation in the field of food processing. Reconsidering infant formula manufacturing in the context of phytosterols oxidation will lead to several opportunities for food engineers and technologists in the food safety.Practical applicationsPhytosterols are plant‐based bioactive lipids with health benefits. Therefore, they have been implemented as a supplement in infant formula through the addition of vegetable oils. Processing, packaging, and storage contribute to the oxidative process of these compounds. A surveillance of the entire food chain is needed to reduce the oxidative load in the final product.

Cytotoxic activity of stigmasteryl esters and products of their thermo-oxidative degradation against drug sensitive and drug resistant human acute lymphoblastic leukemia cells.

Phytosterols are mainly known as a cholesterol-lowering factor, although they form oxidation products during food storage and processing. Moreover, phytosterol oxidation products (POP) can be ab- sorbed and found in human serum, so there is the need to investigate their impact on different kinds of cells. Esters of fatty acids (oleic, linoleic and linolenic) with stigmasterol were synthetized and heated at 180°C, for 1–12 hours. The cytotoxic effect on the leukemic cells of unheated stigmasteryl esters and the mixture of compounds after heating was determined using MTT assays. POP were identified using GC-MS. The total number of POP was analysed by SPE fractionation and GC-FID separation. Dimers, trimers and oligomers in non-polar fraction were determined by gel permeation chromatography with refractive index detection. After heating, stigmasterol oxidation products were formed (up to 1.1 mg/g ester). The heating increased the potency of the compounds to reduce cell population and form POPs and oligomers in a time-dependent manner. The cytotoxicity depends on the kind of ester, dose and time. The strongest cytotoxic effect was found after 72 hours of cell treatment. Among the three stigmasteryl esters tested the most cytotoxic effect was caused by stigmasteryl linoleate.

Risk assessment of dietary exposure to phytosterol oxidation products from baked food in China

ABSTRACTPhytosterols are nutritional phytochemicals that may undergo oxidation and be transformed into phytosterol oxidation products (POPs), thus inducing pathological and toxic effects. This work investigated four main phytosterols and 28 POPs in 104 kinds of commercial baked food by using GC-MS. The dietary exposure and hazard index values (HI) associated with POPs from baked food consumption in China were estimated by using Monte Carlo simulation. Concentrations of the total phytosterols were between 3.39 and 209.80 μg/g. The total concentrations of POPs, including 5α,6α/5β,6β-epoxysterols, 7-ketosterol, 7α/7β-hydroxysterols, 6-hydroxysterols, and triols, ranged from 0.37 to 27.81 μg/g. The median dietary exposure of POP contents in baked food for four age groups in China were 10.91 (children), 6.20 (adolescents), 3.63 (adults), and 3.40 (seniors) mg/(kg×day). Risk assessment of median HI with respect to POPs indicated no risk (HI <1) for people in adolescents, adults, and seniors in the country area of China, while a risk (1 < HI < 10) would refer to the baked food consumption of people in urban area and children in country area of China. Sensitivity and uncertainty analysis showed that the most significant variables for each age group in China were POP concentration, body weight, and ingestion rate.

Safe intake of a plant sterol-enriched beverage with milk fat globule membrane: Bioaccessibility of sterol oxides during storage

Sterols in foods are susceptible to oxidation to form oxysterols. It is interesting for consumer health to know real intake and the possible associated adverse effects associated to oxysterols. This study measured oxysterol formation and bioaccessibility (BA) in a plant sterol (PS)-enriched milk-based fruit beverage with milk fat globule membrane (MFGM) added at 0, 3 and 6 months of storage at room temperature. The same cholesterol (COPs) and phytosterol oxidation products (POPs) (exclusively from β-sitosterol) (7α/β-hydroxy, α/β-epoxy, triol and 7-keto) were detected in the beverage and its bioaccessible fraction. Total COPs and POPs contents were maintained during storage, and their BA ranged between 58 and 80% and 45–49%, respectively, without significant differences throughout storage. β-Sitosterol showed a lower mean oxidation percentage (0.028%) than cholesterol (1.24%), but the estimated POPs intake (0.5mg/day) was two-fold higher than that of COPs (0.25mg/day) from 250g of beverage. These results show that the presence of milk fat and MFGM in the formulation of this beverage did not imply an increase in the contents of oxysterols and their BA. Thus, the beverage is suitable as a PS-enriched food matrix for the length of its shelf-life, and its consumption appears to be safe for consumers.

Oxysterols in cosmetics—Determination by planar solid phase extraction and gas chromatography–mass spectrometry

Sterol oxidation products (SOPs) are linked to several toxicological effects. Therefore, investigation of potential dietary uptake sources particularly food of animal origin has been a key issue for these compounds. For the simultaneous determination of oxysterols from cholesterol, phytosterols, dihydrolanosterol and lanosterol in complex cosmetic matrices, planar solid phase extraction (pSPE) was applied as clean-up tool. SOPs were first separated from more non-polar and polar matrix constituents by normal phase thin-layer chromatography and then focussed into one target zone. Zone extraction was performed with the TLC–MS interface, followed by gas chromatography-mass spectrometry analysis. pSPE showed to be effective for cleaning up cosmetic samples as sample extracts were free of interferences, and gas chromatographic columns did not show any signs of overloading. Recoveries were between 86 and 113% with relative standard deviations of below 10% (n=6). Results of our market survey in 2016 showed that some cosmetics with ingredients of plant origin contained phytosterol oxidation products (POPs) in the low ppm range and therefore in line with levels reported for food. In lanolin containing products, total SOPs levels (cholesterol oxidation products (COPs), lanosterol oxidation products (LOPs), dihydrolanosterol oxidation products (DOPs)) being in the low percent range exceeded reported levels for food by several orders of magnitudes.