Losses Of Phytosterols Research Articles

Analysis of Changes in the Amount of Phytosterols after the Bleaching Process of Hemp Oils.

Unrefined vegetable oils from niche oilseeds are now sought after by consumers because of their unique nutritional properties and taste qualities. The color and flavor intensity of niche oils is a big problem, and their refining is not industrially feasible due to the small production scale. The study undertaken aimed analyze the effect of changing the amount of phytosterols (PSs) after the bleaching process of hemp oils of the 'Finola', 'Earlina 8FC' and 'Secuieni Jubileu' varieties. Cold-pressed (C) and hot-pressed (H) crude vegetable oils were bleached with selected bleaching earth (BE) at two concentrations. The post-process BE was extracted with methanol. The amount of PSs in the crude oils and the extract after washing the BE with methanol was analyzed by GC (gas chromatography). The study shows that the bleaching process did not significantly affect the depletion of PSs in the oils. Trace amounts of PSs remain on the BE and, due to methanol extraction, can be extracted from the oil. The conclusion of the performed research is that the bleaching of hemp oil does not cause depletion of the oil, and it significantly improves organoleptic properties. The oil bleaching process results in an oil loss of less than 2% by weight of the bleached oil, while the loss depends on the type of BE used. The study shows that the loss of phytosterols after the bleaching process averages 2.69 ± 0.69%, and depends on the type of BE used and the oil extracted from different varieties of hemp seeds.

Effects of Drying Conditions on the Content of Biologically Active Compounds in Winter Camelina Sativa Seeds

AbstractThe moisture content of Camelina sativa seeds has to be maintained at 7–12% during storage in order to preserve their quality. If seeds with higher moisture contents are to be stored, they first need to be dried. This study presents the effects of high‐temperature drying (at 40, 60, 80, 100, 120, and 140 °C) of C. sativa seeds on the technological usefulness (expressed as the acid value) and bioactive compound content (as polyenoic fatty acid, vitamin‐E active compounds, and phytosterols). It is shown that drying temperature significantly affects levels of bioactive compounds. Losses of phytosterols reached a maximum of 24% (for temperatures in the 80–140 °C range), while losses of tocopherols range from 2–11%, depending on cultivar. A change in the percentage composition of polyenoic acids is observed upon air drying at 100–140 °C. It is recommended not to exceed 60 °C when drying C. sativa seeds, in order to guarantee that high‐quality cold‐pressed oil with high levels of bioactive compounds is obtained.Practical application: The seeds of Camelina sativa, like other oilseeds, require appropriate storage after harvesting in order to maintain continuity of production. Maintaining the high seed quality during storage requires drying them after harvesting to a moisture content of 7–12%. Drying conditions have a significant effect on seed quality, expressed as acid number, and also affect the levels of bioactive compounds (such as polyene fatty acids, tocopherols, plastochromanol‐8, and phytosterols) in the oil. Information on optimum drying conditions will contribute to the availability of high‐quality camelina oils produced by small local manufacturers.

Molecular insights into the loss of phytosterols during the neutralisation of corn oil

Herein, the physical migration and chemical conversion of phytosterols during the alkali neutralisation process of corn oil were investigated with molecular insights. A significant decrease in the phytosterol content was attributed to the migration from oil to the soapstock, along with slight chemical conversions between free phytosterols and phytosteryl esters in the heterogeneous system. Moreover, the migration of phytosterols was positively correlated with the water content in a model system through low-field nuclear magnetic resonance spectroscopy, which was attributed to the hydrogen bonding between free phytosterols and water. Compared to sodium oleate and sodium linoleate, sodium palmitate caused a higher loss of phytosterols due to its low solubility. X-ray diffraction analysis confirmed the formation of a bilayer structure of the sodium salt of fatty acids, suggesting the aggregation of the sodium salt of fatty acids and phytosterols at neutralisation temperatures. Small-angle X-ray scattering analysis suggested that the concentration of the NaOH solution affected the structure of sodium oleate and the area of the polar head base, which was associated with the loss of free phytosterols. The study presents an important fundamental scientific basis for the retention of phytosterols toward the development of more healthy and nutritious edible oils.

Phytosterols in edible oil: Distribution, analysis and variation during processing

Phytosterols, which are naturally occurring in plants, have excellent nutritional and health values on lowering both the blood cholesterol level and the risk of cardiovascular diseases. Edible oils are the main source of daily intake of phytosterols, whereas the properties of phytosterols may vary a lot depending on their sources. During the processing of edible oil including refining and frying, phytosterol's content fluctuates, which influences the properties of the final product. Phytosterols and their derivatives undergo physical migration between different phases and chemical conversion during the processing, which reduces the quality and the commercial value of edible oils. Therein, the loss of phytosterols is the major concern in the process of neutralization and deodorization. In addition, oxidation and thermal degradation of phytosterols occur simultaneously during frying, which also reduces the content of phytosterols. Nevertheless, the oil matrix has a promoting or an inhibitory effect on the thermal oxidation of phytosterols. Therefore, various efforts have been devoted to analyzing and improving the remaining contents of phytosterols in edible oil. Regardless of the processing method, temperature plays an important role in the loss of phytosterols. At present, the main analysis methods of phytosterols include gas chromatography and liquid chromatography, in which the pretreatment of different types of phytosterols is also a crucial step. This review focused on the following topics comprehensively: (i) the distribution of phytosterols in the oil-containing plants and edible oils during the refining processing; (ii) the pretreatment and analysis methods of various phytosterols (free phytosterols, phytosteryl fatty acid esters, phytosteryl glycosides and acylated phytosteryl glycosides); (iii) the variation of phytosterols in process of esterification and oxidation, storage and so on. The study also proposed that the investigation in the loss and safety of phytosterols during processing of the vegetable oils should be proceeded further in combination with efficient and accurate chromatography methods.

Changes in phytosterol contents during rape seed storage under conditions simulating industrial silos

During seed storage in tall silos the low layers of rape seeds are exposed to static pressure exerted by the upper layers. This may cause deformation and damage of seeds found in the lower layers and losses of biologically active compounds. The aim of this study was to simulate under laboratory conditions the actual ecosystem found in industrial plants and to evaluate the effect of not only the temperature and moisture content, but also static pressure on degradation of phytosterols contained in rape seeds in the course of storage. Changes in phytosterol levels were assessed using GC-MS. During storage in all samples of seeds (7–16% moisture content) under the adopted conditions of overpressure (20–60 kPa) and temperature (25–35 °C) the total content of phytosterols decreased by 3–57%. The smallest losses in the total phytosterol contents (3–4%) were recorded during storage of seeds with a 7% moisture content, irrespective of the applied storage temperature (25–35 °C) and overpressure variants (20–60 kPa). The greatest losses of phytosterols (43–57%) were observed during storage of seeds with a 16% moisture content at a temperature of 35 °C, while the higher the applied overpressure, the greater these losses were. The study showed that the greatest influence on sterol content during storage was increased seed moisture, and subsequently the temperature and the pressure. Experimental results also showed that for seeds with higher moisture contents (13 and 16%) an increase in storage temperature from 30 to 35 °C intensifies losses of individual phytosterols much more markedly that an increase in temperature from 25 to 30 °C. Moreover it was observed that overpressure over 20 kPa enhanced losses of investigated phytosterols.

The effect of drying temperature of milk thistle seeds on quality and bioactive compounds in the lipid fraction

Milk thistle oils are available on the market and appeal to consumers because of their healthy properties as cold-pressed oils. The raw material for producing such oils is purchased from a range of domestic and foreign sources. The aim of this work was to determine the effect of drying temperature on the peroxide value, acid value, fatty acid composition, tocopherol and phytosterol contents in the lipid fraction extracted from milk thistle seeds. The seeds were purchased in three different farms and were dried in a thin layer at 40 °C, 60 °C, 80 °C, 100 °C, 120 °C, and 140 °C. The level of phytosterols and the fatty acid composition were determined using GC-FID, while tocopherols concentrations were determined using HPLC. The study showed that the quality of seeds used in the production of oil varies. The drying of milk thistle seeds using air cooler than 80 °C caused no statistically significant changes in AV, p-AnV, phytosterol levels, tocopherols, or SFA levels. Drying temperatures in the 100–140 °C range caused significant losses of phytosterols and tocopherols and also resulted in changes in fatty acid composition. When seeds were dried at 140 °C, phytosterol levels dropped by 19–23%, tocopherols by 10–23%, MUFA by 30%, and PUFA by 11%.

Evolution of phytosterols in Chardonnay grape berry skins during last stages of ripening

This study presents the results of rapid phytosterols analysis in grape skins during last stages of ripening. The analysis is related to the evolution of sterol content by comparison with ripening degree on two vineyards of Chardonnay grape variety in Burgundy: Meursault ler Cru and Hautes Cotes de Beaune. The characterization of sterols is realized by using combined gas chromatography-mass spectrometry from trimethylsilyl ethers of sterols. After optimization of extraction by azeotropic mixture (chloroform/methanol 2:1 v/v), the analysis allows to identify four sterols in grape skins: beta-sitosterol, campesterol, stigmasterol and lanosterol. In all the samples, beta-sitosterol is the major phytosterol (86 to 89 % of the total detected phytosterols). The evolution of phytosterols content during last stages of ripening shows a similar comportment of β-sitosterol, campesterol and stigmasterol in grape skins: the maturation induces a loss of phytosterols in grape skins. An increase of phytosterol contents occurs at peak maturity and can be related with over-maturation phenomenon. The relationship between phytosterol content in grape skins and S/A ratio indicates a markedly negative correlation.

A high drying temperature causes degradation of sterols and tocopherols in yellow‐seeded Brassica napus oils

The aim of the conducted investigations was to determine the effect of drying temperature on the changes in free fatty acid, phytosterol and tocopherol (T) contents in yellow‐seeded Brassica napus oils. Seeds were dried in a thin layer at 40, 60, 80, 100 and 120°C. Changes in phytosterols were assessed using GC‐MS, while tocopherols were assessed by HPLC. Degradation of phytosterols and tocopherols and an increased content of free fatty acids followed the applied drying temperature. During drying at 40 and 60°C, changes were statistically non‐significant, while at 120°C, losses of phytosterols reached 29% and tocopherols 23%.Practical applications: Drying of rapeseeds is an important stage of its production. However, we need to remember that these seeds are biological material highly sensitive to thermal treatment. Thus we need to search for the most advantageous conditions for their drying, with special emphasis on the preservation of bioactive components affecting human health. The analyses conducted compared the range of losses of bioactive components—phytosterols, tocopherols and plastochromanol‐8 during drying.Yellow‐seeded Brassica napus were dried in a thin layer at 40, 60, 80, 100 and 120°C. The effect of drying temperature on the free fatty acid, phytosterol and tocopherol content changes in oils was determined. Degradation of phytosterols, tocopherols and the increase in free fatty acid content were related to the applied drying temperature.

Stabilisation of phytosterols by natural and synthetic antioxidants in high temperature conditions

The aim of the study was to assess the potential applicability of natural antioxidants in the stabilisation of phytosterols. A mixture of β-sitosterol and campesterol was incorporated into triacylglycerols (TAGs). The following antioxidants were added to the prepared matrix: green tea extract, rosemary extract, a mix of tocopherols from rapeseed oil, a mix of synthetic tocopherols, phenolic compounds extracted from rapeseed meal, sinapic acid and butylated hydroxytoluene (BHT). Samples were heated at a temperature of 180°C for 4h. After the completion of heating, the losses of phytosterols were analysed, as well as the contents of β-sitosterol and campesterol oxidation products. The total content of phytosterol oxidation products in samples ranged from 96.69 to 268.35μg/g of oil. The effectiveness of antioxidants decreased in the following order: phenolic compounds from rapeseed meal>rosemary extract>mix of tocopherols from rapeseed oil>mix of synthetic tocopherols>green tea extract>sinapic acid>BHT.

Fermentation of soybean oil deodorizer distillate with Candida tropicalis to concentrate phytosterols and to produce sterols-rich yeast cells

Phytosterols have been recovered from the deodorizer distillate produced in the final deodorization step of vegetable oil refining by various processes. The deodorizer distillate contains mainly free fatty acids (FFAs), phytosterols, and tocopherols. The presence of FFAs hinders recovery of phytosterols. In this study, fermentation of soybean oil deodorizer distillate (SODD) with Candida tropicalis 1253 was carried out. FFAs were utilized as carbon source and converted into cellular components as the yeast cells grew. Phytosterols concentration in SODD increased from 15.2 to 28.43% after fermentation. No significant loss of phytosterols was observed during the process. Microbial fermentation of SODD is a potential approach to concentrate phytosterols before the recovery of phytosterols from SODD. During SODD fermentation, sterols-rich yeast cells were produced and the content of total sterols was as high as 6.96%, but its major sterol was not ergosterol, which is the major sterol encountered in Saccharomyces cerevisiae. Except ergosterol, other sterols synthesized in the cells need to be identified.

Characterization of Lipids and Their Oxidation Products in Baked or Fried Breaded Shrimp Products

Baking and frying are two common food preparation methods, but there is limited knowledge about the lipid oxidation events that occur in food products prepared in these ways. Two commercially available breaded shrimp products were examined using gas chromatography, for changes in cholesterol, phytosterols, and fatty acids as a result of baking and deep frying after separation into breading and shrimp components. Additionally, changes in oil quality factors were determined for the cooking oils used to prepare the fried products. Sterol concentrations changed in both shrimp products due to degradation. Oxidation products of cholesterol and fatty acids were found in the shrimp portions of both the baked and fried samples as well as the oils used for frying using gas chromatography in tandem with mass spectroscopy. Phytos- terol oxides were detected in the frying oils, but not in the baked or fried shrimp products. The frying oils showed some oxidative losses of phytosterols. This work demonstrated that measurable lipid oxidation occurred, even over the short time periods needed to prepare these products. This may have implications for human health effects.

The effect of phytosterol concentration on oxidative stability and thermal polymerization of heated oils

AbstractThis study determined the effect of adding mixed phytosterols, at various concentrations, on the thermal polymerization and oxidative stability index (OSI) of soybean and high‐oleic sunflower oils. The indigenous tocopherols and phytosterols were removed from the oils by molecular distillation. Pure phytosterols were added back to these stripped oils at concentrations of 0.25, 0.5, 1, and 2.5 wt‐%. These oils were heated at 180 °C, and triacylglycerol dimers and polymers, fatty acid composition, and residual phytosterols were determined. Added phytosterols at 1 and 2.5% significantly decreased thermal polymerization of stripped soybean oil over 8 h. Phytosterols at 2.5% significantly increased polymerization of stripped high‐oleic sunflower oil over 12 h. Added phytosterols did not affect the loss of polyunsaturated fatty acids in either oil. The decomposition of the added phytosterols was followed in both oils during the heating study. The loss of phytosterols in soybean oil ranged from 7 to 13%, while loss in stripped high‐oleic sunflower oil ranged from 13 to 20%. Phytosterols added at 1 and 2.5% significantly decreased the OSI for stripped high‐oleic sunflower oil. This research shows that added phytosterols, especially at higher concentrations, will have an impact on the thermal and oxidative stability of oils.

Effect of Deep‐Fat Frying on Phytosterol Content in Oils with Differing Fatty Acid Composition

AbstractThe objective of this study was to determine the fate of phytosterols in vegetable oils with varying fatty acid composition used for frying. High oleic sunflower (HOSun), corn (Corn), hydrogenated soybean (HSBO), expeller pressed soybean (ESBO), and expeller pressed low‐linolenic acid soybean oil (ELLSBO) were used for frying potato chips in a pilot plant‐scale continuous fryer. The same oils, and regular soybean oil (SBO) were also used in intermittent batch frying of tortilla chips. Phytosterols were measured in oils collected at various times during frying by GC to determine their loss. The formation of polymerized triacylglycerides (PTAGs) and total polar compounds (TPC) were analyzed to determine the extent of oil degradation. In the continuous frying system, phytosterol loss ranged between 4 and 6% in ESBO, ELLSBO, HOSun, and Corn, with no loss in HSBO. PTAGs and TPC were highest in ESBO and ELLSBO, followed by Corn, HOSun, and HSBO. In the batch frying experiment, phytosterol loss ranged from 1 to 15%, and was highest in Corn followed by SBO and HSBO. There was no significant loss of phytosterols in ESBO, ELLSBO, and HOSun. Formation of PTAGs and TPC during batch frying was highest in SBO and ESBO, followed by Corn, ELLSBO, HOSun, and HSBO. In conclusion, phytosterol loss in both the continuous fryer and in the batch frying system appeared to be unrelated either to fatty acid composition, or to the extent of oil degradation.

Oxidation of phytosterols in a test food system

AbstractThe oxidative stability of phytosterols in canola, coconut, peanut, and soybean oils was examined under simulated frying conditions of 100, 150, and 180°C for 20 h. The degree of oxidative decomposition was assessed by the loss of phytosterols, accumulation of phytosterol oxides, and the change in fatty acid profiles. The phytosterol oxides produced in the oils were identified using mass spectroscopy. Oils with higher levels of polyunsaturated fatty acids showed greater amounts of sterol loss; however, the sterol loss was less complete than in the more saturated oils. A greater variety of sterol oxides was observed at the lower temperatures of 100 and 150°C compared to 180°C. This study demonstrates that under conditions similar to frying, there is a loss of phytosterols and polyunsaturated fatty acids. The accumulation of phytosterol oxides may be temperature‐limited because of further break‐down into products not measurable by typical gas chromatography‐mass spectrometry techniques.