Oil Body Suspensions Research Articles

Enhancing the recovery of oilseed rape seed oil bodies (oleosomes) using bicarbonate-based soaking and grinding media

An aqueous process for the recovery of oil bodies from rapeseed using sodium bicarbonate-based soaking and grinding media (pH 9.5) was investigated. The effect of the ratio between seed and mass of media during grinding and molarity of the medium used on oil body integrity, purity and storage stability have been studied. The grinding of seeds in solution at a ratio of 1:7 (w/w) significantly improved the quality of oil body suspension to a size more in-line with that seen in vivo (average D4,3 of 1.19µm). The purity and the composition of the recovered oil bodies depends on the molarity of medium used; the use of a sodium bicarbonate solution (pH 9.5, 0.1M) in the grinding and washing steps produced oil body preparations with the same purity as that resulting from washing a crude preparation with 9M urea. The resultant emulsion had improved physical stability over a storage period of one month.

Changes in physiochemical properties and stability of peanut oil body emulsions by applying gum arabic

Abstract The physiochemical properties of peanut oil bodies were studied, which was reflected in zeta potential, particle size, and stability. Zeta potential of oil bodies changed from around +37.23 mV at pH 3 to −21.83 mV at pH 7. High temperature (95 °C) did not influence zeta potential and particle size whereas low temperature (−20 °C) lead to the increase in particle sizes of peanut oil body suspension at both pH 3 and 7. However, the effects of low temperature on the particle size were weakened by the addition of gum arabic (GA). Thus, the peanut oil bodies were proved to be a new useful source of lipids for application in emulsion system. The peanut oil bodies can be a food ingredient applied in food industry and gum arabic (GA) could enhance the stability of peanut oil body under several environments.

Aggregation behaviour and stability of maize germ oil body suspension

To utilize maize germ oil bodies as ingredients in the food industry, zeta potential determination and particle diameter analysis were used in this study as indicators of the stability of maize germ oil body suspensions. The stability and aggregation properties of maize germ oil body suspensions were studied at different pH and ion strength conditions, and different thermal treatments. Zeta potential measurement, mean particle size determination, and confocal laser scanning microscopy were also performed. The zeta potential and mean particle diameter of the oil bodies were easily affected by salt (7.05mV and d32=1.43μm at 100mM NaCl) and pH (23.30, 15.00, −16.43mV and d32=1.02, 2.55, and 0.95μm at pH 3, pH 4, and pH 7, respectively). Results demonstrated that aggregation and instability of the oil bodies were promoted by high salt concentrations and acidic pH but not by heating. The association between oil bodies and surfactant properties resulted in the disruption of hydrophobic interactions among oil body surface proteins because of the smaller mean particle sizes and the reduced negative charges (−75.73mV and d32=0.46μm at pH 3). Thus, the oil body aggregation behavior and stability of proteins are based on hydrophobic interactions present on the surface of the oil bodies.

Physical and oxidative stability of pre-emulsified oil bodies extracted from soybeans

Soybeans contain oil bodies that are coated by a layer of oleosin proteins. In nature, this protein coating protects the oil bodies from environmental stresses and might be utilised by food manufacturers for the same purpose. In this study, an aqueous extraction method was developed to increase the yield of oil bodies extracted from soybean. This method involved a two-step procedure: (i) blending, dispersion, and filtration of soybeans; (ii) homogenisation, suspension, and centrifugation of the filter cake. Using this extraction method about 65% of the oil bodies could be obtained. The mean particle diameter (d43) and sedimentation of the resulting oil bodies increased during storage, suggesting they were prone to aggregation. Heat treatment (90°C, 30min) of the oil body suspensions immediately after extraction improved their storage stability, which was attributed to deactivation of endogenous enzymes such as lipase and lipoxygenase. Heat treatment did not adversely affect the oxidative stability of the oil body suspensions at pH 3 or 7 during storage at 37°C. These results suggest that this aqueous extraction method can be used to prepare oil body suspensions with improved long-term stability.

Soybean (Glycine max) Oil Bodies and Their Associated Phytochemicals

Soybean oil bodies were isolated from 3 cultivars (Ustie, K98, and Elena) and the occurrence of 2 classes of phytochemicals (tocopherol isoforms and isoflavones) and strength of their association with isolated oil bodies was evaluated. Tocopherol is shown to be closely associated with soybean oil bodies; δ-tocopherol demonstrated a significantly greater association with oil bodies over other tocopherol isoforms. Isoflavones do not show a significant physical association with oil bodies, although there is some indication of a passive association of the more hydrophobic aglycones during oil body isolation. Oil bodies are small droplets of oil that are stored as energy reserves in the seeds of oil seeds, and have the potential to be used as future food ingredients. If oil body suspensions are commercialized on a large scale, knowledge of the association of phytochemicals with oil bodies will be valuable in deciding species of preference and predicting shelf life and nutritional value.

Aroma encapsulation and aroma delivery by oil body suspensions derived from sunflower seeds (Helianthus annus)

Oil bodies are small discrete cell organelles that can be found within oilseeds. Oil bodies have been investigated previously as a potential technology platform for use within the food industry, offering stable, antioxidant-enriched lipid-delivery systems. In this study, the use of oil bodies as a flavour delivery agent is evaluated. Fresh aromatized oil bodies show comparable headspace flavour intensity to phospholipid-stabilized emulsions when in a static equilibrium state, and when evaluated by dynamic headspace dilution, aromatized oil bodies showed a significantly stronger potential to maintain their headspace volatile concentration, which may indicate that oil bodies would offer greater retronasal flavour delivery than current commercial systems.

Stabilization of Soybean Oil Bodies by Enzyme (Laccase) Cross-Linking of Adsorbed Beet Pectin Coatings

Soybean oil bodies are naturally coated by a layer of phospholipids and oleosin proteins, which protect them from in vivo environmental stresses. When oil bodies are incorporated into food products, they encounter new environmental stresses such as changes in pH, ionic strength, and temperature. Consequently, additional protection mechanisms are often needed to stabilize them. The purpose of this study was to determine whether soybean oil bodies could be stabilized by coating them with a layer of cross-linked anionic polysaccharide (beet pectin). The beet pectin layer was cross-linked via its ferulic acid groups using laccase (an enzyme that catalyzes the oxidation of phenolic groups). Oil body suspensions were prepared that contained 1 wt % oil and 0.06 wt % beet pectin at pH 7 and were then adjusted to pH 4.5 to promote electrostatic deposition of the beet pectin molecules onto the surfaces of the oil bodies. Laccase was then added to promote cross-linking of the adsorbed beet pectin layer. Cross-linked pectin-coated oil bodies had similar or better stability than uncoated oil bodies to pH changes (3 to 7), NaCl addition (0 to 500 mM), and freeze-thaw cycling (-20 °C for 22 h; +40 °C for 2 h). These pectin-coated oil bodies may provide a convenient means of incorporating soybean oil into food and other products.

The Mechanisms for Yuba Formation and Its Stable Lipid

Yuba is a protein-lipid film formed on soymilk surface by heating. It is characteristic of textured structure and long shelf life (3-6 months) in the dry state at room temperature. It was known that soymilk contained oil bodies, protein particles and soluble protein as main components. In this study their roles on Yuba formation were examined. Film was formed by heating an oil body suspension, but it was dispersed again by mixing; Tosan 205 soluble protein (mainly alpha' and alpha subunits of beta-conglycinin) formed film after a long time heating; Yumeminori soluble protein (mainly acidic peptides of glycinin) did not form a film even after all water was evaporated; Tosan 205 and Yumeminori non-lipid soymilks (containing protein particles and soluble protein) formed films by heating. Thus, it was concluded that protein particles were the most important for Yuba formation. In addition, Yuba was treated by liquid nitrogen, vacuum freeze-drying and observed by field emission scanning electron microscope (FESEM). The FESEM pictures showed that oil bodies, protein particles and soluble protein themselves were the "blocks" for Yuba network formation; the Yuba network was formed from protein, but oil bodies were incorporated in the network.

In Vitro Assessment of the Bioaccessibility of Tocopherol and Fatty Acids from Sunflower Seed Oil Bodies

The in vitro digestibility (proteolytic and lipolytic) and bioaccessibility of nutritionally important compounds (alpha-tocopherol and fatty acids) have been studied for natural sunflower ( Helianthus annuus ) oil body suspensions in comparison to artificial emulsions emulsified with polyoxyethylene-20-sorbitan-monolaurate (Tween 20) or whey protein isolate. Proteolytic digestion of emulsions with pepsin (pH 2) promoted significant increases in mean particle size of the whey protein isolate stabilized emulsion (1.8-2.9 mum) and oil bodies (2.3-22.5 mum) but not the Tween 20 stabilized emulsions. SDS-PAGE of proteolytic digestion products suggested degradation of the stabilizing oleosin protein (ca. 18-21 kDa) in oil bodies. The rate of oil body hydrolysis with lipase was significantly slower than the lipase-catalyzed hydrolysis of the artificial emulsions and exhibited a prolonged lag phase. Results from simulated human digestion in vitro suggested that the mean bioaccessibility of alpha-tocopherol and total fatty acids from oil bodies (0.6 and 8.4%, respectively) was significantly lower than that from the Tween 20 stabilized emulsion (35 and 52%, respectively) and the whey protein isolate stabilized emulsion (17 and 33%, respectively). These in vitro results suggest that oil bodies could provide a natural emulsion in food that is digested at a relatively slow rate, the physiological consequence of which may be increased satiety.

Aqueous Extraction of Oil Bodies from Maize Germ (Zea mays) and Characterization of the Resulting Natural Oil-in-Water Emulsion

Oil bodies in the form of an adequately dispersed suspension were extracted from maize germ by applying aqueous extraction. The effect on the yield of oil body extraction of parameters, such as pH of aqueous medium, state of germ comminution, and number of successive extraction steps applied, was evaluated, indicating that an extraction yield as high as 95% could be reached when a finely comminuted germ material is extracted 3 times under alkaline conditions. The extracted oil body suspension was coagulated by pH manipulation, and the resulting cream, consisting of intact oil bodies, was studied with respect to protein composition, particle size distribution, and oil body zeta potential. Changes in particle mean diameter resulting during oil body cream storage as well as the creaming behavior of emulsions prepared by cream dilution with water were also investigated. The findings are discussed in terms of the presence at the oil body surface of an adsorbed mixed layer made up of phospholipids, oleosins, and extraneous germ proteins that determine the physical stability of oil droplets upon long-term storage.

Oxidative stability of sunflower oil bodies

AbstractThis study investigates the oxidative stability of sunflower oil body suspensions (10 wt‐% lipid). Two washed suspensions of oil bodies were evaluated over 8 days at three temperatures (5, 25 and 45 °C) against three comparable sunflower oil emulsions stabilized with dodecyltrimethylammonium bromide (DTAB), polyoxyethylene‐sorbitan monolaurate (Tween 20) and sodium dodecyl sulfate (SDS) (17 mM). The development of oxidation was monitored by measuring the presence of lipid hydroperoxides and the formation of hexanal. Lipid hydroperoxide concentrations in the DTAB, SDS and Tween 20 emulsions were consistently higher than in the oil body suspensions; furthermore, hexanal formation was not detected in the oil body emulsions, whereas hexanal was present in the headspace of the formulated emulsions. The reasons for the extended resistance to oxidation of the oil body suspensions are hypothesized to be due to the presence of residual seed proteins in the continuous phase and the presence of a strongly stabilized lipid‐water interface.

Large scale purification of an almond oleosin using an organic solvent procedure

Oleosins are small proteins which are specific to oil-bodies, the plant organelles specialized in oil storage. These proteins are thought to stabilize the structure and to prevent the oil droplets from coalescing. Since oleosins are insoluble in water, they are usually purified either as aggregates in water or as polypeptides solubilized with SDS. These conditions raise major problems for performing biophysical studies, however. We have taken advantage of the solubility of almond oleosin in chloroform to purify it by differential extraction using solvent mixtures. Detergent-free oleosin was purified to apparent homogeneity with a purification yield of 20 % using almond meal as starting material. An oil-body suspension was reconstituted by sonicating the solvent-purified oleosin with phospholipids and triacylglycerols. Protease protection experiments suggest that oleosins are inserted into the reconstituted oil-body as they are in native organelles. This simple purification procedure allows to obtain a detergent-free solution of oleosin easy to handle which can be used for oil-body reconstitution and biophysical studies by the Wilhemly plate method.