Saturated Monoglycerides Research Articles

The Effects of Emulsifier Addition on the Functionalization of a High-Oleic Palm Oil-Based Oleogel.

Alternatives to oils with high saturated fatty acid content are often liquid oils (high in unsaturated fatty acids) that have a modified structure created either through additives or processing. Emulsifiers are additives that can be used as structuring agents of liquid fats; this process results in products such as oleogels, which can broaden the applications of these oils. This study assessed and compared the effects of mono- and diglycerides at 3%, 5%, 7% and 10% w/w on the mechanical and thermal properties of high-oleic palm oil (HOPO) oleogels. HOPO was heated to 75 °C and mixed with mono- or diglycerides at those four concentrations. The thermomechanical properties of the melted oleogels were assessed using differential scanning calorimetry (DSC). The melted oleogels were cooled to final temperatures of 5 °C, 10 °C and 15 °C under identical cooling rates, after which a puncture test (via a texture analyzer) was used to assess their textures. Finally, polarized light microscopy was used to assess the mechanical changes induced through emulsifier addition. The results showed that the use of mono- and diglycerides significantly modified the thermal and mechanical properties of the oleogels. The addition of saturated monoglycerides promoted a higher-temperature nucleation stage that did not previously occur in HOPO. The onset crystallization temperature increased with the addition of diglycerides, promoting crystallization at higher temperatures of the high-melting fraction of HOPO. The hardness of the oleogel generally increased with emulsifier addition and a reduction of the temperature. The effect of the temperature on the hardness was significantly greater in the diglyceride oleogel than in the monoglyceride oleogel. This study shows that the addition of mono- and diglycerides allows companies to customize their formulations to achieve desired results that may not previously have been possible, thereby facilitating novel uses for these oils within the industry.

Solubility limitations of residual steryl glucosides, saturated monoglycerides and glycerol in commercial biodiesel fuels as determinants of filter blockages

AbstractNewer, improved high pressure common rail diesel engines require increased protection from damaging particles in fuel, resulting in tighter, low‐micron filtration requirements. The unobstructed flow of fuel through filters underlies the well‐known efficiencies and reduced exhaust emissions of diesel engines, and when flows are hindered, these efficiencies become severely compromised. Biodiesel fuels frequently contain saturated monoglycerides, glycerol (GLY) and/or steryl glucosides, systemic impurities that become problematic when low concentrations exceed ill‐defined solubility limits, usually unexpectedly at low temperatures. Here, filters and blended fuels from seven flow obstruction incidents were subjected to detailed compositional analyses. With one exception the fuels contain estimated levels within international specifications, yet exhibit heterophase (HP) formation in the laboratory at 2°C, well above measured cloud points. Feedstock composition, pretreatment and/or purification processes are found to modulate insolubility risks. Interferences in standard gas chromatography methods used without modification can hide or complicate estimates of residual levels of GLY. The data show that classical variables controlling solubility, such as concentrations and temperatures, play important roles in setting the risks associated with in situ formation of HPs from these common impurities. Further, such risks are likely attenuated considerably by reductions in critical impurities beyond currently specified limits.

Comprehensive evaluation of saturated monoglycerides for the forming of oleogels

To investigate the effect of monoglyceride (MGs) acyl chain length and compounding of MGs on the oleogel properties and stability, 3 different pure MGs and 7 mixtures with different glycerol monostearate (MS): glycerol monobehenate (MB) ratios were studied with high oleic sunflower oil (HOSO) as the liquid oil. The oleogel properties were characterized in terms of structuring potential including oil binding capacity (OBC), hardness and rheological behavior, and the microstructural features associated with these properties determined by differential scanning calorimetry (DSC), solid fat content (SFC), X-ray diffractometry (XRD) and polarized light microscopy (PLM). Changes in oleogel properties (OBC and hardness) and the microstructure during 30 days of storage were also evaluated. Different chain lengths and ratios of MS:MB led to different crystallization rates, polymorphic transitions and aggregation rates, so as to form different crystalline networks and stabilities. In general, the MB oleogel exhibited the highest properties and stability. An increase in OBC in the order of glycerol monolaurate (ML) < MS < MB was observed for pure MG oleogels. The oleogels with mixed MGs outperformed the mechanical properties of the single ones. The best oleogel properties and stabilities were obtained for the oleogel with the MS:MB ratio as 2:8.

Preparation and characterization of oleogels with tallow and partially hydrolyzed tallow as organogelators

The aim of this study was to evaluate the organogelation potential of tallow fat (TF) and partially hydrolyzed tallow fat (HTF) against saturated monoglyceride (MG) and a saturated monoglyceride + diglyceride mixture (MDG) as the organogelators. TF itself created oleogel at a 30% addition level, while HTF, MG and MDG oleogels were prepared at 10% addition levels. Fatty acid composition data showed that the oleogel of HTF (HTFO) was quite similar to those of MG and MDG oleogels. Solid fat content, free fatty acidity and peroxide values were found to be in acceptable ranges for HTFO. Thermal properties, crystal morphology and X-ray diffraction patterns were also evaluated. Rheological analyses indicated that all oleogels had higher storage modulus (G´) than loss modulus (G´´). The time-sweep test showed that after applying higher shear rates, the gels re-formed at rest. Further, all oleogels maintained their gelled consistency until around 54 °C. The results suggest that HTF could be a cheap, efficient, fast melting, safe and readily available organogelator.

Design of Roll‐In Margarine Analogous by Partial Drying of Monoglyceride‐Structured Emulsions

AbstractA novel process is proposed to turn soft gelled emulsions containing saturated monoglyceride (MG), sunflower oil, and water into a fat material with the typical water content (20 g/100 g) and rheological properties of roll‐in margarine. A gentle drying procedure at 30 °C is proposed to allow partial water removal from the emulsions, without causing phase separation. Upon water removal, the soft emulsion, initially stabilized by a highly hydrated liquid crystalline lamellar phase of MG, converts into a high internal phase oil–water emulsion (HIPE) stabilized thanks to the presence of MG crystals around gelled oil particles, which are interconnected via polar groups of MG. HIPE at the highest MG content (13.7 g/100 g) shows rheological properties (Gʹ = 4.6 × 105 Pa, critical stress = 634 Pa) comparable to those of commercial roll‐in margarine and is successfully used in baking trials of puff pastry.Practical Applications: The last years have seen an increasing demand for strategies for the nutritional improvement of lipid‐containing foods, due to the emerging health concern related to the consumption of unbalanced saturate/unsaturated fats. Moreover, sustainability issues have arisen due to the abundant use of tropical fats in foods. However, the unique technological and sensory properties of fats make this task very challenging, especially considering the production of laminated products requiring the use of plastic fat materials with peculiar rheological properties. The results obtained in this study are very promising, as they show that the novel fat can be used as an alternative to traditional laminating margarine.

Removal of Saturated Monoglyceride in Biodiesel Using Adsorption and Its Effect on Low-Temperature Properties of Biodiesel Blends

Saturated monoglyceride (SMG) is a main cause of precipitate formed above cloud point of biodiesel (B100), which leads to filter plugging in diesel engine. In this work, we studied the effect of SMG content (0.1–0.7 wt%) of palm biodiesel (PO-B100) on the cloud point (CP) of diesel fuels blended with PO-B100 at different concentrations (B0, B7, B10 and B20). Euro 4 and Euro 5 diesels with a high and low aromatic content were used, respectively. The effect of SMG concentration on CP of biodiesel blends was more pronounced in case of a low aromatic Euro 5 diesel. An extent of CP change was also affected by the initial SMG concentration of PO-B100 and biodiesel blending ratios since they determined the SMG content of the final biodiesel blends. An adsorptive removal of SMG in PO-B100 was investigated by using natural zeolite as much cheaper adsorbents than commercial magnesium silicate (MS) and silica gel. The crystalline structure of natural zeolite and MS was studied by X-ray diffraction. Both MS and silica gel exhibited higher performance than natural zeolite in the SMG removal at 45 °C. To improve the SMG adsorption capacity, the natural zeolite was treated with 1 M nitric acid solution at 60 °C. The resulting modified zeolite had an increased SiO2 content, as measured by X-ray fluorescence spectroscopy, due to dealumination effect. Moreover, it showed an improved adsorption performance: the capacity of SMG adsorption was 31.5 mgSMG g-1, corresponding to a decrease of SMG content of PO-B100 from 0.7 wt% to 0.35 wt%, when using 10 wt% adsorbent loading at 45 oC for 50 min. As a result, an increase in the cloud point of biodiesel blends was significantly retarded.

Effect of the formulation and structure of monoglyceride-based gels on the viability of probiotic Lactobacillus rhamnosus upon in vitro digestion.

This research was conducted to evaluate the potential use of saturated monoglyceride (MG)-based gels in the protection of probiotics upon in vitro digestion. For this purpose, a Lactobacillus rhamnosus strain was inoculated into binary and ternary systems, containing MGs, a water phase composed of an aqueous solution at controlled pH or UHT skimmed milk, and in ternary gels, sunflower oil. Gel structure characterization was initially performed just after preparation and after 14 days of storage at 4 °C by rheological, mechanical, thermal, and microscopy analyses. Afterwards, probiotic viability upon in vitro digestion was evaluated. The results highlighted that all freshly prepared samples showed good capability to protect L. rhamnosus with the exception of the binary system containing milk. However, the digestion of samples after 14 days of storage showed that the ternary system containing skimmed milk exhibited the best protection performance ensuring a L. rhamnosus viability of almost 106 CFU g-1 at the end of the gastrointestinal passage. Confocal microscopy results demonstrated that bacterial cells were located prevalently within the aqueous domain near the monoglycerides and protein aggregates. Under these conditions, they can simultaneously achieve physical protection and find nutrients to survive environmental stresses. These findings suggest that MG-based gels can be proposed as efficient carriers of probiotic bacteria not only during food processing and storage but also upon digestion.

Reconsideration of regulated contamination limits to improve filterability of biodiesel and blends with diesel fuels

Abstract For the fulfillment of the Directive EU/2001/2018 targets for 2030, one of the main restrictions in the development of biodiesel fuels from sustainable feedstocks are currently the filterability problems. Contaminants such as saturated monoglycerides, sodium soaps and free steryl glucosides in biodiesel fuels have been found to clog fuel filters in vehicles, fuel dispensers and other industrial equipment which reduces the lifetime of the filters, and may result in fuel starvation, with engine operating difficulties and possible fuel-injection equipment damage. From a distilled biodiesel fuel spiked with these contaminants and subsequently blended with diesel fuel, samples fulfilling quality standards were prepared. filter blocking tendency, cold soak filtration test and total contamination tests were measured. It was found that filterability properties were affected always by the highest contaminant contents, both individually and synergistically. Total contamination test presented inconclusive results. The following conclusions were achieved: i) improvements in the precision of filterability and total contamination methods should be searched; ii) future regulations of biodiesel fuels should limit the free steryl-glucoside, saturated monoglyceride and sodium soap contents; iii) the current biodiesel fuel standards around the world do not secure the filterability properties, which could cause premature fuel filter clogging.

Effect of different oleogelators on lipolysis and curcuminoid bioaccessibility upon in vitro digestion of sunflower oil oleogels

Sunflower oil enriched with curcuminoid compounds (CUs) was gelled by adding 5% (w/w) saturated monoglycerides (MG), rice bran waxes (RW) or a mixture of β-sitosterol and γ-oryzanol (PS). The resulting oleogels differed for rheological properties and firmness due to the difference in gel network structure. PS oleogel was the firmest sample followed by RW and MG ones. Upon in vitro digestion, fatty acid release as a function of digestion time was greatly affected by oleogel structure: the extent of lipolysis decreased as oleogel strength increased (PS < RW < MG). On the other hand, the nature of the oleogelator affected CUs bioaccessibility, which was lower in oleogels containing crystalline particles (MG and RW). These findings appear interesting in the attempt to develop oleogels able to control lipid digestion as well as to deliver bioactive molecules in food systems.

The Influence of Sorbitan Monooleate as a Surfactant and Octanol as a Co-surfactant to Restore Biodiesel’s Flow Properties at the Cold Temperatures

The application of the biodiesel-diesel mixed fuel at the cold temperatures causes problem stoppage in the diesel engine. This is caused by the precipitation of agglomerate Saturated Monoglycerides (SMG). From the previous study, the addition of 1% Sorbitan Monooleate (SMO) could reduce the Cloud Point (CP) and Cold Filter Plugging Point (CFPP) respectively by 4.2°C and 2°C. In this study, SMO was used as a surfactant with octanol as a co-surfactant. For each biodiesel with 0.4-0.6% MG, the SMO was varied by 0.1-1% v/v. The molar ratio of the SMO/octanol is 1:1. Samples of biodiesel were stored at the cold temperatures (±16°C). The effect of addition SMO and octanol was analyzed by Differential Scanning Calorimetry (DSC) and the changes of MG’s droplet particle size were analyzed by Particle Size Analyzer (PSA). As the results, the addition of SMO and octanol reduced CP by 4.6°C and CFPP by 3°C. The PSA and DSC method proved that there were changes in MG’s particle diameter and onset temperature respectively from 8.18-68.30 µm to 0.29-8.88 µm and from 9.79°C to 4.97°C. The changes indicate that the SMO and octanol have roles in reducing the agglomeration of MG in biodiesel.

Methylene volumes in monoglyceride bilayers are larger than in liquid alkanes

The densities as a function of temperature of four fully hydrated saturated monoglycerides with even chain lengths ranging from eight to fourteen were determined by vibrating tube densitometry and their phase transition temperatures were determined by differential scanning calorimetry (DSC). We find the volume of a methylene group in a monoglyceride bilayer is 2% larger than in liquid alkanes at physiological temperatures, similar to the methylene group volumes found in phosphatidylcholine (PC) bilayers. Additionally, we carefully consider the traditional method of calculating component volumes from experimental data and note potential difficulties in this approach. In the literature, the ratio of terminal methyl volume (CH3) to methylene (CH2) volumes is typically assumed to be 2. By analysis of literature alkane data, we find this ratio actually ranges from 1.9 to 2.3 for temperatures ranging from 0 °C to 100 °C. For a rough sense of scale, we note that to effect a 2% reduction in volume requires of order 200 atmospheres of pressure, and pressures of this magnitude are biologically relevant. For instance, this amount of pressure is sufficient to reverse the effect of anesthesia. The component volumes obtained are an important parameter used for determining the structure of lipid bilayers and for molecular dynamics simulations.

Applications and effects of monoglycerides on frozen dessert stability

The main variations in monoglycerides are its fatty acid composition and degree of unsaturation. This study aimed to evaluate monoglycerides of different degree of unsaturation on stability of ice creams, which is also known as frozen desserts because of vegetable fat usage. This was in view of the fact that saturated monoglycerides and its blend with polysorbate 80 had been used historically in ice creams formulations instead of unsaturated monoglycerides. Stability in terms of aeration performances were measured through quantification of fat globules size distribution, meltdown resistance and heat shock stability. The meltdown rate between the saturated and unsaturated monoglycerides was 0.17–0.26% per min and 0.12–0.19% per min respectively. Frozen desserts with meltdown rate below 0.2% per min was defined to have good meltdown resistance performance. Unsaturated monoglycerides performed better than saturated monoglycerides alone and saturated monoglycerides blended with polysorbate 80 in frozen dessert stability.

Muffins Elaborated with Optimized Monoglycerides Oleogels: From Solid Fat Replacer Obtention to Product Quality Evaluation.

The food industry demands new ways to reduce the use of saturated and trans fats in food formulations. To contribute to this search, oleogels from high oleic sunflower oil and saturated monoglycerides were prepared under optimized conditions in order to obtain a product with similar functionality to margarine, and its potential application as a semisolid fat ingredient in muffins was evaluated. Muffins formulated with oleogels showed an improved quality compare with those obtained using a commercial margarine with the added benefit of a healthier nutritional profile.

Potential application of monoglyceride structured emulsions as delivery systems of probiotic bacteria in reduced saturated fat ice cream

This study investigated the potentialities of saturated monoglyceride structured emulsions (MSEs) as delivery systems of probiotics in ice cream. MSEs containing a probiotic Lactobacillus rhamnosus strain were prepared using anhydrous milk fat (AMF-MSE) or sunflower oil (Oil-MSE) as lipid phase and were added to the ice cream mix in substitution to milk cream just before freezing. Results highlighted the good capacity of MSEs to protect probiotic bacteria cells against stresses suffered during processing and storage. The physical state of the lipid phase included in the emulsion did not affect the survival of microorganisms. At the same time, the use of MSEs as fat phase allowed to obtain ice cream with minor modifications in terms of quality characteristics in comparison to control sample. In particular, Oil-MSE demonstrated the ability to create a melt-resistant fat network structure in ice cream when milk fat was replaced with sunflower oil. It was concluded that the monoglyceride crystalline structures formed in the MSE played both probiotic protective and structuring role. This approach allowed obtaining a low-saturated fat ice cream functionalized with probiotic bacteria.

Methylene Volumes in Monoglyceride Bilayers are Larger than in Liquid Alkanes

Abstract The densities as a function of temperature of four fully hydrated saturated monoglycerides with even chain lengths ranging from eight to fourteen were determined by vibrating tube densitometry and their phase transition temperatures were determined by differential scanning calorimetry (DSC). We find the volume of a methylene group in a monoglyceride bilayer is 2% larger than in liquid alkanes at physiological temperatures, similar to the methylene group volumes found in phosphatidylcholine (PC) bilayers. Additionally, we carefully consider the traditional method of calculating component volumes from experimental data and note potential difficulties in this approach. In the literature, the ratio of terminal methyl volume (CH3) to methylene (CH2) volumes is typically assumed to be 2. By analysis of literature alkane data, we find this ratio actually ranges from 1.9 to 2.3 for temperatures ranging from 0 °C to 100 °C. For a rough sense of scale, we note that to effect a 2% reduction in volume requires of order 200 atmospheres of pressure, and pressures of this magnitude are biologically relevant. For instance, this amount of pressure is sufficient to reverse the effect of anesthesia. The component volumes obtained are an important parameter used for determining the structure of lipid bilayers and for molecular dynamics simulations.

Monostearin effects on the formation of precipitate in palm oil biodiesel and petroleum diesel blends with various storage temperature

Biodiesel is one of the renewable energy forms that is on demand in Indonesia. In the biodiesel production process, impurities such as Saturated Monoglycerides (SMG) in the form of monostearin that precipitate at low temperature are commonly formed. This is caused by high Final Melting Temperature (FMT) of SMG. Formation of solid deposits when it reaches a temperature above Cloud Point (CP) is then unavoidable under these conditions. The use of palm oil biodiesel and petroleum diesel blends (BXX) with biodiesel blend ratio of 10% (B10), 20% (B20) and 30% (B30) accelerates precipation process which renders clogging on fuel filters. These works examined the effect monostearin content and temperature on the precipitation rate. Investigation is carried out at 15°C, 20°C, 25°C, and room temperature (30-33°C) with varying content of monostearin (0.4%, 0.7%, and 0.9%). Early results show that for 0.4% monostearin content in 100 ml B20, the amount of precipitate formed at temperature 15 oC was 31.3 mg. This value was higher than that at room temperature (6.3 mg) after 2 weeks storage time. This value was higher compared to B20 (21.5 mg). This indicates that as the biodiesel ratio in BXX become higher, the amount of FAME will increase which effect monostearin solubility in BXX at low temperature.

Effect of monopalmitic content and temperature on precipitation rate in biodiesel-petroleum diesel blends

The need for cleaner fuel increases alongside the necessity of reducing greenhouse gas emissions. Biodiesel is considered as one of best options for cleaner energy. However, it has disadvantages due to lower stability, lesser cold flow properties (CFP), and higher viscosity, which are mainly caused by fatty acid type and content. These works investigate CFP of various biodiesel blends B20 &amp; B30, with the objective on how the monopalmytic as one of the saturated monoglycerides (SMG) content and Temperatures affect the precipitation rate. A set of 100ml separatory funnels containing various samples were put in refrigerators in controlled-temperature, i.e.15°C; 20°C; and room temperature. The rate of precipitation was observed every day for 2 weeks using 0.8μm membrane filter. Results indicated precipitation rate of B30 was higher than that of B20. As it was expected, the precipitate was taken at the same temperature, 20°C, resulting in B30 had more precipitate in the end (37.6 mg) compared to B20 (22.2 mg). The closer to cloud point also indicates the higher rate of precipitation as 4th day B20 at 15°C (25.4 mg) compared 4th day B20 at 20°C (19.3 mg). The change of crystal from less stable α-phase to more stable, less soluble β-phase is also proven to significantly affect the rate of precipitation.

β-Carotene degradation kinetics as affected by fat crystal network and solid/liquid ratio

The aim of this research was to study β-carotene degradation kinetics into lipid systems containing different fat crystal networks in the presence of increasing liquid oil amounts. To this purpose, fat blends containing liquid saturated medium chain triacylglycerols (MCT) with increasing content of saturated monoglycerides (MG), tripalmitin (PPP) and tristearin (SSS) were added with 0.6mg/g β-carotene. The fat crystal networks formed in the fat blends were characterized by using polarized light microscopy and synchrotron X-ray diffraction (XRD). In addition, β-carotene degradation was monitored during storage in the dark at 20°C. Results highlighted that fat crystallization could differently affect β-carotene stability. In bulk SSS and PPP, β-carotene degradation proceeded at comparable rate, whereas when the saturated liquid oil MCT is included in the fat network, the rate of oxidation slightly decreased. Interestingly, the oxidation rate was not significantly affected by the solid/liquid ratio of the systems. A completely different behavior was observed in MG containing systems: the rate of β-carotene oxidation was in every case significantly lower than that observed in SSS and PPP containing samples. Also in this case, the MG protective effect was independent on its content in the fat mixtures.

Viability of probiotic Lactobacillus rhamnosus in structured emulsions containing saturated monoglycerides

The influence of structured emulsions containing saturated monoglycerides (MG) on the viability of a probiotic Lactobacillus rhamnosus strain during cold storage for up to 56days was investigated. Six emulsions were prepared, containing sunflower oil or anhydrous milk fat (AMF) as lipid phase, and UHT skim milk or an aqueous solution of potassium bicarbonate or potassium carbonate as water phase, and the probiotic strain. All samples behaved like weak gels, but MG-based emulsion containing AMF show values of storage (G′) and loss (G″) moduli as well as strength significantly higher than those of the samples containing oil. Probiotic strain added as fresh pellet survived the gel preparation procedure regardless the type of MG-based emulsion. During cold storage, bacteria in the MG-based emulsion prepared using skim milk maintained a viability much higher than that of the control and other samples. The proposed approach could offer a way to protect probiotic bacteria and to deliver them into dairy products.

Influence of oil type on formation, structure, thermal, and physical properties of monoglyceride‐based organogel

This research studied the possible relation between oil properties and structure and physical properties of saturated monoglyceride (MG)‐based organogels. To this aim different oils (castor, cod liver, corn, extra virgin olive, flax‐seed, peanut and sunflower oil, and mixture of medium chain triacylglycerols (MCT)) were used to prepare organogels by adding 10% w/w of monoglycerides. The fatty acid composition, viscosity, and dielectric properties of oils were measured. Then, organogels were characterized for crystallization induction time, dielectric properties, firmness, rheological behavior, thermal properties, crystal morphology by polarized light microscopy, and crystal polymorphism by synchrotron X‐ray diffraction (XRD) analysis.Results acquired showed that the addition of MG in different types of oils led to the formation of organogels with different properties. In all cases, β polymorph formed in the system irrespective of oil type. Regarding oils containing long chain fatty acids, gel firmness, and other structural parameters correlated well with the dielectric constant and/or viscosity of oils: increasing oil viscosity or decreasing oil dielectric constant, firmness and rheological parameters linearly increased. On the other hand, these correlations cannot be found including in the statistical analysis castor oil or MCT, probably due to the higher ability of these oils to make dipole–dipole rotation as well as the higher solubility of MG in castor oil.Practical applications: Oil gelation (organogelation) is a relative novel strategy to convert liquid oils into structured systems that has attracted food scientists and industry managers looking for solutions to reduce saturated/trans fats, deliver bioactive molecules, and minimize oil migration in foods. Results acquired in this research highlight that the choice of oil to be structured by means of saturated monoglycerides could affect the final gel structure. These findings could be useful in the attempt to applied organogels in different food products having different physical properties.This research studies the effect of oil properties on structure and physical properties of saturated monoglyceride‐based organogels. Results show that only the dielectric constant and/or viscosity of long chain fatty acid oils correlated well with gel firmness and other structural parameters.