Rate Of Free Fatty Acid Release Research Articles

Comparison of sea buckthorn fruit oil nanoemulsions stabilized by protein-polysaccharide conjugates prepared using β-glucan from various sources

To understand the influence of β-glucans structure on the emulsifying properties of protein-polysaccharide conjugates, sodium caseinate (NaCas) was utilized to form glycosylation conjugates with varying degrees of glycosylation (10.68–17.50%) using three β-glucans from bacteria, yeast, and oats. This process induced alterations in the secondary structure of protein. The nanoemulsions prepared with the glycosylated conjugates exhibited superior stability compared to those formulated solely with NaCas, particularly under conditions of drastic pH fluctuations and extended storage periods. The nanoemulsion prepared with the NaCas-Salecan conjugate demonstrated exceptional stability at pH 4 and 6, or storage for 20 days. Additionally, it significantly attenuated the oxidation of unsaturated fatty acids and exhibited the lowest levels of aggregation, flocculation, and free fatty acid release rate during in vitro digestion. This study suggested the potential of the NaCas-Salecan conjugates in enhancing the stability of nanoemulsions and facilitating the colorectal-targeted delivery of sea buckthorn fruit oil.

Conjugated safflower seed oil and its oleogels stabilization properties: Thermodynamic properties, rheology, oxidative stability

Conjugated safflower seed oil (CSSO) was used as the base oil, and beeswax (BW) was used as the gelling agent to prepare BW-CSSO oleogel. The effects of different additions of wax on the properties of BW-CSSO oleogel, as well as their oxidative stability, were investigated. The results indicated that an oleogel could be formed with CSSO at a BW concentration of 5 wt% at 25 °C, and the oil-holding capacity and hardness of the oleogel increased significantly as the BW concentration increased from 5 wt% to 11 wt%. Differential scanning calorimetry results showed that the peak crystallization and melting temperatures of the oleogel generally increased with the increase of wax addition, and both the crystallization and melting peaks became clearer and sharper. The rheological results indicated that all the samples showed shear-thinning behavior and higher concentrations of BW-CSSO oleogel were more capable of forming robust structures with lower frequency dependence. The free fatty acid release rate from BW-CSSO oleogel decreased with increasing BW concentration because the oleogel was stronger due to the formation of a more robust network, and the network of strong crystals influences the contact between lipase and oil, slowing down the release of oil from the interior of the oleogel structure and affecting the hydrolysis of oil. The network structure of the oleogel could inhibit the generation of CSSO secondary oxidation products and improve the oxidative stability of CSSO. This study provides the relevant parameters of the BW-CSSO oleogel and lays the foundation for subsequent studies.

Stability and gastrointestinal behavior of curcumin-loaded emulsion stabilized by multi-conformation soy proteins: Influence of oil volume fraction

The aim of this work was to assess the potential of nanoemulsions stabilized by mixed soy protein with multi-conformation as curcumin carrier, and the influence of oil volume fraction on stability and gastrointestinal behavior of curcumin-loaded emulsion was investigated. Loading efficiency showed a slight increase with higher oil content, though the difference was not statistically significant. With the increase of oil, the viscosity (Pa‧s), thixotropy (area of hysteresis loop) and particle size of the emulsion increased, which facilitated the physical and chemical stability of curcumin-loaded emulsion. However, the free fatty acid release rate and bioaccessibility of curcumin was negatively correlated with the oil volume fraction and the particle size of emulsion after gastric digestion. Notably, the digestion in stomach did not affect the structure of interfacial protein, demonstrating that protein-based nanoemulsions exhibited resistance to gastric digestion. This study provides theoretical guidance for the application of protein-based emulsion in curcumin delivery.

Physicochemical properties and in vitro digestion behavior of emulsion gels stabilized by rice bran protein aggregates: Effects of heating time and induction methods

To investigate the effects of heating time and induction methods on the physicochemical properties and in vitro digestion behavior of emulsion gels, rice bran protein aggregates (RBPAs) were formed by acid-heat induction (90 °C, pH 2.0) and the emulsion gels were further prepared by adding GDL or/and laccase for single/double cross-linked induction. Heating time affected the aggregation and oil/water interfacial adsorption behavior of RBPAs. Suitable heating (1–6 h) was conducive to faster and more adsorption of aggregates at the oil/water interface. While excessive heating (7–10 h) resulted in protein precipitation, which inhibited the adsorption at the oil/water interface. The heating time at 2, 4, 5 and 6 h was thus chosen to prepare the subsequent emulsion gels. Compared with the single cross-linked emulsion gels, the double-cross-linked emulsion gels showed higher water holding capacity (WHC). After simulated gastrointestinal digestion, the single/double cross-linked emulsion gels all exhibited slow-release effect on free fatty acid (FFA). Moreover, the WHC and final FFA release rate of emulsion gels were closely related to the surface hydrophobicity, molecular flexibility, sulfhydryl, disulfide bond and interface behavior of RBPAs. Generally, these findings proved the potential of emulsion gels in designing fat alternatives, which could provide a novel technique for the fabrication of low-fat food.

Effects of carboxymethyl cellulose on the emulsifying, gel and digestive properties of myofibrillar protein-soybean oil emulsion

Improving the qualities of vegetable oil replaced animal fat meat products is particularly fascinating for the development of healthy meat products. This work was designed to investigate the effects of different carboxymethyl cellulose (CMC) concentrations (0.01 %, 0.05 %, 0.1 %, 0.2 %, and 0.5 %) on the emulsifying, gelation, and digestive properties of myofibrillar protein (MP)-soybean oil emulsions. The changes in MP emulsion characteristics, gelation properties, protein digestibility, and oil release rate were determined. Results demonstrated that CMC addition decreased the average droplet size and increased the apparent viscosity, storage modulus, and loss modulus of MP emulsions, and a 0.5 % CMC addition significantly increased the storage stability during 6 weeks. Lower CMC addition (0.01 % to 0.1 %) increased the hardness, chewiness, and gumminess of emulsion gel especially for the 0.1 % CMC addition, while higher CMC (0.5 %) content decreased the texture properties and water holding capacity of emulsion gels. The addition of CMC decreased protein digestibility during the gastric stage, and 0.01 % and 0.05 % CMC addition significantly decreased the free fatty acid release rate. In summary, the addition of CMC could improve the stability of MP emulsion and the texture properties of the emulsion gels, and decrease protein digestibility during the gastric stage.

Effect of gelation technique on lipid digestibility of emulsion-loaded alginate microparticles: a systematic review and meta-analysis.

Alginate microparticles fabricated via calcium gelation or layer-by-layer assembly are commonly used for encapsulating emulsions. In this study, the impact of these two gelation methods on the lipid digestibility of emulsions was reviewed through a systematic screening of relevant studies. From the literature search (Scopus, PubMed, and Web of Science databases), 604 records were screened and 25 articles were included in the analysis. The fold change of free fatty acid release rate at the end of in vitro digestion process between alginate-encapsulated emulsion and emulsions not encapsulated by alginate was calculated for calcium gelation (weighted mean of response ratio 0.64, 95% CI 0.54-0.75) and layer-by-layer assembly (weighted mean of response ratio 0.89, 95% CI 0.81-0.98). Alginate-calcium hydrogels showed stronger inhibition of the extent of lipid digestion than alginate-coated multilayer emulsions. The structural and particle size differences between alginate microparticles acquired using different techniques may contribute to this phenomenon.

Pickering emulsion stabilised by double‐modified starch particles and its delivery property for curcumin

SummaryRice starch was hydrophobised by octenyl succinic anhydride (OSA) and then modified by roast dry heating at 180°C for 40 min (RDH‐40) to improve its digestibility. The oil‐in‐water Pickering emulsions stabilised by double‐modified starch particles were fabricated. The emulsion stability under different formulation parameters was investigated. Results showed that the suitable parameters for fabrication of Pickering emulsion were RDH‐40 concentration of 4.0 wt.%, oil volume ratio of 50% and pH of the system was 7.0. The addition of NaCl and sucrose (0–200 mmol/L) slightly reduced the emulsion stability. Microstructure results revealed that the starch particles and a few gelatinized starch macromolecules distributed around the oil droplets, making the emulsion more stable. Compared with the emulsions stabilised by Tween 20 and OSA starch, the Pickering emulsion stabilised by 4.0% RDH‐40 starch showed the highest loading and embedding rates for curcumin at 25 and 40°C. The emulsion stabilised by RDH‐40 had a faster free fatty acid release rate and higher curcumin bioaccessibility than that stabilised by OSA starch during in vitro digestion. This study helps to develop new starch‐based Pickering emulsions for the delivery of oil‐soluble bioactive substances.

Development of whey protein isolate–phytosterols complexes stabilized oil-in-water emulsion for β-carotene protection and delivery

Although β-carotene (BC) exerts beneficial effects on human health, the direct use of this compound as a nutritional supplement is hindered by its low water solubility and oxidation stability. Herein, we develop an oil-in-water emulsion stabilized by whey protein isolate (WPI)–phytosterols (PS) complexes as a delivery system for BC to overcome the above limitations. The rheology and stability of the emulsion were characterized, and the influence of the emulsion on the chemical stability and bioaccessibility of BC was discussed. The results showed that the PSs promoted the adsorption of WPI at the oil–water interface and improved the viscosity and viscoelasticity of the emulsion. The emulsion with a WPI:PS mass ratio of 25:2 (EWPI-PS) featured the highest fraction of interfacial adsorbed protein (88.73 %), excellent stability during 21-day storage at 25 °C. The BC retention rate of EWPI-PS (61.48 %) was significantly higher than that of the emulsion stabilized by WPI only (EWPI, 31.90 %) after 21-day storage at 50 °C. In addition, BC-loaded EWPI-PS showed higher freeze–thaw and thermal stability than BC-loaded EWPI, and a lower free fatty acid release rate and BC bioaccessibility than BC-loaded EWPI in simulated gastrointestinal digestion experiments. These results provide a theoretical basis for the WPI-PS complexes-stabilized emulsion as BC delivery system.

Gastrointestinal Fate and Fatty Acid Release of Pickering Emulsions Stabilized by Mixtures of Plant Protein Microgels + Cellulose Particles: an In Vitro Static Digestion Study

The present study aims to investigate the in vitro intestinal digestion fate of Pickering emulsions with complex dual particle interfaces. Pickering oil-in-water emulsions (PPM-E) stabilized by plant (pea) protein-based microgels (PPM), as well as PPM-E where the interface was additionally covered by cellulose nanocrystals (CNC), were designed at acidic pH (pH 3.0). The gastrointestinal fate of the PPM-E and free fatty acid (FFA) release, was tested via the INFOGEST static in vitro digestion model and data was fitted using theoretical models. Lipid digestion was also monitored using lipase alone bypassing the gastric phase to understand the impact of proteolysis on FFA release. Coalescence was observed in the PPM-stabilized emulsions in the gastric phase, but not in those co-stabilized by CNC. However, coalescence occurred during the intestinal digestion stage, irrespective of the CNC concentration added (1–3 wt % CNC). The presence of CNC lowered the lipolysis kinetics but raised the extent of FFA release as compared to in its absence (p < 0.05), due to lower levels of gastric coalescence, i.e., a higher interfacial area. The trends were similar when just lipase was added with no prior gastric phase, although the extent and rate of FFA release was reduced in all emulsions, highlighting the importance of prior proteolysis in lipolysis of such systems. In summary, an electrostatically self-assembled interfacial structure of two types of oppositely-charged particles (at gastric pH) might be a useful strategy to enable enhanced delivery of lipophilic compounds that require protection in the stomach but release in the intestines.

Preparation, characterisation and in vitro digestibility of potato starch‐fatty acid complexes

SummaryThe starch‐fatty acid (FA) complex belongs to a new type of resistant starch (RS5) and has become a prevalent research topic because of its slow‐digestion and enzymatic resistance properties. In this study, the starch‐FA complexes were prepared from potato starch (PS) and FAs with various carbon chain lengths and unsaturation by hydrothermal treatment (HT), alcohothermal treatment (AT) or ultrasound treatment (UT), and their physicochemical properties and digestibility were interpreted. The PS‐8% lauric acid (Lau) with the highest complex index value (approximately 95%) and RS content (approximately 31%) was obtained by HT; meanwhile, it had a slow glucose diffusion rate and a low free fatty acid release rate in simulated gastrointestinal digestion compared to native PS. Besides, the V‐type crystalline structure was formed obviously after HT, but it was too weak for AT and UT samples to be detected. The gelatinisation viscosity was reduced due to the physical combination of PS and Lau. Therefore, HT was a relatively efficient and safe approach to prepare starch‐FA complex with high RS content, and the obtained starch‐FA complex has the potential to become an alternative functional food ingredient.

Modification of the interfacial structure of droplet-stabilised emulsions during in vitro dynamic gastric digestion: Impact on in vitro intestinal lipid digestion

The in-vitro gastrointestinal digestion behaviour of an oil-in-water emulsion with an interface consisting of nano-sized droplets coated with caseinate particles, referred to as a droplet-stabilised emulsion (DSE), was explored using the human gastric simulator and pH-stat models. A caseinate-particle-stabilised emulsion (PSE) was used as a control, with a similar droplet size distribution and the same composition as the DSE. The nanodroplet-stabilised interface of the DSE was preserved during the first 180 min of gastric digestion. During 240 min, the droplet sizes of the DSE and the PSE increased from 22.71 ± 1.14 to 63.34 ± 6.57 μm and from 17.98 ± 1.16 to 85.11 ± 9.35 μm respectively. The small droplet size of the DSE that was released from the gastric phase contributed to slightly higher total free fatty acid (FFA) release (56.18 ± 3.55%) than that from the PSE (49.4 ± 2.67%). The FFA release rate of the DSE (1.21 % min−1) was greater than that of the PSE (1.06 % min−1) during the first 30 min of small intestinal digestion; similar FFA release rates (0.5 µmol s−1 m−2 × 10−4) were obtained for both emulsions beyond 30 min of digestion. This study provides new information on lipid digestion using a novel interfacial layer that was stabilised with nanodroplets.

In Vitro Gastrointestinal Digestion of Palm Olein and Palm Stearin-in-Water Emulsions with Different Physical States and Fat Contents.

The impacts of lipid physical state and content on lipid digestion behavior were investigated using 4 and 20% palm olein-in-water emulsions (4% PO and 20% PO) and 4 and 20% palm stearin-in-water emulsions (4% PS and 20% PS). The changes of lipid physical state, particle size, and microstructure during gastrointestinal digestion; the free fatty acid (FFA) released in the intestinal phase; and the fatty acid composition of micellar phases were investigated. After gastric digestion, all emulsions underwent flocculation and coalescence, with 20% PS showing the most extensive aggregation. During intestinal digestion, the FFA release rate and level decreased as the lipid content increased from 4 to 20%, with 4% PO presenting the highest digestion rate and extent. Besides, the solid fat in 4% PS and 20% PS decreased and increased the maximum lipid digestibility, respectively. These results highlighted the combined roles of lipid physical state and content in modulating dietary lipid digestion.

Oligomer Procyanidins from Lotus Seedpod Regulate Lipid Homeostasis Partially by Modifying Fat Emulsification and Digestion.

Dietary polyphenols have shown hypolipidemic effects by reducing triglyceride absorption. The mechanisms may involve modifying fat emulsion during digestion in the gastrointestinal tract and suppressing lipase during hydrolysis in the small intestine. In an in vivo study, lotus seedpod oligomeric procyanidin (LSOPC) decreased total serum triglyceride and total cholesterol and elevated the high-density lipoprotein level in the hyperlipidemic rat model. In addition, LSOPC suppressed de novo lipogenesis-related gene expressions. In an in vitro study, the LSOPC-enriched emulsion decreased the mean droplet size from 0.36 to 0.33 μm and increased the viscosity of the emulsion. Moreover, the LSOPC-enriched emulsion improved the antioxidant properties. A digestion model was developed and showed that the particle size of the LSOPC-enriched emulsion increased in the oral cavity. However, an increase and then a significant drop of the particle size was measured in the stomach and small intestine. The free fatty acid release rate was decreased in the LSOPC-enriched emulsion partly ascribed to the inhibition of lipase by LSOPC.

Glyceroneogenesis revisited

Glyceroneogenesis is the synthesis of 3-glycerol phosphate by an abbreviated version of gluconeogenesis. The research that led to the discovery of glyceroneogenesis in white adipose tissue is presented. This pathway is active during fasting in white and brown adipose tissue and in the liver as part of the triglyceride/fatty acid cycle. Glyceroneogenesis is critical for the extensive recycling of free fatty acid (FFA) back to triglyceride that occurs in mammals, including humans, after lipolysis, when up to 65% of the fatty acids are re-esterified back to triglyceride. The rate-limiting enzyme in this pathway is the cytosolic form of phosphoenolpyruvate carboxykinase (GTP) (4.1.1.32) (PEPCK-C). Transcription of this gene is induced in adipose tissue and liver during fasting. Ablation of expression of the gene for PEPCK-C in white adipose tissue of mice results in lipodsytrophy, while overexpression of the gene for this enzyme in adipose tissue causes obesity. The critical role of glyceroneogenesis in diabetes was suggested by experiments in which the gene for PEPCK-C is induced in white adipose tissue by rosiglitazone, a drug used to control diabetes in humans. This was accompanied by a marked decrease in FFA release from adipose tissue due to an induction in glyceroneogenesis in the tissue. Since the chronic release of FFA by adipose tissue is a critical factor in the development Type 2 diabetes, it is likely that rosiglitazone acts in part by stimulating transcription of the gene for PEPCK-C, thereby increasing rate of glyceroneogenesis and lowering the rate of FFA release from adipose tissue.

Effect of insulin on fat metabolism during and after normal pregnancy.

Whereas development of resistance to the action of insulin on glucose metabolism during gestation has been recognized, it is presently not known whether there is also resistance to the action of insulin on lipid metabolism. We have, therefore, examined the effect of physiological hyperinsulinemia (during euglycemic-hyperinsulinemic clamping) on free fatty acid (FFA) turnover in seven nondiabetic overweight or obese women during and after pregnancy. Basal rates of FFA release, oxidation, and reesterification and basal plasma FFA concentrations were not significantly different from each other during the 2nd and 3rd trimester of pregnancy and postpartum. During euglycemic-hyperinsulinemic (approximately 500 pmol/l) clamping, however, lipolysis was significantly less inhibited during the 3rd trimester (from 7.0 +/- 0.9 to 4.9 +/- 0.9 micromol x kg(-1) x min(-1), -30%) than during the 2nd trimester (from 8.4 +/- 0.6 to 4.1 +/- 0.9 micromol x kg(-1) x min(-1), -51%) and postpartum (from 8.5 +/- 1.1 to 4.2 +/- 0.6 micromol x kg(-1) x min(-1), -51%). Similarly, fat oxidation was not inhibited at all (from 3.5 +/- 0.3 to 3.8 +/- 0.5 micromol x kg(-1) x min(-1)) during the 3rd trimester but was suppressed by 51% (from 3.9 +/- 0.2 to 1.9 +/- 0.3 micromol x kg(-1) x min(-1)) during the 2nd trimester and by 38% (from 2.6 +/- 0.7 to 1.6 +/- 0.5 micromol x kg(-1) x min(-1) postpartum. These data demonstrated that resistance to the action of insulin on lipolysis and on fat oxidation developed during late gestation and disappeared postpartum.

Effect of endurance training on plasma free fatty acid turnover and oxidation during exercise.

Plasma free fatty acid (FFA) levels tend to be lower and the plasma lipolytic hormone response to prolonged exercise of the same intensity is blunted after endurance exercise training. To determine whether training elicits a corresponding decrease in plasma FFA turnover and metabolism during prolonged exercise, we measured plasma [1-13C]palmitate kinetics and oxidation and respiratory gas exchange in 13 subjects during the latter portion of a 90- to 120-min bout of cycle ergometer work performed before and after 12 wk of alternate-day cycling and running. Training increased total fat oxidation during prolonged exercise by 41% (P < 0.005). However, for the final 30-60 min of the cycle ergometer protocol, the rate of 13CO2 production from [1-13C]palmitate oxidation was 27% lower (P < 0.05), the rate of palmitate turnover was 33% less (P < 0.05), and plasma FFA and glycerol concentrations were 32 and 20% lower (P < 0.05), respectively, than in the untrained state. Thus endurance exercise training results in decreased plasma FFA turnover and oxidation during a 90- to 120-min bout of submaximal exercise because of a slower rate of FFA release from adipose tissue.

Decapitation ischemia-induced release of free fatty acids in mouse brain

In this study, the release of lysophospholipids (to depict phospholipase A2 activity) and diacylglycerols (DG) (to depict stimulated hydrolysis of polyphosphoinositides) was related to the decapitation-induced release of free fatty acid (FFA) in the mouse brain. To assay for lysophospholipids, Balb/c mice were injected intracerebrally with either [3H]choline or [3H]inositol for 16 h in order to label their respective phospholipids. These lipids were examined at various times (30 s to 30.5 min) after decapitation. Between 30 s and 1.5 min after decapitation, the rate of FFA release (3 micrograms FA/mg FA in phospholipids/min) was three times more rapid than that between 10 and 15 min (0.8 microgram FA/mg FA in phospholipids/min). FFA released during the initial phase were enriched in 20:4 and 18:0 whereas those released during the latter phase were nonspecific. The DG fatty acids are enriched in 18:0 and 20:4. Ischemia induced a rapid release of DG as measured by its fatty acid content (3.2 micrograms FA/mg FA in phospholipids/min). Unlike FFA, the level of DG reached a plateau after 1.5 min and remained elevated for the entire 30.5 min. In agreement with previous notions indicating the involvement of phospholipase A2 in ischemic insult, steady increases in radioactivity of both lysophosphatidylcholines and lysophosphatidylinositols were observed with time after decapitation. Based on the preferential increase in both 18:0 and 20:4 during the initial time period, the results suggest that poly-PI hydrolysis coupled to DG-lipase may contribute to the initial release of FFA, whereas the FFA released subsequent to the initial phase may be mainly a result of activation of phospholipase A2 acting on phosphatidylcholines and phosphatidylinositols.

Pharmacological manipulations of anoxia-induced free fatty acid accumulation in the mouse brain

The accumulation of free fatty acid (FFA) in the brain occurs within minutes of anoxia, induced by exposing mice to a 100% N2 atmosphere. The rate of FFA release is high within the first minute and continues to increase moderately hereafter. FFA is apparently accumulated at the highest concentration in the cerebral hemispheres. The release of FFA can be inhibited partly by CNS depressants like N6-cyclopentyladenosine, pentobarbital, ethanol, or 4,5,6,7-tetrahydroisoxazolo-[5,4-c]pyridin-3(2H)-one (THIP). Antiadrenergic compounds such as reserpine, clondine, or prazosine were also found to be active. The N2 anoxia was initially and temporarily associated with motor excitation termed fight and flight reaction. This behavior could be reduced by administration of N6-cyclopentyl-adenosine, pentobarbital, ethanol, reserpine, and prazosine, but not by THIP or clonidine. The glutamate antagonist MK-801 inhibited the fight and flight reaction, but did not affect the FFA accumulation. The data are consistent with the view that brain anoxia initially increases FFA by receptor-mediated polyphosphoinositide breakdown and that the alpha-1 adrenergic receptor is one of the receptors involved. The data also indicate that the fight and flight reaction is dissociated from the events that lead to FFA release, and may involve the stimulation of glutaminergic NMDA receptors.

Effect of exercise on FFA metabolism of pancreatectomized dogs

Normal and pancreatectomized dogs with indwelling arterial and venous catheters were exercised on the treadmill for 35 min. Palmitate-1-C14 was infused intravenously for 3 hr during the experiment, or administered orally 15 hr before the experiment. The plasma free fatty acid (FFA) level was decreased in normal dogs but increased in the pancreatectomized animals during exercise. This was due to corresponding changes in the rate of FFA release. The rate of uptake of plasma FFA followed the rate of release with some delay, so that at the end of exercise the uptake was tenfold higher in the pancreatectomized dogs than in the controls. In spite of this striking difference, the C14O2 output was increased during exercise four- to fivefold in both groups in the infusion experiments. When the radiopalmitate was administered orally, however, the specific activity of the exhaled C14O2 rapidly decreased in the exercising pancreatectomized dogs but remained rather constant in the controls. It is suggested that during heavy exercise the muscles of the normal dog oxidize their endogenous fat pools, whereas the pancreatectomized animal relies for fat oxidation on the plasma FFA, the concentration of which is considerably increased by norepinephrine in the absence of insulin.