Formation of Epoxy Fatty Acids in Triacylglycerol Standards during Heating.

Epoxy fatty acid formation during heating was estimated using triolein (OOO) and trilinolein (LLL). Epoxy octadecanoic acids were found in heated OOO, while epoxy octadecenoic acids were found in heated LLL. The content of epoxy fatty acids increased with heating time, and trans-epoxy fatty acids were formed significantly more than cis-epoxy fatty acids. A comparison between OOO and LLL indicated that epoxy fatty acid formation was higher in the OOO than that in the LLL. Heating tests in the presence of α- tocopherol suggested that the formation of epoxy fatty acids could be suppressed by antioxidants.

Structural characteristics and in vitro starch digestibility of oil-modified cooked rice with varied addition manipulations.

Lipid has crucial applications in improving the quality of starchy products during heat processing. Herein, the influence of lipid modification and thermal treatment on the physicochemical properties and starch digestibility of cooked rice prepared with varied addition manipulations was investigated. Rice bran oil (RO) and medium chain triglyceride oil (MO) manipulations were performed either before (BC) or after cooking (AC). GC-MS was applied to determine the fatty acid profiles. Nutritional quality was analyzed by quantifying total phenolics, atherogenic, and thrombogenic indices. All complexes exhibited higher surface firmness, a soft core, and less adhesive. FTIR spectrum demonstrated that the guest component affected some of the dense structural attributes of V-amylose. The kinetic constant was in the range between 0.47 and 0.86 min-1 wherein before mode presented a higher value. The lowest glucose release was observed in the RO_BC sample, whereas the highest complexing index was observed in the RO_AC sample, indicating that the dense molecular configuration of complexes that could resist enzymatic digestion was more critical than the quantity of complex formation. Despite the damage caused by mass and heat transfer, physical barrier, intact granule forms, and strengthened dense structure were the central contributors affecting the digestion characteristics of lipid-starch complexes.

Fabrication of Human Milk Fat Substitute: Based on the Similarity Evaluation Model and Computer Software.

We aimed to obtain the optimal formula for human milk fat substitute (HMFS) through a combination of software and an evaluation model and further verify its practicability through an animal experiment. The results showed that a total of 33 fatty acid (FA) and 63 triglyceride (TAG) molecular species were detected in vegetable oils. Palmitic acid, oleic acid, linoleic acid, 18:1/16:0/18:1, 18:2/16:0/18:2, 18:1/18:1/18:1 and 18:1/18:2/18:1, were the main molecular species among the FAs and TAGs in the vegetable oils. Based on the HMFS evaluation model, the optimal mixed vegetable oil formula was blended with 21.3% palm oil, 2.8% linseed oil, 2.6% soybean oil, 29.9% rapeseed oil and 43.4% maize oil, with the highest score of 83.146. Moreover, there was no difference in the weight, blood routine indices or calcium and magnesium concentrations in the feces of the mice between the homemade mixed vegetable oil (HMVO) group and the commercial mixed vegetable oil (CMVO) group, while nervonic acid (C24:1) and octanoic acid (C8:0) were absorbed easily in the HMVO group. Therefore, these results demonstrate that the mixing of the different vegetable oils was feasible via a combination of computer software and an evaluation model and provided a new way to produce HMFS.

The bile salt/phospholipid ratio determines the extent of in vitro intestinal lipolysis of triglycerides: Interfacial and emulsion studies.

This study focused on the protein-stabilised triglyceride (TG)/water interfaces and oil-in-water emulsions, and explored the influence of varying molar ratios of bile salts (BSs) and phospholipids (PLs) on the intestinal lipolysis of TGs. The presence of these two major groups of biosurfactants delivered with human bile to the physiological environment of intestinal digestion was replicated in our experiments by using mixtures of individual BSs and PLs under in vitro small intestinal lipolysis conditions. Conducted initially, retrospective analysis of available scientific literature revealed that an average molar ratio of 9:4 for BSs to PLs (BS/PL) can be considered physiological in the postprandial adult human small intestine. Our experimental data showed that combining BSs and PLs synergistically enhanced interfacial activity, substantially reducing oil-water interfacial tension (IFT) during interfacial lipolysis experiments with pancreatic lipase, especially at the BS/PL-9:4 ratio. Other BS/PL molar proportions (BS/PL-6.5:6.5 and BS/PL-4:9) and an equimolar amount of BSs (BS-13) followed in IFT reduction efficiency, while using PLs alone as biosurfactants was the least efficient. In the following emulsion lipolysis experiments, BS/PL-9:4 outperformed other BS/PL mixtures in terms of enhancing the TG digestion extent. The degree of TG conversion and the desorption efficiency of interfacial material post-lipolysis correlated directly with the BS/PL ratio, decreasing as the PL proportion increased. In conclusion, this study highlights the crucial role of biliary PLs, alongside BSs, in replicating the physiological function of bile in intestinal lipolysis of emulsified TGs. Our results showed different contributions of PLs and BSs to lipolysis, strongly suggesting that any future in vitro studies aiming to simulate the human digestion conditions should take into account the impact of biliary PLs - not just BSs - to accurately mimic the physiological role of bile in intestinal lipolysis. This is particularly crucial given the fact that existing in vitro digestion protocols typically focus solely on applying specific concentrations and/or compositions of BSs to simulate the action of human bile during intestinal digestion, while overlooking the presence and concentration of biliary PLs under physiological gut conditions.

Exploration of the Lipid Profile of Edible Oleaginous Microgreens by Mass Spectrometry-Based Lipidomics.

The spreading awareness of the health benefits associated with the consumption of plant-based foods is fueling the market of innovative vegetable products, including microgreens, recognized as a promising source of bioactive compounds. To evaluate the potential of oleaginous plant microgreens as a source of bioactive fatty acids, gas chromatography-mass spectrometry was exploited to characterize the total fatty acid content of five microgreens, namely, chia, flax, soy, sunflower, and rapeseed (canola). Chia and flax microgreens appeared as interesting sources of α-linolenic acid (ALA), with total concentrations of 2.6 and 2.9 g/100 g of dried weight (DW), respectively. Based on these amounts, approximately 15% of the ALA daily intake recommended by the European Food Safety Authority can be provided by 100 g of the corresponding fresh products. Flow injection analysis with high-resolution Fourier transform single and tandem mass spectrometry enabled a semi-quantitative profiling of triacylglycerols (TGs) and sterol esters (SEs) in the examined microgreen crops, confirming their role as additional sources of fatty acids like ALA and linoleic acid (LA), along with glycerophospholipids. The highest amounts of TGs and SEs were observed in rapeseed and sunflower microgreens (ca. 50 and 4-5 µmol/g of DW, respectively), followed by flax (ca. 20 and 3 µmol/g DW). TG 54:9, 54:8, and 54:7 prevailed in the case of flax and chia, whereas TG 54:3, 54:4, and 54:5 were the most abundant TGs in the case of rapeseed. ß-Sitosteryl linoleate and linolenate were generally prevailing in the SE profiles, although campesteryl oleate, linoleate, and linolenate exhibited a comparable amount in the case of rapeseed microgreens.

Absolute kinetics of peroxidation and antioxidant protection of intact triglyceride vegetable oils.

To verfy their difference from isolated fatty acids, the absolute kinetics of peroxidation was studied for seven triglyceride-based oils of olive (OLI-1, OLI-2), high-oleic sunflower (SUN-HO), high-oleic and high-linoleic safflower (SAF-HO, SAF-HL) grapeseed (GRA) and borage (BOR), by oxygen uptake monitoring, using 2,6-di-tert-butyl-4-methoxyphenol and 2,2,5,7,8-pentamethyl-6-chromanol as reference inhibitors. Propagation constants (kp/M-1 s-1 at 303 K in PhCl) were respectively 34.8 ± 2.3, 35.1 ± 1.8, 40.6 ± 5.5, 36.0 ± 7.7, 160.8 ± 5.1, 145.1 ± 24.5, 275.1 ± 63.8, while oxidizability responded to empirical equation kp(2kt)-½/M-½s-½ = 1.63 × 10-3[allyl >CH2/M] + 1.82 × 10-2[bisallyl >CH2/M], based on fatty acids residues assessed by GC-MS. Peroxidation kinetics was markedly different from that of isolated fatty acids. The H-bond basicity of all oils was measured by FT-IR affording Abraham's ßH2 values in the range 0.55 ± 0.03. H-bonding explained the protection of oils measured for seven reference phenolic antioxidants, except for the catechols quercetin and caffeic acid phenethyl ester, which were 2-to-4-folds more effective than expected, supporting a proposed different mechanism.

Predigested Mixture of Arachidonic and Docosahexaenoic Acids for Better Bio-Accessibility.

A predigested product from arachidonic acid oil (ARA) and docosahexaenoic acid (DHA) oil in a 2:1 (w/w) ratio has been developed and evaluated in an in vitro digestion model. To produce this predigested lipid mixture, first, the two oils were enzymatically hydrolyzed up to 90% of free fatty acids (FFAs) were achieved. Then, these two fatty acid (FA) mixtures were mixed in a 2:1 ARA-to-DHA ratio (w/w) and enzymatically esterified with glycerol to produce a mixture of FFAs, mono-, di-, and triacylglycerides. Different glycerol ratios and temperatures were evaluated. The best results were attained at 10 °C and a glycerol-to-FA molar ratio of 3:1. The bio-accessibility of this predigested mixture was studied in an in vitro digestion model. A total of 90% of the digestion product was found in the micellar phase, which contained 30% monoacylglycerides, more than 50% FFAs, and a very small amount of triacylglycerols (3% w/w). All these data indicate an excellent bio-accessibility of this predigested mixture.

Enzymatic Preparation, In-Depth Molecular Analysis, and In Vitro Digestion Simulation of Palmitoleic Acid (ω-7)-Enriched Fish Oil Triacylglycerols.

In this study, an enzymatic reaction was developed for synthesizing pure triacylglycerols (TAG) with a high content of palmitoleic acid (POA) using fish byproduct oil. The characteristics of synthesized structural TAGs rich in POA (POA-TAG) were analyzed in detail through ultrahigh-performance liquid chromatography Q Exactive orbitrap mass spectrometry. Optimal conditions were thoroughly investigated and determined for reaction systems, including the use of Lipozyme TL IM and Novozym 435, 15 wt % lipase loading, substrate mass ratio of 1:3, and water content of 2.5 and 0.5 wt %, respectively, resulting in yields of 67.50 and 67.45% for POA-TAG, respectively. Multivariate statistical analysis revealed that TAG 16:1/16:1/20:4, TAG 16:1/16:1/16:1, TAG 16:1/16:1/18:1, and TAG 16:0/16:1/18:1 were the main variables in Lipozyme TL IM and Novozym 435 enzyme-catalyzed products under different water content conditions. Finally, the fate of POA-TAG across the gastrointestinal tract was simulated using an in vitro digestion model. The results showed that the maximum release of free fatty acids and apparent rate constants were 71.44% and 0.0347 s-1, respectively, for POA-TAG lipids, and the physical and structural characteristics during digestion depended on their microenvironments. These findings provide a theoretical basis for studying the rational design of POA-structural lipids and exploring the nutritional and functional benefits of POA products.

Advanced Tandem Mass Spectrometric Analysis of Complex Mixtures of Triacylglycerol Regioisomers: A Case Study of Bovine Milk Fat.

Comprehensive analysis of triacylglycerol (TAG) regioisomers is extremely challenging, with many variables that can influence the results. Previously, we reported a novel algorithmic method for resolving regioisomers of complex mixtures of TAGs. In the current study, the TAG Analyzer software and its mass spectrometric fragmentation model were further developed and validated for a much wider range of TAGs. To demonstrate the method, we performed for the first time a comprehensive analysis of TAG regioisomers of bovine milk fat, a very important and one of the most complex TAG mixtures in nature containing FAs ranging from short to long carbon chains. This analysis method forms a solid basis for further investigation of TAG regioisomer profiles in various natural fats and oils, potentially aiding in the development of new and healthier foods and nutraceuticals with targeted lipid structures.

Pickering emulsion emulsified using novel cellulose nanofibers significantly lowers the lipid release rate and cellular absorption.

A Pickering emulsion is an emulsion system stabilized by solid particles and represents a promising candidate for emulsifying lipids. Cellulose nanofibers (CNFs) have excellent ability to control the lipid release rate. This study aims to find the optimal formulation for a nanocellulose-stabilized Pickering emulsion that is the most effective in reducing the lipid release rate. The Pickering emulsion was prepared by homogenizing pretreated nanocellulose with medium-chain triglycerides using high-speed and ultrasonic homogenizers. The results show that the Pickering emulsion with 0.709% nanocellulose and 30.6% medium-chain fatty acid content yielded an average particle size of approximately 2.5 µm, which is the most stable and effective in reducing the amount of the lipids released. The nanocellulose Pickering emulsion formulation developed in this study forms a significant foundation for future research and applications regarding the use of nanotechnology and Pickering emulsions to maintain the balance between one's health and the desirable flavor of fat.

Enabling superior drug loading in lipid-based formulations with lipophilic salts for a brick dust molecule: Exploration of lipophilic counterions and in vitro-in vivo evaluation.

Lipid-based formulations (LbFs) are an extensively used approach for oral delivery of poorly soluble drug compounds in the form of lipid suspension and lipid solution. However, the high target dose and inadequate lipid solubility limit the potential of brick dust molecules to be formulated as LbFs. Thus, the complexation of such molecules with a lipophilic counterion can be a plausible approach to improve the solubility in lipid-based solutions via reducing drug crystallinity and polar surface area. The study aimed to enhance drug loading in lipid solution for Nilotinib (Nil) through complexation or salt formation with different lipophilic counterions. We synthesized different lipophilic salts/ complexes via metathesis reactions and confirmed their formation by 1H NMR and FTIR. Docusate-based lipophilic salt showed improved solubility in medium-chain triglycerides (∼7 to 7.5-fold) and long-chain triglycerides (∼30 to 35-fold) based lipids compared to unformulated crystalline Nil. The increased lipid solubility could be attributed to the reduction in drug crystallinity which was further confirmed by the PXRD and DSC. Prototype LbFs were prepared to evaluate drug loading and their physicochemical characteristics. The findings suggested that structural features of counterion including chain length and lipophilicity affect the drug loading in LbF. In addition, physical stability testing of formulations was performed, inferring that aliphatic sulfate-based LbFs were stable with no sign of drug precipitation or salt disproportionation. An in vitro lipolysis-permeation study revealed that the primary driver of absorptive flux is the solubilization of the drug and reduced amount of lipid. Further, the in vivo characterization was conducted to measure the influence of increased drug load on oral bioavailability. Overall, the results revealed enhanced absorption of lipophilic salt-based LbF over unformulated crystalline Nil and conventional LbF (drug load equivalent to equilibrium solubility) which supports the idea that lipophilic salt-based LbF enhances drug loading, and supersaturation-mediated drug solubilization, unlocking the full potential of LbF.

On the structural and mechanical properties of mixed coconut and olive oil oleogels and bigels.

The interaction of monoglycerides and phytosterols in olive- and coconut oil on the structuring of oleogels was analyzed. Specifically, bigels with gelatin hydrogel in different ratios (40:60 and 60:40 w/w) were formed. The physicochemical and microstructural attributes of these systems were assessed. The olive oil to coconut oil ratio (0-100 w/w) and the added oleogelators affected the crystal structure and the mechanical properties of the oleogels. Polarized light microscopy revealed that the addition of coconut oil created a denser triglycerides crystal network and the presence of phytosterols created more needle-like crystals, enhancing the textural properties of the oleogels and of the resulting bigels. The hardness of the oleogels ranged from 0.50 N to 1.24 N and for bigels was 5.96-36.75 N. Bigels hardness decreased as the oleogel ratio in the bigel increased. Microscopy and FTIR revealed that the addition of coconut oil in oleogels hampered the formation of a distinct crystalline monoglycerides network. Also, the absence of new peaks in the bigels indicated that the two structured phases interact with each other mostly physically, without the formation of new chemical bonds. Consequently, the oleogels and bigels developed, comprise a promising hard fat substitute with improved nutritional profile.

Concentration and composition of odd-chain fatty acids in phospholipids and triacylglycerols in Chinese human milk throughout lactation.

Human milk represents the gold standard for infant nutrition, with approximately 50% of the energy in human milk derived from lipids. Odd-chain fatty acids (OCFAs) have been recognized as a category of bioactive milk fatty acids in recent research; however, limited data exist on OCFAs in human milk. This study collected human milk samples spanning the postpartum period from 0 to 400 days. Phospholipids containing OCFAs (PL-OCFAs) were determined in 486 human milk samples using hydrophilic liquid chromatography-electrospray ionization-triquadrupole-mass spectrometry. Triacylglycerols containing OCFAs (TAG-OCFAs) were analyzed in 296 human milk samples using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. The average total concentration of PL-OCFA ranged from 30.89 ± 14.27 mg L-1 to 93.48 ± 36.55 mg L-1 during lactation, and the average total TAG-OCFA content ranged from 103.1 ± 147.15 mg L-1 to 965.41 ± 651.67 mg L-1. Despite the lower absolute concentration of PL-OCFA, its relative concentration (8.75%-11.75%) was significantly higher than that of TAG-OCFA (0.37%-1.85%) throughout lactation. PC-OCFA, SM-OCFA and PE-OCFA are major sub-classes of PL-OCFA. Furthermore, C17:0 was the major chain length in both PL-OCFA and TAG-OCFA, followed by C15:0. C17:1 was characteristic of TAG-OCFA, while long-chain fatty acids C19:0, C21:0 and C23:0 were characteristic of PL-OCFA. Our findings highlighted the importance of bioactive lipids in human milk, suggesting that OCFAs could be targeted in future studies in relation to the health and development of infants.

Internal Factors Affecting the Crystallization of the Lipid System: Triacylglycerol Structure, Composition, and Minor Components.

The process of lipid crystallization influences the characteristics of lipid. By changing the chemical composition of the lipid system, the crystallization behavior could be controlled. This review elucidates the internal factors affecting lipid crystallization, including triacylglycerol (TAG) structure, TAG composition, and minor components. The influence of these factors on the TAG crystal polymorphic form, nanostructure, microstructure, and physical properties is discussed. The interplay of these factors collectively influences crystallization across various scales. Variations in fatty acid chain length, double bonds, and branching, along with their arrangement on the glycerol backbone, dictate molecular interactions within and between TAG molecules. High-melting-point TAG dominates crystallization, while liquid oil hinders the process but facilitates polymorphic transitions. Unique molecular interactions arise from specific TAG combinations, yielding molecular compounds with distinctive properties. Nanoscale crystallization is significantly impacted by liquid oil and minor components. The interaction between the TAG and minor components determines the influence of minor components on the crystallization process. In addition, future perspectives on better design and control of lipid crystallization are also presented.

Characterization of Palm Fatty Acid Distillate, Diacylglycerol Regioisomers, and Esterification Products Using High-Performance Size Exclusion Chromatography.

High-performance size exclusion chromatography (HPSEC) equipped with an evaporative light scattering detector (ELSD) was utilized for characterization of palm fatty acid distillate (PFAD) and its esterified products, with a particular focus on lipid profiles and diacylglycerol (DAG) regioisomers. The separation of triacylglycerol (TAG), DAG, monoacylglycerol (MAG), and free fatty acid (FFA) was achieved through a single 100-Å Phenogel column, coupled with a 2-cm C18 guard, utilizing toluene/acetic acid (100:0.25, v/v) as the mobile phase. This separation was based on size sieving principles and the interactions between the hydroxyl group(s) and the Phenogel matrix. The limit of detection (LOD) and limit of quantification (LOQ) for the esterified PFAD products analyzed by this method fell within the range of 4.8-5.5 µg/mL and 14.7-16.7 µg/mL, respectively. Additionally, the same column, paired with a 2-cm silica guard and a mobile phase comprised of toluene/isooctane/acetic acid (35:65:0.15, v/v/v), was used for the characterization of DAG regioisomers within the esterified PFAD. LODs and LOQs for sn-1,3-DAG and sn- 1,2-DAG were determined to be 39.2 and 118.7 µg/mL, and 32.8 and 99.5 µg/mL, respectively. Investigation of esterified PFAD products prepared using 4% H2SO4 at 120°C. After 2 h, the analysis revealed the highest MAG content at 31.85%, accompanied by 51.54% DAG, 2.35% TAG, and a residual 14.27% FFA. Notably, as the reaction time extended, the MAG content decreased, while both DAG and TAG levels exhibited an increasing trend. Further examination of DAG regioisomers during PFAD esterification, under varying catalyst concentrations (2-10%) and reaction temperatures (80-140°C), demonstrated a significant increase in the percentage of sn-1,3-DAG, inversely correlated with the reduction in FFA from 2% H 2 SO 4 and 80°C onwards. Remarkably, the percentage of sn-1,2-DAG remained relatively stable regardless of changes in catalyst concentrations or temperatures, confirming its susceptibility to isomerization into the thermodynamically more stable sn-1,3-DAG form. This study provides valuable insights into the composition and behavior of esterified PFAD products.

Lipase in-situ immobilized in covalent organic framework: Enzymatic properties and application in the preparation of 1, 3-dioleoyl-2-palmitoylglycerol.

In this study, the critical importance of designing an appropriate immobilized carrier and method for free lipase to ensure exceptional biological catalytic activity and stability was emphasized. Covalent organic frameworks (COF-1) were synthesized as a novel porous carrier with an azine structure (-CN-NC-) through the condensation of hydrazine hydrate and benzene-1,3,5-tricarbaldehyde at room temperature. Simultaneously, Rhizomucor miehei lipase (RML) was immobilized within the COF-1 carrier using an in-situ aqueous phase method. Characterization of the carrier and RML@COF-1 and evaluation of the lipase properties of RML and RML@COF-1 through p-Nitrophenyl palmitate hydrolysis were conducted. Additionally, application in the synthesis of 1, 3-dioleoyl-2-palmitoylglycerol (OPO) was explored. The results showed that RML@COF-1 exhibited a high enzymatic loading of 285.4 mg/g. Under 60℃ conditions, the activity of RML@COF-1 was 2.31 times higher than that of free RML, and RML@COF-1 retained 77.25% of its original activity after 10 cycles of repeated use, indicating its excellent thermal stability and repeatability. Under the optimal conditions (10%, 1:8 PPP/OA, 45℃, 5 h), the yield of OPO reached 47.35%, showcasing the promising application prospects of the novel immobilized enzyme synthesized via in-situ aqueous phase synthesis for OPO preparation.

Paternò-Büchi Reaction Mass Spectrometry Enables Positional Assignment of Polymethylene-Interrupted Double Bonds in Food-Derived Lipids.

Fatty acids (FAs) containing polymethylene-interrupted (PMI) double bonds are a component of human foods; however, they present a significant analytical challenge for de novo identification. Covalent adduct chemical ionization and ozone-induced dissociation mass spectrometry (MS) methods enable unambiguous assignment of PMI-FA double bond positions, however, no method has been reported with electrospray ionization (ESI) platform using off-the-shelf systems. In the current work, we studied the Paternò-Büchi (PB) fragmentation patterns of PMI-FA and triacylglycerol (TG) by analyzing several known food sources. PB-MS/MS and MS3 enabled complete double bond location assignments, including the isolated double bond in PMI-FA and triacylglycerols. Sea urchin ("uni"), oyster, pine nut, and ginkgo nut were characterized for their signature PMI-FA, 20:2(5Z,11Z), 22:2(7Z, 15Z), 18:3(5Z,9Z,12Z), and 20:3(5Z,11Z,14Z), respectively. Quantitative analyses of the relative abundance of these PMI-FA led to results similar to reference methods. 18:3(5Z,9Z,12Z) was enriched at the sn-1/sn-3 position in pine nut major TG.

Batch and continuous enzymatic interesterification of beef tallow: Interesterification degree, reaction relationship, and physicochemical properties.

The relationship between batch and continuous enzymatic interesterification was studied through enzymatic interesterification of beef tallow. The interesterification degree (ID) during the batch reaction was monitored based on triacylglycerol composition, sn-2 fatty acid composition, solid fat content, and melting profile and was described by an exponential model. A relationship equation featuring reaction parameters of the two reations was established to predict the ID and physicochemical characteristics in continuous interesterification. The prediction of the ID based on triacylglycerol composition was reliable, with an R2 value greater than 0.85. Interesterification produced more high-melting-point components for both reactions, but the acyl migration in the batch-stirring reactor was much greater, resulting in faster crystallization, a more delicate crystal network, and lower hardness. The relationship equation can be employed to predict the ID, but the prediction of physicochemical properties was constrained by the difference in acyl migration degree between the two reactions.

Interface chemistry affected the digestion fate of ketogenic diet based on medium- and long-chain triglycerides.

Ketogenic diet, characterized by high fat and low carbohydrate content, is gradually becoming a new perspective in the human diet; however, the mechanism of digestion of ketogenic diet remains unknown. In this study, we explored the oil-water interface to elucidate the digestion of a ketogenic diet based on typical representative medium- and long-chain triglycerides. The free fatty acids (FFAs) release indicated that glycerol trioctanoate with a shorter carbon chain (FFA = 920.55 ± 10.17 µmol) was significantly more digestible than glycerol tripalmitate (851.36 ± 9.48 µmol) and glycerol tristearate (805.81 ± 10.03 µmol). Particle size analysis revealed that the length of the carbon chain increased the size of triglycerides, resulting in a decreased contact area with lipase. The interfacial phenomenon indicated that the longer the carbon chain of triglycerides, the greater the reduction in binding capacity with salt ions in the digestive solution. Fluorescence spectroscopy analysis showed that the length of the carbon chain induced the displacement of the lipase peak, suggesting that the carbon chain length could alter the structure of lipase. Molecular dynamics simulation showed that the longer the carbon chain of triglycerides, the easier it was to loosen the structure of lipase. Bond energy analysis showed that the carbon chain length of triglycerides was positively correlated with the bond energy strength of the ester bonding. In conclusion, this study emphasizes that the ketogenic diet should primarily consist of shorter carbon chain triglycerides because carbon chain length can alter the digestion of triglycerides. This provides a new perspective on the quest for more effective ketogenic diet, in line with the current view of healthy diet.

The triacylglycerol structures are key factors influencing lipid digestion in preterm formulas during in vitro digestion.

Preterm formulas are usually supplemented with medium-chain triacylglycerols (MCT) whereas breast milk contains more medium and long-chain triacylglycerols (MLCT). Different types of triacylglycerol (TAG) containing medium-chain fatty acids may influence lipid digestion. In this study, the digestive characteristics of breast milk and preterm formulas with different MCT contents were evaluated using a dynamic in vitro system simulating the gastrointestinal tract of preterm infants. The lipolysis products, including diacylglycerols, monoacylglycerols (MAGs), free fatty acids, and undigested TAGs, were analyzed. Formulas with MCT addition has significantly (P < 0.05) lower lipolysis degree (LD, 69.35%-71.28%) than breast milk (76.93%). Higher amounts of C8:0 and C10:0 were released in the formulas with MCT addition. Breast milk released more C18:1n-9, C18:2n-6, and MAG containing C16:0, whereas formulas released more free C16:0. The Pearson correlation heatmap showed that the LD value was significantly and positively (P < 0.05) related to the MLCT and sn-2 C16:0 content.