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BACKGROUND Understanding the interactions between feed additives and the functional properties of egg white protein (EWP) may offer novel insights into the effects of feed additives on laying hens and may provide an alternative for modification of the functional properties of EWP by using laying hens as bioreactors. Glycerol monolaurate (GML) is widely used in the food industry as an effective antibacterial emulsifier. In this work, the effects of three doses of dietary GML supplementation (150, 300, and 450 mg kg−1 hen) on the functional properties of EWP were investigated. RESULTS: The hardness of EWP gels was significantly improved by 300 and 450 mg kg−1 GML supplementation. Foaming capacity (FC) and foaming stability (FS) were increased after GML treatment; 450 mg kg−1 GML supplementation showed the most significant improvements, with 44.82% in FC and 23.39% in FS. Stabilization of EWP‐oil emulsions was also improved, supported by a slowed creaming process and the formation of smaller oil droplets. The heat denaturation temperature and rheological properties were also modified by dietary GML supplementation, implying improved thermal stability. CONCLUSION: Our study demonstrated that GML supplementation has the potential to modify the functional properties of EWP, broadening the application of GML and providing a new perspective for evaluation of the efficacy of feed additives. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Intake of GML induced adverse effects on body weight, serum lipids and gut microbiota. • L. plantarum ZJUFT17 could attenuate the adverse effects induced by GML in mice. • Administration of L. plantarum ZJUFT17 could modulate the gut microbiota in mice. • L. plantarum ZJUFT17 may be a candidate for probiotics. Abstract Glycerol monolaurate (GML) is a naturally occurring surfactant and is widely used as a food emulsifier. New evidence, however, has shown that intake of GML could result in metabolic syndrome as well as gut microbiota dysbiosis in mice. In this study, male C57BL/6J mice fed normal chow diet with or without GML supplementation were administered with Lactobacillus plantarum strains isolated from Chinese sourdough for 6 weeks to investigate the influence of GML and the L. plantarum strains on body weight, serum lipid profiles, inflammatory responses and gut microbiota. The results showed that L. plantarum could attenuate the adverse effects induced by GML, especially the strain L. plantarum ZJUFT17, which showed good performance in suppressing body weight gain, lowering total cholesterol, reducing the serum tumor necrosis factor (TNF)-α level and enhancing the α-diversity of gut microbiota in mice supplemented with GML. [ABSTRACT FROM AUTHOR]

Glycerol monolaurate (GML) has the potential of antibacterial and growth-promoting in food. Recent research reported that GML could significantly increase the body index of fish, but whether GML can exert growth-promoting ability via regulating bone metabolism remains unknown. This study explored the effects of GML on the bone growth of fish models and its mechanisms by analyzing the expression of insulin-like growth factor 1(IGF-1). The micro-CT scanning results showed that the dietary supplementation of 750 mg/kg GML significantly increased the body length and bone mineral density, and improved the bone microarchitecture parameters of the caudal vertebrae of zebrafish (Danio rerio). The centrum part of the vertebra was easier to respond to the regulatory effect of GML than the neural arch and the haemal arch. Mechanistically, the content of serum IGF-1, the expression of osteogenic differentiation-related genes, and genes involved in IGF-1/PI3K/Akt signaling pathway were significantly increased. The liver proteomic analysis showed the consistent results that GML supplementation could up-regulate the expression of hepatic IGF-1, and that energy metabolism and growth and development-related metabolic pathways were implicated in the GML bone growth boosting effects. These findings highlight that GML could be used as a functional food additive to improve bone growth and health. [Display omitted] • Glycerol monolaurate (GML) increased body length and bone mineral density of Carassius auratus and Danio rerio. • The phenotype of precaudal and caudal vertebrae in Danio rerio was evaluated using micro-CT. • The expression of insulin-like growth factor 1(IGF-1) and bone metabolism-related genes was increased. • Liver proteomic assays displayed the activation of energy metabolism and growth-related metabolic pathways by GML. • 750 mg/kg GML supplementation effectively improved the bone growth and health of the fish model. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to improve the depression, enhance the bioavailability, hence strengthen the antimicrobial ability of poorly water-soluble glycerol monolaurate (GML) by loading it in microemulsion system. Microemulsions were prepared with GML as oil, tweens as surfactant, and medium-and-short chain alcohols at different ratio as cosurfactants. The effect of the ratio of surfactant to cosurfactant on the stability of microemulsion was tested. And the effect of the composition and ratio of cosurfactant and the effect of potassium sorbate dissolved in water at different concentration on the area of O/W microemulsion region in pseudo-ternary phase diagrams were also investigated. The results showed that the microemulsion is most stable when the ratio of surfactant to cosurfactant was 3:2, the suitable cosurfactant is pentanol to dodecane at 2:1, the area of O/W microemulsion region in pseudo-ternary phase diagram increased with increasing content of potassium sorbate. The conclusion of this study was that GML loaded in microemulsion had much higher anti-microbial activity than GML alone. [Copyright &y& Elsevier]

As it is known to all that the laying rate of commercial laying hens is significantly decreased during the late laying period, paralleled with increased feed conversion rate (FCR) and declined egg quality. However, recent studies demonstrate that reproductive performance as well as egg quality in aged hens can be largely improved by feed supplements. Among them, glycerol monolaurate (GML), a monoglyceride of medium chain fatty acids, is regarded as a promising supplement in poultry production. The aim of this experiment was to evaluate the effect of dietary GML on laying performance, serum biochemical indices, egg quality and gut microbiota in hens during 40–64 weeks of age. A total of 378 (40-week-old) Hy-Line Brown laying hens were randomly assigned into three treatments (21 hens/replicate and 6 replicates/treatment). The control group received a basal diet, and the treated groups fed basal diets containing 150 and 300 mg/kg GML. The results revealed that laying rate (p < 0.05) was significantly increased and the FCR (p < 0.05) was reduced in GML-containing groups compared with the control group. The egg quality (including eggshell thickness and strength) was notably improved by GML supplementation at the later late laying period, and the content of total amino acids and flavor amino acids in the albumen were also increased. Inclusion of 300 mg/kg GML in diet increased the levels of laying-related sex hormones (serum follicle stimulating hormone, luteinizing hormone and estradiol, p < 0.05), serum calcium and lipid (total serum cholesterol, triglycerides and low-density lipoprotein cholesterol, p < 0.05). Moreover, the community and microbial function of gut microbiota were notably altered by GML supplementation. These findings revealed that dietary GML improved the reproductive performance and egg quality mainly by stimulating the sex hormones secretion, serum calcium metabolism and nutrients utilization, which provided us a new approach to simultaneously promote the egg production and improve the egg quality at aged hens. [ABSTRACT FROM AUTHOR]

Glycerol monolaurate (GML) has potent antimicrobial and anti-inflammatory activities. The present study aimed to assess the dose-dependent antimicrobial-effects of GML on the gut microbiota, glucose and lipid metabolism and inflammatory response in C57BL/6 mice. Mice were fed on diets supplemented with GML at dose of 400, 800 and 1600 mg kg−1 for 4 months, respectively. Results showed that supplementation of GML, regardless of the dosages, induced modest body weight gain without affecting epididymal/brown fat pad, lipid profiles and glycemic markers. A high dose of GML (1600 mg kg−1) showed positive impacts on the anti-inflammatory TGF-β1 and IL-22. GML modulated the indigenous microbiota in a dose-dependent manner. It was found that 400 and 800 mg kg−1 GML improved the richness of Barnesiella, whereas a high dosage of GML (1600 mg kg−1) significantly increased the relative abundances of Clostridium XIVa, Oscillibacter and Parasutterella. The present work indicated that GML could upregulate the favorable microbial taxa without inducing systemic inflammation and dysfunction of glucose and lipid metabolism. [ABSTRACT FROM AUTHOR]

Glycerol monolaurate (GML) is a fatty acid monoglyceride, which richly exists in coconut oil, palm oil, and human milk. Except for the recognized emulsifying properties, GML's good antibacterial ability and low energy density also make it an ideal functional additive and food quality improver. This review discusses GML synthesis, health benefits, positive effects on food storage and quality, and critically discusses its fate and safety in vivo. The routine emulsification of GML in foods is beyond the scope of this review. GML is synthesized through direct esterification, methyl laurate glycerolysis or laurate glycerolysis. Although the in vivo fate of GML is assumed to be similar to that of glyceryl trilaurate, there is no direct experimental evidence for this inference. Previous studies proved that GML functions beyond an emulsifier. In food quality, GML inhibits the growth of harmful microorganisms and extends shelf life. It also improves the nutritional value and sensory properties of animal-derived food by regulating amino acid and fatty acid metabolism. In health efficacies, GML reduces lipid accumulation, rebuilds the intestinal barrier, modulates immune activity, and may have positive effects on the nervous system. These are associated with the direct intervention of GML on gut microbiota, immune cell activity and energy metabolism. However, developing more efficient GML synthesis schemes, enhancing the application of GML on food quality, and exploring the in vivo fate, health efficacy mechanism or safety of GML in different experimental models remain interesting topics in the future. • The main preparation methods of glycerol monolaurate (GML) were reviewed. • The in vivo fate of GML was speculated and discussed. • GML can be used as food quality improver and preservative. • GML are benefit on obesity, gut, immune and cognition. [ABSTRACT FROM AUTHOR]

• Dynamic effects of glycerol monolaurate (GML) on Larimichthys crocea were explored including feeding and fasting stages. • GML supplementation (1.0 g kg−1) significantly improved the flesh quality and productive performance of Larimichthys crocea. • The flesh quality was evaluated from color, texture, flavor and nutritional value. • GML supplementation (1.0 g kg−1) exhibited promising amelioration effects on Larimichthys crocea. The effects of GML (Glycerol monolaurate) supplementation with two level (0.5 and 1.0 g kg−1) on the productive performance and flesh quality of large yellow croaker (360 per group) were investigated during feeding (23,50-days) and fasting stage (23,70-days). The GML supplementation significantly increased body weight after 23-days and crude protein, inosinic acid, and yellowness after 50-days. Moreover, it increased hardness, springiness, and chewiness by increasing the collagen content, myofiber density, and decreasing myofiber diameter. The high GML supplementation increased the total free amino acids, delicate amino acids, monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (n-3 PUFA), and EPA + DHA, whereas it decreased the content of saturated fatty acids/unsaturated fatty acids (SFA/UFA). During fasting, better body shape and color were shown were shown at high GML supplementation. Conclusively, high dose GML supplementation exerted promising effects on the productive performance and flesh quality of large yellow croaker. [ABSTRACT FROM AUTHOR]

Organogels have been prepared with corn oil as organic solvent and glycerol monolaurate (GML) as organogelator for antimicrobial purpose. The critical gelation concentration (CGC) was found to be 3% (w/w) by the inverted tube method. The physical properties of the organogels containing 3%, 10%, 20%, 30%, 40% GML were studied by light microscopy, differential scanning calorimetry, and rheological analysis. The results showed that with the increasing organogelator concentration, the gels had a more compact three-dimensional network as the GML molecules crystallized and grew into a stronger backbone network as the gel skeleton, leading to higher thermal stability, higher resistance to deformations and lower spreadability. The antimicrobial assay using zone of inhibition indicated that the prepared organogels possessed strong antimicrobial activities against Staphylococcus aureus and Escherichia coli . The successful development of GML-based organogels suggests the potential application as new gelled capsules or spreadable products for controlled drug delivery. [ABSTRACT FROM AUTHOR]

[Display omitted] • LA, GML and GTL ameliorated HFD-induced hyperlipidemia. • GML performed better effects on glucose metabolism and systemic inflammation. • LA and its glycerides-induced improvements were related to gut microbiota regulation. • GML regulated phospholipid metabolism and gut microbe-related metabolites. • GML promoted endogenous unsaturated fatty acids synthesis. The anti-bacterial properties of lauric acid (LA) and its glycerides had been studied. However, their effects on gut microbiota remain unclear. Moreover, LA and its glycerides performed controversial influences on lipid metabolism. This study evaluated the regulation of LA, glycerol monolaurate (GML) and lauric triglyceride (GTL) on metabolic health and gut microbiota in high fat diet-fed mice. Serum metabolomics and lipidomics contributed to elucidate the underlying mechanisms. LA and its glycerides ameliorated hyperlipidemia, while GML performed more pronounced modulation on glucose metabolism and inflammation. LA and its glycerides modulated gut microbiota with increased Bifidobacterium and decreased Desulfovibrio , which closely related with metabolic improvements. Furthermore, the integrative multi-omics analyses identified that the regulation of phospholipid metabolism, intestinal microbial metabolites (bile acids and indole derivatives) and endogenous unsaturated fatty acids synthesis conduced to the more evident modulation of GML. Our findings suggested an effective strategy of GML for improving metabolism and gut health. [ABSTRACT FROM AUTHOR]

• S BL may reduce the release of butyric acid in simulated gastric digestion. • The release rate of GML in S LBL was low in simulated digestion. • S BL and S LBL retarded the release of GML in intestinal digestion in vivo. • S BL and S LBL induced positive changes in gut microbes rapidly. Structuring is a feasible scheme to improve lipids' value. Here, S BL and S LBL (C4-C12 structural lipids) were obtained through enzymatic ester-ester transesterification or acidolysis interesterification using glyceryl tributyrate/glyceryl tridodecanoate and lauric acid/glyceryl tributyrate as raw materials, respectively. The digestive characteristics of S BL and S LBL were investigated in vitro and in vivo , meanwhile, their effects on gut microbes were studied. Compared with their corresponding triglyceride physical mixture, S BL possessed an ideal butyric acid sustained-release effect in simulated stomach digestion. Moreover, the sustained-release effect of S LBL on glycerol monolaurate (GML) was revealed both in vivo and in vitro , while this effect of the S BL was obviously occurred in small intestine. S BL significantly increased the abundance of Bifidobacterium and S LBL promoted the growth of Clostridiales within 24 h. Overall, both S BL and S LBL showed ideal sustained-release effects on GML rather than butyric acid, which may lead to positive changes in gut microbes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Glycerol monolaurate (GML) supplementation could significantly improve the flesh quality of Larimichthys crocea. • A diet with 0.075% GML increased the non-essential amino acid and unsaturated fatty acid contents of Larimichthys crocea in muscle. • The addition of GML dramatically augmented amino acid biosynthesis and metabolism. • GML could activate the myogenic-related signaling pathway of Larimichthys crocea in muscle. To improve the quality of cultured large yellow croaker (Larimichthys crocea), this study was performed to study the impacts of glycerol monolaurate (GML) on the nutritional value, growth performance, muscle texture, and taste intensity of L. crocea. The results showed that GML as a feed additive significantly increased the crude lipid content and reduced the diameters of muscle fibers, which in turn markedly altered the flesh texture in terms of cohesiveness. Moreover, the taste indicators (umami and richness) and flavor-related amino acid (glutamic acid, glycine, and proline) contents of L. crocea muscle were significantly higher in the GML group. Metabolomic and gene expression analyses showed that GML supplementation could significantly improve amino acid biosynthesis and metabolism, promote protein and lipid synthesis, and activate myogenic-related signaling pathways of L. crocea. Consequently, adding an appropriate amount of GML to fish feed would be conducive to providing healthy, nutrient-rich and acceptably flavored aquatic-products. [ABSTRACT FROM AUTHOR]

Abstract: The characterization of a pharmaceutical microemulsion system with glycerol monolaurate as oil, ethanol as cosurfactant, Tween 40 as surfactant, sodium diacetate and water, and the antimicrobial activities against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Aspergillus niger and Penicillium expansum have been studied. The influence of ethanol and sodium diacetate on oil solubilization capability was clearly reflected in the phase behavior of these systems. One microemulsion formulation was obtained and remained stable by physical stability studies. The antimicrobial assay using solid medium diffusion method showed that the prepared microemulsion was comparable to the commonly used antimicrobials as positive controls. The kinetics of killing experiments demonstrated that the microemulsion caused a complete loss of viability of bacterial cells (E. coli, S. aureus and B. subtilis) in 1min, killed over 99% A. niger and P. expansum spores and 99.9% C. albicans cells rapidly within 2min and resulted in a complete loss of fungal viability in 5min. The fast killing kinetics of the microemulsion was in good agreement with the transmission electron microscopy observations, indicating the antimembrane activity of the microemulsion on bacterial and fungal cells due to the disruption and dysfunction of biological membranes and cell walls. [Copyright &y& Elsevier]

Abstract: Microemulsions are colloidal nanodispersions of oil and water stabilized by an interfacial film of surfactant molecules, typically in conjunction with a cosurfactant. There is a limited number of reports in the literature on microemulsion use for antimicrobial purposes. The physicochemical characterization of a food-grade fully dilutable microemulsion system with glycerol monolaurate (GML) as oil, organic acids as cosurfactant, Tween 80 as surfactant, and the antimicrobial activities against Escherichia coli and Staphylococcus aureus have been studied in this paper. The influence of organic acids on oil solubilization was clearly reflected in the phase behavior of these systems. Propionic acid demonstrated the greatest capability to improve the oil solubilization among the tested linear and nonlinear chain organic acids and contributed to the formation of U-type microemulsion systems. One microemulsion formulation with an average particle size of 8nm was selected, the composition is GML/propionic acid/Tween 80/water=3:9:8:12. The kinetics of killing experiments demonstrated that the undiluted microemulsion caused a complete loss of viability of E. coli or S. aureus cells in 1min and still had effective bactericidal effects even when diluted, more than 99% viable E. coli cells were killed within 15min and a complete loss of viability was achieved at 45min while more than 99% viable S. aureus cells were killed within 30min and a complete loss of viability was achieved at 60min in the presence of the 10-fold diluted microemulsion. The fast killing kinetics of the ten-fold serial dilutions of microemulsions were in good agreement with the mode of action studies, indicating that the interaction between the antimicrobial microemulsions and bacterial membranes significantly decreased the bacterial cell surface hydrophobicity and induced the quick release of 260nm absorbing materials. This work suggests the potential use of food-grade fully dilutable microemulsions for antimicrobial purposes in beverages or seafood products. [Copyright &y& Elsevier]

Abstract: The physicochemical characterization of a food-grade glycerol monolaurate (GML)/ethanol/Tween 20/sodium lactate (SL)/water microemulsion system and the antimicrobial activities against Bacillus subtilis have been studied in this paper. The influence of ethanol and SL on oil solubilization capability was clearly reflected in the phase behavior of these systems. The addition of ethanol in GML/Tween 20/water system greatly improved the oil solubilization and induced the formation of a U-type microemulsion system, while a transition from U-type to S-type microemulsion system was observed with the increasing concentration of sodium lactate. Two microemulsion formulations were obtained and remained stable by physical stability studies. Antimicrobial results showed that the microemulsions were effective in inhibiting the viable bacteria cells and the bacteria growth. Later it was found that the microemulsions had synergistic antimicrobial activities with a major contribution of GML and the solubilization of SL enhanced the antimicrobial effects. This work indicated that microemulsions are promising delivery vectors for antimicrobial applications in food industry. [Copyright &y& Elsevier]