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Ziani K, Chang Y, McLandsborough L, McClements DJ. Influence of surfactant charge on antimicrobial efficacy of surfactant-stabilized thyme oil nanoemulsions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:6247-55. [PMID: 21520914 DOI: 10.1021/jf200450m] [Citation(s) in RCA: 159] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Thyme oil-in-water nanoemulsions stabilized by a nonionic surfactant (Tween 80, T80) were prepared as potential antimicrobial delivery systems (pH 4). The nanoemulsions were highly unstable to droplet growth and phase separation, which was attributed to Ostwald ripening due to the relatively high water solubility of thyme oil. Ostwald ripening could be inhibited by incorporating ≥75% of corn oil (a hydrophobic material with a low water solubility) into the nanoemulsion droplets. The electrical characteristics of the droplets in the nanoemulsions were varied by incorporating ionic surfactants with different charges after homogenization: a cationic surfactant (lauric arginate, LAE) or an anionic surfactant (sodium dodecyl sulfate, SDS). The antifungal activity of nanoemulsions containing positive, negative, or neutral thymol droplets was then conducted against four strains of acid-resistant spoilage yeasts: Zygosaccharomyces bailli, Saccharomyces cerevisiae, Brettanomyces bruxellensis, and Brettanomyces naardenensis. The antifungal properties of the three surfactants (T80, LAE, SDS) were also tested in the absence of thymol droplets. Both ionic surfactants showed strong antifungal activity in the absence of thymol droplets, but no antimicrobial activity in their presence. This effect was attributed to partitioning of the antimicrobial surfactant molecules between the oil droplet and microbial surfaces, thereby reducing the effective concentration of active surfactants available to act as antimicrobials. This study shows oil droplets may decrease the efficacy of surfactant-based antimicrobials, which has important consequences for formulating effective antimicrobial agents for utilization in emulsion-based food and beverage products.
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Affiliation(s)
- Khalid Ziani
- Department of Food Science, Chenoweth Laboratory, University of Massachusetts, Amherst, Massachusetts 01003, USA
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Keogh JB, Wooster TJ, Golding M, Day L, Otto B, Clifton PM. Slowly and rapidly digested fat emulsions are equally satiating but their triglycerides are differentially absorbed and metabolized in humans. J Nutr 2011; 141:809-15. [PMID: 21411612 DOI: 10.3945/jn.110.131110] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Little is known about the effect of dietary fat emulsion microstructure on plasma TG concentrations, satiety hormones, and food intake. The aim of this study was to structure dietary fat to slow digestion and flatten postprandial plasma TG concentrations but not increase food intake. Emulsions were stabilized by egg lecithin (control), sodium sterol lactylate, or sodium caseinate/monoglyceride (CasMag) with either liquid oil or a liquid oil/solid fat mixture. In a randomized, double-blind, crossover design, 4 emulsions containing 30 g of fat in a 350-mL preload were consumed by 10 men and 10 women (BMI = 25.1 ± 2.8 kg/m(2); age = 58.8 ± 4.8 y). Pre- and postprandial plasma TG, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) concentrations and food intake were measured. In a second experiment in a subset of the participants (n = 8, 4 men and 4 women), (13)C-labeled mixed TG was incorporated into 2 different emulsions and breath (13)C was measured over 6 h. In the first experiment, the postprandial rise in plasma TG concentrations following the CasMag-stabilized emulsion containing 30% solid fat was lower than all other emulsions at 90 and 120 min (P < 0.05). Plasma CCK (P < 0.0001), GLP-1 (P < 0.01), and PYY (P < 0.001) concentrations were also reduced following this emulsion compared with control. Food intake at a test meal, eaten 3 h after the preload, did not differ among the emulsions. In the second experiment, when measured by the (13)C breath test, 25% of the TG in the CasMag emulsion was absorbed and metabolized compared with control. In conclusion, fat can be structured to decrease its effect on plasma TG concentrations without increasing food intake.
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Affiliation(s)
- Jennifer B Keogh
- Commonwealth Scientific and Industrial Research Organization Preventative Health Flagship, Commonwealth Scientific and Industrial Research Organization Food and Nutritional Sciences, Adelaide 5000, South Australia, Australia
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Wu T, Rayner CK, Jones K, Horowitz M. Dietary effects on incretin hormone secretion. VITAMINS AND HORMONES 2011; 84:81-110. [PMID: 21094897 DOI: 10.1016/b978-0-12-381517-0.00003-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The delivery of nutrients from the stomach into the duodenum and their subsequent interaction with the small intestine to stimulate incretin hormone release are central determinants of the glycemic response. The incretin effect has hitherto been attributed to the secretion of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) from enteroendocrine cells in the intestinal epithelium. A number of recent studies have yielded fundamental insights into the influence of individual nutrients on incretin release and the mechanisms involved in the detection of carbohydrates, fats, and proteins by enteroendocrine cells, including the K(ATP) channel, sodium-glucose cotransporter 1 (SGLT1), sweet taste receptors, G-protein-coupled receptors (GPRs), and oligopeptide transporter 1 (PepT1). Dietary modification, including modifying macronutrient composition or the consumption of "preloads" in advance of a meal, represents a novel approach to manipulate the incretin response and thereby regulate glucose homeostasis in patients with type 2 diabetes. This review focuses on the effects of individual nutrients on incretin hormone secretion, our current understanding of the signaling mechanisms that trigger secretion by enteroendocrine cells, and the therapeutic implications of these observations.
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Affiliation(s)
- Tongzhi Wu
- University of Adelaide Discipline of Medicine, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, Australia
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Stewart JE, Seimon RV, Otto B, Keast RSJ, Clifton PM, Feinle-Bisset C. Marked differences in gustatory and gastrointestinal sensitivity to oleic acid between lean and obese men. Am J Clin Nutr 2011; 93:703-11. [PMID: 21310831 DOI: 10.3945/ajcn.110.007583] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Both orosensory stimulation and feedback from the gastrointestinal tract contribute to energy intake regulation. OBJECTIVE We evaluated the hypothesis that overweight or obese subjects would be less sensitive to both oral and intraduodenal oleic acid exposure than would lean subjects. DESIGN Eleven overweight or obese and 8 lean men were studied on 2 occasions, during which antropyloroduodenal pressures, plasma cholecystokinin and peptide YY, and appetite were measured during 90-min intraduodenal infusions of saline or oleic acid (18:1 load: 0.78 kcal/min); energy intake (buffet lunch) was determined immediately afterward. Oral detection thresholds for 18:1 and recent dietary intake (2-d recall) were also quantified. RESULTS In lean subjects, the number of isolated pyloric pressure waves (IPPWs) was greater during 18:1 infusion than during saline infusion (P < 0.05); no significant differences were observed between the 18:1 and saline infusions in the overweight or obese subjects. In both groups, 18:1 stimulated plasma cholecystokinin and peptide YY and suppressed energy intake compared with saline (P < 0.05), with trends for reduced cholecystokinin and energy intake responses in the overweight or obese subjects. Detection thresholds for 18:1 were greater in overweight or obese (7.9 ± 0.1 mmol/L) than in lean (4.1 ± 0.4 mmol/L) subjects (P < 0.05). Overweight or obese subjects had greater recent energy (P < 0.05) and fat (P = 0.07) intakes than did lean subjects. There was a direct relation (r = 0.669) of body mass index with 18:1 detection thresholds and inverse relations (r < -0.51) of IPPWs with body mass index and 18:1 detection thresholds (P < 0.05). CONCLUSIONS The ability to detect oleic acid both orally and within the gastrointestinal tract is compromised in obese men, and oral and gastrointestinal responses to oleic acid are related. This trial was registered at www.actr.org.au (Australian New Zealand Clinical Trials Registry) as 12609000557235.
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Affiliation(s)
- Jessica E Stewart
- University of Adelaide Discipline of Medicine, Royal Adelaide Hospital, Adelaide, Australia
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Brennan IM, Seimon RV, Luscombe-Marsh ND, Otto B, Horowitz M, Feinle-Bisset C. Effects of acute dietary restriction on gut motor, hormone and energy intake responses to duodenal fat in obese men. Int J Obes (Lond) 2011; 35:448-56. [PMID: 20680017 DOI: 10.1038/ijo.2010.153] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Previous patterns of energy intake influence gastrointestinal function and appetite, probably reflecting changes in small-intestinal nutrient-mediated feedback. Obese individuals consume more fat and may be less sensitive to its gastrointestinal and appetite-suppressant effects than lean individuals. OBJECTIVE To evaluate the hypothesis that, in obese individuals, the effects of duodenal fat on gastrointestinal motor and hormone function, and appetite would be enhanced by a short period on a very-low-calorie diet (VLCD). METHODS Eight obese men (body mass index 34±0.6 kg m(-2)) were studied on two occasions, before (V1), and immediately after (V2), a 4-day VLCD. On both occasions, antropyloroduodenal motility, plasma cholecystokinin (CCK), peptide-YY (PYY) and ghrelin concentrations, and appetite perceptions were measured during a 120-min intraduodenal fat infusion (2.86 kcal min(-1)). Immediately afterwards, energy intake was quantified. RESULTS During V2, basal pyloric pressure and the number and amplitude of isolated pyloric pressure waves (PWs) were greater, whereas the number of antral and duodenal PWs was less, compared with V1 (all P<0.05). Moreover, during V2, baseline ghrelin concentration was higher; the stimulation of PYY and suppression of ghrelin by lipid were greater, with no difference in CCK concentration; and hunger and energy intake (kJ; V1: 4378±691, V2: 3634±700) were less (all P<0.05), compared with V1. CONCLUSIONS In obese males, the effects of small-intestinal lipid on gastrointestinal motility and some hormone responses and appetite are enhanced after a 4-day VLCD.
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Affiliation(s)
- I M Brennan
- University of Adelaide Discipline of Medicine, Royal Adelaide Hospital, Adelaide, South Australia, Australia
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Little TJ, Feinle-Bisset C. Oral and gastrointestinal sensing of dietary fat and appetite regulation in humans: modification by diet and obesity. Front Neurosci 2010; 4:178. [PMID: 21088697 PMCID: PMC2981385 DOI: 10.3389/fnins.2010.00178] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 09/23/2010] [Indexed: 01/25/2023] Open
Abstract
Dietary fat interacts with receptors in both the oral cavity and the gastrointestinal (GI) tract to regulate fat and energy intake. This review discusses recent developments in our understanding of the mechanisms underlying the effects of fat, through its digestive products, fatty acids (FAs), on GI function and energy intake, the role of oral and intestinal FA receptors, and the implications that changes in oral and small intestinal sensitivity in response to ingested fat may have for the development of obesity.
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Affiliation(s)
- Tanya J. Little
- Discipline of Medicine, Royal Adelaide Hospital, University of AdelaideAdelaide, SA, Australia
- NHMRC Centre of Clinical Research Excellence in Nutritional Physiology, Interactions and Outcomes, University of AdelaideAdelaide, SA, Australia
| | - Christine Feinle-Bisset
- Discipline of Medicine, Royal Adelaide Hospital, University of AdelaideAdelaide, SA, Australia
- NHMRC Centre of Clinical Research Excellence in Nutritional Physiology, Interactions and Outcomes, University of AdelaideAdelaide, SA, Australia
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McClements DJ, Li Y. Review of in vitro digestion models for rapid screening of emulsion-based systems. Food Funct 2010; 1:32-59. [PMID: 21776455 DOI: 10.1039/c0fo00111b] [Citation(s) in RCA: 302] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
There is increasing interest in understanding and controlling the digestion of emulsified lipids within the food and pharmaceutical industries. Emulsion-based delivery systems are being developed to encapsulate, protect, and release non-polar lipids, vitamins, nutraceuticals, and drugs. These delivery systems are also being used to control the stability and digestion of lipids within the human gastrointestinal tract so as to create foods that enhance satiety and reduce hunger. In vitro digestion models are therefore needed to test the efficacy of different approaches of controlling lipid digestion under conditions that simulate the human gastrointestinal tract. This article reviews the current status of in vitro digestion models for simulating lipid digestion, with special emphasis on the pH stat method. The pH stat method is particularly useful for the rapid screening of food emulsions and emulsion-based delivery systems with different compositions and structures. Successful candidates can then be tested with more rigorous in vitro digestion models, or using animal or human feeding studies.
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Affiliation(s)
- David Julian McClements
- Biopolymers and Colloids Research Laboratory, Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA
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Li Y, McClements DJ. New mathematical model for interpreting pH-stat digestion profiles: impact of lipid droplet characteristics on in vitro digestibility. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:8085-8092. [PMID: 20557040 DOI: 10.1021/jf101325m] [Citation(s) in RCA: 281] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The pH-stat method is commonly used to characterize the in vitro digestibility of lipids under simulated small intestine conditions. This method measures the fraction of free fatty acids (FFA) released from triacylglycerols over time. A new mathematical model has been developed to characterize the FFA versus time profiles generated by the pH-stat method, which can be used to quantify the influence of physicochemical parameters on the rate (k) and extent (phi(max)) of lipid digestion. In this model, k is the amount of FFA produced per unit time per unit surface area, whereas phi(max) is the maximum fraction of digestible FFAs released. This model is used to quantify the influence of lipid droplet characteristics (size, concentration, composition, and emulsifier type) on the digestion of emulsified lipids. The rate (k) of lipid digestion increased with decreasing lipid content (from 2.5 to 0.5 wt %), increasing droplet diameter (from d = 200-15000 nm), and decreasing fatty acid molecular weight (MCT versus corn oil). The extent (phi(max)) of lipid digestion was also considerably less for corn oil than for MCT. The rate and extent of lipid digestion did not depend strongly on initial emulsifier type: beta-lactoglobulin, Tween 20, lecithin, or lyso-lecithin. These results are interpreted in terms of differences in the concentrations of reactants, products, catalysts and cofactors at the lipid droplet surfaces during digestion, for example, triacylglycerols, emulsifiers, FFA, lipase, and bile salts. This model provides a useful means of quantifying the influence of specific parameters on lipid digestion using the pH-stat method.
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Affiliation(s)
- Yan Li
- Biopolymers and Colloids Research Laboratory, Department of Food Science, University of Massachusetts, Amherst, Massachusetts 01003, USA
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Seimon RV, Lange K, Little TJ, Brennan IM, Pilichiewicz AN, Feltrin KL, Smeets AJ, Horowitz M, Feinle-Bisset C. Pooled-data analysis identifies pyloric pressures and plasma cholecystokinin concentrations as major determinants of acute energy intake in healthy, lean men. Am J Clin Nutr 2010; 92:61-8. [PMID: 20484444 DOI: 10.3945/ajcn.2009.29015] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The interaction of nutrients with the small intestine modulates gastropyloroduodenal motility, stimulates the release of gut hormones, and suppresses appetite and energy intake. OBJECTIVE We evaluated which, if any, of these variables are independent determinants of acute energy intake in healthy, lean men. DESIGN We pooled data from 8 published studies that involved a total of 67 healthy, lean men in whom antropyloroduodenal pressures, gastrointestinal hormones, and perceptions were measured during intraduodenal nutrient or intravenous hormone infusions. In all of the studies, the energy intake at a buffet lunch was quantified immediately after the infusions. To select specific motor, hormone, or perception variables for inclusion in a multivariable mixed-effects model for determination of independent predictors of energy intake, we assessed all variables for collinearity and determined within-subject correlations between energy intake and these variables by using bivariate analyses adjusted for repeated measures. RESULTS Although correlations were shown between energy intake and antropyloroduodenal pressures, plasma hormone concentrations, and gastrointestinal perceptions, only the peak number of isolated pyloric-pressure waves, peak plasma cholecystokinin concentration, and area under the curve of nausea were identified as independent predictors of energy intake (all P < 0.05), so that increases of 1 pressure wave, 1 pmol/L, and 1 mm . min were associated with reductions in energy intake of approximately 36, approximately 88, and approximately 0.4, respectively. CONCLUSION We identified specific changes in gastrointestinal motor and hormone functions (ie, stimulation of pyloric pressures and plasma cholecystokinin) and nausea that are associated with the suppression of acute energy intake.
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Affiliation(s)
- Radhika V Seimon
- University of Adelaide, Discipline of Medicine, Adelaide, South Australia Australia
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van Aken GA. Relating Food Emulsion Structure and Composition to the Way It Is Processed in the Gastrointestinal Tract and Physiological Responses: What Are the Opportunities? FOOD BIOPHYS 2010. [DOI: 10.1007/s11483-010-9160-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Golding M, Wooster TJ. The influence of emulsion structure and stability on lipid digestion. Curr Opin Colloid Interface Sci 2010. [DOI: 10.1016/j.cocis.2009.11.006] [Citation(s) in RCA: 416] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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