Interaction between Chitosan and Oil under Stomach and Duodenal Digestive Chemical Conditions (original) (raw)
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Effect of chitosan on oil in water emulsions
Chitosan is a cationic biopolymer that has been used extensively in dietary supplements to reduce fat absorption in the fight against obesity. The mechanism of fat binding of chitosan is still not fully understood and has been the subject of controversy. This study was designed to improve the understanding of the underlying mechanism by investigating the interaction of chitosan with oil-in-water emulsion droplets. Our results indicated that (0.1% w/w) chitosan adsorbed to a 20% w/w phosphatidylcholine-stabilized anionic primary emulsion to form a secondary cationic emulsion by electrostatic attraction forces under conditions resembling the stomach (pH 2). Bile salts (6 mM) were added to simulate secretion in the small intestine and pH increase. Bile salts adsorbed to the chitosan secondary emulsion, which resulted in aggregation of oil droplets followed by coalescence due to close packing of droplets. Increased viscosity (267-2531 cp) and increased degree of deacetylation (40-92% DDA) of chitosan enhanced emulsion breakdown. Increasing the pH to 7.5 without addition of bile salts yielded little aggregation. Pronounced aggregation is thought to decrease the accessibility of lipase to the oil resulting in lower bioavailability and reduced caloric intake. Understanding how chitosan interacts with oil droplets in the digestive tract is vital to developing a comprehensive model of the influence of chitosan on the bioavailability of dietary lipids. The information gained in this study may be useful for the interpretation and experimental design of animal and human feeding studies and for the rational design of chitosan-based functional foods for fat reduction.
LWT - Food Science and Technology, 2016
The correlation of physical and physicochemical characteristics of five different chitosan on their fatbinding capacities was studied using in vitro model of gastrointestinal conditions. Increasing molecular weight (Mw) and tap density of chitosan could significantly increase their fat-binding ability. Higher Mw chitosan (2100 and 890 kDa) show significantly higher fat binding capacity than 30 kDa. When tested at chitosan to fat 1:40, the ratio often used as dietary supplement, higher tap density chitosan showed an improved fat-binding capacity at around 2-fold increase. Interestingly, 2100 kDa high density (HD1P) could maintain the highest oil entrapment, ranging between 0.77 and 27.50 g oil/g chitosan depending on the interaction ratios. In addition, HD1P already maximized its fat-binding capacity since 30 min under in vitro gastric condition. In vitro cholesterol-and bile acids-binding experiments were also performed with HD1P and found to bind cholesterol at 820.9 ± 21.43 mg/g chitosan, deoxycholic acid at 17.50 ± 0.18 mg/g chitosan, and cholic acid at 5.28 ± 0.57 mg/g chitosan. Therefore, this study shows that the ability of HD1P for binding high amount of fat at short dissolution time might be due to the combination characteristics of having high Mw and being in a high density form.
Influence of lipid type on gastrointestinal fate of oil-in-water emulsions: In vitro digestion study
Food Research International, 2015
The potential gastrointestinal fate of oil-in-water emulsions containing lipid phases from different sources was examined: vegetable oils (corn, olive, sunflower, and canola oil); marine oils (fish and krill oil); flavor oils (orange and lemon oil); and, medium chain triglycerides (MCT). The lowest rates and extents of lipid digestion were observed for emulsified flavor oil, followed by emulsified krill oil. There was no appreciable difference between the final amounts of free fatty acids released for emulsified digestible oils. Differences in the digestibility of emulsions prepared using different oils were attributed to differences in their compositions, e.g., fatty acid chain length and unsaturation. The particle size distribution, particle charge, microstructure, and macroscopic appearance of the emulsions during passage through the simulated GIT depended on oil type. The results of this study may facilitate the design of functional foods that control the digestion and absorption of triglycerides, as well as the bioaccessibility of hydrophobic bioactives.
Food Chemistry, 2015
Recent studies have shown that it should be possible to control lipid bioavailability through food structural approaches. Nevertheless, the gastrointestinal-tract physiological conditions must also be considered. To get a better understanding of this phenomenon, we evaluated the effect of emulsification, as well as the use of sodium caseinate or chitosan, on the postprandial bioavailability of interesterifiedlipids in O/W emulsions after oral gastric feeding Sprague-Dawley rats. We verified that emulsification may increase lipid absorption, as determined after feeding sodium-caseinate emulsions. However, this result could not be generalised. Interesterified-lipids that were emulsified with chitosan were equally absorbed as those contained in non-emulsified interesterified-lipids/distilled-water blends.
Carbohydrate Polymers, 2000
Chitin, chitosan and the newly synthesized and fully characterized N-lauryl chitosan and N-dimethylaminopropyl chitosan, endowed with higher hydrophobicity and cationicity, respectively, were tested for their capacity to alter the composition of olive oil upon percolation of the latter through a bed of their respective powders. The oil samples were extracted, saponi®ed and submitted to gas-chromatography. Results indicated that the percentages of 12 fatty acids were not modi®ed, but the diacylglycerol and steroid concentrations were greatly altered. The percolated oil was depleted of C34 and C36 diacylglycerols (lowered to 42% of the control) when the oil was contacted with chitosan and N-lauryl chitosan, whilst the oil fraction percolated through chitin became 30% enriched. N-Dimethylaminopropyl chitosan was also effective in retaining diacylglycerols. The direct analysis of the unsaponi®able fraction revealed that campesterol, stigmasterol and avenasterol were enriched in the oil fraction retained by chitin and N-lauryl chitosan, while b-sitosterol increased slightly in the fraction retained by chitosan and N-lauryl chitosan. Triterpene alcohols were higher in the oil fraction retained by chitin. This work indicates that chitin might be more suitable than chitosan for sequestering steroids, and that, in general, the chitin derivatives discriminate among the various lipids.
Food Chemistry, 2012
Chitosan, a deacetylated form of chitin, is a dietary fibre known for its hypolipidemic properties, which are mainly attributed to its unique cationic characteristics. We studied the selective in vivo effect of chitosan on fat excretion in order to elucidate its hypolipidemic mechanism. A 4-week longitudinal study was conducted in guinea pigs and the effect of chitosan on fat-absorption was compared to that of a soluble fibre: digestion-resistant maltodextrin. Animals were fed with high-fat isocaloric diets containing 12/ 100 g of cellulose, digestion-resistant maltodextrin or chitosan. Subsequently, the excretion of fatty acids, neutral sterols and bile acids was determined. Chitosan selectively reduced fat absorption in comparison to digestion-resistant maltodextrin. The excretion of lauric, myristic and palmitic fatty acids of animals fed with chitosan was more than 10-, 5-and 2-fold higher, respectively, than in the cellulose group, whereas stearic acid excretion was not significantly altered. Oleic, linoleic and a-linolenic acid excretion were also significantly higher (P < 0.001). The nÀ6/nÀ3 ratio in faeces of the chitosan group was 23.68, compared to 13.95 in the cellulose group. Total neutral sterol excretion was increased by both dietary fibres, whereas bile acid excretion was only increased by chitosan. Nevertheless, chitosan inhibited the intestinal bioconversion of cholesterol and primary bile acids to secondary metabolites. Hence, these results reveal that chitosan and digestion resistant maltodextrin exert their hypolipidemic activity by different mechanisms.
The Effect of Physicochemical Factors on Adsorption Properties of Chitosans in Vitro Model
2008
Numerous natural macromolecular compounds, the action of which is to support weight reduction, are used in the clinical treatment of obesity. These compounds swell in the digestive tract and form a polymer gel, which is able to adsorb 5 times more lipids in relation to its mass. The task of bile acids present in the digestive tract is to emulsify lipids and provide an extensive digestive surface for pancreatic juice lipase.
Structuring food emulsions in the gastrointestinal tract to modify lipid digestion
Progress in lipid research, 2009
The importance of nutrient lipids in the human diet has led to major advances in understanding the mechanisms of lipid digestion and absorption. With these advances has come new recognition that the matrix in which lipids are presented (i.e. food structure) in the diet could influence the rate of lipid digestion and hence the bioavailability of fatty acids. As a consequence, there is growing interest in understanding how food material properties can be manipulated under physiological conditions to control the uptake of lipids and lipid-soluble components. The lipids in many, if not most, processed foods are normally present as emulsions, which can be end products in themselves or part of a more complex food system. In this review, we discuss the formation and properties of oil-in-water (O/W) emulsions, especially how these emulsions are modified as they traverse through the gastrointestinal tract. Among other factors, the changes in the nature of the droplet adsorbed layer and the d...
International Journal of Pharmaceutics, 1999
A new positively charged, submicronized fat emulsion with appropriate stability during the autoclaving process was developed. Only the emulsions prepared with a combination of ABA block co-polymer (F68) and chitosan were stable enough to resist the thermic shock induced by autoclaving sterilization. The results indicate that a mixed film consisting of the ABA block co-polymer and chitosan molecules was formed at the o/w interface with an overall positive surface charge. Conversely, a combination between chitosan with phospholipids and/or with a mixture of phospholipids with ABA block co-polymer showed a phase separation during autoclaving. A chitosan type with a low viscosity was used which was intended for a possible use in the ocular and parenteral application. An experimental factorial design 3 2 was used to investigate the effect of chitosan and F68 concentrations on the physicochemical properties of the system and consequently their influence on the stability of emulsions during autoclaving. Both size and surface charge of emulsions were significantly affected as a function of the chitosan concentration. Formulation with a mean particle size ranging from 125 to 130 nm and with a positive surface charge of 20-23 mV was achieved. Moreover, the chitosan emulsions were autoclaved without a significant change in their particle size. However, increasing the concentration of chitosan needs a higher amount of F68 in order to achieve stable emulsions during autoclaving. This may be due to the interaction between the positively-charged chitosan and the negatively-charged free fatty acids, which are contained in the oil phase (castor oil).
Digestion behaviour of chia seed oil encapsulated in chia seed protein-gum complex coacervates
Spray dried chia seed oil (CSO) microcapsules were prepared by using chia seed protein isolate (CPI), chia seed gum (CSG) and CPI-CSG complex coacervate as shell materials. Release and digestion behaviours of CSO from above capsules were studied. The release and lipolysis of CSO from these microcapsules in simulated oral, gastric and intestinal conditions were found to depend on shell composition. Oil release was negligible in oral stage, was highest in gastric stage due to hydrolysis of CPI and subsequent erosion of shell structure. Lipolysis of oil occurred only in the intestinal stage due to the presence of pancreatic lipase. Almost all the unencapsulated oil was hydrolysed, whereas only 60% of the oil encapsulated in CPI-CSG shell was hydrolysed during in vitro digestion. Thus, CPI-CSG complex coacervate was found to be suitable for delivery of CSO to intestinal stage of digestion.