Fatty acid bioaccessibility and structural breakdown from in vitro digestion of almond particles.

Previous studies have shown that the size of almond particles influences lipid bioaccessibility during digestion. However, the extent of structural breakdown of almond particles during gastric digestion and its impact on lipid bioaccessibility is unclear. In this study, in vitro digestion of almond particles was conducted using a dynamic model (Human Gastric Simulator) and a static model (shaking water bath). Structural breakdown of particles during the gastric phase occurred only in the Human Gastric Simulator, as evidenced by a reduction in particle size (15.89 ± 0.68 mm2 to 12.19 ± 1.29 mm2, p < 0.05). Fatty acid bioaccessibility at the end of the gastric phase was greater in the Human Gastric Simulator than in the shaking water bath (6.55 ± 0.85% vs. 4.54 ± 0.36%, p < 0.01). Results showed that the in vitro model of digestion which included peristaltic contractions (Human Gastric Simulator) led to breakdown of almond particles during gastric digestion which increased fatty acid bioaccessibility

In vitro digestion of protein-enriched restructured beef steaks with pea protein isolate, rice protein and lentil flour following sous vide processing

peer-reviewedThe effect of plant protein inclusion in cooked meat upon in vitro gastro-intestinal (GI) digestion was investigated. Pea protein isolate, rice protein and lentil flour were used to increase the protein content in a meat model system restructured using two transglutaminase enzymes [Activa®EB (TG) and Transgluseen™-M (TS)]. Restructured beef steaks were subjected to simulated GI digestion using the static INFOGEST method. Samples taken at different digestion times were analysed using SDS-PAGE, size exclusion-HPLC, free amino acid analysis and microscopy. SDS-PAGE analysis revealed significant protein hydrolysis during GI digestion. Most soluble peptides had a molecular weight smaller than 500 Da, corresponding to peptides of <5 amino acids, regardless of food treatment. The amounts of released, free amino acids isoleucine, lysine, phenylalanine and valine were higher (P < 0.05) in lentil-enriched restructured beef steaks following GI digestion. Confocal laser scanning microscopy (CSLM) revealed pronounced aggregation in digested samples. In vitro digestates of protein-enriched restructured beef steaks showed lower production of small molecular weight peptides. This study demonstrated how the bioaccessibility of protein-enriched restructured beef steaks are influenced by formulation and processing

Aryl hydrocarbon receptor activation during in vitro and in vivo digestion of raw and cooked broccoli (brassica oleracea var. Italica)

Broccoli is rich in glucosinolates, which can be converted upon chewing and processing into Aryl hydrocarbon Receptor (AhR) ligands. Activation of AhR plays an important role in overall gut homeostasis but the role of broccoli processing on the generation of AhR ligands is still largely unknown. In this study, the effects of temperature, cooking method (steaming versus boiling), gastric pH and further digestion of broccoli on AhR activation were investigated in vitro and in ileostomy subjects. For the in vitro study, raw, steamed (t = 3 min and t = 6 min) and boiled (t = 3 min and t = 6 min) broccoli were digested in vitro with different gastric pH. In the in vivo ileostomy study, 8 subjects received a broccoli soup or a broccoli soup plus an exogenous myrosinase source. AhR activation was measured in both in vitro and in vivo samples by using HepG2-Lucia™ AhR reporter cells. Cooking broccoli reduced the AhR activation measured after gastric digestion in vitro, but no effect of gastric pH was found. Indole AhR ligands were not detected or detected at very low levels both after intestinal in vitro digestion and in the ileostomy patient samples, which resulted in no AhR activation. This suggests that the evaluation of the relevance of glucosinolates for AhR modulation in the gut cannot prescind from the way broccoli is processed, and that broccoli consumption does not necessarily produce substantial amounts of AhR ligands in the large intestine

Evaluation of Digestibility of Cooked Rice Grain using in vitro Digestion Technique

Impact of postharvest and/or food processing (such as flour milling to agricultural and food-resource materials) on the digestibility of foodstuffs was investigated through a simulated gastro-intestinal in vitro digestion technique. The differences among the starch digestibilities of cooked rice grain and slurry were examined. In vitro digestion techniques are commonly applied to starch-based milled materials such as flours used for bread making. However, rice is not usually milled to flour but cooked as a whole for consumption. Therefore, maintaining an intact structure of cooked grain during in vitro digestion is very important to evaluate its starch digestibility. Two hundred grams of polished rice grain were cooked using electric rice cooker with 300 ml RO water after soaking for 30 min at 30 &deg;C. A part of cooked grain was grinded using a cutter mill to produce cooked rice slurry. The starch hydrolysis of the rice sample was measured and calculated during in vitro digestion process and regarded as sample digestibility (%). Changes in grain tissue structure during in vitro digestion process were also measured and evaluated. The overall digestion percentage at the end of in vitro small intestine digestion for the cooked rice slurry and grain was approximately 94%. However, nearly 65% of cooked rice slurry was digested within 5 min of small intestinal digestion, whereas the cooked rice grain digestibility (%) ranged at 24% at the same time period. These results indicated that the digestion rate of grain was different from the slurry. The kinetic constant of the slurry digestion, which was calculated using curve fitting method and regarded as an estimated digestion rate, was 8 times larger than the grain. To examine the differences in in vitro digestion rate, microstructural changes in the grain during in vitro digestion process were observed using fluorescent microscopic techniques. As a result, the aleurone and the sub-aleurone layers of endosperm appeared as thin-film like materials during in vitro digestion, therefore may be regarded as less digestive materials during the cooked rice grain digestion. These results may be useful in predicting the glucose release and other glycaemic properties of whole grain-based, starch-based slurries and milled starchy foods during human digestion

Brush border digestion : development of a physiologically relevant in vitro model : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physiology at Massey University, Manawatū, New Zealand

Chapter Two has, in part, been published in the Springer publication, Reviews of Physiology, Biochemistry and Pharmacology, but the Author retains the right to publish the material in any collection consisting of the Author's own works: Hooton, D., Lentle, R., Monro, J., Wickham, M., & Simpson, R. (2015). The secretion and action of brush border enzymes in the mammalian small intestine. In: B. Nilius, T. Gudermann, R. Jahn, R. Lill, O. Petersen, & P. de Tombe (Eds.), Reviews of Physiology, Biochemistry and Pharmacology (vol 168, pp. 59-118). Cham: Springer. doi: 10.1007/112_2015_24The majority of current in vitro digestion methods either exclude the small intestinal brush border (BB) phase of digestion or do not incorporate the entire array of BB enzymes that are required to achieve terminal endogenous digestion in vivo. Accordingly, the digestate, and its derivitives, may not be representative of the digestive process in vivo. In order to improve the fidelity of the in vitro digestion process this thesis developed a physiologically relevant small intestinal BB phase using enzymes isolated from rat small intestinal mucosal tissue. The activities of BB enzymes were assessed and compared with known values, and under conditions physiologically representative of the small intestine. Although there were significant differences in BB enzyme activities depending on pH, enzyme solubilisation, and upon prolonged exposure to biliopancreatic secretions the BB preparation was deemed suitable for use in an in vitro digestion method. A rationale for the composition of the BB digestive phase was developed based on published physiological data, and was validated using glycosylated polyphenolic compounds as substrates. Liquid chromatography mass spectrometry (LC-MS) was used to assess the derivatisation products of BB digestion. In the absence of biliopancreatic secretions the onion flesh polyphenolic compounds quercetin-4ʹ-glucoside and isorhamnetin-4ʹ-glucoside, but not quercetin-3-glucoside or quercetin-34ʹ-diglucoside were hydrolysed. The positive control quercetin-3-glucoside was hydrolysed, and the negative control quercetin-3-rutinoside was not hydrolysed. The deglycosylation of quercetin-3-glucoside was monitored under conditions representative of the small intestine, i.e. incorporating bile and pancreatin, while at the appropriate pH. Quercetin-3-glucoside was significantly deglycosylated in BB treatments (no treatment or pancreatin alone) compared to BB treatments with bile (bile alone or pancreatin and bile). The mammalian digestive system is equipped to hydrolyse macronutrients from their polymeric form through to monomers and oligomers suitable for absorption across the epithelial layer. As such the inactivation or degradation of some BB enzymes during the BB digestive phase by bile or pancreatin was not unexpected, and does not preclude its use as an in vitro tool in the future

The in vitro assessment of the bioavailability of iron in New Zealand beef : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Physiology at Massey University, Palmerston North, New Zealand /

The bioavailability of iron in New Zealand beef either alone or as part of a 'typical' New Zealand meal was investigated. The solubility of iron and its in vitro absorption by mouse intestinal tissue were used to evaluate iron bioavailability. The solubility of haem and/or non-haem iron in meat (beef longissimus muscle), vegetables and meat-plus-vegetables was investigated. Samples were cooked and then subjected to in vitro gastrointestinal digestion with pepsin followed by a combination of pancreatic enzymes and bile. Cooking at 65°C for 90 minutes reduced the soluble iron concentration in meat by 81% and reduced the haem iron concentration by 27%, which coincided with a 175% increase in non-haem iron concentrations. However, gastrointestinal digestion increased the solubility of iron in cooked meat (333%), vegetables (367%) and meat-plus-vegetables (167%). A proportion (35%) of the haem iron in the meat was broken down by the action of pancreatic enzymes leading to a 46% increase in non-haem iron concentrations, although this was not the case for the meat-plus-vegetables. Validation studies showed that mouse intestinal segments mounted in Ussing chambers maintained integrity and viability, and were responsive to glucose, theophylline and carbachol. Intestinal tissue from iron deficient mice was then used in the Ussing chambers to investigate the absorption of iron from ferrous gluconate and the soluble fractions of meat, vegetables and meat-plus-vegetables after gastrointestinal digestion. Results indicated a trend towards a higher absorption of iron from meat and ferrous gluconate, compared to vegetables and meat-plus-vegetables. However, iron absorption results were difficult to interpret due to the wide variation in the data. This variation was possibly due to errors associated with the sample processing and the analysis of iron, which was by inductively coupled-mass spectroscopy. Overall, the present study showed that before estimations can be made on the bioavailability of food iron, the effects of the cooking and gastrointestinal digestion processes must be considered. Further, the use of in vitro gastrointestinal digestion followed by the use of Ussing chambers to assess intestinal absorption is a potentially valuable system for assessing mineral bioavailability

Effects of in vitro digestion on the antioxidant activity of three phenolic extracts from olive mill wastewaters

The aim of this study was to assess the impact of in vitro digestion on the antioxidant activity of three extracts rich in phenols (two purified organic extracts (A20, A21) and one powdered extract stabilized with maltodextrins (SP)) obtained from olive mill wastewaters (OMWW). The content and composition of phenols and antioxidant activity was determined before and after in vitro digestion. The phenol content of the A20 and A21 samples were higher (&gt;75%) than that of the SP sample before in vitro digestion. After the entire in vitro digestion, 89.3, 76.9, and 50% loss of phenols was found in A20, A21 and SP, respectively. ABTS•+ and ORAC values decreased during in vitro digestion of A20 and A21 samples, while they remained almost constant in SP. IC50 increased during digestion of A20 and A21, evidencing a loss of antioxidant capacity after the intestinal phase; an opposite IC50 trend was noted in SP, confirming the protective role of maltodextrins. For these reasons, SP represents a promising formulation to be used in the food field

Characterisation of food fibres and their effect on starch digestion in an in-vitro system at physiological shear rates : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Anatomy and Physiology at Massey University, New Zealand

Material removed from thesis for copyright reasons: Appendix 5 - Hardacre, A.K., Yap, S-Y., Lentle, R.G., Janssen, P.W.M., & Monro, J.A. (2014). The partitioning of water in aggregates of undigested and digested dietary particles, Food Chemistry, 142, 446-454. https://doi.org/10.1016/j.foodchem.2013.07.063 Appendix 6 - Hardacre, A.K., Yap, S-Y., Lentle, R.G., & Monro, J.A. (2015). The effect of fibre and gelatinised starch type on amylolysis and apparent viscosity during in vitro digestion at a physiological shear rate, Carbohydrate Polymers, 123, 80-88. https://doi.org/10.1016/j.carbpol.2015.01.013 Appendix 7 - Hardacre, A.K., Lentle, R.G., Yap, S-Y., & Monro, J.A. (2016). Does viscosity or structure govern the rate at which starch granules are digested? Carbohydrate Polymers, 136, 667-675. https://doi.org/10.1016/j.carbpol.2015.08.060The fast pace of life promotes the excessive consumption of processed starchy food containing high levels of sugar, salt and oil; which can increase the prevalence of type II diabetes, colon and cardiovascular diseases. The addition of dietary fibres in the diet increases the viscosity of digesta, delays mixing in the gut, and promotes laxation. However, few studies attempt to quantify the possible physical and chemical effects of either soluble (food gums) and insoluble (largely cellulose) fibre in the diet. These effects may encompass the retention of water inside the fibre particles, between particles in the fibre mass and direct effects of the chemical nature of the fibre on the digestion process. In this study, the fractions of water held in the various partitions of insoluble particulate dietary fibres are quantified. The relationship between the volume fraction of soluble and insoluble dietary fibres in simulated digesta at physiological concentrations and the rheological properties of the suspension at physiological shear rates is determined. Furthermore, the impact of fibre and shear rates on the digestion of starch in-vitro at physiological shear rates was measured. This work provides the first quantitative assessment of the effects of the physical attributes of dietary fibre on the digestion of starch in-vitro, at physiological shear rates. In this work, four insoluble fibre types were used to construct aqueous suspensions containing solid volume fractions similar to those of pig digesta from the small intestine; these suspensions also were shown to have similar rheological properties to those of pig digesta at physiological shear rates. In addition, a soluble fibre (Guar gum) was used to construct solutions with viscosities comparable to those of the particulate suspensions. Gelatinised and partially gelatinised starch was added to these suspensions and its rate of digestion at 37°C under simulated small intestinal conditions was measured at shear rates covering the reported physiological range. Important results from this work include: - The proportion of water retained by a given volume of hydrated mass of large fibre particles (AllBran®) was double that of smaller particles (wheat fibre). For all of the solid particles used, the proportion of water sequestered by the intra-particulate voids was less than 4% of the volume of the particles, similar proportions were determined for indigestible particles recovered from the colon of pigs and from human faeces. - Food fibre systems containing less than 20% by volume (solid volume fraction, φ = 0.20) of insoluble dietary fibres showed Newtonian rheological properties and the viscosity of these suspensions could be predicted from φ by the Maron-Pierce model. Starch/fibre suspensions prepared with φ below 20% (φ = 0.68-0.98) had a similar viscosity to that of starch/guar suspension comprising 10% (w/v) starch and 0.4% (w/v) guar. During in-vitro digestion, the viscosity of the starch/fibre suspensions decreased logarithmically over the first 20 minutes during which about 30% of the starch was hydrolysed, this was followed by a prolonged period of slow digestion as the slowly digested starch (SDS) and resistant starch (RS) were hydrolysed. The rate of starch digestion was independent of the type of insoluble fibre and was not affected by suspension viscosities used providing shear rates could be maintained within physiological levels. For guar, rates of digestion were slowed probably due to non-competitive inhibition of the amylase by the guar. - When shear rates were below the physiological range (0.1 s-1) or gelatinisation was incomplete, the rate of digestion became linear over the first 20 minutes of digestion suggesting that the rate of digestion was limited by transport processes at low shear in viscous suspensions. - This study provides useful information regarding the limiting concentration of particles and hence viscosity of digesta in the gut if rates of digestion are to be maximised. Additionally, it is suggested that guar, even at low concentration may reduce glycemia by reducing rates of amylolysis

Development of a realistic in vitro digestion model (RGM) coupled UV-VIS-SWNIR fibre optics spectroscopy

Background: The development of realistic gastric models unlocked the possibility of studying important digestion phenomena occurring during the digestion of food (e.g., retropulsion). Understanding the dynamics of food digestion in real-time, without sample manipulation, is still a challenge, but brings a huge potential in providing important insights regarding the dynamic process of food digestion (e.g., real time nutrient release kinetics) This study presents a realistic 3D printed in vitro gastric model coupled with ultraviolet-visibleshort- wave-near-infrared (UV-VIS-SWNIR) spectroscope that can be used for real time quantification of nutrients/bioactive compounds. Methods: The INFOGEST semi-dynamic in vitro protocol was used to simulate the digestion of rice (model food). The spectroscope was calibrated for glucose analysis, and the spectra were pre-processed and both chemometric and machine learning techniques were used for glucose quantification using the correlation coefficient as assessment metric. Results: The machine learning algorithms showed to be more accurate at predicting glucose release during the in vitro gastric digestion. Conclusions: The gastric compartment development techniques provide the opportunity to develop a potential standard dynamic in vitro gastric model. Furthermore, it was possible to accurately measure and quantify glucose release during the in vitro digestion process, in real time, using UV-VIS-SWNIR fibre optics spectroscopic.info:eu-repo/semantics/publishedVersio

Application of in vitro human digestion models in the field of nutrition science

Simulating digestion that takes place in the gastrointestinal tract is a widely used pro-cedure in various fields of food and nutrition science, as well as in the pharmaceuti-cal industry, as it is less costly and labor-intensive in human clinical trials and animal experiments, while not raising ethical issues either. The process of digestion converts nutrients and bioactive compounds in foods into physiologically active compounds. In vitro digestion models have been proved to be effective tools for the complete understanding and observation of the complex transformation processes that occur during digestion. Of course, in vitro studies cannot be substitutes for in vivo experiments, but they play a key role in the pre-screening, ranking and classification of samples before in vivo studies. In this article, we show why in vitro digestion models are important, how and in what systems they can be used. Several in vitro digestion models have been developed in static, dynamic and semidynamic forms. In this summary, we present the unified static model developed within the framework of the COST INFOGEST program, a unified, convention-based protocol for in vitro digestion of food samples prepared with the involvement of more than 200 researchers from 32 countries. The application of the unified model allowed the comparison of the results of different research groups