Pectin influences the kinetics of in vitro lipid digestion in oil-in-water emulsions

Comparative Evaluation of Micellization and Cellular Uptake of β-Carotene Affected by Flavonoids

Based on in vitro digestion, micellar synthesis, and Caco-2 cell model, this study investigated the effects of typical flavonoids in citrus (naringenin, naringin, hesperetin, hesperidin, quercetin, and rutin) at different doses on the micellization and cellular uptake of β-carotene. In in vitro digestion, low-dose flavonoids enhanced β-carotene bioaccesssibility by regulating the stability and dispersibility of the intestinal medium, particularly quercetin, which significantly increased the bioaccessibility by 44.6% (p < 0.05). Furthermore, naringenin, hesperetin, hesperidin, and quercetin enhanced the micellar incorporation rate of β-carotene; however, naringin and rutin exhibited an opposite effect, particularly naringin, which significantly reduced it by 71.3% (p < 0.05). This phenomenon could be attributed to the high solubility of naringin and rutin in micelles, resulting in a competitive inhibitory effect on β-carotene. Besides, all treatments significantly enhanced β-carotene cellular uptake (p < 0.05) by promoting the expression of scavenger receptor class B type I and Niemann-Pick C1-Like 1.

Enhancing the nutritional and bioactive benefits of faba bean flour by combining preprocessing and thermoplastic extrusion: A comprehensive study on digestion-resistant peptides

This research assessed how three preprocessing techniques [soaking (S), soaking and reconstitution (SR), and soaking and dehulling (SD)] impact the protein digestibility and bioactivity of faba bean flours when combined with thermoplastic extrusion. Samples were compared against a control (C) of extruded faba bean flour without preprocessing. Applying preprocessing techniques followed by extrusion diminished antinutrient levels while enhancing protein hydrolysis and in vitro bioactivity in higher extent compared to C. Specifically, SD combined with extrusion was the most effective, achieving an 80% rate of protein hydrolysis and uniquely promoting the release of gastric digestion-resistant proteins (50-70 kDa). It also resulted in the highest release of small peptides (<3kDa, 22.51%) and free amino acids (15.50%) during intestinal digestion. Moreover, while all preprocessing techniques increased antioxidant (ABTS radical-scavenging), antidiabetic, and anti-hypertensive activities, SD extruded flour displayed the highest levels of dipeptidyl peptidase inhibition (DPP-IVi, IC50=13.20 µg/mL), pancreatic α-amylase inhibition (IC50=8.59 mg/mL), and angiotensin I-converting enzyme inhibition (ACEi, IC50=1.71 mg protein/mL). As a result, it was selected for further peptide and in silico bioactive analysis. A total of 24 bioactive peptides were identified in intestinal digests from SD extruded flour, all with potential DPP-IVi and ACEi activities, and six were also predicted as antioxidant peptides. VIPAGYPVAIK and GLTETWNPNHPEL were highlighted as resistant bioactive peptides with the highest antidiabetic and antioxidant potential. Our findings demonstrated that combining preprocessing (particularly SD) and thermoplastic extrusion enhances protein digestibility in faba beans and promotes the release of beneficial bioactive peptides in the intestine.

Effect of wheat aleurone on lard emulsions during in vitro digestion

Dietary wheat aleurone has been shown to affect lipid metabolism and reduce the incidence of obesity. However, the underlying mechanisms are not fully understood. This work aimed to investigate how whole wheat aleurone affects lipolysis during the whole digestion process in vitro. The physicochemical and microstructural changes and the lipolysis kinetics of different lard emulsion mixtures were determined. The results showed that the lipolysis rate and degree are inversely proportional to the amount of wheat aleurone. Wheat aleurone and flour promoted the aggregation and flocculation of lipid droplets by increasing the viscosity. More importantly, the dietary fibers released from aleurone digestion can reduced the binding of lipase to lipid droplets by adsorbing lipid droplets to increase the steric hindrance effect. These results provide a better understanding of how whole grains affect lipid digestibility and will further contribute to the development of functional foods and the improvement of individual health.

Excipient emulsion prepared with pectin and sodium caseinate to improve the bioaccessibility of carotenoids in mandarin juice: The effect of emulsifier and polymer concentration

Excipient emulsions were prepared using different emulsifiers (pectin and sodium caseinate, individually or compositely) to study the emulsifying properties and their co-digested effects on the retention and bioaccessibility of carotenoids in mandarin juice, which is a good source of carotenoids in people's diet. Results showed that both pectin (PC) and pectin-sodium caseinate (PC-SC) emulsion significantly increased the carotenoids retention and bioaccessibility of mandarin juice, with the effects depending on both emulsifiers and polymer concentration. Whether for PC or PC-SC emulsion, lower pectin content accompanied with lower viscosity showed higher carotenoids bioaccessibility. And for the complexed emulsions, appropriate sodium caseinate addition could be more beneficial in improving carotenoids bioaccessibility. It had been found that the viscosity comparing with particle size seemed to play a more important role in affecting carotenoid bioaccessibility during the co-digestion. This study could provide a basis for improving the carotenoids bioaccessibility in the real system of fruits and vegetables with excipient emulsions.

A critical review of RG-I pectin: sources, extraction methods, structure, and applications

In recent years, RG-I pectin isolated by low-temperature alkaline extraction methods has attracted the attention of a large number of researchers due to its huge health benefits. However, studies on other applications of RG-I pectin are still lacking. In this study, we summarized the sources (e.g. potato pulp, sugar beet pulp, okra, apple pomace, citrus peel, pumpkin, grapefruit, ginseng, etc.), extraction methods, fine structure and applications of RG-I pectin in physiological activities (e.g. anti-cancer, anti-inflammatory, anti-obesity, anti-oxidation, immune regulation, prebiotics, etc.), emulsions, gels, etc. These neutral sugar side chains not only endow RG-I pectin with various physiological activities but the entanglement and cross-linking of these side chains also endow RG-I pectin with excellent emulsifying and gelling properties. We believe that this review can not only provide a comprehensive reading for new workers interested in RG-I pectin, but also provide a valuable reference for future research directions of RG-I pectin.

Food nanoemulsions: how simulated gastrointestinal digestion models, nanoemulsion, and food matrix properties affect bioaccessibility of encapsulated bioactive compounds

Food nanoemulsions are known as very effective and excellent carriers for both lipophilic and hydrophilic bioactive compounds (BCs) and have been successfully used for controlled delivery and protection of BCs during gastrointestinal digestion (GID). However, due to sensitive and fragile morphology, BCs-loaded nanoemulsions have different digestion pathways depending on their properties, food matrix properties, and applied models for testing their digestibility and BCs bioaccessibility. Thus, this review gives a critical review of the behavior of encapsulated BCs into food nanoemulsions during each phase of GID in different static and dynamic in vitro digestion models, as well as of the influence of nanoemulsion and food matrix properties on BCs bioaccessibility. In the last section, the toxicity and safety of BCs-loaded nanoemulsions evaluated on in vitro and in vivo GID models have also been discussed. Better knowledge of food nanoemulsions' behavior in different models of simulated GI conditions and within different nanoemulsion and food matrix types can help to standardize the protocol for their testing aiming for researchers to compare results and design BCs-loaded nanoemulsions with better performance and higher targeted BCs bioaccessibility.

Emulsion-Based Delivery Systems to Enhance the Functionality of Bioactive Compounds: Towards the Use of Ingredients from Natural, Sustainable Sources

In recent years, the trend in the population towards consuming more natural and sustainable foods has increased significantly. This claim has led to the search for new sources of bioactive compounds and extraction methods that have less impact on the environment. Moreover, the formulation of systems to protect these compounds is also focusing on the use of ingredients of natural origin. This article reviews novel, natural alternative sources of bioactive compounds with a positive impact on sustainability. In addition, it also contains information on the most recent studies based on the use of natural (especially from plants) emulsifiers in the design of emulsion-based delivery systems to protect bioactive compounds. The properties of these natural-based emulsion-delivery systems, as well as their functionality, including in vitro and in vivo studies, are also discussed. This review provides relevant information on the latest advances in the development of emulsion delivery systems based on ingredients from sustainable natural sources.

Enhancing the Gastrointestinal Stability of Curcumin by Using Sodium Alginate-Based Nanoemulsions Containing Natural Emulsifiers

Curcumin presents interesting biological activities but low chemical stability, so it has been incorporated into different emulsion-based systems in order to increase its bioaccessibility. Many strategies are being investigated to increase the stability of these systems. Among them, the use of polysaccharides has been seen to highly improve the emulsion stability but also to modulate their digestibility and the release of the encapsulated compounds. However, the effect of these polysaccharides on nanoemulsions depends on the presence of other components. Then, this work aimed to study the effect of alginate addition at different concentrations (0-1.5%) on the gastrointestinal fate and stability of curcumin-loaded nanoemulsions formulated using soybean lecithin or whey protein as emulsifiers. Results showed that, in the absence of polysaccharides, whey protein was more effective than lecithin in preventing curcumin degradation during digestion and its use also provided greater lipid digestibility and higher curcumin bioaccessibility. The addition of alginate, especially at ≥1%, greatly prevented curcumin degradation during digestion up to 23% and improved the stability of nanoemulsions over time. However, it reduced lipid digestibility and curcumin bioaccessibility. Our results provide relevant information on the use of alginate on different emulsifier-based nanoemulsions to act as carriers of curcumin.

Review of phytochemical and nutritional characteristics and food applications of Citrus L. fruits

Since the dietary regimen rich in fruits is being widely recognized and encouraged, Citrus L. fruits have been growing in popularity worldwide due to their high amounts of health-promoting phytonutrients and bioactive compounds, such as flavonoids, phenolic acids, vitamins, carotenoids, pectins, and fatty acids. The diverse physicochemical properties and multiple utilization of citrus fruits in food industry are associated with their unique chemical compositions. Throughout the world, citrus has been used for producing various value-added and nutritionally enhanced products, including juices, wines, jams, canned citrus, and dried citrus. However, the current studies regarding the phytochemical and nutritional characteristics and food applications of citrus are scattered. This review systematically summarizes the existing bibliography on the chemical characteristics, functional and nutraceutical benefits, processing, and potential applications of citrus. A thorough understanding of this information may provide scientific guidance for better utilizing citrus as a functional fruit and benefit the extension of citrus value chain.

Compositional, Structural, and Kinetic Aspects of Lipid Digestion and Bioavailability: In Vitro, In Vivo, and Modeling Approaches

Lipid digestion and bioavailability are usually investigated separately, using different approaches (in vitro, modeling, in vivo). However, a few inclusive studies show that their kinetics are closely linked. Lipid bioavailability kinetics is likely involved in the development and evolution of several diseases, so lipid digestion kinetics could be involved as well and can be modulated by food design or combination. To illustrate this possibility, the compositional and structural aspects of lipid digestion kinetics, as investigated using in vitro and modeling approaches, are presented first. Then, in vivo and mixed approaches enabling the study of both kinetics are reviewed and discussed. Finally, disparate modeling approaches are introduced, and a unifying modeling scheme is proposed, opening new perspectives for understanding the role and interactions of various factors (chemical, physical, and biological) involved in lipid metabolism.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Effect of high pressure homogenization on water-soluble pectin characteristics and bioaccessibility of carotenoids in mixed juice

The effect of high pressure homogenization (HPH) compared with simple blending and milling on mixed juice properties, including water-soluble pectin (WSP) characteristics and total carotenoid bioaccessibility (TCB) was investigated. Overall, HPH treatments, which comprised of varied pressures, passes and inlet temperature (IT) affected WSP characteristics. Increased pressure showed decreased molecular weight (M_w), galacturonic acid (GalA) content and branching, and enhanced degree of methylesterification (DM) and chain linearity, suggesting degradation of RG-I fragments. Two passes at 140 MPa enhanced GalA content, nevertheless it reduced DM, implying rearrangement of depolymerized fractions. Besides, elevated IT combined with high pressure increased GalA content and DM signifying thermo-solubilization of certain HG-rich pectin. Notably, the TCB was enhanced by higher pressure and elevated temperature, which had positive relationship with DM and chain linearity of WSP and negative correlations with GalA content and M_w. Results highlighted the potential of HPH to improve WSP characteristics to enhance TCB.

Physiological fluid interfaces: Functional microenvironments, drug delivery targets, and first line of defense

Fluid interfaces, i.e. the boundary layer of two liquids or a liquid and a gas, play a vital role in physiological processes as diverse as visual perception, oral health and taste, lipid metabolism, and pulmonary breathing. These fluid interfaces exhibit a complex composition, structure, and rheology tailored to their individual physiological functions. Advances in interfacial thin film techniques have facilitated the analysis of such complex interfaces under physiologically relevant conditions. This allowed new insights on the origin of their physiological functionality, how deviations may cause disease, and has revealed new therapy strategies. Furthermore, the interactions of physiological fluid interfaces with exogenous substances is crucial for understanding certain disorders and exploiting drug delivery routes to or across fluid interfaces. Here, we provide an overview on fluid interfaces with physiological relevance, namely tear films, interfacial aspects of saliva, lipid droplet digestion and storage in the cell, and the functioning of lung surfactant. We elucidate their structure-function relationship, discuss diseases associated with interfacial composition, and describe therapies and drug delivery approaches targeted at fluid interfaces. STATEMENT OF SIGNIFICANCE: Fluid interfaces are inherent to all living organisms and play a vital role in various physiological processes. Examples are the eye tear film, saliva, lipid digestion & storage in cells, and pulmonary breathing. These fluid interfaces exhibit complex interfacial compositions and structures to meet their specific physiological function. We provide an overview on physiological fluid interfaces with a focus on interfacial phenomena. We elucidate their structure-function relationship, discuss diseases associated with interfacial composition, and describe novel therapies and drug delivery approaches targeted at fluid interfaces. This sets the scene for ocular, oral, or pulmonary surface engineering and drug delivery approaches.

Kinetic Modeling of In Vitro Small Intestinal Lipid Digestion as Affected by the Emulsion Interfacial Composition and Gastric Prelipolysis

This research evaluated the impact of the emulsion interfacial composition on in vitro small intestinal lipolysis kinetics with the inclusion of rabbit gastric lipase resulting in a gastric prelipolysis step. O/w emulsions contained 5% triolein (w/w) and 1% (w/w) of the following emulsifiers: sodium taurodeoxycholate, citrus pectin, soy protein isolate, soy lecithin, and tween 80. Emulsions were subjected to static in vitro digestion and diverse lipolysis species quantified via a HPLC-charged aerosol detector. Single-response modeling indicated that the kinetics of lipolysis in the small intestinal phase were impacted by the emulsion particle size at the beginning of this phase. Multiresponse modeling permitted the elucidation of the lipolysis mechanism under in vitro conditions. The final reaction scheme included enzymatic and chemical conversions. The modeling strategies used in this research allowed to gain more insights into the kinetics and mechanism of in vitro lipid digestion.

Biopolymer Additives Enhance Tangeretin Bioavailability in Emulsion-Based Delivery Systems: An In Vitro and In Vivo Study

The oral bioavailability of tangeretin, a poly(methoxyflavone) found in citrus fruits, is typically very low because of its extremely limited solubility. In this research, tangeretin was encapsulated within whey protein-stabilized emulsions containing ingredients that may alter their behavior under gastrointestinal conditions and enhance the bioavailability of tangeretin after oral administration: cinnamaldehyde (CA), gum arabic (GA), or hydroxypropyl methylcellulose (HPMC). The presence of these ingredients altered the size, aggregation state, and encapsulation efficiency of tangeretin in the emulsions. In vitro studies demonstrated that the bioaccessibility of the encapsulated tangeretin was much higher than that of a crude tangeretin oil suspension. Particularly, the addition of HPMC increased the bioaccessibility of tangeretin from around 36 to 90%. In vivo pharmacokinetics results using rats indicated that tangeretin concentration in the plasma increased from 4- to 20-fold after encapsulation, especially in the presence of HPMC. HPMC also prolonged the release of tangeretin to 22 h. Tangeretin preferentially accumulated within the liver and kidney of the animals. Overall, the knowledge confirmed that structured emulsion-based delivery systems could be used to improve the oral bioavailability of hydrophobic functional ingredients.

Impact of Pleurotus ostreatus β-Glucans on Oxidative Stability of Active Compounds Encapsulated in Powders during Storage and In Vitro Digestion

Polyunsaturated fatty acids and α-tocopherol were encapsulated in powders by spray drying using maltodextrins DE 12 as wall material and different emulsifiers (Tween®20, acacia gum or β-glucans-rich extracts from Pleurotus ostreatus). The aim was to study the effects of the surfactants on: (a) the oil droplet size distribution and α-tocopherol stability during in vitro digestion, and (b) the oxidative stability during 15 days of accelerated storage. Acacia gum sample had the most stable particle size distribution up to the gastric phase, but showed a significant α-tocopherol degradation prior to the intestinal stage. On the contrary, β-glucan-samples displayed a bimodal distribution in the oral and gastric phases but retained α-tocopherol up to the beginning of the intestinal stage. At the end of intestinal stage, no α-tocopherol was found in the samples. The storage study showed that β-glucans improved the oxidative stability of the powders, which displayed 82% α-tocopherol retention after 5 days under accelerated conditions (60 °C), corresponding to 310 days at 20 °C, while acacia gum and Tween® 20 did not delay α-tocopherol degradation. Results highlight the potential antioxidant activity of β-glucans used as emulsifying agents during in vitro digestion and accelerated aging conditions.

Evaluation of processing methods and oral mastication on the carotenoid bioaccessibility of restructured carrot chips

BACKGROUND

Carrot carotenoids are typically located in chromoplasts, forming a crystalline substructure. Cell walls and chromoplasts therefore constitute two major physical barriers to the release of carotenoids from the food matrix during digestion. The release of carotenoids from these physical barriers is supposed to be substantially affected by mechanical factors during food processing and oral mastication. Given the implications of this, the effects of four different processing procedures, and various mastication levels, on the carotenoid bioaccessibility of carrot chips were evaluated.

RESULTS

Restructuring and drying methods substantially affected the carotenoid bioaccessibility of carrot chips. The highest carotenoid bioaccessibility was obtained for the air-dried combined with instant pressure-drop-dried (AD-DIC) restructured chips. Although the fresh carrots possessed the highest carotenoid content, their bioaccessibility was lower than that of the carrot chips. The evolution of the particle sizes of the samples was responsible for the changes in carotenoid bioaccessibility due to oral masitication. The particle size of the fresh carrots decreased with increasing oral masitication, which favored carotenoid bioaccessibilty. However, the restructured chips that combined freeze drying with instant pressure-drop drying (R-FD-DIC) demonstrated the opposite trend, probably caused by the severe aggregation of the sample during digestion, which compromised the effect of mastication on the release of carotenoid.

CONCLUSION

Data regarding the effects of the drying process and oral mastication digestion behavior on the samples suggested that AD-DIC-dried restructured carrot chips are effective in enhancing carotenoid bioaccessibility, which explains the key factors involved in the release of carotenoids from carrot chips prepared by different processes. © 2020 Society of Chemical Industry.

Effect of particle size on the stability and flavor of cloudy apple juice

Different particle sizes in cloudy apple juice were obtained following filtration with different mesh sizes (100, 200, 300, and 400-mesh). The effects of cloud particle size on the stability, nutrient content, and volatile flavor of cloudy apple juice were evaluated. With increasing mesh number, particle size decreased (p < 0.05) and particle shape changed. Particle size had an effect on volatile flavor compounds, especially nitrogen oxides, alcohols, and aromatic compounds. The content of pectin and total phenol decreased with decreasing particle size, while the content of soluble protein was not affected. The reduction of cloud particle size increased absolute value of ζ-potential, cloud stability, and apparent viscosity and decreased turbidity and cloud values. Pearson correlation analysis showed that there was a strong correlation between particle size and quality indicators, except for soluble protein.

Improving the In Vitro Bioaccessibility of β-Carotene Using Pectin Added Nanoemulsions

The intestinal absorption of lipophilic compounds such as β-carotene has been reported to increase when they are incorporated in emulsion-based delivery systems. Moreover, the reduction of emulsions particle size and the addition of biopolymers in the systems seems to play an important role in the emulsion properties but also in their behavior under gastrointestinal conditions and the absorption of the encapsulated compound in the intestine. Hence, the present study aimed to evaluate the effect of pectin addition (0%, 1%, and 2%) on the physicochemical stability of oil-in-water nanoemulsions containing β-carotene during 35 days at 4 °C, the oil digestibility and the compound bioaccessibility. The results showed that nanoemulsions presented greater stability and lower β-carotene degradation over time in comparison with coarse emulsion, which was further reduced with the addition of pectin. Moreover, nanoemulsions presented a faster digestibility irrespective of the pectin concentration used and a higher β-carotene bioaccessibility as the pectin concentration increased, being the maximum of ≈36% in nanoemulsion with 2% of pectin. These results highlight the potential of adding pectin to β-carotene nanoemulsions to enhance their functionality by efficiently preventing the compound degradation and increasing the in vitro bioaccessibility.

Preparation and Characterization of Emulsion-based Peony Seed Oil Microcapsule

Microcapsules were constructed with starch sodium octenyl succinate (SSOS), β-cyclodextrin (β-CD), and pectin walls and peony seed oil cores. A rheological phenomenon occurred in which the emulsion initially behaved like a shear-thickening fluid and then a shear-thinning fluid within a shear range. The emulsion exhibited good stability under low amplitude stress; however, as amplitude increased the concentration of pectin played an important role in maintaining the stability of the emulsion system. The optimum embedding yield of peony seed oil (92.5%) was achieved with a ratio of 70% SSOS, 22.5% β-CD, and 7.5% pectin. This ratio produced 4.521 μm particles with the lowest surface-oil content (2.60%) and moisture content (1.76%). The peony seed oil microcapsules were spherical with smooth surfaces and a synchronous thermogravimetric analysis showed they possessed good thermal stability. Encapsulation increased the induction period to 5-7 times that of unencapsulated peony seed oil.

Polysaccharides at fluid interfaces of food systems

Fabrication of next generation polysaccharides with interfacial properties is driven by the need to create high performance surfactants that operate at extreme environments, as for example in complex food formulations or in the gastrointestinal tract. The present review examines the behaviour of polysaccharides at fluid food interfaces focusing on their performance in the absence of any other intentionally added interfacially active components. Relevant theoretical principles of colloidal stabilisation using concepts that have been developed for synthetic polymers at interfaces are firstly introduced. The role of protein that in most cases is present in polysaccharide preparations either as contaminant or as integral part of the structure is also discussed. Critical assessment of the literature reveals that although protein may contribute to emulsion formation mostly as an anchor for polysaccharides to attach, it is not the determinant factor for the long-term emulsion stability, irrespectively of polysaccharide structure. Interfacial performance of key polysaccharides is also assessed revealing shared characteristics in their modes of adsorption. Conformation of polysaccharides, as affected by the composition of the aqueous solvent needs to be closely controlled, as it seems to be the underlying fundamental cause of stabilisation events and appears to be more important than the constituent polysaccharide sugar-monomers. Finally, polysaccharide adsorption is better understood by regarding them as copolymers, as this approach may assist to better control their properties with the aim to create the next generation biosurfactants.

Vitamin E Encapsulation within Oil-in-Water Emulsions: Impact of Emulsifier Type on Physicochemical Stability and Bioaccessibility

The influence of plant-based (gum arabic and quillaja saponin) and animal-based (whey protein isolate, WPI) emulsifiers on the production and stability of vitamin E-fortified emulsions was investigated. Their impact on lipid digestibility and vitamin bioaccessibility was also studied utilizing an in vitro gastrointestinal tract. WPI and saponin produced smaller emulsions than gum arabic. All emulsions had good storage stability at room temperature (4 weeks, pH 7). Saponin- and gum arabic-emulsions were resistant to droplet aggregation from pH 2 to 8 because these emulsifiers generated strong electrosteric repulsion. WPI-coated droplets flocculated around pH 5 due to a reduction in charge near their isoelectric point. Lipid digestion was slower in saponin-emulsions, presumably because the high surface activity of saponins inhibited their removal by bile acids and lipase. Vitamin bioaccessibility was higher in WPI- than in saponin- or gum arabic-emulsions. This information may facilitate the design of more efficacious vitamin-fortified delivery systems.

Bioaccessibility of Lipophilic Compounds Vehiculated in Emulsions: Choice of Lipids and Emulsifiers

Great efforts have been made to design emulsions considering the need to perform an effective encapsulation, protection, vehiculation, and bioaccessibility of lipophilic compounds. This task can be achieved by manipulating the structure of the emulsion based on the choice of the processes and ingredients of the aqueous phase, interface, and lipid matrix. Thus, the main focus of this perspective is to provide insights into the use of ingredient engineering in manipulating/building emulsion structures that enhance lipophilic compound release and bioaccessibility.