Soluble fibers, like pectin, are known to influence the physicochemical processes during the digestion of dietary fat and may therefore affect the absorption of lipophilic micronutrients such as carotenoids. The objective of the current work was to investigate whether the pectin concentration and degree of methyl-esterification (DM) influence the bioaccessibility of carotenoids loaded in the oil phase of oil-in-water emulsions. The in vitro β-carotene bioaccessibility was determined for different oil-in-water emulsions in which 1 or 2% citrus pectin with a DM of 99%, 66% and 14% was present. Results show that pectin concentration and DM influence the initial emulsion properties.The most stable emulsions with the smallest oil droplets (D(v,0.9) of 15-16 µm) were obtained when medium or high methyl-esterified pectin was present in a 2% concentration while gel-like pectin structures (D(v,0.9) of 114 µm), entrapping oil droplets, were observed in case low methyl-esterified pectin was present in the aqueous emulsion phase. During in vitro stomach digestion, these gel-like structures, entrapping β-carotene loaded oil droplets, significantly enlarged (D(v,0.9) of 738 µm), 2 whereas the emulsion structure could be preserved when medium or high methyl-esterified pectin was present. Initial emulsion viscosity differences, due to pectin concentration and especially due to pectin DM, largely disappeared during in vitro digestion, but were still significant after the stomach digestion phase. The observed differences in emulsion structure before and during in vitro digestion only resulted in a significant difference between emulsions containing low methyl-esterified pectin (β-carotene bioaccessibility of 33-37%) and medium/high methyl-esterified pectin (β-carotene bioaccessibility of 56-62%).

Document VersionAccepted manuscript including changes made at the peer-review stage Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publicationCitation for published version (APA): Moelants, K. R. N., Cardinaels, R. M., Jolie, R. P., Verrijssen, T. A. J., Van Buggenhout, S., Zumalacarregui, L. M., ... Hendrickx, M. E. (2013). Relation between particle properties and rheological characteristics of carrotderived suspensions. Food and Bioprocess Technology, 6(5), 1127-1143. DOI: 10.1007/s11947-011-0718-0 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The effect of particle properties on the rheological behaviour of carrot-derived suspensions was 15 investigated systematically. Hereto, a range of relative monodisperse suspensions, with varying 16 average particle size (~73, 176, 262 and 369 µm) and pulp content (from 30 to 65 w%), was 17 prepared by the reconstitution of carrot tissue particles in water. Suspensions with average 18 particle size of ~73 µm consisted of cell fragments whereas suspensions with larger particle sizes 19 contained mainly cell clusters of which the cell number increased with increasing particle size. 20The rheological characteristics showed that the carrot-derived suspensions have a non-21Newtonian behaviour with a yield stress, depending on particle concentration, size and type). 22The network structure of all suspensions could be described as a weak gel. Increase in yield 23 stress and storage modulus with particle concentration could be fitted to a power law model. A 24 unique linear relation was found between the yield stress and the plateau modulus, independent 25 of the particle size and type. Particle concentration, size and type appeared to be key structural 26 pa...

Document VersionAccepted manuscript including changes made at the peer-review stage Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publicationCitation for published version (APA): Moelants, K. R. N., Cardinaels, R. M., Jolie, R. P., Verrijssen, T. A. J., Van Loey, A. M., Moldenaers, P., & Hendrickx, M. E. (2014). Rheology of concentrated tomato-derived suspensions : effects of particle characteristics. Food and Bioprocess Technology, 7(1), 248-264. DOI: 10.1007/s11947-013-1070-3 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. In the present work, the effect of particle properties on the rheological behaviour of tomato-12 derived suspensions was investigated systematically. Hereto, a range of relatively monodisperse 13 suspensions, containing either cell fragments or single cells with varying average particle size 14 (~148, 267, 303 and 393 µm) and pulp content (from 25 to 60 wt.%), was prepared by the 15 reconstitution of tomato tissue-based particles in water. The effect of the presence of a serum 16 phase on the rheological properties of tomato-derived suspensions was investigated by the 17 comparison of the rheology of reconstituted tomato purées in water with those in serum. All the 18 tomato-derived suspensions were non-Newtonian liquids exhibiting a yield stress. The flow 19 behaviour could be described well by the Herschel-Bulkley model. The undisrupted network 20 structure of all suspensions could be classified as a weak gel with a rather low critical strain. 21Particle concentration, size and morphology (surface/shape) turned out to be key structural 22properties controlling the rheological parameters of these tomato-derived suspensions. Increase 23 in yield stress and storage mod...

In view of consumer health, it is desirable to promote the bioaccessibility of lipid-soluble compounds like carotenoids, while limiting the lipid intake. The objective of this work was to examine the relation between in vitro lipid digestion and β-carotene bioaccessibility of carrot-based model food emulsions containing water, 5% olive oil enriched with β-carotene (from carrots) and different concentrations (1-2-3-4%) of L-α-phosphatidylcholine (PHC), as an emulsifier. The lipid digestion (hydrolysis of triacylglycerols (TAGS) and incorporation of free fatty acids (FFAs) and monoacylglycerols (MAGs) in the micelles) and the β-carotene bioaccessibility (incorporation of β-carotene in the micelles) were studied after an in vitro digestion procedure wherein the stomach phase was mimicked for 2.0 h (37 °C) and the small intestinal phase was mimicked for 1.0 h, 1.5 h and 2.0 h (37 °C) (both end-over-end rotations). As a consequence, not only the influence of the emulsifier concentration, but also the influence of the duration in the small intestinal phase was investigated in this study. The oil droplet size distributions of the emulsions at different stages of digestion were shown to be dependent on the phosphatidylcholine concentration, but independent on the duration in the small intestinal phase (1.0 h-2.0 h). Furthermore, all TAGs were already hydrolysed into FFAs and MAGs after 1.0 h small intestinal phase and the incorporation of FFAs and MAGs into micelles seemed to reach a maximum for all emulsions (approximately 26.5%), independent on the phoshpatidylcholine concentration and thus on the particle size distributions. Finally, the β-carotene bioaccessibility increased with increasing phosphatidylcholine concentration, ranging from 33.2% to 79.8% for a 1% and 4% PHC emulsion respectively. No significant differences in β-carotene bioaccessibility were however noticed for the different durations in the small intestinal phase tested. In conclusion, a higher phosphatidylcholine concentration in emulsions leads to higher β-carotene bioaccessibility while the incorporation of lipids into micelles did not increase.

11Soluble fibers, like pectin, are known to influence the physicochemical processes during the digestion 12 of dietary fat and may therefore affect the absorption of lipophilic micronutrients such as 13 carotenoids. The objective of the current work was to investigate whether the pectin concentration 14 and degree of methyl-esterification (DM) influence the bioaccessibility of carotenoids loaded in the 15 oil phase of oil-in-water emulsions. The in vitro β-carotene bioaccessibility was determined for 16 different oil-in-water emulsions in which 1 or 2% citrus pectin with a DM of 99%, 66% and 14% was 17 present. Results show that pectin concentration and DM influence the initial emulsion properties. 18The most stable emulsions with the smallest oil droplets (D(v,0.9) of 15-16 µm) were obtained when 19 medium or high methyl-esterified pectin was present in a 2% concentration while gel-like pectin 20 structures (D(v,0.9) of 114 µm), entrapping oil droplets, were observed in case low methyl-esterified 21 pectin was present in the aqueous emulsion phase. During in vitro stomach digestion, these gel-like 22 structures, entrapping β-carotene loaded oil droplets, significantly enlarged (D(v,0.9) of 738 µm), 23 2 whereas the emulsion structure could be preserved when medium or high methyl-esterified pectin 24 was present. Initial emulsion viscosity differences, due to pectin concentration and especially due to 25 pectin DM, largely disappeared during in vitro digestion, but were still significant after the stomach 26 digestion phase. The observed differences in emulsion structure before and during in vitro digestion 27 only resulted in a significant difference between emulsions containing low methyl-esterified pectin 28 (β-carotene bioaccessibility of 33-37%) and medium/high methyl-esterified pectin (β-carotene 29 bioaccessibility of 56-62%). 30

Citrus pectin (CP) and sugar beet pectin (SBP) were demethoxylated and fully characterized in terms of pectin properties in order to investigate the influence of the pectin degree of methyl-esterification (DM) and the pectin type on the in vitro β-carotene bioaccessibility and lipid digestion in emulsions. For the CP based emulsions containing β-carotene enriched oil, water and pectin, the β-carotene bioaccessibility, and lipid digestion were higher in the emulsions with pectin with a higher DM (57%; "CP57 emulsion") compared to the emulsions with pectin with a lower DM (30%; "CP30 emulsion") showing that the DM plays an important role. In contrast, in SBP-based emulsions, nor β-carotene bioaccessibility nor lipid digestion were dependent on pectin DM. Probably here, other pectin properties are more important factors. It was observed that β-carotene bioaccessibility and lipid digestion were lower in the CP30 emulsion in comparison with the CP57, SBP32, and SBP58 emulsions. However, the β-carotene bioaccessibility of CP57 emulsion was similar to that of the SBP emulsions, whereas the lipid digestion was not. It seems that pectin type and pectin DM (in case of CP) are determining which components can be incorporated into micelles. Because carotenoids and lipids have different structures and polarities, their incorporation may be different. This knowledge can be used to engineer targeted (digestive) functionalities in food products. If both high β-carotene bioaccessibility and high lipid digestion are targeted, SBP emulsions are the best options. The CP57 emulsion can be chosen if high β-carotene bioaccessibility but lower lipid digestion is desired.

The objective of this study was to examine the impact of flow conditions during the stomach phase of a simple in vitro digestion procedure on the microstructural properties and the β-carotene bioaccessibility of carrot-based model food systems containing oil and different barriers for βcarotene bioaccessibility. A 'periodic forces' stomach model, in which the flow characteristics (measured by Particle Image Velocimetry) corresponded well with experimental in vivo and in silico literature data, was successfully developed and implemented and used in a two-step static in vitro digestion procedure. This stomach model was compared with a conventional end-over-end rotation stomach model in which flow conditions were uncontrolled. Both models in combination with an end-over-end intestinal phase revealed differences in β-carotene bioaccessibility of carrot-based fractions due to the presence of different barriers (the plant chromoplast structure and/or the cell wall). Absolute β-carotene bioaccessibility values however differed between the models. The periodic forces stomach flow behavior lowered the β-carotene bioaccessibility in the β-carotene-enriched emulsion (72% versus 45%), the chromoplast fraction (66% versus 36%) and the large cell cluster fraction (22% versus 13%). The model also resulted in the presence of clusters of small oil droplets interspersed by surface-active compounds while large, coalesced oil droplets (D(v;0.9) of 189 µm) were observed after digestion in the end-over-end stomach model. As a consequence of the periodic forces stomach flow behavior also a slightly higher disintegration of carrot particles (to a D(v;0.9) of 450 µm instead of 492 µm) was observed which was however not linked to a higher β-carotene bioaccessibility in carrot cell clusters.Food industry has great interest in carotenoids because this group of fat-soluble bioactive compounds seems to have a positive impact on human health, including antioxidant capacity, provitamin A activity and immune system enhancing properties (Dutta et al., 2005;Fernandez-Garcia et al., 2012). Since mammals need to obtain carotenoids from their diet, maximal absorption, or bioavailability of carotenoids from the food is desirable. Bioavailability is the fraction of the ingested carotenoids that is available for utilization in physiological functions and for storage in the body. It is partially determined by bioaccessibility, which is the fraction of the ingested carotenoids that is incorporated into micelles and thus becomes available for absorption in the body (Hedrén et al., 2002;Palafox-Carlos et al., 2011). Carotenoid bioaccessibility depends on several factors, such as the presence of oil and the matrix in which the carotenoids are embedded (Castenmiller & West, 1998;Hedrén et al., 2002). This is because on the one hand carotenoids are lipophilic molecules, and thus need to be incorporated in micelles before they can be absorbed and on the other hand because the localization of carotenoids within the plant structure is important. Carotenoids are l...

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