Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Fundamenteel inzicht in calorie- en zoutverlaging. De kern van herformulering
Sman, R.G.M. van der; Renzetti, S. ; Noort, M.W.J. - \ 2019
Food Reformulation: Experts dagen voedingsindustrie uit
Renzetti, S. ; Noort, M.W.J. ; Janssen, A.M. ; Sman, R.G.M. van der - \ 2019
Understanding functionality of sucrose in biscuits for reformulation purposes
Sman, R.G.M. van der; Renzetti, S. - \ 2019
Critical Reviews in Food Science and Nutrition 59 (2019)14. - ISSN 1040-8398 - p. 2225 - 2239.
Biscuit baking - Food structure - Sugar functionality - Sugar replacement

We review the functionality of sucrose during the manufacture of biscuits from the perspective of sugar replacement. Besides to providing sweetness, sucrose has important functionalities concerning structure and texture formation. These functionalities also need to be mimicked in reformulated biscuits. First, we review the hypotheses concerning the development of structure and texture of biscuits during manufacturing, which are conveniently summarized in a qualitative way using the Complex Dispersed Systems methodology. Subsequently, we represent the changes of the state of the biscuit during manufacturing in the supplemented state diagram, which indicates the important phase transitions occurring during mixing and baking. We propose that when reformulated biscuits follow similar paths in the state diagram, similar structures and textures can be obtained. Physical theories exist for predicting these phase transitions for existing sucrose-rich biscuits and also reformulated biscuits containing extensive sweeteners as sugar replacers. More accurate predictions of structure and texture can be eventually obtained if they are combined with computational models, including heat and moisture transfer.

Moisture diffusivity in concentrated and dry protein-carbohydrate films
Siemons, I. ; Boom, R.M. ; Sman, R.G.M. van der; Schutyser, M.A.I. - \ 2019
Food Hydrocolloids 97 (2019). - ISSN 0268-005X
Casein - Free volume - Maltodextrin - Moisture diffusion coefficient - Thin film drying - Whey protein

Understanding moisture diffusivity behaviour over a wide range of moisture contents is pivotal for optimising drying operations. Generally, data on moisture diffusivity are scarce and the effect of matrix composition on moisture diffusivity at relevant temperature for drying processes is not yet well described. In this paper moisture diffusivity in protein-carbohydrate films is systematically investigated for a wide range of moisture contents at 80 °C. Diffusion data are obtained from controlled thin film drying experiments following the regular regime method and compared to theoretical models. Moisture diffusivity for binary maltodextrin-water and whey protein-water systems appeared similar and were reasonably well described with the Darken relation. Diffusivity was lower for casein-water systems at moisture contents above 0.15 kg water/kg, which may be explained by compartmentalization of water in the casein micelles. At low moisture contents all binary systems showed universal behaviour, which may be explained by random coil behaviour leading to similar water-molecule interactions. This behaviour could be well described by free-volume theory. In mixed systems of proteins and carbohydrates moisture diffusivity appeared strongly influenced by the presence of casein, probably due to their high voluminosity. Finally, it was surprisingly observed that diffusivity in multicomponent systems decreased sharply at lower water contents when compared to binary systems. This might be explained by a denser molecular packed system in the dry regime for multicomponent systems or water trapping by protein-carbohydrate complexes.

Scaling of Flory-Huggins interaction parameter for polyols with chain length and number of hydroxyl groups
Sman, R.G.M. van der - \ 2019
Food Hydrocolloids 96 (2019). - ISSN 0268-005X - p. 396 - 401.
Flory-huggins - Hydrophilicity - Sorption isotherm - Thermodynamics

The Flory-Huggins-Free-Volume (FHFV)theory, describing the moisture sorption of carbohydrates, is extended towards a wider range of compounds. Earlier application of the FHFV theory has been to carbohydrate/water mixtures, as can be found in foods. Now, we have extended the theory towards polyols (or polyalcohols)which are investigated in as proxies for secondary organic aerosols, whose behaviour is important for understanding climate behaviour. The investigated polyols are characterized by the ratio of the number hydroxyl groups NOH and the number of carbon atoms NC, which is often lower than ratios found in carbohydrates in food materials. We have found that the value of the Flory-Huggins interaction parameter is a function of the solute molecular properties, namely its chain length NC and the ratio NOH/NC of the solute. The deviation of this ratio from [Formula presented] can be viewed as a measure for its hydrophilicity. For food science, the extension of the theory has also significant implications, as the interaction parameter of newly investigated ingredients (rich in hydroxyl groups)can be estimated by means of the molecular properties. One must think of insoluble food fibers like xylan-glucans or arabinoxylans, or modified biopolymers based on starch or cellulose.

Starch gelatinization temperature in sugar and polyol solutions explained by hydrogen bond density
Sman, R.G.M. van der; Mauer, Lisa J. - \ 2019
Food Hydrocolloids 94 (2019). - ISSN 0268-005X - p. 371 - 380.
Glass transition - Plasticizers - Starch gelatinization - Viscosity

In this paper we show that the shift of the gelatinization temperature of starch in sugar and polyol solutions is explained by nOH,eff , the volumetric density of hydrogen bonds in the solutions. nOH,eff is computed using the dry glass transition temperatures of the low molecular weight carbohydrates. This correlation of starch gelatinization temperature to nOH,eff is shown for 19 different sugar and polyol compounds in solutions at different concentrations, as measured in an earlier study by Allan et al. (2018). The earlier study found that the measured viscosity of the solutions best correlated to starch gelatinization temperature, but it was assumed that there is a more fundamental property of the sweetener that alters both the viscosity and the starch gelatnization behaviour. Here, it is shown that nOH,eff is this fundamental property responsible for controlling both the viscosity and starch gelatinization temperature differences in the used sugar and polyol solutions. Because nOH,eff is also related to Tg, the glass transition temperature of the carbohydrate solutions, the viscosity of a wide variety of carbohydrate solutions can be mapped to a single master curve if plotted against Tg/T, the ratio of glass transition and the actual temperature. Older hypotheses concerning the shift of the starch gelatinization temperature in carbohydrate solutions have explained it in terms of water activity. However, we show that nOH,eff relates to water activity only for carbohydrates with similar molecular weights. We conclude that sugar and polyol solutions can be viewed effectively as a single solvent, which is characterized by nOH,eff . This measure for volumetric density of hydrogen bonds in these solutions can be used to predict the starch gelatinization temperature in different formulations.

Manipulation of Recrystallization and Network Formation of Oil-Dispersed Micronized Fat Crystals
Nikolaeva, Tatiana ; Adel, Ruud den; Sman, Ruud van der; Martens, Koen J.A. ; As, Henk Van; Voda, Adrian ; Duynhoven, John van - \ 2019
Langmuir 35 (2019)6. - ISSN 0743-7463 - p. 2221 - 2229.

A detailed investigation was carried out on the modulation of the coupling between network formation and the recrystallization of oil-dispersed micronized fat crystal (MFC) nanoplatelets by varying oil composition, shear, and temperature. Sunflower (SF) and bean (BO) oils were used as dispersing media for MFC nanoplatelets. During MFC dispersion production at high shear, a significant increase in the average crystal thickness (ACT) could be observed, pointing to recrystallization of the MFC nanoplatelets. More rapid recrystallization of MFC occurred in the SF dispersion than in the BO dispersion, which is attributed to higher solubility of MFC in the SF oil. When the dispersions were maintained under low shear in narrow gap Couette geometry, we witnessed two stages of recrystallization (measured via rheo-SAXD) and the development of a local yield stress (measured via rheo-MRI). In the first stage, shear-enabled mass transfer induces rapid recrystallization of randomly distributed MFC nanoplatelets, which is reflected in a rapid increase in ACT (rheo-SAXD). The formation of a space-filling weak-link MFC network explains the increase in yield stress (assessed in real time by rheo-MRI). In this second stage, recrystallization slows down and yield stress decreases as a result of the formation of MFC aggregates in the weak link network, as observed by confocal Raman imaging. The high fractal dimension of the weak-link network indicates that aggregation takes place via a particle-cluster mechanism. The effects of oil type and shear on the recrystallization rate and network strength could be reproduced in a stirred bowl with a heterogeneous shear stress field, which opens perspectives for the rational manipulation of MFC thickness and network strength under industrial processing conditions.

Phase separation, antiplasticization and moisture sorption in ternary systems containing polysaccharides and polyols
Sman, R.G.M. van der - \ 2019
Food Hydrocolloids 87 (2019). - ISSN 0268-005X - p. 360 - 370.
Antiplasticization - phase separation - Sorption isotherm - Starch - Thermodynamics

In this paper, we investigate whether the Flory-Huggins-Free-Volume (FHFV) theory can describe the rich thermodynamics of the ternary mixtures of starch, polyol, and water. These systems exhibit 1) non-monotonic moisture sorption with increasing plasticizer concentration, 2) phase separation, and 3) antiplasticization. After extending the FHFV theory with 1) the proper formulation of the chemical potential of water and polyol, and 2) the proper composition dependency of the interaction parameter between starch and water, the theory is well able to describe the above described complex thermodynamic behavior, showing good agreement with experimental data. Furthermore, our analysis shows that phase separation can already occur when the ternary mixture is still in the glassy state. Overall, the phase separation happens after the antiplasticization/plasticization transition, which can be linked to the minimum in moisture sorption, when increasing the polyol concentration at equal water activity. We think that the extended theory will become an important tool for analysis and design of complex food materials, pharmaceutical systems, and biopolymeric films having carbohydrates as plasticizers.

Effects of filler ingredients on the structure and texture of starchy, extruded snacks
Sman, R.G.M. van der; Vollebregt, H.M. ; Meinders, M.B.J. ; Beri, A. - \ 2018
Food Structure 18 (2018). - ISSN 2213-3291 - 13 p.
Crispiness - Expanded snacks - Filler ingredients

Several starchy snacks differing in filler ingredients have been analysed regarding (1) the fate of filler ingredients during processing, and (2) the role of filler ingredients with respect to texture and structure. The structure has been characterized with X-ray tomography, and the texture has been evaluated via acoustic emissions from snack compression using a texture analyzer, which is assumed to be representative for crispiness. Our study shows that one has to distinguish hard and soft fillers. The absence of any filler or the presence of many hard fillers lead to a snack with a hard, coarse and non-crispy texture. However, if a significant amount of soft fillers is used then one attains a fine, and crispy texture.

Analysis of particle formation during drying of very small droplets
Siemons, Isabel ; Boom, R.M. ; Schutyser, M.A.I. ; Sman, R.G.M. van der - \ 2018
Clumping of frozen par-fried foods : Lessons from frosting on structured surfaces
Sman, R.G.M. van der - \ 2018
Food Structure 17 (2018). - ISSN 2213-3291 - p. 9 - 20.
Frosting - Frying - Structured surfaces

In this paper, we review the problem of clumping due to frost formation on frozen vegetables, like par-fried potato products. This problem has been very scarcely investigated in the scientific literature. Yet in the industry it is a significant problem, as evident by the various patents on this topic. Thanks to the enormous, recent growth of scientific literature on frost formation on engineered, structured surfaces, we have drawn a multitude of hypotheses of factors governing the clumping and frost formation of frozen foods, which can also be viewed as a structured surface.

Theoretical investigation of the swelling of polysaccharide microgels in sugar solutions
Sman, R.G.M. Van Der - \ 2018
Food & Function 9 (2018)5. - ISSN 2042-6496 - p. 2716 - 2724.

In this paper, we explain the increased swelling of crosslinked polysaccharide microgels by the increase of sugar concentration using a modified Flory-Rehner theory. This theory is validated via the investigation of the swelling of dextran microgels in sugar solutions, which can be viewed as a model system for crosslinked starch in sugar solution and custard. An essential part of our modified theory is that starch perceives the sugar solution as an effective solvent rendering a certain hydrogen bond density. Our simulations show that the often experimentally observed maximum in swelling of starch at 20% sugar concentration is probably due to the fact that equilibrium is not reached within practical time scales. Also, we discuss the use of our theory as a tool in sugar reformulation issues of custard. From simulation results one can produce a state diagram showing which formulations render a creamy, space-filling network.

In-situ Single Mode Dielectric Measurements of microwaveable snack pellets
Esveld, Erik ; Bows, John ; Vollebregt, Martijntje ; Sman, Ruud van der - \ 2018
Journal of Food Engineering 231 (2018). - ISSN 0260-8774 - p. 109 - 122.
Dielectric properties - Expansion - Microwave - Starch

The dielectric properties of starch based snack pellets have been measured in situ during microwave heating and expansion. The microwave setup consists of a single mode shorted waveguide, equipped with a six-port impedance analyser which measures the absorbed power and complex reflection coefficient during heating. The pellet is suspended in the electric field maximum, with an optic temperature sensor inserted in the centre. The dielectric properties of the pellet during heating and after expansion are obtained via an inverse mapping of the recorded reflection coefficient to dielectric properties, which are pre-computed via finite elements simulations. Experiments show that the dielectric properties of the starch pellets change significantly during heating, expansion and subsequent drying. The dielectric properties increase with increasing temperature up to the moment that the pellet starts expanding. Subsequently, the power absorption shows a sudden decline, which is mainly due to the sudden change in porosity. Addition of salt (2.5%) to the starch pellet composition results in a slight decrease of the dielectric constant and loss factor, as it apparently lowers the effective mobility of the dipoles. The dielectric properties as function of temperature and moisture content were fitted with a polynomial model. The strong effect of porosity for the dielectric properties of the expanded snack is well predicted with the effective medium mixing rule.

Critical factors in microwave expansion of starchy snacks
Sman, R.G.M. van der; Bows, J.R. - \ 2017
Journal of Food Engineering 211 (2017). - ISSN 0260-8774 - p. 69 - 84.
Expanded snacks - Microwave - Popcorn - Starch

Popping of starchy pellets in a domestic microwave oven has proven difficult compared to pellets expanded in frying oil, and even to microwave expanded popcorn. These pellets encounter problems like uneven popping, burning and the absence of an audible cue for the end of popping. The lack of a moisture barrier, like the pericarp of popcorn, leads to the development of an inverse temperature gradient in the pellets and a significant moisture loss before and after expansion. In this paper we review the hypotheses and solutions for the criticality of microwave popping of starchy pellets, as discussed in scientific and patent literature. We have found a large collection of critical factors and their associated hypotheses, which have been structured via linking them to specific steps in the physical expansion process. We conclude with a list of hypotheses that we view valuable for further investigation.

Model for electrical conductivity of muscle meat during Ohmic heating
Sman, R.G.M. van der - \ 2017
Journal of Food Engineering 208 (2017). - ISSN 0260-8774 - p. 37 - 47.
Electrical conductivity - Ohmic heating - Protein denaturation
A model is presented for predicting the electrical conductivity of muscle meat, which can be used for the evaluation of Ohmic heating. The model computes the conductivity as a function of composition, temperature and microstructure. The muscle meat is thought to be composed of protein, water, salt. Concerning the microstructure, the model takes into account the muscle fiber orientation with respect to the electric field, and the development of drip channels due to protein denaturation. The model includes a description of the protein denaturation kinetics. The model has been validated for different types of meat, varying in composition and heating rate. The submodel for protein denaturation is validated using independent DSC measurements. For meats heated faster than 20° per minute, the conductivity is a linear function of temperature - due to the absence of protein denaturation, and thus drip channel formation. If meat is heated slower than 10° per minute the conductivity is showing non-linear behaviour, with a significant decrease at temperatures above 70 degrees Celsius. This decrease is explained by the action of the complete protein denaturation. Our study shows that if Ohmic heating of meat is performed at fast rates, there is a large potential to retain most of its moisture during heating.
Predicting the solubility of mixtures of sugars and their replacers using the Flory-Huggins theory
Sman, R.G.M. van der - \ 2017
Food & Function 8 (2017)1. - ISSN 2042-6496 - p. 360 - 371.

In this paper we investigate whether the Flory-Huggins theory can describe the thermodynamics of solutions of simple carbohydrates, like sugars and polyols. In particular, we focus on the description of the solubility of the carbohydrates in water. This is investigated for both binary and ternary mixtures, having two types of these carbohydrates. This research question arises especially in the case of bakery products, where one seeks to replace sucrose with other simple carbohydrates-which are often polyols. Based on the model parameters obtained from fitting the theory to the experimental data of binary solutions, we show that the theory can predict (a) solubility data for ternary mixtures, over a broad range of concentrations and temperatures, and (b) the deliquescence point of binary mixtures of carbohydrate crystals as a function of temperature. The theory can even be applied to carbohydrates, which form hydrate crystals. Together with our earlier theories on the thermodynamics of complex food mixtures, we have now a complete thermodynamic framework to describe the phase and state transitions of food materials as confectionery and bakery products, where the question of sucrose replacement is urgent.

Flow through a filter plate backed by a packed bed of spheres
Sman, R.G.M. van der - \ 2017
Chemical Engineering Science 158 (2017). - ISSN 0009-2509 - p. 154 - 163.
Filtration - Fluid flow - Orifice - Simulation

In this paper we perform direct numerical simulation (DNS) on the problem of fluid flow through a filter plate backed by a packed bed of spheres, resembling a cake layer on top of a membrane. For both the complete problem, and its single components (the filter plate and a bed of spheres of finite height) we have observed three flow regimes, depending on the Reynolds number. In each regime the flow resistance is showing a different scaling with the Reynolds number. In the Stokes flow regime the total flow resistance can be decomposed in linear independent components. The interior flows inside the filter holes and inside the packed bed follow the same correlations as hold for the single component. However, at the transition zone between filter plate and packed bed, there is a diverging flow in the first row of the packed bed, whose contribution in the flow resistance scales with the fractional hole to the power −1.5. Similar scaling exponent has been found earlier for the viscous-inertial regime with Reynolds numbers larger than 10, which has been modelled using the porous medium approach. Our findings suggest that also in the Stokes flow and the weakly flow regime the problem can also be solved with the same porous medium approach using the Navier-Stokes equation having Darcy–Brinkman terms incorporated. This investigation provides a good basis for developing more accurate analytical models for the flow resistance of membrane filters with a cake layer on top.

More efficient mushroom canning through pinch and exergy analysis
Paudel, Ekaraj ; Sman, Ruud G.M. van der; Westerik, Nieke ; Awasthi, Ashutosh ; Dewi, Belinda P.C. ; Boom, Remko M. - \ 2017
Journal of Food Engineering 195 (2017). - ISSN 0260-8774 - p. 105 - 113.
Canned mushroom production - Exergy - Pinch analysis - Sustainability

Conventional production of canned mushrooms involves multiple processing steps as vacuum hydration, blanching, sterilization, etc. that are intensive in energy and water usage. We analyzed the current mushroom processing technique plus three alternative scenarios via pinch and exergy analysis. The product yield, utility use, exergy loss, and water use are used as sustainability indicators. Whilst re-arrangement of the production process could maximally save up to 28% of the heat input and up to 25% of the water usage, the most important improvement is obtained by re-using blanch water, which improves the overall yield of the preservation and canning process by 9%, also saving water and exergy use in the production.

Filler functionality in edible solid foams
Sman, R.G.M. van der - \ 2016
Advances in Colloid and Interface Science 231 (2016). - ISSN 0001-8686 - p. 23 - 35.

We review the functionality of particulate ingredients in edible brittle foams, such as expanded starchy snacks. In food science and industry there is not a complete awareness of the full functionality of these filler ingredients, which can be fibers, proteins, starch granules and whole grains. But, we show that much can be learned about that from the field of synthetic polymeric foams with (nano)fillers. For edible brittle foams the enhancement of mechanical strength by filler ingredients is less relevant compared to the additional functionalities such as 1) the promotion of bubble nucleation and 2) cell opening - which are much more relevant for the snack texture. The survey of particulate ingredients added to snack formulations shows that they cannot be viewed as inert fillers, because of their strong hygroscopic properties. Hence, these fillers will compete with starch for water, and that will modify the glass transition and boiling point, which are important factors for snack expansion. Filler properties can be modified via extrusion, but it is better if that processing step is decoupled from the subsequent processing steps as mixing and expansion. Several filler ingredients are also added because of their nutritional value, but can have adverse effect on snack expansion. These adverse effects can be reduced if the increase of nutritional value is decoupled from other filler functionality via compartmentalization using micropellets.

Effects of cellular structure and cell wall components on water holding capacity of mushrooms
Paudel, Ekaraj ; Boom, Remko M. ; Haaren, Els van; Siccama, Joanne ; Sman, Ruud G.M. van der - \ 2016
Journal of Food Engineering 187 (2016). - ISSN 0260-8774 - p. 106 - 113.
Cell membrane integrity - Cell wall components - Mushroom - Water holding capacity

In a sequel of papers we have investigated effects of different physical contributions to the water holding capacity of foods by considering the common white button mushroom (Agaricus bisporus). In the current paper of our sequel, we consider individual contributions of the cellular phase to water holding. The water holding capacity of hydrated mushroom is studied in relation to cell membrane integrity loss and change of state of structural polymers of the cell wall. We show that the loss in water holding capacity after heat treatment is closely correlated with cell membrane integrity loss. The intrinsic water holding capacity of the cell wall components, mostly chitin and proteins also play a role. The contribution of protein manifests largely via a significant response of WHC towards change in pH.

Phase field simulations of ice crystal growth in sugar solutions
Sman, R.G.M. Van Der - \ 2016
International Journal of Heat and Mass Transfer 95 (2016). - ISSN 0017-9310 - p. 153 - 161.
Computer simulation - Ice crystal growth - Phase field method - Sugar solution

We present the first model ever, that describes explicitly ice crystal growth in a sugar solution during freezing. This 2-D model uses the phase field method, supplemented with realistic, and predictive theories on the thermodynamics and (diffusion) kinetics of this food system. We have to make use of a novel type of phase field to obtain realistic, micron-sized ice crystals, and exclusion of sugar from the crystalline phase. Via simulation of a single ice crystal, we identify important time scales governing the growth. These times scales are also important for the coarsening of the ice morphology in freezing systems with multiple ice crystals. These simulations show that the average ice crystal size is governed by the freezing rate via a power law, similar to an empirical relation from literatures, which is deduced from experiment. The presented model is viewed as a good basis for even more realistic simulations of crystal growth in food.

Sugar and polyol solutions as effective solvent for biopolymers
Sman, R.G.M. van der - \ 2016
Food Hydrocolloids 56 (2016). - ISSN 0268-005X - p. 144 - 149.
Biopolymer melting - Hydrogen bonding - Reformulation - State diagram

Ternary mixtures of biopolymers, sugars or polyols and water can be treated as a pseudo binary system with respect to melting of the biopolymer. Sugar and polyol solutions can be treated as an effective solvent, characterized by the density of hydroxyl groups available for intermolecular hydrogen bonding. Such a treatment has been shown earlier for the glass transitions of the ternary mixtures. Now we have analysed the melting behaviour of biopolymers in these ternary mixtures. If the melting points are plotted as function of the density of hydroxyl groups, all data for a variety of sugars and polyols collapse to a single curve. This master curve coincides with the prediction of the melting line for biopolymer/water mixtures as follows from Flory's theory. Such behaviour has been found for starch, gelatin, soy and sunflower proteins.

Effects of Porosity and Thermal Treatment on Hydration of Mushrooms
Paudel, Ekaraj ; Boom, R.M. ; Sman, R.G.M. van der - \ 2016
Food Bioprocess Technology 9 (2016)3. - ISSN 1935-5130 - p. 511 - 519.
Degree of hydration - Mushroom processing - Porosity - Water-holding capacity

In this study, hydration of mushroom as a porous food material has been studied considering their biphasic character. It consists of a solid phase that consists of intertwined hyphae and having cell walls with a swellable polymeric matrix and a pore phase made up by the space in between the hyphae. We have investigated the hydration of mushrooms as a function of initial porosity and thermal treatment. Variation in porosity is induced by the natural variation in the growth of mushroom. Porosity is measured by the weight gain during vacuum infiltration of mushroom caps with the mushroom isotonic solution. The hydration of the heat-treated mushroom shows a linear increase with the porosity of mushroom. Storage of mushroom increases the porosity with the number of storage days, which has also been confirmed with X-ray tomography(XRT) measurements. Finally, we show that the hydration of thermal-treated mushroom has two independent contributions, from porosity and temperature of the heat treatment. Current theories deal only with the latter contribution to the hydration of foods and need to be extended for accounting porosity of the food.

Analysis of improved Lattice Boltzmann phase field method for soluble surfactants
Sman, R.G.M. van der; Meinders, M.B.J. - \ 2016
Computer Physics Communications 199 (2016). - ISSN 0010-4655 - p. 12 - 21.
surfactants - phase field - lattice boltzmann
In this paper we present a novel Lattice Boltzmann model for immiscible fluids with soluble surfactants adsorbing at the interface with improved numerical and extended physical properties. The numerical improvements are based on the use of an analytical representation of a regularized delta-function in the surface free energy functional for the surfactant. Furthermore, the physics of the system have been extended to differential solubility of the surfactant combined with the use of Frumkin sorption behaviour. This enables the scheme to approach more realistic systems like foams and emulsions. This novel scheme is much superior in numerical stability than our previous scheme, based on a squared gradient approximation. Furthermore, we have observed the phenomenon of interface broadening under certain conditions. This phenomenon limits the surface pressure to about 30% of the capillary pressure of a bare droplet. It remains to be investigated whether this interface broadening reflects some physical
effect, as has been observed for proteins.
Mesoscale Lattice Boltzmann Model of Dispersions Stabilized by Surfactants
Meinders, M.B.J. ; Sman, R.G.M. van der - \ 2015
In: Computational Methods for Complex Liquid-Fluid Interfaces / Taeibi Rahni, Mohammad, Karbaschi, Mohsen, Miller, Reinhard, Boca Raton : CRC Press / Taylor & Francis - ISBN 9781498722087 - p. 295 - 308.
Modeling Foam Stability
Meinders, M.B.J. ; Sman, R.G.M. van der - \ 2015
In: Computational Methods for Complex Liquid-Fluid Interfaces / Taeibi Rahni, Mohammad, Karbaschi, Mohsen, Miller, Reinhard, CRC Press / Taylor & Francis (Progress in Colloid and Interface Science ) - ISBN 9781498722087 - p. 503 - 526.
Hyperelastic models for hydration of cellular tissue
Sman, R.G.M. Van Der - \ 2015
Soft Matter 11 (2015)38. - ISSN 1744-683X - p. 7579 - 7591.

In this paper we present hyperelastic models for swelling elastic shells, due to pressurization of the internal cavity. These shells serve as model systems for cells having cell walls, as can be found in bacteria, plants and fungi. The pressurized internal cavity represents the cell vacuole with intact membrane at a certain turgor pressure, and the elastic shell represents the hydrated cell wall. At pressurization the elastic shell undergoes inhomogeneous deformation. Its deformation is governed by a strain energy function. Using the scaling law of Cloizeaux for the osmotic pressure, we obtain approximate analytical expressions of the cell volume versus turgor pressure-which are quite comparable to numerical solutions of the problem. Subsequently, we have simulated the swelling of shells-where the cell wall material is embedded with microfibrils, leading to strain hardening and anisotropic cell expansion. The purpose of our investigations is to elucidate the contribution of cell membrane integrity and turgor to the water holding capacity (hydration) of plant foods. We conclude with a discussion of the impact of this work on the hydration of food material, and other fields like plant science and the soft matter physics of responsive gels.

Editorial overview : Food physics and material science
Sman, R.G.M. van der - \ 2015
Current Opinion in Food Science 3 (2015). - ISSN 2214-7993 - p. 6 - 8.
Comparison of first principles model of beer microfiltration to experiments via systematic parameter identification
Sman, R.G.M. van der; Willigenburg, G. van; Vollebregt, H.M. ; Eisner, V. ; Mepschen, A. - \ 2015
Journal of Membrane Science 484 (2015). - ISSN 0376-7388 - p. 64 - 79.
Beer - Fouling - Microfiltration - Shear-induced diffusion

A first principles microfiltration model based on shear-induced diffusion is compared to experiments performed on the clarification of beer. After performing an identifiability and sensitivity analysis, the model parameters are estimated using global minimization of the sum of least squares. The model is compared to different series of experiments, where either crossflow or permeate flux is varied. This study is concluded with a parameter study on the scaling of the filtration time with various model parameters. We have found that the filtration time primarily depends on two dimensionless numbers, namely the normalized critical distance for cake layer formation, and the dimensionless time required to plug all pores in the selective layer. We have found that there is an optimal setting of these parameters, rendering a maximal amount of filtrated beer in one cycle.

Biopolymer gel swelling analysed with scaling laws and Flory-Rehner theory
Sman, R.G.M. van der - \ 2015
Food Hydrocolloids 48 (2015). - ISSN 0268-005X - p. 94 - 101.
Gel - Swelling - Water holding capacity

The swelling of biopolymer gels is analysed with scaling laws from polymer physics, as an alternative for the classical Flory-Rehner theory. With these scaling laws, holding for polymer concentrations in the semi-dilute regime, experimental data on deswelling of gels can be collapsed to a single universal master curve. The predictions made with the scaling laws are similar to those made with the modified Flory-Rehner, where the osmotic pressure is described with a composition-dependent interaction parameter. For gels in the semi-dilute regime we recommend the use of the scaling laws, because their compact, and universal character.

Change in Water-Holding Capacity in Mushroom with Temperature Analyzed by Flory-Rehner Theory
Paudel, Ekaraj ; Boom, R.M. ; Sman, R.G.M. van der - \ 2015
Food Bioprocess Technology 8 (2015)5. - ISSN 1935-5130 - p. 960 - 970.
Gel compression - Mushroom processing - Thermodynamics - Water-holding capacity

The change in water-holding capacity of mushroom with the temperature was interpreted using the Flory-Rehner theory for swelling of polymeric networks, extended with the Debye-Hückel theory for electrolytic interactions. The validity of these theories has been verified with independent sorption measurements. The change in water-holding capacity with temperature could be quantified as changes in three model parameters: the Flory-Huggins interaction parameter between the biopolymers and the aqueous solvent phase, the cross-link density of the network, and the biopolymer volume fraction at the relaxed state. The elastic pressure is analyzed using the Flory-Rehner theory, which is traditionally used to describe the swelling of polymers. From the explicit knowledge of the elastic pressure, we can determine how model parameters, such as the cross-link density, depend on temperature. We argue that the dependencies of model parameters can be understood as a consequence of protein denaturation. Having knowledge on how all contributions to the swelling pressure depend on temperature, and composition, we can compute the water-holding capacity of mushroom for a wide range of temperatures and mechanical loads.

Water retention in mushroom during sustainable processing
Paudel, E. - \ 2015
Wageningen University. Promotor(en): Remko Boom, co-promotor(en): Ruud van der Sman. - Wageningen : Wageningen University - ISBN 9789462575967 - 148
mushrooms - water holding capacity - physical properties - hydration - chemical composition - heat treatment - canning - process optimization - sustainability - paddestoelen - waterbergend vermogen - fysische eigenschappen - hydratatie - chemische samenstelling - warmtebehandeling - inblikken - procesoptimalisatie - duurzaamheid (sustainability)

This thesis deals with the understanding of the water holding capacity of mushroom, in the context of a redesign of their industrial processing. For designing food process the retention of food quality is of the utmost importance. Water holding capacity is an important quality aspect of mushrooms. A convenient process design methodology which accounts also for product quality is Conceptual Process Design (CPD). An approach to follow CPD methodology is first to explore, the material properties of the products to find optimal processing conditions. In this stage the constraints of (existing) processing equipment are not considered. Later in the second stage, suboptimal processing conditions are determined considering the constrains of equipment.

In mushroom canning, temperature induced loss of water holding capacity (WHC) of tissue manifests as a lower product yield. This loss of water is accompanied with the loss of nutrients, dissolved in the water. In addition to the loss of product quality like water holding capacity, mushroom canning (with alternating heating and cooling steps) also induces losses of useful resources as (potable) water. In terms of water use, water is added at several steps, and is discarded at other places. This shows that there is opportunity to improve the sustainability of the production system, but with the constraint that product quality is not impaired, or evenly improved.

The WHC is an important property that determines several aspects of foods. For example, it determines the juiciness of fruits, vegetables and meat products; the freshness (firmness, or crispiness) of green-leafy vegetables; and the calorie intake per serving for high calorie containing foods such as cheese. Despite being a widely used term in food science, there is no clear definition of water holding capacity and its thermodynamic nature is not fully acknowledged. The understanding of the WHC is even poorer in structured cellular foods such as mushroom, where different water fractions are present in various compartments. In a cellular system water is present as 1) a solution in the vacuoles, 2) water osmotically bound to the cytoplasmic and the cell wall materials and 3) capillary water in pores, which might be filled during processing. Because they have a distinct capillary phase, the mushroom is a good system to study the contributions of various water fraction on the total water retention.

The main aim of the current work is to provide insight for the development of canned mushroom processing where: 1) the resources of energy and water are efficiently used, and 2) the quality of mushroom is maintained. These two aims are related to the efficient use of raw materials and maintenance of full weight of mushroom during processing. The WHC is an important quality indicator of mushrooms. The analysis related to water retention of mushroom has been carried out at microscale where molecular and structural interactions in relation to water retention are studied. The micro scale analysis is discussed in chapter 2, chapter 3 and chapter 4. The sustainability analysis is carried out at mesoscale where analysis is carried out at the unit operation level which is described in chapter 5.

In chapter 2, the heat-induced change in water holding capacity of particular the gel phase of the mushroom is interpreted with the Flory-Rehner theory, commonly applied to polymer gels. As done earlier for meat, we have first assumed that WHC loss in mushroom can also be attributed to the protein denaturation. This assumption is based on the experimental observation that, like meat, mushroom also follows a typical sigmoid relation with change in temperature. In the theory, we have regarded mushroom as a homogeneous biopolymer hydrogel, in which salt and sugar are dissolved. The water holding capacity is then understood as the swelling capacity of the biopolymer gel. The thermodynamic state of this simplified system is characterized by the so-called swelling pressure, which is decomposed into three independent contributions: 1) the mixing pressure induced by sugars and polymers, 2) the ionic pressure induced by the salt, and 3) the elastic pressure induced by the polymers. An assumption was made that the heat treatment denatures mushroom protein, which is reflected in the change of the Flory Huggins interaction for protein. It follows the same temperature dependency as the WHC loss by mushroom under zero mechanical load. The assumption of the temperature dependency of the interaction parameter is tested with an independent sorption measurement. With the assumption, the sorption curve for mushroom sample which were preheated previously at 30, 60 and 90 °C could accurately be predicted. Curve fitting of WHC under various mechanical loads has shown that model parameters that are associated with the elastic pressure, the crosslink density and fraction of the polymer in the relaxed state, are temperature dependant. The values of increased in contrast to the decrease of upon heating of mushroom tissue up to temperature of 70°C. The result indicates that heat treatment increases the polymer chain length between the cross links as original conformation of mushroom is lost. At the same time, more crosslinks are formed by a polymer because of aggregation of polymers. However, in our fitting procedure, we have excluded WHC data at low external pressure values, as water is present in both gel phase as in in the capillaries. This is done as the pores in this range are not fully collapsed and the Flory Rehner theory is valid only for the gel phase

In chapter 2 mushroom is simplified in the sense that only compositional contribution is considered in WHC but not the structural contributions. In subsequent chapters we have acknowledged that mushroom has a cellular structure with a distinct pore phase. The pores are intentionally filled during processing via vacuum impregnation. The contribution of water present in the capillaries due to vacuum impregnation of mushroom has been discussed in chapter 3. Both the temperature of heat treatment and the initial porosity of mushroom contribute independently to water holding capacity of heat treated mushroom. The hydration of heat treated mushroom increases linearly with the initial porosity of mushroom for all the temperatures from 30 to 90 °C. The porosity of mushroom can also largely explain the increase in hydration of heat treated mushroom with storage as both porosity and the hydration increase simultaneously with the storage days. The fluid that filled in the capillaries acts against collapse of the hyphae which have inherent elastic force that works in the other direction. The initial porosity of mushroom is an important aspect that determines the hydration of the heat treated mushroom and therefore, cannot be ignored. In addition, the Flory-Rehner theory alone cannot capture the contribution of the capillary water. Hence an addition is needed in the theory to capture this effect.

The cellular phase in mushroom tissue is even more complicated because water is present in this phase in two other forms, as gel water and the intracellular water. Chapter 4 takes into account the role of structure in the WHC. The role of cell membrane integrity and the cell-wall structural components is investigated for retention of the water fraction. The cell membrane integrity is calculated from the conductivity measurement of the fluid that leaches out from the vacuole that has salts in it. The loss of the cell membrane integrity largely explains the water loss from heat treated mushroom sample. The loss of cell membrane integrity is also related with the water loss from frozen mushroom, but additional losses occur during freezing due to novel crosslinks formed during the growth of ice crystals compressing the unfrozen cell wall material. The enzymatic hydrolysis of mushroom cellular components shows that chitin and mushroom protein both contribute to the water holding capacity either via osmotic binding or by their role to provide the mechanical strength to the mushroom hyphae. In addition, proteins have additional contributions to water retention by mushroom because of their electrostatic interaction as polyelectrolyte. This is evident as the hydration of the mushroom increases with pH of mushroom.

In chapter 5, the efficiency of the use of the resources (raw materials, energy water) is investigated. The mass and exergy flow in the current production system is visualized with the Sankey diagrams. The sustainability of unit operations involved in the current production system of canned are analysed with the second law efficiency using exergy. Using ideas from Process Intensification three alternative routes are proposed for the production of canned mushrooms namely: 1). Slicing before vacuum hydration, and 2) Using hot water for vacuum hydration and 3) Using blanch water for vacuum hydration. Using hot water for vacuum hydration is not seen as a feasible option, since it consumed more resources. Slicing mushroom before their vacuum hydration and using blanch water for hydration of mushroom lowers the resources requirement for production. In addition, using blanch water for hydration also increases the final product yield.

Finally, the main findings of this thesis are summarized in the general discussion in chapter 6. The findings from previous chapters are combined to an overall description of water loss from heat treated mushroom. The overall description of water holding capacity in mushrooms is given in terms of the thermodynamic conditions for equilibrium between the different compartments holding water. The two dimensions of the thesis, the higher water retention of processed mushroom and more sustainable operation are discussed in the light of conceptual process design, using a micro/mesoscale approach. At the microscale material properties of mushroom are discussed. The biggest effect comes from cell membrane integrity loss. The porosity of fresh mushroom and the ionic interactions of polymers are the other effects that influence the WHC. Mesoscale analysis shows that shifting the sequence of unit operations and reusing the blanch water that is discarded in the current production process can improve the sustainability. Finally based on outcome of current work, future perspective of current work is discussed briefly.

Overall, this thesis demonstrated that there is substantial scope in improving the efficiency in the use of resources in producing preserved mushroom. Also scope in retention of water in the mushroom tissue is demonstrated. Thus this thesis shows that both aspects, product and process efficiency, can be improved at the same time.

Optimal adaptive scheduling and control of beer membrane filtration
Willigenburg, L.G. van; Vollebregt, H.M. ; Sman, R.G.M. van der - \ 2015
Control Engineering Practice 34 (2015). - ISSN 0967-0661 - p. 77 - 87.
An adaptive optimal scheduling and controller design is presented that attempts to improve the performance of beer membrane filtration over the ones currently obtained by operators. The research was performed as part of a large European research project called EU Cafe with the aim to investigate the potential of advanced modelling and control to improve the production and quality of food. Significant improvements are demonstrated in this paper through simulation experiments. Optimal scheduling and control comprises a mixed integer non-linear programming problem (MINLP). By making some suitable assumptions that are approximately satisfied in practice, we manage to significantly simplify the problem by turning it into an ordinary non-linear programming problem (NLP) for which solution methods are readily available. The adaptive part of our scheduler and controller performs model parameter adaptations. These are also obtained by solving associated NLP problems. During cleaning stages in between membrane filtrations enough time is available to solve the NLP problems. This allows for real-time implementation.
Moisture transport in swelling media modelled with a Lattice Boltzmann scheme having a deforming lattice
Sman, R.G.M. van der - \ 2014
Journal of Food Engineering 124 (2014). - ISSN 0260-8774 - p. 54 - 63.
non-brownian suspensions - diffusion lattice - water transport - flow - simulations - profiles - kinetics - food - gels - validation
In this paper we present a novel numerical scheme for simulating the one-dimensional deformation of hydrogel material due to drying or rehydration. The scheme is based on the versatile Lattice Boltzmann method, which has been extended such that the computational grid (lattice) deforms due to shrinkage or swelling. This property of a deforming grid is new to the lattice Boltzmann method, and a detailed description of this new method is given. Via simulations we show that self-similar moisture concentration profiles occur in two periods in both drying and swelling processes: the penetration period and the regular regime. Given the property of self-similarity, we have been able to formulate a reduced-order model for the regular regime of swelling.
Multiscale analysis of structure development in expanded starch snacks
Sman, R.G.M. van der; Broeze, J. - \ 2014
Journal of Physics-Condensed Matter 26 (2014)46. - ISSN 0953-8984
mass-transfer - food materials - bubble-growth - porous-media - systems - polymer - phase - model - simulation - extrusion
In this paper we perform a multiscale analysis of the food structuring process of the expansion of starchy snack foods like keropok, which obtains a solid foam structure. In particular, we want to investigate the validity of the hypothesis of Kokini and coworkers, that expansion is optimal at the moisture content, where the glass transition and the boiling line intersect. In our analysis we make use of several tools, (1) time scale analysis from the field of physical transport phenomena, (2) the scale separation map (SSM) developed within a multiscale simulation framework of complex automata, (3) the supplemented state diagram (SSD), depicting phase transition and glass transition lines, and (4) a multiscale simulation model for the bubble expansion. Results of the time scale analysis are plotted in the SSD, and give insight into the dominant physical processes involved in expansion. Furthermore, the results of the time scale analysis are used to construct the SSM, which has aided us in the construction of the multiscale simulation model. Simulation results are plotted in the SSD. This clearly shows that the hypothesis of Kokini is qualitatively true, but has to be refined. Our results show that bubble expansion is optimal for moisture content, where the boiling line for gas pressure of 4 bars intersects the isoviscosity line of the critical viscosity 10(6) Pa.s, which runs parallel to the glass transition line.
Effects of salt on the expansion of starchy snacks: a multiscale analysis
Sman, R.G.M. van der; Broeze, J. - \ 2014
Food & Function 5 (2014)12. - ISSN 2042-6496 - p. 3076 - 3082.
glass-transition - sodium-chloride - aqueous-solutions - mass-transfer - sucrose - extrusion - potato - water - trehalose - mixtures
We investigate the effect of salt on the expansion of starchy snacks during frying by means of a multiscale simulation model. This model has been developed earlier for starchy snacks without salt. The simulation results are analysed by means of the supplemented state diagram. We have found that the optimal expansion for salty snacks occurs under the same conditions as for snacks without salt. This occurs at the moisture content where the 4 bar boiling line intersects the critical isoviscosity line of 1 MPa s. Salt is shown to influence both the boiling line and the critical isoviscosity line, via a change of the glass transition. The optimal moisture content for salty snacks is lower than that of unsalted snacks. We view our findings as important for reformulations of starchy snacks with lower salt levels. Furthermore, the presented tools of the multiscale simulations and supplemented state diagram can generally be used for reformulation problems in structured foods.
Lattice Boltzmann simulation of the stability of thin films in foams
Sman, R.G.M. van der - \ 2014
Chips in hete lucht gebakken
Jong, M. de; Meinders, M.B.J. ; Sman, R.G.M. van der - \ 2014
Voedingsmiddelentechnologie 2014 (2014)13. - ISSN 0042-7934 - p. 20 - 21.
Mesoscale models of dispersions stabilized by surfactants and colloids
Sman, R.G.M. van der; Meinders, M.B.J. - \ 2014
Advances in Colloid and Interface Science 211 (2014). - ISSN 0001-8686 - p. 63 - 76.
dissipative particle dynamics - fluid-fluid interfaces - lattice-boltzmann simulations - phase-separation dynamics - pickering emulsions - soluble surfactants - amphiphilic fluids - binary fluids - adsorption - flows
In this paper we discuss and give an outlook on numerical models describing dispersions, stabilized by surfactants and colloidal particles. Examples of these dispersions are foams and emulsions. In particular, we focus on the potential of the diffuse interface models based on a free energy approach, which describe dispersions with the surface-active agent soluble in one of the bulk phases. The free energy approach renders thermodynamic consistent models with realistic sorption isotherms and adsorption kinetics. The free energy approach is attractive because of its ability to describe highly complex dispersions, such as emulsions stabilized by ionic surfactants, or surfactant mixtures and dispersions with surfactant micelles. We have classified existing numerical methods into classes, using either a Eulerian or a Lagrangian representation for fluid and for the surfactant/colloid. A Eulerian representation gives a more coarse-grained, mean field description of the surface-active agent, while a Lagrangian representation can deal with steric effects and larger complexity concerning geometry and (amphiphilic) wetting properties of colloids and surfactants. However, the similarity between the description of wetting properties of both Eulerian and Lagrangian models allows for the development of hybrid Eulerian/Lagrangian models having advantages of both representations.
Computational physics of edible soft matter
Sman, Ruud van der - \ 2014
Rehydration kinetics of freeze-dried carrots
Vergeldt, F.J. ; Dalen, G. van; Duijster, A.J. ; Voda, A. ; Khalloufi, S. ; Vliet, L.J. van; As, H. van; Duynhoven, J.P.M. van; Sman, R.G.M. van der - \ 2014
Innovative Food Science and Emerging Technologies 24 (2014). - ISSN 1466-8564 - p. 40 - 47.
fruits - foods - microstructure - vegetables - quality - impact - nmr
Rehydration kinetics by two modes of imbibition is studied in pieces of freeze-dried winter carrot, after different thermal pre-treatments. Water ingress at room temperature is measured in real time by in situ MRI and NMR relaxometry. Blanched samples rehydrate substantially faster compared to non-blanched samples, independent of their porous microstructure. It is proposed that for non-blanched tissues immobilized sugars result in nearly complete swelling of the solid matrix, hindering the ingress of water through the porous network. Nonblanched carrot pieces frozen at-28 °C rehydrate faster compared to those frozen at-150 °C, due to blocking of smaller pores by swelling. In blanched tissues themobilization of sugars results in amore homogeneous Sugar distribution, leading to less swelling of the solid matrix and allowing fast ingress of water via capillary suction. Industrial relevance: The dried fruits and vegetables that are currently available on the market are a poor compromise between convenience (rehydration kinetics) and sensorial quality. This is a major bottleneck for consumers to “Make the Healthy Choice the Easy Choice” and this also negatively impacts market growth. Currently, rational optimization of drying processes is impeded by lack of insight which structural features determine rehydration kinetics (convenience) and texture (sensorial quality) upon rehydration. We therefore started a program to quantitatively assess and model microstructural features and rehydration behavior of freeze-dried carrots as a model system.
Impact of different drying trajectories on degradation of nutritional compounds in broccoli (Brassica oleracea var. italica)
Jin, X. ; Oliviero, T. ; Sman, R.G.M. van der; Verkerk, R. ; Dekker, M. ; Boxtel, A.J.B. van - \ 2014
Food Science and Technology = Lebensmittel-Wissenschaft und Technologie 59 (2014)1. - ISSN 0023-6438 - p. 189 - 195.
ascorbic-acid - antioxidant capacity - cooking methods - tomato halves - red cabbage - vitamin-c - temperature - vegetables - myrosinase - retention
This work concerns the degradation of the nutritional compounds glucoraphanin (GR) and vitamin C (Vc), and the inactivation of the enzyme myrosinase (MYR) in broccoli (Brassica oleracea var. italica) during drying with air temperatures in the range of 30e60 C. Dynamic optimization is applied to find the optimized temperature trajectories that minimize degradation and inactivation. Simulation and experimental results for optimized temperature trajectories are compared to constant inlet air temperature drying at 40 and 50 C. The results show that with the optimized temperature trajectories the retention of GR, MYR and Vc improved significantly. Moreover, the experiments show that degradation and inactivation during drying is slower than expected from kinetic studies. The deviation is explained from the difference in the physical state of the samples used in the drying experiments, i.e. original plant tissue versus the grounded state of the plant tissue used in the experiments for the kinetic studies. The results indicate that besides temperature and moisture content the physical state is also an important aspect in the degradation of nutritional compounds and enzymes.
Energy efficient drying strategies to retain nutritional components in broccoli broccoli (Brassica oleracea var. italica)
Jin, X. ; Sman, R.G.M. van der; Straten, G. van; Boom, R.M. ; Boxtel, A.J.B. van - \ 2014
Journal of Food Engineering 123 (2014). - ISSN 0260-8774 - p. 172 - 178.
ascorbic-acid - tomato halves - vitamin-c - optimization - heat - temperature - consumption - degradation - health - trends
This work concerns the combined optimization of the retention of bioactive components and energy efficiency during drying of broccoli. Kinetics for the degradation of glucosinolates, vitamin C and drying of broccoli are used to calculate optimal drying trajectories for the control variables air flow rate and temperature. It is shown from plots of the optimal drying trajectories in moisture–temperature state diagrams with degradation and drying rates, that areas with high degradation rates are circumvented. The optimized drying strategies result in significant improvement of energy efficiency (65%) and vitamin C retention of 55%.
Multiphysics pore-scale model for the rehydration of porous foods
Sman, R.G.M. van der; Vergeldt, F.J. ; As, H. van; Dalen, G. van; Voda, A. ; Duynhoven, J.P.M. van - \ 2014
Innovative Food Science and Emerging Technologies 24 (2014). - ISSN 1466-8564 - p. 69 - 79.
moisture transport - mass-transfer - water - imbibition - quality - media - pressure - lattice - liquid - fruits
In this paper we present a pore-scale model describing the multiphysics occurring during the rehydration of freeze-dried vegetables. This pore-scale model is part of a multiscale simulation model, which should explain the effect of microstructure and pre-treatments on the rehydration rate. Simulation results are compared to experimental data, obtained by MRI and XRT. Time scale estimates based on the pore-scale model formulation agree with the experimental observations. Furthermore, the pore-scale simulation model provides a plausible explanation for the strongly increased rehydration rate, induced by the blanching pre-treatment. Industrial relevance The increased insight in the physical processes governing the rehydration of porous or freeze-dried foods gives more rationale for optimizing all processing steps. Industry is seeking for means to give dried fruits and vegetables more convenience, but also higher quality concerning health and texture. This study shows that blanching pretreatment prior to freeze-drying strongly enhances the rehydration, while the loss of nutrients is hardly affected.
Measuring and modelling of diffusivities in carbohydrate-rich matrices during thin film drying
Perdana, J.A. ; Sman, R.G.M. van der; Fox, M.B. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2014
Journal of Food Engineering 122 (2014). - ISSN 0260-8774 - p. 38 - 47.
glass-transition temperature - free-volume theory - lactobacillus-plantarum - diffusion-coefficients - sucrose solutions - moisture-content - solvent systems - sugar solutions - water - droplet
Knowledge about moisture diffusivity in solid matrices is a key for understanding drying behaviour of for example probiotic or enzymatic formulations. This paper presents an experimental procedure to determine moisture diffusivity on the basis of thin film drying and gravimetric analysis in a Dynamic Vapour Sorption (DVS) system. The extraction of moisture diffusivity is based on the “regular regime approach”. The method was explored and verified for its assumptions. It provided insight in the effect of moisture content and temperature on moisture diffusivity. Moreover, it was found that moisture diffusivity in different carbohydrate systems was similar and decreased with moisture content. The latter was explained by similar molecular interactions in carbohydrate systems and formation of a percolating network at low moisture content that affects water mobility. Subsequently, measured moisture diffusivities were compared to model predictions based on the generalised Darken relation. It was found that predicted moisture diffusivities were in fair agreement with these, including the effect of moisture content and temperature on moisture diffusivity. At low moisture content the model overestimated the sensitivity of moisture diffusivity towards temperature. This was explained by the fact that the different water–solid interactions at lower moisture content (including relaxation behaviour in the glassy state) are not considered in the modelling. Finally, the methodology was successfully evaluated to other solid matrices such as glycerol, skimmed milk and casein, providing different moisture diffusivities as function of moisture content.
Moisture Sorption Isotherms of Broccoli Interpreted with the Flory-Huggins Free Volume Theory
Jin, X. ; Sman, R.G.M. van der; Maanen, J.F.C. van; Deventer, H.C. van; Straten, G. van; Boom, R.M. ; Boxtel, A.J.B. van - \ 2014
Food Biophysics 9 (2014)1. - ISSN 1557-1858 - p. 1 - 9.
water activity - glassy-polymers - drying methods - carrot slices - tissue-damage - quality - vegetables - mixtures - heat - pretreatment
In this work, the Flory Huggins Free Volume theory is used to interpret the sorption isotherms of broccoli from its composition and using physical properties of the components. This theory considers the mixing properties of water, biopolymers and solutes and has the potential to describe the sorption isotherms for varying product moisture content, composition and temperature. The required physical properties of the pure components in food became available in recent years and allow now the prediction of the sorption isotherms with this theory. Sorption isotherm experiments have been performed for broccoli florets and stalks, at two temperatures. Experimental data shows that the Flory Huggins Free Volume (FHFV) theory represents the sorption isotherm of fresh and blanched broccoli samples accurately. The results also show that blanching affects the sorption isotherm due to the change of composition via leaching solutes and the change of interaction parameter due to protein denaturation
Stability of foam films investigated by Lattice-Bolzmann phase-field method
Sman, R.G.M. van der; Meinders, M.B.J. - \ 2013
Water dynamics in solid foams
Sman, Ruud van der - \ 2013
Multiscale modeling in food engineering
Ho, Q.T. ; Carmeliet, J. ; Datta, A.K. ; Defraeye, T. ; Delele, M.A. ; Herremans, E. ; Opara, L. ; Ramon, H. ; Tijskens, E. ; Sman, R.G.M. van der; Liedekerke, P. Van; Verboven, P. ; Nicolai, B.M. - \ 2013
Journal of Food Engineering 114 (2013)3. - ISSN 0260-8774 - p. 279 - 291.
dissipative particle dynamics - lattice-boltzmann simulations - ray computed-tomography - random-field parameters - subsp mitis wallr. - mass-transfer - porous-media - moisture transport - discrete element - air-flow
Since many years food engineers have attempted to describe physical phenomena such as heat and mass transfer that occur in food during unit operations by means of mathematical models. Foods are hierarchically structured and have features that extend from the molecular scale to the food plant scale. In order to reduce computational complexity, food features at the fine scale are usually not modeled explicitly but incorporated through averaging procedures into models that operate at the coarse scale. As a consequence, detailed insight into the processes at the microscale is lost, and the coarse scale model parameters are apparent rather than physical parameters. As it is impractical to measure these parameters for the large number of foods that exist, the use of advanced mathematical models in the food industry is still limited. A new modeling paradigm - multiscale modeling - has appeared that may alleviate these problems. Multiscale models are essentially a hierarchy of sub-models which describe the material behavior at different spatial scales in such a way that the sub-models are interconnected. In this article we will introduce the underlying physical and computational concepts. We will give an overview of applications of multiscale modeling in food engineering, and discuss future prospects. (C) 2012 Elsevier Ltd. All rights reserved.
Moisture sorption in mixtures of biopolymer, disaccharides and water
Sman, R.G.M. van der - \ 2013
Food Hydrocolloids 32 (2013)1. - ISSN 0268-005X - p. 186 - 194.
glass-transition temperature - frozen state transitions - vapor sorption - poly(ethylene glycol) - amorphous mixtures - sucrose - behavior - prediction - polymers - crystallization
The moisture sorption of ternary mixtures of biopolymer, sugar and water is investigated by means of the Free-Volume-Flory-Huggins (FVFH) theory. The earlier FVFH theory developed for binary mixtures of biopolymer/water and sugar/water has to be modified to account for two effects: 1) the change in the glass temperature due to the non-ideal mixing of biopolymer and 2) inhibition of self-association of the polymer if the mixture is quenched very fast into the glassy state. The modified FVFH theory forms a good basis for predicting moisture sorption for quaternary mixtures of biopolymers, di-, mono-saccharides and water - which can be viewed as a model for vegetables and fruits. (c) 2013 Elsevier Ltd. All rights reserved.
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