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.

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