Andreas Håkansson

• PhD
• Professor (Associate) at Lund University

For more than a century, the dairy industry has used high-pressure homogenization for size reduction of fat globules. The prevailing break-up mechanism, turbulence, has been thoroughly investigated and the equipment continuously optimized thereafter. However, the high-pressure homogenizer is also used in size reduction of plant cell structures, for...

Turbulent emulsification is of considerable industrial interest. Nevertheless, numerical experiments (direct numerical simulations,DNS,with highly resolved interface tracking) have been mainly used to study drop breakup in idealized flows. This study, therefore, compares drop breakup in two different settings (homogenous and isotropic flow, and a s...

Turbulent emulsification is an important unit operation in chemical engineering. Due to its high energy cost, there is substantial interest in increasing the fundamental understanding of drop breakup in these devices, e.g., for optimization. In this study, numerical breakup experiments are used to study turbulent fragmentation of viscous drops, und...

There is a large interest in predicting high-pressure homogenizer (HPH) valve hydrodynamics using CFD, in academic research and industrial R&D. Most of these studies still use two-equation RANS turbulence models, whereas only a few have used LES formulations. From a theoretical perspective, LES is known to be more accurate than RANS, especially in...

The fragmentation rate function connects the fundamental drop breakup process with the resulting drop size distribution and is central to understanding or modeling emulsification processes. There is a large interest in being able to reliably measure it from an emulsification experiment, both for generating data for validating theoretical fragmentat...

Experimentally determined vitamin degradation kinetic parameters are vital input for process optimization, e.g., of nutrient rich beverages such as milk and fruit juices. The standard method of obtaining these parameters is to subject a test-tube of the nutrient (in its food matrix) to a water bath at elevated temperatures and measure remaining con...

Experimental methods to study the breakup frequency in industrial devices are increasingly important. Since industrial production-scale devices are often inaccessible to single-drop experiments, breakup frequencies for these devices can only be studied with “global methods”; i.e., breakup frequency estimated from analyzing emulsification-experiment...

The growing interest in using population balance modeling to describe emulsification processes has spurred an interest in experimentally measuring the breakup frequency. This contribution classifies, compares, and critically reviews the different methods that have been suggested for measuring the breakup frequency, applicable to emulsification devi...

Lactobacillus rhamnosus GG (ATCC 53103) and Bifidobacterium longum NCC 2705 are among the most studied probiotics. However, the first evidence of acyl hydrolase/lipase of two annotated proteins, one in each genome of these strains, is reported in this work. Signal peptide analysis has predicted that these proteins are exported to the extracellular...

Myricetin, a flavonoid found in the plant kingdom, has previously been identified as a food molecule with beneficial effects against obesity. This property has been related with its potential to inhibit lipase, the enzyme responsible for fat digestion. In this study, we investigate the interaction between myricetin and lipase under simplified intes...

Single drop breakup visualizations are the golden standard for experimentally measuring breakup frequency, g, in turbulent flows. There is a growing demand for empirically obtained breakup frequencies, for population balance equation (PBE) based predictive modelling and for comparing to theoretical suggestions. However, five different methods to es...

Diets rich in flavonoids have been related with low obesity rates, which could be related with their potential to inhibit pancreatic lipase, the main enzyme of fat assimilation. Some flavonoids can aggregate in aqueous medium suggesting that the inhibition mechanism could occur on both molecular and colloidal levels. This study investigates the int...

Earlier studies have implied a change in dietary habits of the Swedish population towards a low carbohydrate, high fat diet. Questions have been raised about the development in recent years and potential health effects. We have investigated the dietary intake of Swedish female students enrolled in a university nutrition course between 2002 and 2017...

High-pressure homogenizers are often used in tomato juice production to fragment tomato cells, to increase viscosity. Compared to emulsification, little is known about the mechanism of cell breakup in general and of vegetable cell breakup in particular. The objective of this contribution is to extend the mechanistic understanding of vegetable cell...

Diets rich in flavonoids have been related with low obesity rates, which could be related with their potential to inhibit pancreatic lipase, the main enzyme of fat assimilation. Some flavonoids can aggregate in aqueous medium suggesting that the inhibition mechanism could occur on both molecular and colloidal levels. This study investigates the int...

Myricetin, a flavonoid found in the plant kingdom, has previously been identified as a food molecule with beneficial effects against obesity. This property has been related with its potential to inhibit lipase, the enzyme responsible of fat digestion. In this study we investigate the interaction between myricetin and lipase under simplified intesti...

Drop breakup in high-energy emulsification is often modelled using a population balance equation (PBE) framework. For cases with high emulsifier to disperse phase concentration, the PBE is dominated by the fragmentation term. Since there are no analytical solutions to the continuous PBE for physically reasonable fragmentation rate expressions, a di...

Although extensively studied (and of large importance for food processing) there is still no general consensus on the time-dependent convective heat transfer coefficient (h) in immersion frying – reported values differ by orders of magnitude (4–7000 W m⁻² K⁻¹). Moreover, none of the many methods suggested have become a generally agreed upon standar...

The rate of convective heat transfer is often required to design and optimize food engineering processes. The temperature sensor technique is the most widely used method to measure convective heat transfer coefficients (h-values). Being able to reliably determine h-values is becoming increasingly important with the advances in sophisticated food en...

Emulsion formation by homogenization is commonly used in food production and research to increase product stability and to design colloidal structures. High-energy methods such as high-pressure homogenizers and rotor–stator mixers are the two most common techniques. However, to what extent does the research community understand the emulsion formati...

What do we need to know about our students to better provide for more equitable outcomes? Who will succeed depends on many factors, and student personality traits constitute one factor that has received less attention in the engagement and teaching literature. The aim of the present study is to add to discussions on teaching in higher education by...

Most experimental and numerical investigations of high-pressure homogenizers assume that the valve is fed with a constant flowrate. However, technical homogenizers use piston pumps with either 3 or 5 pistons (production- and pilot-scale machines) or a single piston (laboratory-scale machines). This results in flow pulsation. It is still unknown to...

Obesity is one of the principal human health problems and one of the main treatments against it is the inhibition of pancreatic lipase, the main responsible enzyme of lipid digestion. For that purpose, previous studies have tested several phenolic compounds against lipase, without considering their aggregation behavior in aqueous solutions. Because...

Although originally developed for fat globule disruption in dairy applications, high-pressure homogenizers are extensively used in other food processing applications. Two newer applications are in forming nanoemulsion for delivering supplemented nutrients and as a preservation technique, both using higher pressures than traditional applications. Th...

Although continuous production processes are often desired, many processing industries still work in batch mode due to technical limitations. Transitioning to continuous production requires an in-depth understanding of how each unit operation is affected by the shift. This contribution reviews the scientific understanding of similarities and differ...

High-pressure valve homogenization is a standard technique for nanoemulsion formation in low-viscosity formulations. It is applied extensively in industrial applications and in academic research. This chapter summarizes the scientific-based knowledge in terms of principal mechanisms of operation and practical applicability of the methodology. It is...

Emulsion formation is a challenging task. Breaking a large drop into smaller fragments gives rise to an increase in the total interfacial area and, consequently, in the interfacial energy. External energy must, therefore, be supplied to form an emulsion. Nanoemulsion formation is even more challenging since small drops require even higher interfaci...

Varying processing conditions can strongly affect the microstructure of mayonnaise, opening up new applications for the creation of products tailored to meet different consumer preferences. The aim of the study was to evaluate the effect of emulsification intensity on sensory and instrumental characteristics of full-fat mayonnaise. Mayonnaise, base...

This study suggests a novel method for determination of the channel height in asymmetrical flow field-flow fractionation (AF4), which can be used for calibration of the channel for hydrodynamic radius determinations. The novel method uses an oil-in-water nanoemulsion together with multi angle light scattering (MALS) and elution theory to determine...

Rotor–stator mixers (RSMs) are widely used for emulsification and mixing. However, relatively little is known about the relationship between RSM design, hydrodynamics and performance. Previous studies have investigated shaft power draw as a function of design. However, power draw alone is not sufficient to predict efficiency. In order to understand...

Föreläsningen är en märklig undervisningsform. Samtidigt som den är den vanligast förekommande metoden, är den också den mest föraktade. Det finns gott om högskolepedagogisk litteratur som förklarar varför föreläsningen är olämplig för att stimulera lärande. Ändå fortsätter vi föreläsa. Det kan tyckas motsägelsefullt.Denna reflektion vänder på fråg...

Computational fluid dynamics (CFD) has been applied extensively for studying rotor-stator mixers (RSM) in the past, both as a design-tool and in modelling mixing and emulsification. Modelling is always a balance between accuracy and computational cost. The theoretically soundest methods (i.e. fully resolved transient simulations) have often been de...

The high-pressure homogenizer (HPH) is, together with the rotor–stator mixer (RSM), the standard equipment for emulsification in many fields of chemical processing. Both give rise to intense turbulence which, in turn, gives rise to drop breakup. Previous investigations focus on average turbulent disruptive stress. However, turbulence is a stochasti...

Supplementary MATLAB code used to draw the range of permissible parameters.

CONCLUSIONS: ‘Meal’ is commonly defined by being equal to intrinsic properties, specifically food composition or type. BACKGROUND: University level education rests on science and proven experience (1). Within the scientific area Food and Meal Science, defining the word meal has been in focus. The meal is a concept frequently used by scholars in aca...

Coalescence during emulsification has a significant effect on the outcome of the process, especially for the high volume fractions of disperse phase common in food and pharmaceutical processing. Controlling emulsification requires that the extent of coalescence during different conditions can be quantified. The step-down technique is the most commo...

Drop fragmentation in high intensity turbulent emulsification processing equipment–such as rotor-stator mixers (RSMs)–has traditionally been described in terms of a stress balance; between the stabilizing stress of the drop and the time-averaged turbulent stress at the most intense position of the flow. As shown in part 1 of this series, this appro...

Despite large industrial relevance, the relation between rotor-stator geometry, hydrodynamics and drop breakup is poorly understood, partly since no methods for measuring the fragmenting stresses acting on drops have been established. This study attempts to bridge this gap by developing, applying and evaluating two approaches for estimating local t...

Rotor-stator mixers (RSMs) are available in different designs, e.g. with different number of stator slots and slot dimensions. However, the relationship between stator design and the RSM hydrodynamics is not well understood. Consequently, manufacturers still base design and stator screen recommendations on trial-and-error. This study reports experi...

The high-pressure homogenizer (HPH) is used extensively in the processing of non-solid foods. Food researchers and producers use HPHs of different scales, from laboratory-scale (∼10 L/h) to the largest production-scale machines (∼50 000 L/h). Hence, the process design and interpretation of academic findings regarding industrial condition requires a...

The theoretical understanding of inline rotor-stator mixer (RSM) efficiency, described in terms of the dissipation rate of turbulent kinetic energy as a function of mixer design and operation, is still poor. As opposed to the correlations for shaft power draw, where a substantial amount of experimental support for the suggested correlations exists,...

Unhealthy food in advertising has been suggested as a mediator for the increase in diet-related illness. This study quantitatively investigates changes in food advertising between 1995 and 2014 in terms of food categories promoted, macronutrient content, and percentage of foods classified as heathy or unhealthy from a sample of 7,199 ads from three...

Rotor stator mixers (RSMs) can be operated in either batch or inline mode. When operating a rotor-stator geometry in batch mode, it typically experiences an order of magnitude higher volumetric flow through the stator than in inline mode. This is expected to cause difference to the flow and turbulence in the rotor-stator region. This study uses com...

Mechanistic understanding of industrial food-emulsification is necessary for optimal operation and design. Industrial mayonnaise production is yet poorly understood, partly due to a lack of experimental data and partly due to the complexity of the product. This study suggests a systematic method for building mechanistic insight, by investigating su...

Emulsification is a common process in the production in many non-solid foods. These food-emulsions often have high disperse phase volume fractions and slow emulsifier dynamics, giving rise to substantial coalescence during emulsification. Optimal design and operation of food-emulsification requires experimental methods to study how emulsification i...

Food-emulsions often have high volume fractions of dispersed phase and are thus expected to show coalescence during emulsification, however, food-emulsion coalescence is difficult to measure in homogenizer equipment. This study experimentally estimates the rates of fragmentation and coalescence in a high viscosity and high volume fraction model emu...

Aims: To investigate the trends in nutritional compliance of recipes from a Swedish food magazine to offer a perspective on the effects of home cooking on public health. Methods: The nutritional content of 654 recipes from magazine issues published in 1970, 1980, 2000, and 2010 were collected. The recipes were analyzed for macronutrient energy c...

Background: Previous studies have demonstrated a correlation between diet cost and adherence to nutritional recommendations among consumers in general. This has adverse effects on diet and health inequality. It could be hypothesized that consumers knowledgeable in nutrition escape this correlation. Objective: Investigate whether the previously o...

Historically, home economics (HE) in general, and the consumer education sections in particular, have been criticized for transferring norms and values of conservative elites to the masses. This is in stark contrast to contemporary theoretical views of a modern HE aimed at educating emancipated and critical citizens, and also to modern curricula th...

Health-related illnesses such as obesity and diabetes continue to increase, particularly in groups of low socioeconomic status. The increasing cost of nutritious food has been suggested as an explanation. To construct a price index describing the cost of a diet adhering to nutritional recommendations for a rational and knowledgeable consumer and, f...

Almost two thirds of home economics teachers in Sweden are formally unqualified. Historically, home economics has focused more on fostering and prescribing the “right” choices whereas the modern (2011-) curriculum focuses on teaching consequences of choices and giving students tools for assessing alternatives. Restraining from prescribing norms req...

Linear programming has been used extensively as a tool for nutritional recommendations. Extending the methodology to food formulation presents new challenges, since not all combinations of nutritious ingredients will produce an acceptable food. Furthermore, it would help in implementation and in ensuring the feasibility of the suggested recommendat...

Overconsumption is a widely used term in science, media and among concerned consumers. What do we mean by this term? This study is based on the assumption that both the public debate on consumption and consumer research could benefit from better understanding how this term is used and from clarifying the definition. The primary aim of this study wa...

Increasing competition and regulatory changes place micro-sized enterprises (MSEs) in the agri-food sector under strong competitive pressure. Smallness may be a substantial barrier to success. Previous research suggests that networks can be used strategically to combat these constraints. However, there is a lack of understanding of the extent to wh...

The emulsification process is primarily determined by the rate of fragmentation and coalescence of emulsion drops. However, there is presently no fast, reliable method for measuring these rates for pilot and production scale high pressure homogenizers.In this paper a method for simultaneous estimating fragmentation and coalescence is developed and...

The high-pressure homogenizer emulsification modelling framework by Håkansson et al. (2009a, Chemical Engineering Science 64, 2915–2925; 2009b. Food Hydrocolloids 23, 1177–1183), is further developed in this study. The model, including the simultaneous fragmentation of drops, coalescence of drops and kinetic adsorption of macromolecular emulsifiers...

The effect of disperse phase volume fraction on the turbulence in a scale model of a high-pressure homogenizer was studied experimentally. Velocity fields of the continuous phase were measured using particle image velocimetry. Refractive index matching combined with digital filtering enabled measurement with disperse phase present. Geometry and phy...

Direct determination of hydrodynamic radius from retention time is an advantage of the field-flow fractionation techniques. However, this is not always completely straight forward since non-idealities exist and assumptions have been made in deriving the retention equations. In this study we investigate the effect on accuracy from two factors: (1) l...

In this study we investigate the effect of programmed cross-flows on the error in the hydrodynamic radii (r(h)) determination with asymmetrical flow field-flow fractionation (AsFlFFF). Three different standard polystyrene particles (nominal radii of 30 and 40 and 50 nm) are fractionated with exponentially and linearly decaying cross-flows with diff...

The aim of this study was to find models for turbulent fragmenting forces in the high-pressure homogeniser from data available in Computational Fluid Dynamics (CFD) simulations with Reynolds Averaged Navier Stokes (RANS) turbulence models. In addition to the more common RANS k–ε turbulence models, a Multi-scale k–ε model was tested since experiment...

Since the emulsification in the High-Pressure Homogenizer (HPH) is controlled by hydrodynamic forces, the turbulent flow field in the valve region is of significant interest. Computational Fluid Dynamics (CFD) simulations have been used for this in many studies. However, there are reasons to question if the utilized turbulence models, with their in...

The Oil Transfer Technique (OTT) was developed by Taisne et al. [1] to measure coalescence during emulsification and has been applied since in several studies. One of the main drawbacks of this technique is that it only gives a qualitative measure of coalescence. This paper proposes a new evaluation method of OTT experimental results for estimating...

In this paper we study the properties of molecular and supra molecular species in cereal β-glucan solutions/dispersions by the utilization of asymmetrical flow field-flow fractionation coupled to multi-angle light scattering and refractive index (AsFlFFF-MALS-RI) detectors. The samples were purified barley and oat β-glucans which were dissolved in...

The hydrodynamics of the High Pressure Homogenizer has been investigated in order to increase the understanding of the emulsification process. Fragmentation of drops in the homogenizer is generally assumed to be caused by cavitation and/or turbulence. Both processes are investigated experimentally in order to find its location in the HPH valve regi...

Particle image velocimetry is performed on a model of a high pressure homogenizer, scaled for qualitative similarity of the one phase turbulent flow field in a production scale homogenizer. Flow fields in gap entrance, gap and gap outlet chamber are obtained with high resolution. The measurements show gap flow development and formation of a turbule...

Cavitation is common in high-pressure homogenizers, and has severe negative effects such as noise and mechanical wear, but may also have a beneficial effect in promoting fragmentation. Greater knowledge concerning cavitation in the homogenizer valve is thus important in optimizing the design and utilization of emulsification equipment. The aim of t...

Casein (CN) micelles are naturally occurring colloidal protein aggregates present in a dispersed state in milk. In this paper we aim to obtain a detailed description of physicochemical properties of CN micelles over the entire size distribution using asymmetrical flow field-flow fractionation (AsFlFFF) connected to multiangle light scattering (MALS...

A simulation model for emulsification in high pressure homogenization (HPH), based on a population balance approach, is developed assuming it to be controlled by three simultaneous processes; fragmentation, coalescence and adsorption of a macromolecular emulsifier. The aim is to investigate the implications of adding a set of models together; study...

The emulsification in a high pressure homogenizer was studied using a dynamic simulation model based on the population balance equation. The model includes fragmentation, recoalescence and adsorption of macromolecular emulsifier and uses a simple flow model in order to link the hydrodynamics in the homogenizer to the three physical processes mentio...

Två företag, konkurrenter på en duopolmarknad, undersöks under ett antal förenklande antagande för att finna jämviktsbeteende. Företagen antas förutom pris ha möjlighet att konkurrera genom att erbjuda produkter differentierade i två horisontella dimensioner. En tolkning är att företagen konkurrerar genom pris och lokalisering i en tvådimensionell...

Följande uppsats utgör en litteraturstudie över två vanliga konsumtionsvalsteoretiska antagande och deras biologiska rimlighet. De antagande som testas är: (A) En ekonomisk agent handlar som om hon maximerar en nyttofunktion. (B) Individen är självisk. Angående (A) dras slutsatsen att denna kan antas uppfylld. Antagande (B) är mer komplicerat. Både...