Emulsifier adsorption kinetics influences drop deformation and breakup in turbulent emulsification.

Turbulent drop breakup is of large importance for applications such as food and pharmaceutical processing, as well as of substantial fundamental scientific interest. Emulsification typically takes place in the presence of surface-active emulsifiers (natural occurring and/or added). Under equilibrium conditions, these lower the interfacial tension, enabling deformation and breakup. However, turbulent deformation is fast in relation to emulsifier kinetics. Little is known about the details of how the emulsifier influences drop deformation under turbulent conditions. During the last years, significant insight in the mechanism of turbulent drop breakup has been reached using numerical experiments. However, these studies typically use a highly simplistic description of how the interface responds to turbulent stress. This study investigates how the limited exchange rate of emulsifier between the bulk and the interface influences the deformation process in turbulent drop breakup for application-relevant emulsifiers and concentrations, in the context of state-of-the-art single drop breakup simulations. In conclusion, if the Weber number is high or the emulsifier is supplied at a concentration giving an adsorption time less than 1/10th of the drop breakup time, deformation proceeds as if the emulsifier adsorbed infinitely fast. Otherwise, the limited emulsifier kinetics delays breakup and can alter the breakup mechanism.

First Evidence of Acyl-Hydrolase/Lipase Activity From Human Probiotic Bacteria: Lactobacillus rhamnosus GG and Bifidobacterium longum NCC 2705.

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 medium. Both proteins were produced in Escherichia coli, purified and characterized. Molecular masses (without signal peptides) were 27 and 52.3 kDa for the proteins of L. rhamnosus and B. longum, respectively. Asymmetrical flow field-flow fractionation analysis has shown that both proteins are present as monomers in their native forms at pH 7. Both have shown enzymatic activity on pNP-laurate at pH 7 and 37°C. The enzyme from L. rhamnosus was characterized deeper, showing preference on pNP-esters with short chain fatty acids. In addition, a computational model of the 3D structure has allowed the prediction of the catalytic amino acids. The enzymatic activities using synthetic substrates were very low for both enzymes. The investigation of natural substrates and biological functions of these enzymes is still open.

Interaction between Myricetin Aggregates and Lipase under Simplified Intestinal Conditions.

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 intestinal conditions from a colloidal point of view. The results show that myricetin form aggregates in aqueous medium and under simplified intestinal condition, where it was found that lipase is in its monomeric form. Although lipase inhibition by myricetin at a molecular level has been reported previously, the results of this study suggest that myricetin aggregates inhibit lipase by a sequestering mechanism as well. The size of these aggregates was determined to be in the range of a few nm to >200 nm.

Interaction of quercetin and epigallocatechin gallate (EGCG) aggregates with pancreatic lipase under simplified intestinal conditions.

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 interaction of two flavonoid aggregates, quercetin and epigallocatechin gallate (EGCG), with pancreatic lipase under simplified intestinal conditions. The stability and the morphology of these flavonoid aggregates were studied in four different solutions: Control (water), salt, low lipase concentration and high lipase concentration. Particles were found by optical microscopy in almost all the solutions tested, except EGCG-control. The results show that the precipitation rate decreases for quercetin and increases for EGCG in salt solution and that lipase stabilize quercetin aggregates. In addition, both flavonoids were shown to precipitate together with pancreatic lipase resulting in a sequestering of the enzyme.

From carbohydrates to fat: Trends in food intake among Swedish nutrition students from 2002 to 2017.

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. The students carried out self-reporting of all food and drink intake over one weekday and one weekend day. Intake of macronutrients (E%) and micronutrients were calculated for the whole period while statistical analysis was performed for changes between 2009 and 2017 (729 women). Results showed significant changes in carbohydrate intake (from 47.0 to 41.4 E%) and fat intake (from 31.7 to 37.5 E%). Carbohydrate intake was significantly lower than the Nordic Nutrition Recommendations (45-60 E%). However, daily fiber intake remains high (3.0 g/MJ) in a national context, and intake of vitamin D and folate appears to increase during the period. The results suggest that the observed national transition from carbohydrate to fat intake persists, and that it might be especially evident among individuals interested in food and nutrition. Considering the fiber and micronutrient intake, the change is not necessarily unfavorable for this particular group.

Emulsion Formation by Homogenization: Current Understanding and Future Perspectives.

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 formation taking place in these devices? This contribution attempts to answer this question through critically reviewing the scientific literature, starting with the hydrodynamics of homogenizers and continuing by reviewing drop breakup and coalescence. It is concluded that although research in this field has been ongoing for a century and has provided a substantial amount of empirical correlations and scaling laws, the fundamental understanding is still limited, especially in the case of emulsions with a high-volume fraction of the disperse phase, as seen in many food applications. These limitations in the current understanding are also used to provide future perspectives and suggest directions for further investigation.

Interaction Between Phenolic Compounds and Lipase: The Influence of Solubility and Presence of Particles in the IC50 Value.

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 of this, the present study focuses on understanding how the solubility and the presence of particles affect the IC50 value of the interaction between lipase and phenolic compounds present in beverages like fruit juices and teas. Therefore, the inhibitory capacity against pancreatic lipase and the aggregate formation of 9 phenolic compounds (quercetin, rutin, myricetin, catechin, epigallocatechin gallate, cyanidin, caffeic acid, chlorogenic acid, and vanillic acid) were analyzed. The results obtained together with the solubility data from literature were treated by principal component analysis and indicate that the IC50 value does not correlate with the solubility or aggregate formation of the phenolic compounds. However, the IC50 values of phenolic compounds which aggregate during the assay conditions have low reproducibility. This study shows that the aggregate formation of phenolic compounds plays an important role during in vitro assays for pancreatic lipase inhibition and should be considered in future experiments as it can lead to false positive results. In terms of particle formation, the flavonoids investigated in this study are more prone to aggregation compared to the phenolic acids.

The Effect of Emulsion Intensity on Selected Sensory and Instrumental Texture Properties of Full-Fat Mayonnaise.

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, based on a standard recipe, was processed at low and high emulsification intensities, with selected sensory and instrumental properties then evaluated using an analytical panel and a back extrusion method. The evaluation also included a commercial reference mayonnaise. The overall effects of a higher emulsification intensity on the sensory and instrumental characteristics of full-fat mayonnaise were limited. However, texture was affected, with a more intense emulsification resulting in a firmer mayonnaise according to both back extrusion data and the analytical sensory panel. Appearance, taste and flavor attributes were not affected by processing.

An alternative method for calibration of flow field flow fractionation channels for hydrodynamic radius determination: The nanoemulsion method (featuring multi angle light scattering).

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 channel height from an AF4 experiment. The method is validated using two orthogonal methods; first, by using standard particle elution experiments and, secondly, by imaging an assembled and carrier liquid filled channel by x-ray computed tomography (XCT). It is concluded that the channel height can be determined with approximately the same accuracy as with the traditional channel height determination technique. However, the nanoemulsion method can be used under more challenging conditions than standard particles, as the nanoemulsion remains stable in a wider pH range than the previously used standard particles. Moreover, the novel method is also more cost effective.

Error estimation, validity and best practice guidelines for quantifying coalescence frequency during emulsification using the step-down technique.

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 commonly used method for measuring coalescence frequency during emulsification. However, the validity of the method has been questioned. No in-depth theoretical validation or best practice guidelines have been provided for the step-down technique, or for any of the suggested alternative methods. This contribution derives error estimates for three non-idealities present in every step-down experiment: i) limited sampling rate, ii) non-instantaneous step-down and iii) residual fragmentation after the step. It is concluded that all three factors give rise to systematic errors in estimating coalescence rate. However, by carefully choosing experimental settings, the errors can be kept small. The method, thus, remains suitable for many conditions. Best practice guidelines for applying the method are given, both generally, and more specifically for stirred tank oil-in-water emulsification.

Are Food Advertisements Promoting More Unhealthy Foods and Beverages over Time? Evidence from Three Swedish Food Magazines, 1995-2014.

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 Swedish food magazines. With the exception of increased alcoholic beverage and decreased carbohydrate-rich-food promotion, no monotonic trends of increasingly unhealthy food advertisement are found. From these findings, it is argued that food magazine advertising is not a mediator of the adverse dietary trend.

Internet-delivered acceptance-based behaviour therapy for generalized anxiety disorder: A randomized controlled trial.

Generalized anxiety disorder (GAD) is a disabling condition which can be treated with cognitive behaviour therapy (CBT). The present study tested the effects of therapist-guided internet-delivered acceptance-based behaviour therapy on symptoms of GAD and quality of life. An audio CD with acceptance and mindfulness exercises and a separate workbook were also included in the treatment. Participants diagnosed with GAD (N = 103) were randomly allocated to immediate therapist-guided internet-delivered acceptance-based behaviour therapy or to a waiting-list control condition. A six month follow-up was also included. Results using hierarchical linear modelling showed moderate to large effects on symptoms of GAD (Cohen's d = 0.70 to 0.98), moderate effects on depressive symptoms (Cohen's d = 0.51 to 0.56), and no effect on quality of life. Follow-up data showed maintained effects. While there was a 20% dropout rate, sensitivity analyses showed that dropouts did not differ in their degree of change during treatment. To conclude, our study suggests that internet-delivered acceptance-based behaviour therapy can be effective in reducing the symptoms of GAD.

Home cooking trends and dietary illness: nutritional compliance of recipes in a Swedish food magazine 1970-2010.

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 contribution, sodium content, and composition. RESULTS: The recipes were in poor agreement with nutritional recommendations (excessive fat, protein, and sodium and insufficient carbohydrate and fiber content). Significant changes between 1970 and 2010 were the increased calorific contribution of fat (from 38 to 46%) and the reduced contribution of proteins (from 27 to 21%). The calorific contribution from spreads, cheese, bread, and fruit and vegetables have increased significantly, whereas the contribution from meat has decreased significantly. CONCLUSIONS: The poor nutritional compliance identified in this work indicates that consumers using the recipes as norms for home cooking risk following an unhealthy diet. This might have adverse effects on public health. However, the recipes have not become less compliant over time and therefore the data do not show an adverse trend in these norms.

Diet inequality prevails among consumers interested and knowledgeable in nutrition.

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 observed relationship between diet cost and nutritional quality prevails among consumers with an above-average interest in and knowledge of nutrition. DESIGN: Full open diet registrations of 330 students taking a basic university-level course in nutrition over a total of 780 days. RESULTS: The consumers with the highest daily average diet cost differ from the lowest cost quartile: The diets had higher micronutrient density, more fruits and vegetables, and lower energy density. The highest cost daily diet quartile had a significantly higher energy adjusted intake of the micronutrients that were on average consumed below the recommendation (vitamin D, folate, and iron for women). On the other hand, alcohol intake was significantly higher among the high diet cost group. The highest diet cost respondents consumed more fish, meat, coffee, and spreads, whereas the lowest diet cost respondents had a higher consumption of cereals, bread, jam, sausage, and milk. CONCLUSIONS: Dietary differences prevail even in the above-average interested and knowledgeable group. The respondents did not use their higher level of knowledge to break this commonly observed relationship. This suggests that an increased minimum level of knowledge in nutrition may not by itself eliminate dietary inequality.

From diets to foods: using linear programming to formulate a nutritious, minimum-cost porridge mix for children aged 1 to 2 years.

BACKGROUND: 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 recommendations. OBJECTIVE: To extend the previously used linear programming methodology from diet optimization to food formulation using consistency constraints. In addition, to exemplify usability using the case of a porridge mix formulation for emergency situations in rural Mozambique. METHODS: The linear programming method was extended with a consistency constraint based on previously published empirical studies on swelling of starch in soft porridges. The new method was exemplified using the formulation of a nutritious, minimum-cost porridge mix for children aged 1 to 2 years for use as a complete relief food, based primarily on local ingredients, in rural Mozambique. RESULTS: A nutritious porridge fulfilling the consistency constraints was found; however, the minimum cost was unfeasible with local ingredients only. This illustrates the challenges in formulating nutritious yet economically feasible foods from local ingredients. The high cost was caused by the high cost of mineral-rich foods. A nutritious, low-cost porridge that fulfills the consistency constraints was obtained by including supplements of zinc and calcium salts as ingredients. CONCLUSIONS: The optimizations were successful in fulfilling all constraints and provided a feasible porridge, showing that the extended constrained linear programming methodology provides a systematic tool for designing nutritious foods.

Has it become increasingly expensive to follow a nutritious diet? Insights from a new price index for nutritious diets in Sweden 1980-2012.

BACKGROUND: 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. OBJECTIVE: To construct a price index describing the cost of a diet adhering to nutritional recommendations for a rational and knowledgeable consumer and, furthermore, to investigate which nutrients have become more expensive to obtain over time. METHODS: Linear programming and goal programming were used to calculate two optimal and nutritious diets for each year in the interval under different assumptions. The first model describes the rational choice of a cost-minimizing consumer; the second, the choice of a consumer trying to deviate as little as possible from average consumption. Shadow price analysis was used to investigate how nutrients contribute to the diet cost. RESULTS: The cost of a diet adhering to nutritional recommendations has not increased more than general food prices in Sweden between 1980 and 2012. However, following nutrient recommendations increases the diet cost even for a rational consumer, particularly for vitamin D, iron, and selenium. The cost of adhering to the vitamin D recommendation has increased faster than the general food prices. CONCLUSIONS: Not adhering to recommendations (especially those for vitamin D) offers an opportunity for consumers to lower the diet cost. However, the cost of nutritious diets has not increased more than the cost of food in general between 1980 and 2012 in Sweden.

Hydrodynamic radius determination with asymmetrical flow field-flow fractionation using decaying cross-flows. Part II. Experimental evaluation.

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 different decay rates. Hydrodynamic radii are calculated according to retention theory including steric effects. Rapid decay is expected to give rise to systematic deviations in r(h) determination. The error in r(h) was found to be small when decay rates with half-lives longer than 6 min were used, whereas steeper decays could give rise to errors as high as 16% of the particle size. The error is often explained in terms of secondary relaxation. However, comparisons show that experimental errors are significantly larger than what would be expected due to secondary relaxation, suggesting that other factors also have to be considered in order to fully understand deviations for rapidly decaying cross-flow.

Hydrodynamic radius determination with asymmetrical flow field-flow fractionation using decaying cross-flows. Part I. A theoretical approach.

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) level of sophistication of the equations used to determine channel height from a calibration experiment and (2) the influence of secondary relaxation on the accuracy of hydrodynamic radius determination. A new improved technique for estimating the channel height from calibration experiments is suggested. It is concluded that severe systematic error can arise if the most common channel height equations are used and an alternative more rigorous approach is described. For secondary relaxation it is concluded that this effect increases with the cross-flow decay rate. The secondary relaxation effect is quantified for different conditions. This is part one of two. In the second part the determination of hydrodynamic radius are evaluated experimentally under similar conditions.

A method for estimating effective coalescence rates during emulsification from oil transfer experiments.

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 qualitative coalescence rates, e.g. for investigating the scaling of coalescence with emulsification parameters (such as homogenizing pressure, and emulsifier concentration). The method is based on comparison with simulated OTT experiments using bivariate Population Balance Equation models. Simulations have been performed under a wide variety of conditions in order to investigate the influence of assumptions on coalescence and fragmentation kernels. These investigations show that the scaling of coalescence rates could be determined accurately when the scaling of efficient residence time of drops in the active region of homogenization is known. The proposed evaluation method is also exemplified by analyzing OTT data from two previously published studies.

Asymmetrical flow field-flow fractionation enables the characterization of molecular and supramolecular properties of cereal ß-glucan dispersions.

In this paper we study the properties of molecular and supra molecular species in cereal ß-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 ß-glucans which were dissolved in aqueous solution using either mild conditions or more harsh treatments with alkali. Dissolution in 0.5M NaOH was not sufficient to eliminate aggregated structures in barley ß-glucan. The results in this paper show how distinction can possibly be made between molecular and supra molecular species using scaling approaches and conformational parameters obtained from AsFlFFF-MALS-RI over the entire size distribution. Small species in the barley ß-glucan samples display properties ranging from elongated conformation to random coil conformation. Aggregates have low apparent densities and a swollen micro gel structure. Oat ß-glucan displays no properties that can be attributed to a molecularly dissolved ß-glucan showing that dissolution was incomplete. The aggregate properties analyzed were similar between oat and barley ß-glucan.