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Progressive freeze concentration of whey protein solutions is evaluated. Since solutions in industry are more complex, the effect of the addition of sodium chloride and sucrose on the inclusion behaviour is studied as well. Using a progressive freeze concentrator solutions of whey protein and mixtures of whey protein and/or sucrose and/or sodium chloride were freeze concentrated. At an initial concentration of 4%(w/w), whey proteins were not included in the ice fraction. At higher concentrations the inclusions are caused by the increase in viscosity in the boundary layer, impeding mass transfer. The addition of sucrose caused a similar effect. Presence of sodium chloride causes inclusions through the occurrence of a zone where the solution is locally super-cooled and leads to the formation of dendritic ice which encapsulates pockets of solution in the ice layer. Mixtures of both sucrose and sodium chloride gave no additive effect on solute inclusion but just a concurrent effect.

Material extrudability is a prerequisite for printing 3D structures with extrusion-based food printing. Food materials with different shear-thinning behaviors were printed to develop predictive models for extrudability. A dataset of 131 unique combinations of materials and printing parameters was collected. Image analysis was employed to rapidly quantify extrudability as determined by mode width, line height and width consistency of line filaments. The relation between the printing pressure and the volumetric flow rate followed a power-law relation, which characterizes the extent of shear-thinning of the food materials. Both regression and classification models were trained and tested using the random forest algorithm. The model performance indicated that extrudability can be predicted with moderate to high accuracy by using rheological measurements and printing parameters as inputs. The predictive workflow developed in this study provides a framework to quantitatively assess and predict extrudability for 3D printing of complex food materials. Industrial relevance: Extrusion-based 3D printing has been applied to customize food designs and can potentially enable personalized nutrition. To achieve this, we need to be able to effectively print complex food materials with high accuracy. Variations in composition and rheological properties of complex food materials make achieving proper extrudability not trivial at this moment, and this limits their applicability to extrusion-based food printing. Here, we developed an image analysis tool to measure line filament extrusion of complex food materials that vary in shear-thinning behaviors. We then built predictive models to estimate material extrudability based on material's shear-thinning properties and printing parameters. Data-driven prediction of material's extrudability can help avoid excessive trial-and error experiments in future.

The influence of charging tube materials and diameter on the separation efficiencies of a gluten-starch model mixture and lupine flour was studied. Offline analysis of tribo-charging with different tube materials showed that gluten takes a positive and starch a negative charge. However, the charge of the mixture was found not equal to the sum of the charge of the individual components and measured charges could not be related to the triboelectric series. During electrostatic separation significant protein enrichment was observed for both plant raw-materials. For the model mixture differences in protein, enrichment were observed between tube materials, but this was not the case for lupine flour. The lupine protein content increased from 37 to 65 g/100 g dry flour. Concluding, electrostatic separation needs to be evaluated during separation experiments, as particle-particle interactions dominate the charging process and thus separation of mixtures. Practical applications: The combination of dry milling and electrostatic separation is investigated as a sustainable and mild route for protein fractionation. The results of this study showed that offline charging tube experiments could not predict separation performance of for example finely milled lupin flours. Instead, performance should be directly assessed during separation experiments, which is explained as charging is rather related to differences in material or triboelectric charging properties between powder particles than to charging tube wall properties. The results of this study benefit development of new applications for electrostatic separation.

Progressive freeze concentration is an alternative method to concentrate aqueous industrial streams compared to evaporation or membrane separation. In this research sucrose and maltodextrin solutions were concentrated in a stirred progressive freeze concentrator. The solute inclusion in the formed ice was studied using varying stirring speeds, initial concentrations and freezing plate temperatures. Under constant freezing plate temperature, a lower limit was found for the solute inclusions with increasing stirrer speeds. To improve the freeze concentration process, a decreasing temperature ramp was applied to the freezing plate. This yielded 2 to 3 times less solute inclusions in the ice, while maintaining similar ice yields.

A sustainable dry processing method to obtain nutritional and functional chickpea products was developed, yielding protein concentrates suited to prepare products without additives. Chickpeas were milled and air-classified into protein and starch-enriched concentrates. Subsequently, spontaneous solid state fermentation (SSF) with daily back-slopping was performed at 37 °C. The dominant autochthonous lactic acid bacteria (LAB) strains in chickpea flour and enriched fractions were Pediococcus pentosaceus and Pediococcus acidilactici. Strains were selected on their ability to metabolise flatulence-causing α-galactosides. SSF reduced the pH of the doughs in 24h from 6.6 to 4.2. After 72 h, concentrations of raffinose and stachyose were reduced by 88.3–99.1%, while verbascose became undetectable. Moreover, phytic acid reduced with 17% while total phenolic contents increased with 119%. Besides the observed differences in smell, texture and colour, the sourdoughs showed 67% higher water-holding capacity. This natural route to produce chickpea concentrates thus increases both the nutritive and technical functionality. Industrial relevance Increasing the sustainability of our food production is required to meet the demand for food of our growing world population. A processing route combining dry fractionation and solid state fermentation is developed to prepare chickpea concentrates with improved nutritional properties. This route is more sustainable as the use of water and thus energy-intensive drying steps are minimised. Moreover, it provides more natural ‘clean-label’ foods, i.e., foods with less additives and minimally processed. Solid state fermentation is used to reduce the presence of anti-nutritional factors, i.e., α-galactosides and phytic acid. Autochthonous LAB were accumulated via back-slopping and employed as starter culture as an alternative to the use of a commercial starter culture. Chickpea sourdoughs with enhanced nutritional quality of chickpea were obt

Previous studies suggest that increased intracellular trehalose concentrations can result in increased robustness of probiotics and starter cultures after processing. We evaluated whether pulsed electric field (PEF) pre-treatment, resulting in increased intracellular trehalose concentrations, can lead to enhanced survival during spray drying and subsequent storage and what the effect of the carrier matrix during drying herein is on survival. The applied PEF pre-treatment resulted in increased survival of Lactobacillus plantarum WCFS1 after spray drying and subsequent storage in reconstituted skim milk (RSM), though not in the other evaluated carrier matrices. The same PEF pre-treatment in lactose instead of trehalose electroporation medium resulted also in an increased survival after spray drying in RSM. Further analysis of intracellular trehalose and lactose concentrations revealed that survival after spray drying cannot only be explained by intracellular trehalose and/or lactose concentrations. Experiments with other bacterial strains indicated that strain variability cannot be neglected when designing a process aimed at enhanced bacterial survival after processing. Overall, PEF pre-treatment is promising for enhancing survival of bacteria after drying and storage, though further understanding of the applicability is required for industrial application. Industrial relevance text: Probiotics and starter cultures are very common in food industry. Survival of these cultures during drying processes is essential for their application. A pulsed electric field pre-treatment resulting in increased bacterial survival after spray drying and powder storage may contribute to more energy efficient production processes of dried bacterial cultures.

A two-step dry fractionation process was investigated that further enriches protein from starch-containing legumes. Legumes (pea, lentil, and chickpea) were subjected to milling, air classification, and subsequent triboelectrostatic separation. The air classification first removes starch, whereas the subsequent electrostatic separation removes fiber from the resulting protein concentrate. Successful enrichment was achieved with pea and lentil, but this was not the case for chickpea due to the smaller starch granules and higher fat content. The best conditions for pea were air classification at an air-classifier wheel speed of 8000 rpm. Subsequently, electrostatic separation was optimized with two passes. With this, a protein purity was obtained of 63.4 g/100 g dry basis and a yield of 15.8 g/100 g dry solids. For the overall two-step dry fractionation process, a protein-enriched fraction with a yield of 4.0 g/100 g pea could be obtained, leading to 7.8% of total protein recovered from yellow pea. Industrial relevance: To enrich protein from starch-containing legumes a novel dry method combining air classification and electrostatic separation was developed. Compared to conventional wet extraction, this dry route is much less energy-consuming and preserves the native functionality of the proteins. By adding electrostatic separation to air classification, a higher pea protein purity (up to 63.4–67.6 g/100 g) could be obtained, which is higher than that obtained by air classification only (57.1 g/100 g). It is estimated that for an improved dry fractionation process with increased recovery of material, the yield and protein recovery may be further increased with factor ~ 2.8 compared to the current results.

Arabinoxylans- (AX-) enriched fractions were separated from wheat bran by dry fractionation and utilized for fiber fortification in bread. The obtained AX-enriched fractions (AXF) contained 39.2–55.8% arabinoxylans (dry basis). To produce bread with various AX-fortification levels, wheat flour was partially replaced with AXF in the recipe, i.e., 2%, 5% and 10% of flour weight. Results indicate 10% AX fortification led to decreased specific volume, harder and coarser crumb and darker color of bread, while 2% and 5% showed no significant influence. Next, the bread recipe was adjusted based on Farinograph water absorption and the AXF was pre-soaked in water (with or without xylanase) at 40 ○ C for 16 h before dough mixing. The recipe and process adjustment reduced the detrimental effects of a high-level AX-fortification on bread quality. Bread with 10% AXF showed comparable quality properties as the control and its fiber content (11.75% dry basis) was found twice higher than the control (5.48% dry basis). However, usage of xylanase did not further improve the bread quality under tested conditions. In conclusion, this study shows that AX-enriched fractions from wheat bran have valorization potential for application in food.

Live probiotics can be supplemented to bread as functional ingredients. The viability of probiotics in bread needs to be sufficient to exert a beneficial effect on human health. To maximize the viability, a kinetic study on the inactivation of probiotics during baking was carried out. The thermal inactivation of Lactobacillus plantarum P8 during bread baking was evaluated with rate-dependent kinetic models. The influences of temperature, moisture content, drying rate, and temperature variation rate on the inactivation kinetics were studied explicitly. A kinetic model (Formula presented.), which included temperature (T), moisture content (X), and temperature variation rate (dT/dt) as variables, was found to best describe the concave and sigmoidal survival curves of probiotics in bread crust and in crumb during baking, respectively. The drying rate (dX/dt) was of little influence on the kinetics. The application of the proposed model is limited to baking processes, but could be used to maximize the survival of probiotics in bread products.

Development of 3D food printing applications requires in-depth knowledge on printing behaviour of food materials. In extrusion-based 3D printing, rheological properties of a recipe are critical to achieve successful printing. The objective of this research is to investigate potential correlations between printability of formulations and simple rheological properties. We used tomato paste as a model system to investigate the correlation between printing stability, dispensability and rheological properties. The results show a linear correlation between ingredient's flow stress, zero shear viscosity and corresponding printing stability. The extrusion pressure necessary to extrude tomato paste increased linearly with increasing flow stress. More experiments with other aqueous-based food formulations indicated that their printability aligned reasonably well with the correlation of tomato paste; however, for fat-based products different printing behaviour was observed. Finally, we propose a rational guideline for developing aqueous food recipes with desired printability based on flow stress measured by shear rheology.

Survival of bacteria during drying processes is required for products such as probiotics or starter cultures. In earlier studies high intracellular trehalose concentrations have been related to processing robustness during freezing and drying for several cell types. In this study we evaluated pulsed electric field (PEF) pre-treatment to increase intracellular trehalose in Lactobacillus plantarum WCFS1 and subsequent survival during freeze drying and storage in a trehalose matrix. Surprisingly, despite increased intracellular trehalose by PEF pre-treatment no enhanced survival was observed after drying and storage. Additional analysis of intracellular trehalose before and after freeze drying and spray drying revealed that during the drying process intracellular trehalose concentrations increased. Due to this increase the intracellular trehalose concentrations in the PEF pre-treated and control samples did not differ anymore. To explain what happens during the drying processes, results for trehalose were compared to similar experiments with lactose. A remarkable difference was observed between transfer of trehalose and lactose into cells during the freezing step before freeze drying, while both disaccharides gave similar cellular protection when used as freezing and drying matrix. Generated knowledge on transport of disaccharides into bacterial cells during freezing and drying can benefit processing of living bacterial formulations.

Active ingredients can be supplemented into a bakery product to producefunctional food. However, the preservation of the functionality of these activeingredients during baking remains a challenge for food industry. A deeperunderstanding of the underlying interactions between functionality andbaking is highly desired for developing innovative functional bakery productswith significant health benefits and high product quality. In this work, recentadvances in the development of functional bakery products are reviewed. Theinteractions between the baking process and the functionality of thesupplemented active ingredients are discussed and the perspective of futureresearch is addressed.