Structural strength analysis of partially crystalline trehalose

Strength concept, which is based on the Williams-Landel-Ferry (WLF) model, was developed using mixed structured powders containing amorphous and crystalline components. At the present study, semi crystalline trehalose powders with various (100:0; 80:20; 60:40; 40:60; 20:80) amorphous to crystalline ratios were analyzed. Amorphous components were prepared from water solution by freeze-drying. Strength analysis, which included water sorption, differential scanning calorimetry, dynamic mechanical analysis and microscopy, was applied. The results indicated that water content significantly decreases glass transition (similar to 100 degrees C) and alpha-relaxation temperatures (similar to 90 degrees C) as well as structural strength parameter (similar to 10 degrees C), while, the effect of crystalline component is less pronounced. This study can be used in processing and characterization of various partially crystalline food products including nutritional formulations and infant formulas

Effects of lipids on the water sorption, glass transition and structural strength of carbohydrate-protein systems

peer-reviewedEncapsulant systems are gaining wide practical interest due to their functional and nutritional properties. This paper was focusing on understanding structural relaxations in that systems near glass transition temperature. Freeze-dried trehalose-whey protein isolate-sunflower oil systems with various ratios of the last were used as a carbohydrate-protein-lipid food model. The Guggenheim-Anderson-de Boer (GAB) water sorption relationship was used as a tool to model water sorption isotherms. The glass transition temperature was obtained by differential scanning calorimetry (DSC). Structural α-relaxation temperatures were measured by dynamical mechanical analyses (DMA), dielectric analysis (DEA) and combined to cover a broad range for strength assessment. The microstructure was characterized by optical light microscopy, confocal laser scanning microscopy and scanning electron microscopy. The C1 and C2 constants for Williams-Landel-Ferry (WLF) equation and structural strength parameter were calculated for each system. The effect of sunflower oil and water contents on strength of carbohydrate-protein system was analyzed. Strength shows decreasing with increasing of lipid concentration in the mixtures and more complex dependence on the water content in a system.This investigation was supported by the Food Institutional Research Measure (FIRM) project “Formulation and Design for Food Structure and Stability” funded by the Department of Agriculture, Food and Marine (11-F-001), coordinated by prof. Y.H. Roos, UCC, Ireland and by the Food Institutional Research Measure (FIRM) project “Developing the next generation of high protein spray dried dairy powders with enhanced hydration properties” (15-F-679) funded by the Department of Agriculture, Food and Marine, coordinated by Dr. Mark Auty, Teagasc Food Research Centre, Moorepark, Co. Cork, Ireland

Thermal gelation and hardening of whey protein beads for subsequent dehydration and encapsulation using vitrifying sugars

peer-reviewedSolid beads were developed using whey protein isolate (WPI) and sugars for controlled hardening and vitrification of wall materials. A concentrated mixture of WPI and sucrose in water, intended for use as gelling and glass-forming ingredients, respectively, was used to form liquid feeds with varying pH, viscosities, surface tensions, solids contents and compositions. Using a peristaltic pump, feeds flowed continuously through silicon tubing and formed droplets. Rapid solidification occurred when droplets were submerged in heated, stirred oil; beads were harvested for vacuum oven drying. Dispersions were characterized by viscosity and flow testing. Dried beads were characterized for porosity, hardness, diameters, and water activity, and microstructures were analyzed with microscopy. Drop-forming dispersions comprised of 40% WPI with 10% sucrose by mass possessed structure forming and shape retention qualities. Feed composition influenced characteristics of the final product more strongly than processing conditions including heating times and temperatures.University College Cor

Effect of concentrations of alginate, soy protein isolate and sunflower oil on water loss, shrinkage, elastic and structural properties of alginate-based emulsion gel beads during gelation

peer-reviewedThe aim of this study was to investigate the influence of concentrations of sodium alginate (0.5%–1.5% in the water phase of an emulsion), soy protein isolate (SPI, 0.5%–2.0% in the water phase) and oil phase (10%–40% in the emulsion) on the properties (including water loss, shrinkage, morphological, elastic, and structural properties) of emulsion gel beads during gelation (0–30 min). Gel beads were prepared with external gelation by dropping emulsions into CaCl2 solutions using pipettes. The Young's modulus of emulsion gel beads kept increasing during gelation before reaching a plateau accompanied by syneresis (i.e., water loss), shrinkage, and structural tightening. SPI absorbed at the surface of oil droplets could prevent re-coalescence of droplets during gelation. Additionally, increasing concentrations of sodium alginate and oil increased the Young's modulus of gel beads. Water loss decreased with increasing contents of alginate, SPI and oil, and shrinkage could be diminished by increasing alginate and oil contents.China Scholarship Counci

Fabrication and characterization of highly re-dispersible dry emulsions

peer-reviewedHighly re-dispersible dry emulsions were obtained through drying konjac glucomannan (KGM) or monoglyceride (MG) structured O/W emulsions. Emulsion powders showed different morphologies, particle size and surface microstructures, depending on the drying method (spray/freeze-drying), and the emulsion compositions. The introduction of a low level of KGM (0.15 wt%) and MG (1 wt%) significantly reduced the level of maltodextrin as wall material. All powdered emulsions showed rapid re-hydration in water. Compared with original emulsions before drying, re-constituted emulsions from spray-dried powders showed slightly increased mean droplet size while that from freeze-dried ones showed slightly decreased mean droplet size. KGM significantly decreased the initial viscosity (p 93% in average). The findings in this study make it possible to obtain emulsion powders and their reconstitutions with desired properties by structuring the original emulsions before drying, and confirmed the possibility of KGM and MG in producing low-cost emulsion powders and the potential of these dry emulsions as novel solid delivery carriers for lipophilic components.Teagasc-The Irish Agriculture and Food Development Authorit

Breakage of infant milk formula through three different processing methods and its influence on powder properties

peer-reviewedDairy powder breakage has always occurred during production and transportation though few studies on it have been published. This paper examines the breakage of infant formula using three different processing methods (laboratory high-speed mixing, lab-scale pneumatic conveying, and factory-scale blending) and the effect of breakage on powder properties. In both mixing and high-velocity pneumatic conveying, particles were broken into smaller entities and the particle size of samples significantly decreased. Particle breakage was accompanied by a significant decrease in porosity and increase in density and surface free fat. This in-turn decreased the rehydration properties of samples, especially for high-speed mixing, while breakage had only a small influence on powder flowability. By contrast, some agglomeration occurred during blending for short time in the blender and the particle size did not decrease (P > 0.05) even for blending at longer time, thus, there were only minor impacts on physical and functional properties of powders.Teagas

Breakage behaviour and functionality of spray-dried agglomerated model infant milk formula: Effect of proteins and carbohydrates content

peer-reviewedThis study explored the effect of protein content (whey protein and casein) and carbohydrate content (lactose, sucrose, and maltodextrin) on the breakage behaviour and its influence on spray-dried agglomerated model infant milk formula. Whey protein powders were bigger in particle size, weaker in structural strength, and marginally more irregular in shape, which resulted in better rehydration properties but more breakage than pure casein powders. Similarly, sucrose samples had better rehydration properties and higher glass transition temperatures but suffered more breakage than maltodextrin and pure lactose powders because of their bigger particle size. The influence of proteins on breakage was greater than that of carbohydrates. Breakage changed the physical and structural properties of powders, especially for whey protein and sucrose samples, which caused the deterioration of rehydration properties and the decrease in crystallization temperatures. From the perspective of particle breakage, unwanted dairy powder breakage could be controlled by changing powder formulations

Water sorption and hydration in spray-dried milk protein powders: Selected physicochemical properties

peer-reviewedLow and high protein dairy powders are prone to caking and sticking and can also be highly insoluble; with powder storage conditions an important factor responsible for such issues. The aim of this study focused on the bulk and surface properties of anhydrous and humidified spray-dried milk protein concentrate (MPC) powders (protein content ~40, 50, 60, 70 or 80%, w/w). Water sorption isotherms, polarized light and scanning electron micrographs showed crystallized lactose in low protein powders at high water activities. High protein systems demonstrated increased bulk diffusion coefficients compared to low protein systems. Glass transition temperatures, α-relaxation temperatures and structural strength significantly decreased with water uptake. CLSM measurements showed that humidified systems have slower real time water diffusion compared to anhydrous systems. Overall, the rate of water diffusion was higher for low protein powders but high protein powders absorbed higher levels of water under high humidity conditions

Effect of pasteurisation and foaming temperature on the physicochemical and foaming properties of nano-filtered mineral acid whey

peer-reviewedFoaming can pose a major challenge during processing of acid whey (AW). In this study, nano-filtered mineral AW was collected from a commercial plant before (AW0) and after pasteurisation (AWpast; 75 °C, 15 s). Both AW samples were foamed at 21 °C and in addition, AWpast was foamed at 61 °C, corresponding to the temperature of in-plant foaming. Physicochemical, foaming, and surface properties of AW samples were compared. Foaming at 21 °C resulted in less pronounced foam characteristics for AWpast compared with AW0. Pasteurisation was found not to significantly affect physicochemical properties; however, interfacial kinetics during foaming were altered, which affected foaming behaviour. Foaming of AWpast at 61 °C produced more stable, “dry” foams. FTIR spectra confirmed the influence of protein unfolding at elevated temperatures on foaming, which was reversible upon cooling. This is significant as it gives processors a mean of controlling foaming through temperature control, where possible.Horizon 2020This research was performed under Marie Sklodowska-Curie Career-FIT Fellowship, Project Code MF20180049, organised by Enterprise Ireland. The project received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 713654

The effect of polyvinylpyrrolidone addition on microstructure, surface aspects, the glass transition temperature and structural strength of honey and coconut sugar powders

peer-reviewedDeep knowledge of the microstructure and physicochemical properties of polymeric food systems, such as honey powders (HP) and coconut sugars (CS), has practical importance for industry and end users. This study investigated the effect of polyvinylpyrrolidone (PVP) addition on microstructure, roughness, glass transition, α-relaxation temperatures and structural strength (S) of anhydrous complex carbohydrates mixtures. The addition of PVP slightly increased the glass transition and α-relaxation temperature for HP and CS systems as high molecular weight components. Systems with PVP addition showed “stronger” behaviour according to the S approach. Polarized light, scanning electron and atomic force microscopies showed slight differences in transparency and shapes between controls and systems with PVP addition. Surface morphological changes and roughness were investigated in this study to provide insight into HP and CS particles’ structural changes. Moreover, S-involved structural diagrams were built to determine S parameters for controlling the structural transformation of HP and CS systems with and without PVP addition. The results obtained in this work provide new information on polymer-carbohydrate interactions in complex food systems and structural transformations during their production and storage