Food Structure-Netherlands最新文献

Protein denaturation can be exploited to modulate its physicochemical properties and create different micro- or nano- structures that could be used for the development of innovative protein-enriched food formulations. This study introduces a novel approach for the production of nanoparticles by denaturing whey protein isolate with ethanol. Whey proteins were subjected to water/ethanol mixtures containing up to 70% w/w ethanol, at varying pH values and NaCl concentrations, to prepare protein nanoparticles in a controlled manner. Confocal microscopy, ATR-FTIR spectroscopy, fluorescence spectroscopy, laser diffraction analysis, and dynamic light scattering were employed to investigate their impact on protein denaturation and nanoparticles’ characteristics. A steep decrease of hydrophobicity up to 50% w/w ethanol was found. A dependence between denaturation and lower pH values was observed. Confocal microscopy revealed that small changes in pH affected the protein’s microstructure, while controlling ethanol concentration allowed for the production of different nanoparticles within narrow pH ranges. High concentrations of NaCl led to extended aggregation even at low ethanol content, while nanoparticles were formed at low NaCl (50 mM) and 30% w/w ethanol. Overall, ethanol denaturation of whey proteins presents a promising technique for the formation of protein nanoparticles.

The impact of authentic storage conditions during shipping was tested on whey protein concentrate powders as environmental conditions heavily influence shelf-life performance. Most experimental studies are conducted at constant conditions of temperature and/or humidity whereas in real shipment conditions powders are often transported all over the world in ships which can experience vastly different temperatures and humidity with large amplitudes from day-time to night-time. Here, industrial whey protein concentrates and β-lactoglobulin powders were stored under cycled temperatures and relative humidity fashioned from authentic data collected on ships carrying dairy powders. Protein lactosylation and denaturation, browning index, particle surface and powder functional properties were measured in order to estimate functional and physicochemical modifications occurring close to authentic storage under shipping. It was observed that oscillation amplitudes tested had no impact on powders unlike the storage duration. The presence of residual lactose (1.5 %) in the whey protein powder induced lactosylation during storage leading to particle surface hydrophobicity and surface elasticity increases whereas for β-lactoglobulin powders (depleted in lactose), transformation of initial lactosylated proteins into advanced Maillard products was observed with no particle surface impact. The rehydration was not impacted regardless of the storage conditions and powder chemical composition.

The mechanical behaviour of hygroscopic granular materials is highly influenced by water. The strong dependence of individual particle properties on moisture content affects the response of their packings, which can agglomerate and eventually lead to loss of product functionality. Despite the frequent occurrence of this problem in industry, only few studies tried to explore the underlying phenomena and investigate the fundamental connection between particle and packing behaviour. This work presents an experimental study that aims to link the water uptake to the microstructural changes in assemblies of couscous, a material selected to be representative of hygroscopic granular materials. In the experiments, the samples are exposed to high relative humidity (RH), and the moisture content increase is quantified with TD-NMR, along with the shift in molecular mobility. An analogous test is performed, during which x-ray tomographies are acquired continuously. We analyse the volumetric response of the sample and of thousands of particles. Despite the oversupply of water molecules available to saturate the system, the formation of a swelling heterogeneity is observed, which we attribute to the pressure gradient affecting locally the adsorption kinetics. Combining the results obtained from the two techniques, water uptake and particle swelling are found to be linearly correlated.

This study aims to explore possibility of production of alginate microcapsules by extrusion-dripping onto bovine milk directly. As a source of calcium necessary for capsules formation, three different types of milk were used (skimmed, whole and enriched milk). In that respect, impact of milk type and properties (e.g. density, viscosity, surface tension and soluble calcium content) on capsules formation was studied. In addition, influence of alginate type and concentration on capsules formation was assessed. The properties of the milk, viscosity in particular, contributed to the greater extent of microcapsules deformation in comparison to ones produced using CaCl₂ solution. More concentrated alginate solutions (up to 1.5%), yielded in more spherical capsules; the same was noticed with G-rich alginate. Upon microcapsules production, significant decrease in soluble calcium (23–27% reduction) and total protein content (1–4% reduction) of milk was observed; this can be assigned to the interactions with alginate network, which was further confirmed via confocal laser scanning microscopy. Encapsulation efficiency study showed that developed capsules were able to entrap blue dextrans at satisfactory extent (from 43 ± 2% to 56 ± 1%), where higher efficiency of encapsulation was achieved for the blue dextrans of higher molecular weight.

Surface modification is a prerequisite procedure for using cellulose nanocrystals (CNCs) in food and other industries. This study reports a simple and safe procedure for CNCs surface modification using physically absorbing food protein (lactoferrin, LF) that could improve the emulsification performance and modulating emulsion lipid digestion in vitro. Modification of CNCs by LF was characterized by adsorption percentage (%), zeta-potential, atom force microscopy, and contact angle. The modification occurred electrostatically between negatively CNCs and positively LF. LF-modified CNCs are more hydrophobic and aggregation-prone depending on the ratio of protein to CNCs and pH. Emulsions stabilized by LF-modified CNCs which are characterized by visual appearance, microstructure, droplet size, and stability against lipid oxidation. Modification of CNCs by LF could improve the emulsification performance of CNCs and show high stability against lipid oxidation. In vitro gastrointestinal digestion of emulsions stabilized by LF-modified CNCs was also investigated by Free fatty acid released (FFA, %) and microstructure. Overall, emulsions stabilized by CNCs particles have lower lipid digestion extent than that of tween 20. The findings would have potential applications in fabrication of novel functional emulsions in food and other industries.

Seafood analogs using culture cells or plant-based materials are rising for future food supply, but their bionic design is still an issue on finely simulating the multiscale structure and function of fishes. For salmon, we compared the back, belly and tail tissues via micro computed tomography (micro-CT) scanning with optimized tissue contrast and spatial resolution. The optimum staining conditions of salmon muscle tissue for micro-CT was 3.75 % IKI (iodine-potassium iodide) solution for 7 days, and the muscle could be separated well from fat and connective tissue. The results of visualization analysis were correlated with the texture profile analysis. A relatively high magnification (3 µm/pixel) was used with fiber tracing procedure to analyze the connection of muscle fiber bundles surrounded by soft tissue. Single muscle fiber (e.g., diameter 117 µm) was successfully and artificially separated from whole visualized tissue through manual division. Overall, this study showed a novel ultra-high-resolution method based on micro-CT to conduct digital analysis of muscle fascicle architecture, and constructed printable model of bionic animal/plant tissue for food design.

Soybean oil was structured with carnauba wax to develop oleogels which were evaluated to fry potato chips as an alternative to deep fat frying with soybean oil. The frying conditions of chips were optimized using response surface methodology (RSM). The frying temperature (147 °C) and time (4 min) of chips were decided by assessing the physical properties of the chips (hardness, color and sensory attributes). Thereafter, a comparative study was carried out between chips fried in oil and oleogel. Compared to chips fried in oil, the chips fried in oleogel absorbed approximately 23% less oil. No negative impact on the sensory scores and fatty acid composition of the chips was observed. The peak force of oleogel fried chips was also insignificantly lower (255.7 ± 17.5 g) than oil fried chips (314.2 ± 19.3 g). The appearance (color) of the oleogel fried chips was significantly better than chips fried in oil since oleogel chips had a higher lightness value (63.53 ± 3.94) than oil chips (53.59 ± 1.31). Moreover, the redness value of oleogel chips was also lower (−2.33 ± 0.47) than chips fried in oil (1.66 ± 0.49). However, significantly higher peroxide values were observed in oleogel fried chips during the storage study, which indicates its lower stability.

In this study, emulsion gels based on egg white protein particles were constructed as emulsifiers, with curdlan as gelation factor. The properties of the emulsion gels and their application in low-fat meat batter systems (LFMs) were investigated to reveal the functional performances of emulsion gel mimicking pork fat. The emulsion gel improved the storage modulus of LFM compared with non-fat meat batter, replicating the rheological properties of pork fat meat batter (PFM). The droplet size distribution and microstructure results indicated that oil could be released from the emulsion gel during high-speed shear and stabilized by the interfacial protein film and meat matrix, showing similar emulsifying mechanisms to PFM. The emulsion gel could also perform thickening and lubricate the mixture of LFM and artificial saliva, indicating the emulsion gel replicated the oral behavior of pork fat. LFM had lower hardness and oil-release quality and higher cooking loss and lightness than PFM (p < 0.05). When fat was replaced by emulsion gel (4 wt% curdlan and 40 vt% oil), LFM performed similar physicochemical and oral processing properties to PFM. The constructed emulsion gel showed promising potential as animal fat mimics to be used in healthy meat production systems.

Full-fat milk was fortified with 0.5, 1, 1.5, or 2 % whey protein isolate (WPI) or micellar casein isolate (MCI). The effect of protein addition on composition, microstructure, and physicochemical properties of heat- and acid-induced milk gels was assessed. Lower moisture and higher calcium content was observed in gels with higher amount of MCI compared with WPI. Low-field nuclear magnetic resonance showed that the population with shorter relaxation, assigned to casein micelles and a more dense protein network, may explain the hardest texture of MCI gels. Contrarily, WPI rich gels showed longer relaxation times which is in agreement with a more open and porous microstructure. Increasing the casein content by 0.5 % formed gel significantly harder, while adding 2 % WPI produced more inhomogeneous gels but the texture was not significantly affected compared with native milk. Protein formulation of the milk can modulate the textural and water holding properties of heat- and acid-induced milk gels.

Microalgae attract increasing interest in enhancing the nutritional values of plant-based foods. However, alterations in the final product’s color (by green algae) and mushy texture can be induced. In this study, we incorporated yellow Chlorella vulgaris (Cv) in pea protein-based meat substitutes and aimed to minimize properties alteration by using wet and disrupted Cv biomass. The cell wall disruption, done by high-pressure homogenization (HPH) at 150 MPa and initial biomass temperature below 10 °C, significantly increased the gelation capacity. The effect was confirmed by (i) a 10x increase in the apparent viscosity of 14% (w/w) Cv suspensions, and (ii) a 2x increase in the storage modulus (G’) of 9:1 (w/w) pea protein isolate - Cv gels. Furthermore, the HPH-treated Cv was successfully incorporated (10% (w/w)) into pea protein-based meat substitutes produced with high-moisture extrusion cooking without altering their visual appearance, hardness, or anisotropy index. Finally, spray drying or fractionation steps of the HPH-treated Cv did not improve protein gels, or meat substitutes produced thereof. This study demonstrated that disrupted Cv is a promising nutritious and sustainable ingredient for meat substitutes.