Food Biophysics最新文献

We studied the phase behavior of 1-myristoyl glycerol (C14), 1-palmitoyl glycerol (C16), 1-stearoyl glycerol (C18), 1-monoarachidate glycerol (C20), and 1-monobehenin glycerol (C22) in vegetable (VO) and mineral (MO) oil using X-ray and DSC analysis. The results obtained showed that the Lα, sub-α1, and sub-α2 transitions observed in the neat C16 to C22 were also present in the corresponding VO and MO solutions (1% to 8% MG). The C14 developed just the Lα and the sub α1 phases, that further transformed into the β phase. The differences between the MGs phase diagrams obtained in VO and MO, were mainly associated with the MGs’ polar “head” solubility in the oil as a function of MGs concentration, as affected by the oil’s relative polarity. Thus, in the VO the phase diagrams of C16 to C22 showed zones where the Lα and sub-α1 phases crystallized concomitantly, affecting the sub-α2 transition temperature. In contrast, in MO the Lα, the sub-α1, and the sub-α2 phases of C16 to C22 occurred in well-differentiated temperature zones independently of MG concentration. This is the first report showing that the C16 also develops the sub-α2 phase in the neat state and in the VO and MO solutions. Based on the X-ray analysis and through molecular modeling we established that the neat C16 to C22 crystallized in a monoclinic form with a 2L organization. The inclination of the alkyl chain associated with the monoclinic organization seemed to be a structural requirement for the crystallization of the sub-α2 phase.

In foam products, awareness of sustainable approaches has focused attention on the replacement of synthetic surfactants with natural alternatives. However, commonly used natural surfactants are sensitive to acidity and high temperature, which reduce the foaming property. In this study, the physicochemical and foam properties of natural saponins from Xanthoceras sorbifolium Bunge leaves (XLs) as foam agents under industry-relevant conditions were studied. Results found that XLs saponins exhibited remarkable foaming ability and foam stability and resistance to low-pH and high-temperature. Further, the decrease in pH and the increase in temperature could decrease the surface tension. In addition, conductivity, particle size and zeta potential results showed that decreasing pH and increasing temperature could reduce the critical micelle concentration values of XLs saponins, thus forming additional micelles and increasing the viscoelasticity of the saponins solution. The enhancement of these properties contributed to forming a foam with favorable stability at low-pH and high-temperature. Such XLs saponins are promising natural alternatives to traditional food or cosmetic foaming agents.

Previous study found soybean isolate protein (SPI)-corn starch (CS) composite films (SPI:CS (4:1) composite film, SPI:CS (1:1) composite film) exhibited good mechanical property and better stability during the short-term storage pre-experiment. In order to accordingly understanding the causes, plasticizer emigration and structural properties of SPI-based composite films stored at different temperatures (5 ℃, 20 ℃, 35 ℃) were systematically investigated over a period of time. High storage temperature (> 20 ℃) accelerated plasticizer emigration, which reflected in increased emigration rate of glycerol molecules and decreased moisture content. Furthermore, the decreased free SH partly formed new disulfide bonds and non-covalent inter-molecular interactions (hydrogen bonds) significantly weakened the protein structure, which influenced mechanical properties changes of SPI-based composite films during storage. The polymerization and aggregation appeared in network structure of the films was bond with disulfide bonds, and plasticizer emigration promoted the reorganization into others, with prevalence of extended β-sheet conformation.

In the present work, the interactions and associations between low denatured pea globulins (PPI) and purified main egg white proteins (ovalbumin (OVA), ovotransferrin (OVT), and lysozyme (LYS)) were studied at pH 7.5 and 9.0 by using isothermal titration calorimetry (ITC), dynamic light scattering (DLS), laser granulometry and confocal laser scanning microscopy (CLSM). From ITC, we detected strong exothermic interactions between PPI and LYS at both pHs, which led to aggregation. At these pH values, the net positive charge of lysozyme favored electrostatic interactions with negative charges of pea proteins, and oligomers were formed during titration experiments. Furthermore, DLS, laser granulometry, and CLSM data showed that the particle size of the mixture increased with increasing LYS to PPI molar ratio (from 0.8 to 20). Large irregular aggregates up to 20–25 μm were formed at high molar ratios and no complex coacervate was observed. No or very weak interactions were detected between OVT or OVA and PPI whatever the pH. These results suggest the role of electrostatic interactions between LYS and PPI when considering protein mixtures.

The poor solubility and sensitive photosensitivity of resveratrol (RES) greatly limit its application in functional aqueous food systems. Herein, the composite particles with gliadin (GLI) as the core and type B gelatin (GEL) as the shell were designed to load resveratrol to enhance its ability to resist ultraviolet radiation and bioavailability. The core-shell structure and size (650 nm) of the composite particles were confirmed by dynamic light scattering, isothermal titration calorimetry (ITC) and transmission electron microscopy (TEM), and the binding between gliadin and gelatin was mainly driven by spontaneous electrostatic force (∆H=-3.080*10⁷, ∆G=-9.055*10⁴). The encapsulation efficiency (EE) and loading capacity (LC) of resveratrol by the particles were 7f8.9% and 35.9 µg/mg, and the particles were characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC). Furthermore, compared with free resveratrol, the anti-ultraviolet radiation ability of resveratrol protected by core-shell particles was significantly enhanced (P < 0.05), and the release percentage was increased from 55.1 to 79.5%. These findings indicate that the composite particles have good application potential for the protection and delivery of hydrophobic active substances.

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Carboxymethyl cellulose (CMC) based edible films, reinforced with date seed powder (DSP) were investigated. An increasing concentration of DSP (5%, 10%, 15%, and 20%) was added to the carboxymethyl cellulose film-forming solution. The physical, antioxidant, antibacterial, mechanical, structural, and thermal properties of the films were studied to investigate the effect of DSP incoportation. The addition of DSP increased the thickness of the films from 0.11 to 0.15 mm, reduced the solubility (95.31–77.23%), and exhibited antibacterial activity against the food-borne pathogens: Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium. Especially for Escherichia coli, and Salmonella typhimurium, the antimicrobial activity was seen only at high concentrations (15% and 20%) of DSP. Besides, the antioxidant capacity increased with increasing concentration of DSP: the DPPH radical scavenging activity increased from 0 to 51.98% while ABTS increased from 0 to 84.58%, when the concentration of DSP increased from 0 to 20%. In addition, the water vapor permeability of the films improved but the tensile strength decreased from 7.66 MPa to 5.12 MPa and the elongation at break increased from 79.03 to 85.95%. This study clearly showed that the DSP could be valorised as an active and reinforcing component in CMC-based biodegradable and edible films to create natural active food packaging.

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This work aimed to evaluate α-amylase activity and structure in the presence of Curcuma longa L. extracts obtained with deep eutectic solvent (DES) and curcumin. Isothermal titration calorimetry (ITC), fluorescence, circular dichroism (CD), and molecular docking were applied to study the effect of additives on enzyme activity and structure. Results showed that in the presence of turmeric extracts, there was a lower catalytic rate. Through the ITC analysis, a lower reaction rate was noticed, related to the inhibition of the enzymatic activity, both in the presence of the extract and of curcumin. The turmeric extracts interacted with the enzyme by a static mechanism as demonstrated by fluorescence. CD showed an increase in negative bands characteristic of hydrophobic interactions between the enzyme and the samples, which probably difficult the access of substrate to the enzyme’s active site. Molecular docking showed that curcumin is capable to interact with the active site of α-amylase confirming results obtained by other techniques. Results presented in this work show the turmeric extracts potential for α-amylase inhibition which may be of interest to the pharmaceutical and food industry.

Biopolymer ingredients have received extensive attention as raw materials for film production due to their low cost, nontoxicity, and compatibility. Xanthoceras sorbifolia seed kernel protein isolate (SKPI), which is prepared from defatted kernel meal, can serve as a valuable source for edible film production. Herein, the performance of SKPI-based films was characterized and evaluated under the influence of pH values (8, 9, and 10) and glycerol concentrations (3.5%, 4.0%, and 4.5% W/V) of the film-forming solutions. The water vapor permeability, color, light transmission, mechanical properties, and microstructural changes of the films were investigated. When the pH value increased from 8 to 10, the tensile strength of glycerol plasticized film increased, while the elongation at break decreased. On the contrary, regardless of the alkalization of SKPI, the flexibility of the films was notably improved with increasing glycerol concentration. In addition, all obtained films exhibited excellent UV-blocking properties. The overall results showed that glycerol concentrations and pH values can be combined to produce SKPI films for multiple packaging requirements in the food industry.

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