Food Biophysics最新文献

To improve the emulsifying property of sodium caseinate (NaCas) as stabilizer of oil-in-water emulsions and encapsulation of bioactive compounds, three hexaglycerol mono-fatty acid esters were chosen as small molecular weight surfactants to complex with NaCas. Hexaglycerol monooleate (HGMO) was found to be the optimal surfactant and the optimal mass ratio was 1:1, through characterization of particle size, Zeta-potential, and turbidity. Fluorescence and FTIR spectra indicated that the hydrophobic interaction and hydrogen bond provided driving forces to the formation of stable complex. The complexation of HGMO to NaCas increased the surface hydrophobicity and decreased surface tension compared with NaCas, and strengthened the EAI and ESI. The NaCas-HGMO complex had good stabilization on rice bran oil-in-water emulsions, in a wide pH and ionic strength, and the forwarding Cur encapsulation in O/W emulsions dramatically reduced the degradation during storage at 4℃. Therefore, the present NaCas-HGMO complex might be employed as an effective emulsifier to stable O/W emulsions that load lipophilic bioactives in functional foods or beverages.

Octyl gallate (GAC8) as a bioactive compound has excellent antibacterial effectiveness, but its poor hydrophilicity limits its applications. In this work, GAC8 was encapsulated into hydroxypropyl-β-cyclodextrin (HPβCyD) cavity to form an inclusion complex (GAC8/HPβCyD-IC), and their antibacterial activities were investigated. Phase solubility test suggested that the aqueous solubility of GAC8 was prominently enhanced after forming the inclusion complex. The aqueous solution of GAC8/HPβCyD-IC yielded uniform fiber morphology with ~ 900 nm average fiber diameter. The fabricated GAC8/HPβCyD-IC nanofibers (GAC8/HPβCyD-IC NFs) were characterized by ¹H NMR, FT-IR, XRD, DSC, and TGA, revealing successful synthesis of GAC8/HPβCyD-IC NFs and the thermal stability of GAC8 was enhanced by inclusion complexation with HPβCyD. Furthermore, GAC8/HPβCyD-IC NFs possessed antibacterial activity against E. coli (12.5 mm zone of inhibition), S. aureus (18.5 mm zone of inhibition). The results of DNA and protein leakage in the experiment indicated that GAC8/HPβCyD-IC NFs can disrupt the membrane integrity of bacteria. Meanwhile, GAC8/HPβCyD-IC NFs suppressed the colony growth of E. coli on Chinese giant salamander meat. Overall, the nanofibers encapsulating GAC8/HPβCyD-IC were potential antibacterial food packaging materials.

This study aims to assess the physicochemical and mechanical properties of O/W emulsion gels formulated with quinoa protein partial hydrolysates (QPH). The effect of varying QPH concentrations (0.5%, 1%, and 2%) on these attributes was also investigated. The QPH were obtained from quinoa protein concentrate (QPC) after treatment with alcalase. Surface hydrophobicity (S₀) and emulsifying properties of QPH suspensions were determined. Microstructure, color, water holding capacity (WHC), thermal stability, as well as textural properties of the formulated emulsion gels, were also evaluated. After the hydrolysis treatment, S₀ exhibited a significant increase (p = 0.006). The emulsifying activity of QPH also increased (p = 0.002), while the emulsion stability decreased (p < 0.000) as QPH concentrations increased. Confocal laser scanning microscopy images showed that in QPH-based emulsion gels, oil droplets seemed to be more associated with each other forming a three-dimensional network that was less bound to the matrix, in comparison with QPC-based emulsion gels. In addition, hydrolysis produced a significant reduction in WHC of emulsion gels (p = 0.000); however, in all samples evaluated the WHC was around 70%. Furthermore, after heat treatment, there was a decrease in this parameter (p < 0.000). The evaluation of textural properties showed that hardness was significantly lower for emulsion gels formulated with QPH (p < 0.000); whereas no differences between emulsion gels with 0.5% QPC and those with 0.5, 1, and 2% QPH were obtained. Therefore, hydrolysates have the potential to be used in emulsion gel formulation and could be applied to the development of soft-solid food products.

The gelation of soybean and amaranth proteins through a three-step-strategy: heat-induced denaturation at low protein content (2 or 4 wt%) in the presence of calcium (0.075–0.250 mmol Ca/g protein) and at pH 7.0, followed by freeze drying, and rehydration at higher protein content (10 or 13 wt%) was evaluated for mixtures 80:20 (soybean:amaranth) and for soybean proteins alone. Gelation was favored by high protein contents during denaturation and rehydration, and by a Ca²⁺:protein ratio of 0.100 mmol Ca/g protein. Gels were soft (hardness from texture profile analysis was 0.26 N) and self-supporting and exhibited excellent water-holding capacity (99% upon centrifugation at 20,000xg). The aggregates formed during denaturation were weakly associated upon rehydration and were mostly extractable with water, which partially explained the softness of gels. The appropriate Ca²⁺:protein ratio would lead to a particular distribution of Ca²⁺ between free in solution and bound to proteins, which in turn balanced associations and repulsions allowing gelation. The presence of 20% amaranth proteins led to a more brownish color, a higher adhesiveness and a lower cohesiveness (texture), lower storage modulus, apparent viscosity, consistency index, and area of hysteresis (rheology) when compared to gels containing only soybean proteins. The mechanical differences suggest that soybean proteins dominated the three-dimensional matrix while amaranth proteins were less engaged and acted as a filler.

In this study, α-, β-, γ-cyclodextrin (CD) and carbon quantum dots (CQs) nanocomplexes loaded with quercetin (Qu) were prepared successfully. The results showed that incorporation of CQs increased the Qu encapsulation efficiency and the stability of the nanocomplexes. Fourier transform infrared spectra showed that Qu, CQs and CD were mainly linked by hydrogen bonds. X-ray diffraction results showed that the crystal structures of Qu/CD-CQs were completely different from those of Qu, CD and Qu/CD. The results from differential scanning calorimetry, thermogravimetric analysis and scanning electron microscopy provided evidence for the formation of Qu/CD-CQs. Moreover, compared with Qu, the synthesized Qu/CD-CQs exhibited better physicochemical stabilities, and CD and CQs synergistically improved the stability and bioavailability of Qu. The release of Qu from Qu/CD-CQs was controlled. These results suggested that Qu was efficiently encapsulated by α-, β-, γ-CD and CQs, and the resulting nanocomplexes have great potential for use as nanofunctional foods.

Soy protein isolate (SPI) and its mixture with other biopolymers, such as linear polysaccharides, have been considered as potential components to form biodegradable packaging. Films based on SPI (5% m/m film-forming solution) were prepared with the addition of sodium alginate (ALG) at different concentrations and pH values. The mechanical properties and oxygen permeability were studied and correlated with the crystallinity (X-ray), Fourier transform infrared (FT-IR) spectroscopy and the microstructure (scanning electron microscopy - SEM) of the films. The addition of ALG caused expressive changes in the structural arrangement of the SPI films, especially at pH 6 and 8. The FT-IR spectra of the films also showed the effects of the pH and ALG concentration on the relative intensity of the protein absorption bands, indicating stronger interaction between SPI and ALG at pH 11 than at pH 6 and 8. The resistance of the films was improved with the increasing addition of the polysaccharide, and with the highest alkalinity. Oxygen permeability evaluation of the films formed at pH 11 showed a significant decrease in permeability with increasing incorporation of ALG into the film matrix. The results indicate that the structure and the properties of the SPI-based films were modified and improved with ALG. It was concluded that alginate incorporation in SPI-based films with pH 11 improves mechanical and oxygen barrier properties.

In this research, dual-activated wheat gluten-based nanocomposite active films reinforced by chitosan nanofibers (CHNF) was developed, as well as co-loaded with betanin (BET) and carvone (CAR) for application in food packaging. Free and cationic inulin-coated nanoliposomal forms of BET/CAR were incorporated into the gluten films at 0, 5, and 10% (w/w) gluten concentrations. Fourier-transform infrared spectroscopy was used to detect the formation of new hydrogen bonds between gluten, CHNF, and nanoliposomes (NLPs). Differential scanning calorimetry analysis revealed that the addition of free BET/CAR reduced the endothermic transition temperature of films as compared to the unfortified film; however, the addition of NLPs had no effect on the thermal profile. Similar changes were observed in the crystallinity of films as determined by X-ray powder diffraction analysis. FE-SEM results showed that the incorporation of CHNF and BET/CAR NLPs did not alter the morphology of films but the free BET/CAR induced aggregates formation on the films' surface. CHNF addition enhanced the mechanical, water barrier, and wettability of films. Among the films tested, those containing BET/CAR NLPs had the highest antioxidant potential. However, the encapsulated BET/CAR in inulin-coated NLPs had an improved antimicrobial activity. The films containing the nanoliposomal form of BET/CAR indicated a controlled release behavior.

Rambutan seed protein untreated (No-US) and treated (US) with high intensity ultrasonication (~ 320 W 20 min) had been characterized. LC-MS/MS analysis revealed that molecular sizes of proteins identified in rambutan seed protein were in a range of 4.1 to 318.9 kDa. US protein had higher fractions of small molecular weight proteins than No-US protein, suggesting US disrupted polypeptide structures into smaller units. No-US protein and US protein displayed similar band patterns on SDS PAGE gels. The surface hydrophobicity, the denaturation temperature, and the enthalpy of heat denaturation of No-US protein and US protein were not significantly different. The applied ultrasonication was suggested to not have a strong effect on the protein tertiary conformation. Rambutan seed protein had a relatively high amount of hydrophobic amino acids of 40.2% promoted strong intra-hydrophobic interaction. Emulsions prepared by US protein had lesser bridging flocculation and higher creaming stability than prepared by No-US protein.

The objective of this work was to analyse the effect of partial sucrose replacement by isomalt on the thermal, rheological, and moisture sorption behaviour of cocoa-flavoured confectionery coatings. Formulations were elaborated using sucrose, isomalt, cocoa powder, vegetable oil, lecithin, glycerol, and water. Full-sugar sample (0%) was used as control and reduced-sugar formulations were obtained by replacing 25% and 50% of the sucrose by isomalt. Flow behaviour and thixotropy of liquid formulations were evaluated. Thermal properties (by differential scanning calorimetry) and moisture adsorption and desorption isotherms at 25 °C of films (dried by casting at 40 °C and 26% relative humidity for 24 h) were obtained in the water activity range of 0.225–0.927. Rheological behaviour was described by the Cross model and a first-order structural kinetic model. Sorption isotherms were analysed applying the Generalised D’Arcy and Watt (GDW) and Chi models. The presence of isomalt affected the rheology of liquid formulations, especially in the 50% sample. Similar thixotropic behaviour was found between 0% and 25% samples, with a ~ 100% recovery, indicating a better coating performance. The range of the mean onset (36–41 °C) and melting (95–155 °C) temperatures obtained was high, suggesting that the solid structure of films will be preserved at room storage conditions. The sorption isotherms showed a type-III shape, evidencing two characteristic surfaces with different sorption energies, and hysteresis between adsorption and desorption. The GDW and Chi models accurately described the isotherms. These results are useful to control the elaboration and conservation of reduced-sugar confectionery coatings.