Food Structure-Netherlands最新文献

This study introduces a cold-set lentil protein (LP) gel with significantly improved mechanical strength prepared from protein fibrillar aggregates. First, fibrillar aggregates were formed by thermal treatment at an alkaline pH. Subsequently, glucono-δ-lactone (GDL), transglutaminase (TG), or their sequential combination (GDL/TG) was applied to induce the gelation of LP aggregates at room temperature. The gelling mechanism study revealed the formation of covalent bonds in the gel network induced by TG, which was then reinforced by hydrophobic interactions among the protein aggregates induced by GDL. As expected, the sequentially addition of TG and GDL enabled formation of interconnected networks with thick walls and significantly improved gel hardness. This research has provided a new strategy to develop strong lentil protein gels for food texturization thus potentially expanding food applications of lentil protein as an advantageous plant source of protein.

Protein digestion is commonly studied using in vitro models. Validating these models with more complex in vivo observations remains challenging, in particular due to the need for non-invasive techniques. Here, we explore Magnetization Transfer (MT) and Chemical Exchange Saturation Transfer (CEST) MRI for non-invasive monitoring of protein solubilization and hydrolysis during static in vitro digestion using skim milk (SM). We measured CEST spectra of unheated and heated SM during gastric digestion, from which the relative amount of soluble proteins/peptides was estimated by calculating the asymmetric MT ratio (MTR_asym). We also obtained semi-solid volume fractions (v_ss), MT ratio (MTR) and MTR_asym from the same measurement, within 1.3 min. The MTR_asym area increased with gastric digestion, due to solubilization of the initially-formed coagulum, yielding a mean difference of 20 ± 7% between unheated and heated SM (p < 0.005). The v_ss and MTR decreased during gastric digestion and can be used to monitor changes in the coagulum, but not for assessment of soluble proteins/peptides. The MTR_asym increased for heated SM during gastro-intestinal digestion, proving sensitive to protein solubilization and hydrolysis, and is suitable for monitoring protein hydrolysis at later digestion stages. Future steps will include similar MT and CEST studies under dynamic conditions.

There is a growing interest in sustainable and green technology for the improvement of functional properties of grain proteins by altering their composition and structure. This study investigated the structure, physicochemical and functional properties of Bambara groundnut globulin after hydration with plasma-activated water (PAW). Bambara groundnut globulin was dispersed in PAW and hydrated at 4 ℃ for about 12 h. The exposure of Bambara groundnut globulin to plasma resulted in a significant loss of helical structure and over 3-fold increase in β-turns in comparison with the untreated Bambara groundnut protein. Amino acid data for the plasma-treated globulin showed 20 % reduction in glutamic acid content. A slight redshift was observed in fluorescence intensity data of the plasma-treated Bambara groundnut protein. This suggested an unfolding of the protein structure, which also correlated with the observed increased hydrophobicity. However, protein profiles by gel electrophoresis, surface charge, and pH-solubility patterns appeared similar for both plasma-treated and untreated Bambara groundnut globulin samples. Bambara groundnut globulin had reduced emulsifying ability after exposure to plasma as indicated by an increase in the average oil droplet sizes. However, foaming capacities were significantly better and stable at up to 15 mg protein/mL. The hydration of Bambara groundnut globulin with plasma-activated water modifies the structural conformation, reduces the proportion of acidic amino acids of the protein, and improves the foaming properties. Cold plasma treatment by hydration does not seem to improve the emulsifying properties of Bambara groundnut globulin.

Effects of phenolic compounds with different structural complexity (including protocatechuic acid, naringin and tannic acid) on the properties and functions of maize starch-based film were determined, and the intermolecular force between starch and different phenolic compounds was further analyzed. Different phenolic compounds exhibited varying effects on the thickness (0.101–0.141 mm), moisture content (8.32–9.53 %), color (ΔE value: 1.70–5.01), light transmittance (50–63 %), crystalline structure, thermal resistance characteristics, intermolecular force, microstructure, surface morphology, mechanical properties (tensile strength: 3.2–8.8 MPa; elongation at break: 18–38 %), moisture barrier (6.44–10.12 ×10⁻¹¹ g m⁻¹ s⁻¹ Pa⁻¹) and antioxidant activity of film, owing to the differences in the amount of phenolic hydroxyl groups, molecular size and steric hindrance of phenolic compounds. The present results showed that the proper increase of phenolic hydroxyl number, molecular size and addition dose could improve the binding affinity between phenolic compounds and polysaccharides, so as to promote phenolic compounds to aggregate polysaccharide molecules with themselves as the core, resulting in the change of aggregation and disorder degrees among components in film matrix. Meanwhile, the differences on the interactions between phenolic compounds and polysaccharides could lead to the variation of the dispersion and compatibility of film matrix, as well as the crystallinity, spatial structure, hydrophilic domains of film. Furthermore, phenolic compounds with high amount of hydroxyl groups could enhance the antioxidant activities of film. All present results suggested that phenolic compounds had potential value to enhance the properties and function of maize starch-based film.

The pasting characteristics induced by different milling degrees on the cooking quality of quinoa were investigated. The results showed that significant variations were observed in the basic composition of quinoa with different milling degrees, which indicated the existence of effects due to the degree of milling. The combination of starch and water promoted the pasting of quinoa, and with increasing milling, quinoa textural properties tended to produce softer and more viscous. LF NMR results indicated that more water was present in the dense network formed by the starch gelatinization. Rheological properties further demonstrated that milling degree enhanced the interactions between starch molecules and correspondingly increased the energy storage modulus and loss modulus. The microstructures (SEM and CLSM) confirmed that the physical property changes in quinoa were attributed to a dense network structure caused by starch pasting, which was similar to the results of RVA. The higher the amylose/amylopectin ratio (between 0.113 and 0.167), the more pronounced the characteristic peaks. The different degrees of milling of quinoa changed the quinoa crystallinity. Consequently, the degree of milling improved the cooking characteristics and enhanced the physicochemical properties. These results help the quinoa processing industry to develop healthy quinoa products with moderate milling.

The current research aims to explore the oil structuring performance of di-acylglycerides using di-stearin (DS) oleogels, while their mechanical, thermal and structural properties were compared with mono-stearin (MS) and tri-stearin (TS) oleogels. DS was able to form gels at concentration above 0.15 M (10 wt%), which was higher than MS (0.07 M-2.9 wt%) but lower than TS (0.18 M-18 wt%). DS-oleogels exhibited a thermo-reversible behavior characterized with crossover of storage and loss modulus during cooling, similar to MS and TS gelation behavior. DS-oleogels exhibited three broad melting peaks at 22.0–31.7 ℃, 40.8–46.9 ℃, and 54.5–59.8 ℃, indicating the formation of α polymorph which transformed to β′ and β during melting. This polymorph assignment was confirmed by XRD, while the lamellar crystal layers were confirmed by TEM. DS showed relative frequency-independent behavior suggesting an ideally elastic-like material, similar to MS- and TS-oleogels. Interestingly, at low concentration DS exhibited similar hardness values as TS but lower than MS, however, at ≥ 0.22 M, DS and MS exhibit similar values. This behavior suggests that at low concentration intermolecular bonds, such as hydrogen bonds, play a critical role while at higher concentration, secondary network stabilization mechanism such as crowding and aggregation becomes the predominant force.

Model chocolates were developed by gradually replacing cocoa powder in the chocolate system (containing 54 g cocoa butter, 66 g cocoa powder, and 0.5 g lecithin) with sucrose with different D₉₀ particle sizes (25.0, 40.3, 61.5, 98.6, and 163.1 µm) by 15, 50, or 75% on a volume basis. Bloom extents were evaluated by changes in whiteness index (ΔWI) and white area percentage (WA%) while surface roughness was quantified using a new 4-neighborhood-pixels model. Reducing sucrose D₉₀ particle sizes at higher volume fraction levels significantly increased particle interactions (quantified by the sedimentation volume and Casson viscosity) and led to enhanced visual bloom and greater surface morphological changes, indicating that the microstructures in the chocolate matrix for fat migration and recrystallization had a significant impact on bloom during storage. Surface morphological characteristics such as increased pores and protrusions confirmed the occurrence of fat migration and recrystallization during bloom formation.

The purpose of this study was to investigate the effects of different pH conditions on the properties of heat-induced composite gels of Auricularia auricula-judae polysaccharide (AP) and whey protein isolate (WPI). The color, hydration properties, texture, thermal stability, rheological properties, sulfhydryl content, surface hydrophobicity, and microstructure of the gels were evaluated. Due to the Maillard reaction, the color of the gel changed from white to brown with increasing pH. In contrast to the trend observed for color, the gels formed at pH 8 had better water holding capacity, springiness, hardness, thermal stability compared to pH 4, pH 6, and pH 10. Furthermore, rheological measurements showed that the gels after different pH treatments maintained their morphology by non-covalent interactions (hydrophobic interactions and electrostatic interactions), the gels exhibited shear thinning behavior. The free sulfhydryl content and surface hydrophobicity of the gels further confirmed the contribution of hydrophobic interactions in the gel network. The observation of the microstructure showed that the gel changed from a granular gel with rough surface to a gel with uniform and smooth surface with the increase of pH. This study provides some basic data references for improving the properties of AP-WPI composite gels and developing new gel-type products.

In this paper, the effect of superheated steam treatment (SST) on the thermal， structural and rheological properties of wheat gluten were investigated. The results of low-field nuclear magnetic resonance (LF NMR) illustrated that SST weakened the interaction between water and gluten during hydration. The denaturation of gluten proteins under high temperature broadened exotherm and increased the enthalpy (ΔH) values of differential scanning calorimeter (DSC), increasing from 2.35 J/g (native gluten) to 2.76 J/g (native gluten treated at 150 °C for 4 min). In addition, the increase of degradation temperature indicated that SST enhanced the thermal stability of hydrated gluten. Confocal laser scanning microscopy (CLSM) was employed to observe the micro-structure of hydrated gluten network, indicating that hydrated gluten could not form network structure after SST. This weakened viscoelastic characteristics were linked to the weakened hydrated gluten network structure. The results of the current work help to understand the improvement of wheat flour quality following SST.

Sucrose oleate was assessed as an alternative lipophilic emulsifier to polyglycerol polyricinoleate (PGPR) for the stabilisation of the internal aqueous phase of a water-in-oil-in-water emulsion formulation designed for salt release from the internal aqueous phase during oral processing. A water-in-oil emulsion (30 g water/100 g oil), containing an internalised salt solution (1.5 g salt/100 g), was successfully incorporated as droplets into a salt containing external aqueous phase (0.5 g salt/100 g) with in-situ gelatinised waxy rice starch (WRS) stabilising the oil droplet interface. The droplets of the sucrose ester stabilised water-in-oil emulsion were aggregated, and this microstructure carried over into the water-in-oil-in-water emulsion. The PGPR stabilised water-in-oil emulsion showed no evidence of aggregation, and the primary droplet size was smaller. Mean oil droplet size was comparable, slightly increasing for the sucrose ester containing formulation over a 3-months observation period. Nevertheless, salt encapsulation efficiency, reducing by around 10% over 3-months, as well as in vitro salt release, reducing by 20%, were comparable. This study demonstrated that sucrose ester SE O-170 is a viable alternative for PGPR in w/o/w emulsions designed for salt release during oral processing.