Assessment of Fennel Oil Microfluidized Nanoemulsions Stabilization by Advanced Performance Xanthan Gum

In this work, nanoemulsion-based delivery system was developed by encapsulation of fennel essential oil. A response surface methodology was used to study the influence of the processing conditions in order to obtain monomodal nanoemulsions of fennel essential oil using the microchannel homogenization technique. Results showed that it was possible to obtain nanoemulsions with very narrow monomodal distributions that were homogeneous over the whole observation period (three months) when the appropriate mechanical energy was supplied by microfluidization at 14 MPa and 12 passes. Once the optimal processing condition was established, nanoemulsions were formulated with advanced performance xanthan gum, which was used as both viscosity modifier and emulsion stabilizer. As a result, more desirable results with enhanced physical stability and rheological properties were obtained. From the study of mechanical spectra as a function of aging time, the stability of the nanoemulsions weak gels was confirmed. The mechanical spectra as a function of hydrocolloid concentration revealed that the rheological properties are marked by the biopolymer network and could be modulated depending on the amount of added gum. Therefore, this research supports the role of advanced performance xanthan gum as a stabilizer of microfluidized fennel oil-in-water nanoemulsions. In addition, the results of this research could be useful to design and formulate functional oil-in-water nanoemulsions with potential application in the food industry for the delivery of nutraceuticals and antimicrobials.

Effect of Prebiotic Polysaccharides on the Rheological Properties of Reduced Sugar Potato Starch Based Desserts

The aim of the study was to assess the possibility of using polysaccharides: inulin and polydextrose in combination with steviol glycosides as sucrose substitutes in starch-based desserts with reduced sugar content and to determine their influence on the rheological properties of these desserts. The samples (starch-milk desserts) were prepared from native potato starch, milk, dye, flavouring agent, and sucrose. The sucrose was partially or completely substituted with steviol glycosides and inulin or polydextrose. The rheological evaluation of the desserts was performed by determining pasting characteristics, viscosity curves, creep and recovery curves and mechanical spectra. Substitution of sucrose with prebiotic polysaccharides modified the rheological characteristics of the starch-milk desserts to a degree depending on the type and level of the substituting agent. Inulin reduced the peak viscosity of starch-milk paste, while it had no effect on the final viscosity of the product, contrary to polydextrose, which increased value of the latter parameter. The desserts exhibited a non-Newtonian, shear-thinning flow behaviour. The use of inulin, in both the highest and the lowest concentrations, significantly changed the consistency coefficient and the flow index values, while such a phenomenon was not observed in the case of polydextrose. The desserts with inulin showed increased values of the storage modulus and reduced susceptibility to stress, manifesting strengthened viscoelastic structure. The results indicate that the both prebiotic polysaccharides can serve as substitutes for sucrose in desserts with reduced sugar contents.

Rheological Behavior of Seed Gum from Cassia fistula

The C. fistula gums in aqueous solutions clearly exhibited shear-thinning flow behavior at high shear rate, however, at higher concentrations, pronounced shear thinning was observed. The value of zero shear viscosity [h0] was predicted by fitting Cross model. A plotting of specific viscosity at zero shear rate (hsp0) against coil overlap parameter (C[h]) was shown the linear slope of dilute and simi-dilute as 1.43 and 4.10, respectively, which found the critical concentration (C*) about 7.08/[h]. While, the mechanical spectra in the linear viscoelastic region of gum solutions showed the typical shape for macromolecular solutions.

Impact of Fat Replacement by Core-shell Microparticles on Set Type Yoghurts: Study of Their Physicochemical, Textural and Microstructural Properties

Background: Core-shell micro and nanoparticles can be used to encapsulate bioactive or functional components and to replace fat content also, since they are able to mimic the organoleptic characteristics of the fat globules. </P><P> Objective: The aim of this study was to investigate the effect of replacing milk fat matter by core-shell microparticles in set type yoghurt. </P><P> Method: Microparticles were produced by electrostatic deposition of carboxymethylcellulose (CMC) on thermally induced aggregates of &#946;-lactoglobulin (&#946;-lg)n. Laboratory made yoghurts were prepared with: full fat milk (F), low fat milk (L) and low fat milk with CS microparticles (CS). Yoghurts properties (e.g. physicochemical, rheological, textural) were characterized during storage at 4 &#176;C. Trials were also conducted in commercial yoghurts taken as references. </P><P> Results: Water holding capacity (WHC) and elastic modulus (G´) of CS yoghurts resulted similar to commercial yoghurts. Color properties (L*, a*. b*) were slightly altered and showed no significant variation upon time. CS yoghurts behaved as a weak gel as indicated by the higher n values obtained from mechanical spectra and by the lower firmness obtained from texture measurements. Important differences were observed in microstructure. CS yoghurts showed homogeneous aspect with large aggregates and empty spaces. Bacterial growth in CS yoghurts resulted similar to low fat yoghurts. </P><P> Conclusion: Replacement of milk fat by core-shell microparticles would be feasible giving a final product without major differences, at least instrumentally measurable, to commercial yogurt.

Development of food emulsions containing an advanced performance xanthan gum by microfluidization technique

Gums are often used to increase the viscosity of the continuous phase of oil-in-water emulsions in order to reduce or inhibit some destabilization processes such as creaming. A new type of xanthan gum, advanced performance xanthan gum, which possesses improved rheological properties, has been used as a stabilizer. The addition of advanced performance xanthan gum to egg protein-based emulsions prepared at different homogenization pressures in Microfluidizer was studied. These emulsions showed different droplet size distributions and flocculation degrees. However, all the emulsions studied exhibited the same viscoelastic properties, characterized by a crossover point in the mechanical spectra. This work demonstrates the essential role of this novel gum in the rheology of emulsions. In addition, there is a direct relation between homogenization pressure and flocculation degree. This flocculation led to destabilization by coalescence in these emulsions, being the emulsion processed at the smallest homogenization pressure the most stable.

Effects of the Addition of Grape Seed Powder on the Thermorheological Properties of Frying Batters

The effects of the addition of grape seed powder (GSP) on the thermorheological properties of frying batters were investigated in this study. Thermal properties, including gelatinization (TG) and melting (Tm) temperatures, as well as enthalpies (ΔHG, ΔHm), were determined by a differential scanning calorimeter (DSC). The addition of GSP decreased the TG and Tm as the GSP levels increased. When compared with the control batter, the addition of GSP significantly decreased the apparent viscosity and viscoelastic modules (G′, G′′). The mechanical spectra of batters carried out at 15–80°C showed a transition from fluid-like to gel-like behavior. The batter pick-up values were found to be directly proportional to the batter viscosity. Both water retention capacities (WRC) and consistency index values (K) of the batters were significantly affected by the GSP addition and temperature (p < 0.05). Grape seeds have health-promoting components on a scientific basis; thus, this study provides helpful results in the development of novel frying batters.