Effect of rheological and structural properties of bacterial cellulose fibrils and whey protein biocomposites on electrosprayed food-grade particles.

In this work, we investigated the role of bacterial cellulose nano-fibrils (BCNFs) as an alternative polymer to obtain food-grade particles with the electrospraying technique. Suspensions were prepared using BCNFs (1-16% wt) and whey protein isolate (WPI) in various concentrations (10-30% wt). Surface tension and electrical conductivity depended on the BC concentration and further increased by its increasing amount. A great increase in interfacial viscosity was also noticed according to the BCNFs concentration. A strong impact of BCNFs at the interface, influencing charge density and interactions of the two polymers was suggested. Different groups of the suspensions can be found that resulted in spherical nano- or submicron- particles by electrospraying. Uniform, nano-particles can be successfully produced taking into account the interfacial viscosity of the initial suspensions. Interfacial, compared to bulk viscosity, is a valuable tool to find out the appropriate suspension rheological properties in order to produce fine particles.

Physical properties and sensory evaluation of bread containing micronized whole wheat flour.

The aim of this study was to evaluate the potential use of micronized whole wheat flours in breadmaking. The micronization process was achieved by a jet mill and flours (JF) of particle size, ranged from 17 to 84 µm, were used. According to the particle size of the JF, the amount of water added to dough changed and ranged from 77 to 84% as it was calculated in farinograph experiments. JF breads had higher bread yield, firmer crumb, higher elasticity, lower porosity and darker bread color compared to control whole wheat bread. Overall a lower particle size of JF resulted in a close structure of bread. According to sensory evaluation, difference among samples was difficult to perceive. During storage JF bread presented lower limiting firmness potential. After all, there is evidence that jet milled flour determined bread physical characteristics and further storage stability.

Structural modification of bacterial cellulose fibrils under ultrasonic irradiation.

Ιn the present study we investigated ultrasounds as a pretreatment process for bacterial cellulose (BC) aqueous suspensions. BC suspensions (0.1-1% wt) subjected to an ultrasonic treatment for different time intervals. Untreated BC presented an extensively entangled fibril network. When a sonication time of 1min was applied BC fibrils appeared less bundled and dropped in width from 110nm to 60nm. For a longer treatment (3-5min) the width of the fibrils increased again to 100nm attributed to an entanglement of their structure. The water holding capacity (WHC) and ζ-potnential of the suspensions was proportional to the sonication time. Their viscosity and stability were also affected; an increase could be seen at short treatments, while a decrease was obvious at longer ones. Concluding, a long ultrasonic irradiation led to similar BC characteristics as the untreated, but a short treatment may be a pre-handling method for improving BC properties.