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 1 min was applied BC fibrils appeared less bundled and dropped in width from 110 nm to 60 nm. For a longer treatment (3–5 min) the width of the fibrils increased again to 100 nm 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

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

Encapsulation of hydrophilic and lipophilized catechin into nanoparticles through emulsion electrospraying

In this work, we investigated the potential of emulsion electrospraying that contained bacterial cellulose and proteins for the encapsulation of epigallocatechin gallate (EGCG). Specifically, two different catechins, hydrophilic (H-EGCG) or lipophilized (L-EGCG), were encapsulated either on the aqueous or the oily phase of the emulsions in order to compare the antioxidants’ stability. Emulsion properties in terms of stability, droplet size, bulk and interfacial viscosity were studied combined with the evaluation of the properties of the produced particles, namely the morphology and size of the particles, the encapsulation efficiency (EE) of catechin and the stability of the EGCG within the particles under different storage conditions: humidity, pH and temperature. Low emulsion viscosity combined with low oil droplet size and high stability yielded particles with the smallest diameters. Ultrasound homogenization combined with L-EGCG proved to be the most adequate combination, reaching EE up to 97%. The use of low RH (26–53%) and neutral or alkaline pH (6–9) are necessary for protecting EGCG in the particles. All in all, emulsion electrospraying can be used as a promising technology for encapsulation in the food industry