Fabiana de Assis Perrechil

High- and Low-Energy Emulsifications for Food Applications: A Focus on Process Parameters

High-energy emulsification is traditionally used to produce food-grade emulsions. However, energy input, design of the device and the type of surfactant should be carefully evaluated to achieve the desired emulsion properties. The low-energy processes, as spontaneous emulsification and phase inversion temperature, are alternative methods for producing systems with high stability and smaller particle sizes. Nevertheless, the surfactants and cosurfactants frequently used to produce emulsions from the low-energy process are not food grade or require a higher concentration than is allowed in food products. In this review, the characteristics of emulsions produced from low- and high-energy emulsifications, the mechanisms of droplet formation and their stability are reviewed with a particular focus on recent studies addressing the effects of process parameters on the properties of food emulsions. Knowing the principles and limitations of high- and low-energy processes, adequate process conditions and future trends are suggested depending on the system composition and the desired properties of the final product.

Preparation, characterization and in vitro digestibility of gellan and chitosan–gellan microgels

Gellan microgels with potential application in delivery systems were obtained by physically cross-linked gellan gum. The microgels were produced by atomization followed by ionotropic gelation using CaCl2 (gellan/Ca) or KCl (gellan/K) as hardening agent and part of them were coated with chitosan in order to improve their resistance to gastric digestion. Size distribution, morphology and zeta potential of microgels were evaluated before and after in vitro digestion process. The long term stability was also evaluated. Spherical microparticles were obtained at gellan concentration above 0.6% w/w, showing average size among 70-120 μm. Most of the coated and uncoated microgels showed stability in aqueous media, except the uncoated gellan/K microgel. The in vitro digestion evaluation showed that all particles maintained their size and shape after the gastric digestion step. However, the enteric digestion caused disintegration of microgels indicating their potential application for enteric delivery systems. The chitosan-coated microgels showed lower degree of fragmentation when compared to the uncoated microgels, indicating that the coating process enable a better control of microgels releasing properties during the enteric digestion.

Rheological and structural evaluations of commercial italian salad dressings

The emulsion stability, composition, structure and rheology of four different commercial italian salad dressings manufactured with traditional and light formulations were evaluated. According to the results, the fat content ranged from 8% (w/w) (light) to 34% (w/w) (traditional), the carbohydrate concentration varied between 3.8% (w/w) (traditional) and 14.4% (w/w) (light) and the pH was between 3.6-3.9 for all samples. The microscopic and stability analyses showed that the only stable salad dressing was a light sample, which had the smallest droplet size when compared with the other samples. With respect to the rheological behaviour, all the salad dressings were characterized as thixotropic and shear thinning fluids. However, the stable dressing showed an overshoot at relatively low shear rates. This distinct rheological behavior being explained by the differences in its composition, particularly the presence of a maltodextrin network.