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Food foams may be defined as products containing a gaseous phase stabilized in a matrix containing water and proteins. The rheology of a foam can be altered by how the air bubbles inside are organized, its size and shape, allowing a product that was initially fluid to be molded, like marshmallow. Rheology makes possible to understand how these properties are affected using dynamic oscillatory measurements to evaluate the behavior through GЈ and GЉ, and rotational to characterize the product through stress, and viscosity curves under controlled shear stress. These two methodologies combined are useful to analyze thixotropy. Nine formulations containing albumin and gelatin, and five others containing guar gum were evaluated by oscillatory rheology focusing thixotropy determination. Replacing gelatin by guar gum elasticity and thixotropy were increased, improving film stability around the air bubbles. It is possible to say that gelatin can be replaced by guar gum at concentrations of 0.4%, creating a product with a better ability of structure recovery. PRACTICAL APPLICATIONThis study indicated an important role of thixotropic analysis choice to understand the behavior of structure of products like foam. It was tested with three alternatives to get information about thixotropy of the products. It is very important for those who work with rheological analysis and products formulation.Corresponding

Chocolate is one of the most important products made from cacao, being major commercialized as chocolate filled or plain. Chocolate filled with fruit can contain the fruit or parts of it mixed in the filling. The fillings could be produced using fondant, fat, jelly or the white chocolate, as the truffles, with the addition of flavor and colorants or not. The objective of this work was to produce fruit mixes and filling for chocolate, using fondant, hydrogenated fat and White chocolate (truffles), using those mixes as replacers of flavor and colorants in the final formulations. The mixes were elaborated using inverted sugar, glucose syrup and water, mainly, freeze dried strawberry and passion fruit, and orange, was added to gave flavor of in nature fruit, reducing the use of artificial flavor and colorants. The pH was evaluated for the mixes and fillings; soluble solids content in the mixes; water activity in the fillings. The pH values showed to be lower than 4,0 to the mixes , and lower than 6,0 for the fillings. Water activity didn't show variability during the evaluated period. The soluble solids content was 68 ºBrix, 69 ºBrix and 73 ºBrix, respectively for strawberry, passion fruit and orange mix. The centesimal composition was done to characterize the chocolates filled showing the content of fat, protein, humidity, ashes and energetic value. The chocolates filled with fondant sugar presented the lower values of fat, protein was greater for the truffles. The energetic value varied between 500 to 600 kcal per 100 g of product. The texture study of chocolates filled was done at 25 ºC and characterized the hardness of them. The truffles presented the lower values for hardness. The data of water activity and hardness were analyzed trough ANOVA and Tukey test. Sensory evaluation of chocolates filled was done applying global evaluation test to consumers. The data analysis was done trough ANOVA, Tukey test, Internal Preference Mapping and Cluster Analysis. The rheological study was done at 25 ºC for the mixes, fondant and hydrogenated fat fillings, for the truffles the rotational test was done at 0 ºC and 70 ºC. The oscillatory test was done using a frequency sweep. The sensory evaluation presented significant results, regarding product acceptance, the truffles gotten the greater grades, followed by the hydrogenated fat chocolate filled. The oscillatory study showed stability for all the mixes and fillings, when those are subjected to lower frequencies. In the rotational study, the flow curve determined the mixes behavior. The flow curves obtained trough rotational test, were evaluated for the best rheological model which fitted them. The use of a fruit mix, giving characteristics of in nature fruit, with flavor and color without the need of adding artificial ones, combined with fondant, hydrogenated fat and for the truffles, showed to be an efficient way to produce fillings with low cost, and a greater shelf life, if compared with artisanal products of the market, being well accepted by consumers.

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