Study of the influence of Buchi encapsulator input variables on properties of formed alginate beads

Abstract

New techniques in food manufacturing have led the food industry to create foods with higher quality, organoleptic properties, better taste and new textures, and so-called functional foods, which include in their formulation some additives with especially healthy functions, delivering a high value product for customers and creating new markets. Innovation in the food industry is a key step to offer customers high quality products that meet their needs. One of the ways to add and preserve the active ingredients to foods is their encapsulation in capsules of hydrogels. This work consists of studying the operation and production of the BUCHI Model-390 encapsulator by means of a composite central experimental design, in order to study the parameters that influence the production of capsules and their interactions and obtain a response surface to predict the Properties of the hydrogel spheres obtained fixed the input variables. Alginate was used as a hydrogel, and gelled by external gelation, dripping it with the BUCHI encapsulator over a calcium chloride solution. The properties of the alginate solution (molecular weight, viscosity, concentration ...) will influence the properties of the spheres. The objective of the work is to control the shape and size of the sodium alginate spheres by modifying the operating variables of the Buchi encapsulator. In this study spheres without active ingredient will be prepared, but this work is intended to predict the behavior of spheres with encapsulated active ingredient. It must be taken into account that the viscosity of sodium alginate varies significantly with temperature. By means of a factorial design it is observed that the input variables studied (frequency and position of the valve) have interaction with each other, and therefore their influence on the properties of the spheres can not be studied independently. For this reason, the composite central design is chosen to obtain the response surfaces. The output variables to be studied are the output flow rate of the encapsulator, the average size of the spheres, the standard deviation of that size and the sphericity. Of the obtained, the studied variables do not influence the sphericity and the standard deviation with a 95% probability in the studied range, but in the flow rate and the average size of the spheres. Response surfaces are obtained that are satisfactorily validated by experiments independent of the experimental design