Rheological Characterization of Gum and Jelly Products

Abstract

Beside colour and flavour the texture profile of confectionery products influence their properties. Texture defines shape and more important the chewing character of a wide range of products like gummy articles or jelly fruits. It is therefore necessary to determine texture not only for development work but also for quality assurance. This work shows the possibilities of using texture analysis and oscillating rheometer to determine texture of confectionery jellies with pectin and influences of selected recipe parameters, i.e. pectin raw material, degree of esterification, type of retardator on the texture profile. With a texture analyser beside firmness the breaking distance to determine the brittleness of the manufactured samples was used and differences between the samples measured. The breaking distance could be used to judge the brittleness by comparing the finished products. To come to objective results the measurement of storage modulus (G′) and loss modulus (G″) with an oscillating rheometer was used.

The tests show that for getting an evident texture profile a minimum gel firmness of more than 750 PE was needed. It was then seen that the used retardator had a big influence on the texture. In comparison to sodium citrate with sodium tartrate products having increased firmness but more brittle texture were obtained. Gels made with citrus pectin showed increased brittleness compared to products manufactured using apple pectin but having the same firmness. This behaviour is also valid if the degree of esterification is increased form 60 % to 65 %. From these measurements it was concluded that for jelly fruits with firm and brittle texture citrus pectin will be an appropriate pectin with sodium tartrate as retardator. For soft jellies apple pectin with sodium citrate as retardator should be used. Products with a gummy character can be manufactured with apple pectin having a high degree of esterification in addition with sodium tartrate.