Influence of milk solids content on the microstructure of fermented milks

Abstract

Fermented milks are dairy products, obtained by coagulation by lowering the pH of fluid or reconstituted milk added or not by other dairy products, by lactic fermentation due to the action of specific microorganism cultures. The type of processing and the composition of the ingredients used, promote changes in the sensory, rheological, and nutritional properties of fermented milks. Therefore, the objective of this work was to evaluate the effect of adding four concentrations of total solids (9.0%, 12.2%, 15.0%, and 18.0% m/m) in fermented milks, using the particle size distribution techniques during fermentation and scanning electron microscopy in the final product. The particle size distribution showed that fermented milks with higher levels of total solids (12.2%, 15.0%, and 18.0% m/m) showed higher values of d₉₀, that is, values in which 90% of the particles are below them when compared to the treatment with 9.0% (m/m)of solids. Scanning electron microscopy showed a similar result, in which fermented milk with 9.0% (m/m) of total solids presented a structure with more open pores, while fermented milk with 12.2%, 15.0%, and 18.0% (m/m) of total solids presented a protein network with more compact parts. Therefore, fermented milks with higher levels of total solids showed a larger particle size and a more compact microstructure. In this way, particle size distribution methods and microscopy can be used to provide information about product characteristics according to consumer demand.