Avaliação e comparação dos sistemas coloidais de leites UHT comercializados nas regiões Sul e Sudeste do Brasil

Abstract

UHT milk has great relevance in the Brazilian dairy market. Thermal processing, physical-chemical and compositional properties have relevant impact on the quality of milk processed via UHT. The emergence of new categories of this product makes the production scenario even more challenging. The aim of this study was to investigate UHT milk and the effect of food additives on it, from a colloidal perspective, in the main consumer regions. Furthermore, due to the high relevance of the ionic calcium content in the stability of milk and the need for prompt measurement of this processing indicator by industries, the results obtained using a portable electrode were evaluated in comparison with a reference method. The colloidal systems of samples with or without addition of stabilizers and with or without addition of tricalcium phosphate were evaluated based on analyzes of ionic calcium concentration, pH, sedimentation, HCT (heat coagulation time), ethanol stability, parameter D90 (cut-off diameter of the cumulative distribution curve at 90%), percentage of particles with size <1 µm and zeta potential. Comparison of the results of ionic calcium content was carried out using the Bland-Altman method. The results indicated a relevant colloidal stability for this type of matrix, in addition to an efficient industrial homogenization process. The samples that received stabilizers addition showed lower ionic calcium, higher HCT and greater ethanol stability. There was no significant difference in sediment mass and pH. The samples that received Ca3(PO4)2 addition showed higher sedimentation and lower stability to ethanol. There were no significant differences regarding ionic calcium, pH and HCT. The agreement analysis between the results of ionic calcium levels showed that there is a statistically significant difference between the two analytical methods. However, a proportion bias was not confirmed.