KEFIR MICROPARTICLES PROCESS OPTIMIZATION AND ORGANIC ACIDS CONTENT

Kefir is a dairy fermented beverage, which has a diversified and very variable microbiota. Organic acids are some of lactic and acetic acid bacteria metabolites from the fermented milk and it has an inhibitory power over the growth of pathogenic bacteria and it is also responsible for flavor and aroma characteristics. Aiming to verify the atomization process efficiency and quantify metabolic products related to sensoriality and stability, kefir microparticles were made using “Spray Dryer”. The grain fermentation in skimmed milk was made for 24 h at 25 °C, and maturation for 24h at 4 °C. The authors performed matrixless (SM) (130 a 180 °C), maltodextrin (MD) 1:1 and Capsul® (CAP) 1:1 (140 a 160 °C) microencapsulation processes. The yield was calculated based on Tonon et al (2008). High performance liquid chromatography (HPLC) was used to identify and quantify organic acids. There was no significative difference (40,6 e 54,3 %) between yields of each microencapsulation process. Four treatments (140, 150 e 160°C SM e 160°C MD) were successful (> 50%), and the highest value was SM 140°C. We found acetic, benzoic, butyric, citric, formic, lactic, propionic and succinic acids. Acid lactic concentration increased significantly after fermentation (0,5 to 5,2 mg/g) and after drying (18,2 to 39,2 mg/g). The process also increased acid acetic content (0,34 to 8,87 mg/g), mostly in matrixless samples. This is an essential acid that gives distinctive kefir flavor and aroma and it is a pathogen inhibitory. Therefore, we have shown that yield and organic acid concentration profile in SM were satisfactory and give appropriated conditions to pathogenic bacteria inhibition and to kefir fermented milk sensorial characteristic quality.