MICROWAVE-ASSISTED DEHYDRATION FOR ELECTRON MICROSCOPY SAMPLE PREPARATION IN THE STUDY OF THERMO-SONICATED YOGURT

In electron microscopy, considerable sample preparation time is required to make meaningful observations. The objective of this work was to study the microstructure of sonicated yogurt with three sample preparation techniques. The first sample preparation consisted of the conventional dehydration with organic solvents; technique number 2 consisted of freeze-drying the samples. The third technique consisted of dehydration of samples with solvents assisted with the use of microwave (MW). Images showed that freeze-drying is not a technique suitable for yogurt because of the low resolution. However, high-resolution images were obtained with MW, showing very good homogenization of the components of the sonicated yogurt (fat globules, casein micelles and lactose crystals) and also MW shortened the time of sample preparation to 3 h compared with the conventional dehydration technique (5 days).