Evaluation of Agar Gel Microstructure using Scanning Electron Microscopy (SEM) Images

Scanning electron microscop images provides a logical framework for the development of morphological knowledge, understanding the reactions and self-assembly behavior of food components in small scale, that this issue has effects on building, rheological and bioactivity properties of food on large scale. Agar is one of the strongest and most widely used hydrocolloids in the food industry. In this research, the agar gel microstructure was studied using SEM. Initially 1% agar solution was prepared at 90 °C, then was poured into the network templates of steel. The obtained gel was removed from the templates and were sectioned in dimensions (2×1×1mm). Gel samples were dehydrated in ethanol solution and then dried in a critical point. Then samples with 30 nm of gold/palladium coated and were tested using SEM in the maximum voltage of 15 kv. SEM images provided complete information about the molecular microstructure of agar gel. The SEM results showed that agar makes up a three-dimensional network with regular holes in order to constitute of gel and trapping of water. Results also revealed that polysaccharide fibers of agarose during cooling of agar solution are located next to each other quite regularly and by forming hydrogen bonds constitute the regular cavities wall of agar gel.

Keywords:

Agar , Gel network , Microstructure , SEM , Hydrocolloids