Chia seeds: Microstructure, mucilage extraction and hydration

► Microstructural features of the chia seeds (Salvia hispanica L.) to access where the mucilage was located. ► Microstructure of chia seed permit know how the mucilage was released during hydration. ► Ratio seed:water, temperature and pH on mucilage extraction. ► Temperature, ionic strength and pH effects on mucilage hydration. ► Chia seed mucilage had the capacity to retain 27 times its weight in water. Microstructural features of the chia seeds (Salvia hispanica L.) were studied by light and scanning electron microscopy. The study reports the effect of temperature (4–80°C), pH (4–8) and seed:water ratio (1:20 and 1:40) on extraction of the mucilage of chia seeds and the effect of temperature (20–80°C), pH (3–9) and ionic strength (0–1%) on hydration of the extracted mucilage. The mucilage was localized in cellular structures in the first three layers of the seed coat and upon full hydration filaments (mucilage fibers) became apparent and conformed to a transparent “capsule” attached to the seed. During extraction, temperature and seed:water ratio were found to have a significant effect on yield. Hydration of the extracted mucilage was significantly increased at high pH values, and was higher when salt concentration decreased, being maximal when the temperature reached values close to 80°C.