High-intensity short-term electrical pulses pretreatment on efficiency and functional characteristics of extracted chia seed mucilage: Optimization through response surface methodology

Abstract

Chia seed (Salvia hispanica L.) mucilage with special properties is beneficial in the food industry. The effect of pulsed electric field (PEF) pretreatment on seeds at (0–7 kV/cm) and extraction at (25–80 °C) and (0.10–0.02 w/v) seeds to water ratio on efficiency and functional characteristics of extracted mucilage were assessed. The response surface methodology (RSM) was used for modeling and process optimization. Extraction efficiency was within the 4.60–16 % range and PEF pretreatment had a significant effect on increasing mucilage extracted rate. Mucilage extraction at high temperatures next to PEF pretreatment increased solubility, foaming capacity and stability of mucilage emulsion and reduced creaming index, emulsion particle size, and zeta potential (p < 0.05). Applying PEF at 3.35 kV/cm and extraction at 71 °C and 0.05 w/v seeds to water ratio were the selected conditions for extracting the highest mucilage with the best functional characteristics. The mucilage extracted contained 72.20 % carbohydrates, 11.70 % protein, 6 % lipid, 5.80 % moisture and 4.30 % ash. It has shear-thinning behavior with solid viscoelastic structure in a relatively high strain range. The G′ was higher than G″ and the viscoelastic modulus increased at the entire frequency. Four endothermic peaks were observed in the thermoanalytical curve where the biggest was the first one at 70.99 °C. Microscopic images revealed formed cracks in PEF pretreated seeds wall, which affects the quantity and quality of extracted mucilage. Applying PEF at appropriate electric potential difference with changes in cell wall and surface tension affected the quantity and quality of mucilage. It is essential to the appropriate extraction conditions according to the desired characteristics.