Enhancing functional and structural properties of chia seed flour through combined pH shifting and high-speed homogenization

Abstract

Chia seed flour (CSF) is valued for its nutritional richness and functional attributes; however, its dark colour, high water absorption, and viscosity limit its application in leavened and other processed foods. This study explored the combined use of alkaline pH shifting (pH 8, 10, and 12) and high-speed homogenization (HSH) to improve the techno-functional properties of raw chia seed flour (RCF). The process yielded modified flours (pH 8CF, pH 10CF, pH 12CF) and residues, which were compared with untreated controls. Results showed that flour yield significantly increased with higher pH, with pH12CF reaching ~75%. Colour improved under HSH and pH 8 treatment, while particle size was reduced, creating more homogeneous dispersions. Solubility rose markedly (35–45% vs. 22% in RCF) and zeta potential became more negative, suggesting enhanced colloidal stability. Water-holding and swelling capacities declined, but oil-holding capacity increased, reflecting altered interactions between fibre and protein. Rheological analysis revealed a drastic reduction in viscosity (up to 900 times lower), alleviating the processing limitations of RCF in bakery systems. FTIR and DSC analyses confirmed molecular rearrangements of proteins, polysaccharides, and lipids. Overall, pH–HSH treatment offers a cost-effective and scalable approach to produce lighter, low-viscosity chia flours with improved functionality for bakery, gluten-free, and plant-based product development.