Physicochemical, functional and rheological properties of fermented and non-fermented starch from canary seed (Phalaris canariensis)

Abstract

This research showcases the study of physicochemical, functional and rheological changes associated to the fermentation of canary seed starch (Phalaris canariensis) in order to investigate the application of this bioproduct in food industry. The starch extraction was carried out without the use of commercial reagents and the obtained material was subjected to natural fermentation for 45 days with subsequent drying under ambient atmosphere. Microbiological analysis of the fermented starch evidenced that the microbial level was within the limits stablished in legislation and protein, lipids, moisture content, pH and acidity differed significantly from non-fermented canary seed starch. After the fermentative process, there was an increase of the amylose content of the starch, which showcased gelification at 10 % (w/v). Both fermented and non-fermented starch granules presented polygonal and irregular shape, whose diameter varied from 1.3 μm to 5.5 μm and from 0.9 to 4.4 μm, respectively. The typical crystalline structure (type A) of cereal starches was maintained after fermentation, however exhibited a strong peak of amylose-lipid complexes at diffraction angle of 2θ = 20. The fermented starch also exhibited lower viscosity and retrogradation than the non-fermented canary seed starch, and both samples showcased lower swelling power and solubility index in water than other starches reported in the literature. Furthermore, the expansion property of the fermented starch was minimal, and results suggest therefore that both non-fermented and fermented canary seed starch may have technological applications in food industry such as the production of biscuits.