Guinea Grass Seed (Megathyrsus maximus), a Potential Novel Starch Source: Impact of Isolation Methods on Functional, Morphological, Structural, Pasting, and Rheological Properties

In the present study, Guinea seed starch (GS) is extracted using four different isolation methods (Sodium hydroxide [NaOH], potassium metabisulphite [KMS], citric acid [CA], and distilled water [DW]) to investigate the effect of isolation methods on different properties of starch. The water and oil absorption capacity range from 0.69 to 1.12 g g(-1) and 0.81 to 0.95 g g(-1), respectively. The swelling and solubility of isolated starches are temperature dependent and increase with temperature (70-90 degrees C). The amylose content also varies with isolation method and all the starch showed typical A-type X-ray patterns. The mean particle size of GS is 9.86-13.36 mu m and shows round to polygonal shapes with pores. The isolation method impacts glass transition temperatures and enthalpies, which vary between 73.36-83.67 degrees C and 0.72-23.69 J g(-1), respectively. The pasting temperature (PT) also varies with the isolation method and follows the pattern of CA (84.80 +/- 0.07 degrees C) > KMS (81.97 +/- 0.06 degrees C) > DW (81.95 +/- 0.05 degrees C) > NaOH (79.82 +/- 0.03 degrees C). All the starches showed shear thinning behavior, and storage modulus is higher than loss modulus, representing that the elastic component is higher than the viscous component.

Automated summary

In this study, Guinea seed starch (GS) was extracted using four different methods (NaOH, KMS, CA, and DW) to investigate their effects on starch properties. The water and oil absorption capacity ranged from 0.69 to 1.12 g g(-1) and 0.81 to 0.95 g g(-1), respectively. The swelling and solubility of isolated starches increased with temperature (70-90 degrees C). The amylose content varied with isolation method and all starches showed typical A-type X-ray patterns. The GS particles had a mean size of 9.86-13.36 μm and exhibited round to polygonal shapes with pores. The isolation method influenced glass transition temperatures and enthalpies, which ranged from 73.36-83.67 degrees C and 0.72-23.69 J g(-1), respectively. The pasting temperature (PT) varied with the isolation method, with CA (84.80 +/- 0.07 degrees C) > KMS (81.97 +/- 0.06 degrees C) > DW (81.95 +/- 0.05 degrees C) > NaOH (79.82 +/- 0.03 degrees C). All starches showed shear thinning behavior, with the storage modulus higher than the loss modulus.