Functional and Tableting Properties of Alkali-Isolated and Phosphorylated Barnyard Millet (Echinochloa esculenta) Starch

The functional and tableting properties of barnyard millet starch (Echinochloa esculenta) were investigated in its native (alkali-treated) and chemically modified (phosphorylated) states. The grains were pulverized, soaked, and ground before filtration to separate starch and protein. Multiple NaOH treatments were performed. The starch was washed, neutralized, and dried. Sodium tripolyphosphate (STPP) and sodium sulfate were used to modify the starch, followed by maceration, washing, and drying to remove unreacted chemicals. The amylose content of alkali-treated barnyard millet starch increased by 19.96 ± 3.56% w/w. The amount of protein, the kind of starch used, and the size of the starch granules, all affected the ability of the starch granules to swell up. It was observed that alkali-extracted barnyard millet starch (AZS) has a swelling power of 194.3 ± 0.0064% w/w. The swelling capacity of treated starch was lesser as compared to the native alkali barnyard millet starch. Decrement in swelling power of phosphorylated starch was observed due to tightening of bonds in the molecular structure. The moisture content of the excipients may affect the overall stability of the formulation. The moisture content of the AZS was found to be 15.336 ± 1.012% w/w. Compared to AZS, cross-linked barnyard millet starch had a moisture content that was up to 20% lower than AZS. The Hausner ratio for phosphorylated starch was found to be 1.25, which indicates marked flow property. Similar morphologies could be seen in the alkali-isolated barnyard millet starch and the cross-linked/phosphorylated barnyard millet that was cross-linked using a mixture of sodium sulfate and sodium tripolyphosphate. The modest degree of substitution would have no effect on the surface morphology as shown by the scanning electron microscopic study. The crushing and compacting abilities of modified barnyard millet starch were also improved, but its friability and rate of disintegration were decreased. The whole study revealed that after cross-linking, barnyard millet had good tableting properties and it can be used as an excipient in drug delivery.

2.1. Materials

Barnyard millet grains were obtained from Vivekananda Parvatiya Krishi Anusandhan Sansthan, Almora, Uttarakhand, India. A Megazyme total starch analysis kit was used for the estimation of total starch content, and glucose oxidase peroxidase reagent was used for the quantitative analysis of glucose. All chemicals were of analytical grade. Ethanol absolute (99.9%), sodium sulfate (99%), sodium metaphosphate (70%), potassium dihydrogen phosphate (98%), etc., were also procured and used without further modification.

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Pankaj Bhatt, Vipin Kumar, Harsh Rastogi, Mayank Kumar Malik, Raghav Dixit, Sakshi Garg, Garima Kapoor, and Suruchi Singh, Functional and Tableting Properties of Alkali-Isolated and Phosphorylated Barnyard Millet (Echinochloa esculenta) Starch, ACS Omega Article ASAP,
https://doi.org/10.1021/acsomega.3c03158