Effects of different modification reagents on functional properties of pearl millet starches

Pearl millet starch was chemically modified via succinylation, acetylation, octenyl succinylation, and oxidation. The effects of the aforementioned chemical modifications on the functional properties of pearl millet starch were studied. The yield of the starch was approximately 56.3% on a total grain weight basis. Native starch granules ranged from polygonal to spherical in shape as observed by scanning electron microscopy (SEM). The results revealed that succinylation increased the swelling power and solubility significantly (p<0.05). With regard to paste clarity, octenyl succinylated starch (POS) showed the highest value with the least reduction in percentage transmittance (%T) upon cold storage. Acetylation greatly reduced the re-association tendency of native pearl millet as indicated by the absence of retrogradation peak during thermal analysis. Viscoamylographic analysis revealed that the peak viscosity improved significantly (p<0.05) after succinylation. Chemically modified starches exhibited better cold-storage stability in terms of various textural attributes like hardness, chewiness, springiness, and cohesiveness when compared with native starch. The percentage of retrogradation (%R) for POS was 9.87% as compared with 49.11% for unmodified starch.