抄録
Sago starch samples were collected from Port Moresby of Papua New Guinea (PNG) and Baybay, Leyte, of the Philippines (PLP) to study the polymorph and crystalline disruption of sago starch during gelatinization using corn and potato starch as references. Starch granule suspension was transferred onto a glass slide covered with a cover glass, sealed with nail polish to prevent moisture loss, mounted on a micro-heatplate, and observed using an optical microscope equipped with cross polarizers and a λ-plate. The behavior of sago starch granules during gelatinization was shown by the granular birefringence (Maltese cross) observed under polarized light. The initial, middle, and end gelatinization temperatures determined by a hot stage were, respectively, 78°C, 80°C, and 83°C for PNG sago starch and 76°C, 81°C, and 89°C for PLP sago starch in water. Sago starch still exhibited C-type crystallinity from 60 to 75°C. However, the X-ray diffraction peak at 5 to 6° for 2Θ was observed to decrease, disappearing with increased heating temperature. At 18°, the peaks of PNG and PLP starches began to appear and slightly increase, although the intensity was decreased as a whole. The disappearance of B-type crystallinity from sago starch occurred during gelatinization.
https://ror.org/00b45dj41 
