Influence of blanching and drying methods on molecular structure and functional properties of elephant foot yam (Amorphophallus paeoniifolius) flour

• Starch granules in blanched flours and solar dried flours were observed as heterogeneous and collapsed.
• Freeze dried flours had higher whiteness than solar dried flours.
• Freeze dried raw flour displayed the highest solubility than freeze dried blanched.
• Difference in pasting profile, texture analysis and relative crystallinity were significant.
• ΔHgel value of flours was highest for freeze dried flours.

The purpose of the present study was to investigate the effect of solar and freeze drying approaches on the physico-chemical, thermal and pasting properties of raw and blanched elephant foot yam (Amorphophallus paeoniifolius). Morphologically, starch granules in blanched and solar dried flours were observed as heterogeneous and collapsed while raw freeze dried flour was the least affected. The amylose content was highest in IDSB (29.50%) followed by DSB, FDB, FDR, and IDSR while lowest in DSR (15.83%). Freeze dried flours had higher whiteness (L*) than solar dried flours. Freeze dried raw flour (19.38%) had the highest solubility while freeze dried blanched flour (8.39%) exhibited the lowest. Freeze dried flour samples had the least swelling power. Direct solar dried (raw and blanched) flours showed relatively lower syneresis than freeze dried flours. The differences in pasting profile, textural analysis and relative crystallinity could be explained as a function of variation in amylose content and the drying method employed. The solar dried flours had higher T0, TP, and TC than the freeze dried flours (raw and blanched). The ΔH gel value of flours was highest for freeze dried raw flour and lowest for direct solar dried blanched flour.