Impact of sprouting process on pectin content of ragi seed (Eleusine coracana L. Gaertn): isolation and characterization

Abstract

The study aimed isolation and characterization of pectin from Ragi seeds. The isolation was carried from both sprouted and non-sprouted Ragi seeds. Sprouting of Ragi seeds significantly enhanced pectin yield producing 15–18% more pectin as compared to non-sprouted seeds (4–8%) yield. Isolated pectin was then tested for physico-chemical characters like hygroscopicity, DE, molecular weight, swelling ability, FTIR, DSC, XRD etc. The results indicated non-hygroscopic nature of pectin ideal for use in dry food products and pharmaceutical powders to avoid degradation. The 61% degree of methyl esterification is a mark of good gelling activity for jams, jellies and as an emulsifier. Further 827.6 Da of molecular weight was determined using mass spectrometry. The O–H, C-O, and C-H stretching peak of pectin and the presence of uronic acid was identified by FTIR. Glass transition temperature (Tg) was noted to be 46.81 °C and crystallization temperature (Tc) were observed with an onset of 241.27 °C and end set of 247.29 °C indicating stabilization of structure in the form of crystalline domain. The moderate Tg reflects thermal stability under processing and storage conditions, critical for maintaining functionality in high-temperature food and drug manufacturing processes. XRD and DSC indicate the amorphous nature of pectin. These findings suggest that sprouted Ragi seeds are a promising source of pectin making it suitable for multiple applications like dispersion in sauces and syrups, confectionaries and also as controlled drug release in pharmaceutical formulations like tablets or hydrogels.