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Complete utilization of tigernut tubers, including their use in oil production and use of the meal as a byproduct, is an important aspect in improving their industrial value. However, there are few studies on the use of starch isolated from tiger tuber meals and cakes remaining after oil extraction. In this investigation, starches were isolated from tigernut tubers before and after various oil extraction processes and their structural and functional properties were comparatively investigated. A typical C-type X-ray diffraction pattern was observed for all of the isolated starches. Noticeable decreases in relative crystallinity by XRD and solid state 13C NMR were observed for starches from the cakes of tigernut tubers remaining after oil extraction utilizing a mechanical expeller. The proportion of amorphous phase (PPA) in the starches isolated from meals and cakes was relatively low compared with that of starch isolated from raw tigernut tuber. The branch-chain length distribution of the starches isolated from meals and cakes exhibited a low average chain length of amylopectin. These changes reflect a disruption in the ordered structure of starch granules caused by the various oil extraction processes, which led to significant variability in their functional properties, including paste clarity, freeze-thaw characteristics, thermal transition temperatures, texture, solubility, and swelling power. This investigation provides important information for the complete utilization of tigernut tubers.

Chinese quince seed gum (CQSG) is a novel potential viscosifier or stabilizer with good storage stability. In this work, CQSG was extracted from the surface of Chaenomeles sinensis (Chinese quince) seeds, and purified by DEAE-Sepharose Fast-Flow and Sephacryl S-400 HR chromatography; three fractions were obtained (CQSG-1, -2, -3). The main fraction (CQSG-2) was investigated by monosaccharide analysis, methylation and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) experiments to determine its structure. Results showed that CQSG-2 is composed of arabinose (Ara), glucose (Glu), xylose (Xly), galacturonic acid (Gala) and glucuronic acid (Glua) in a molar ratio of 4.0:0.3:15.2:4.2:3.8. →4-β- d -Xylp-1→ and →2, 4-β- d -Xylp-1→ constitute the backbone in a ratio of 5.9:4.5, and the Arap-1→, α- d -GalpA-1→, →2-α- d -GlcpA-1→, →4-β- d -Glcp-1→, and →2, 3, 5- l -Araf-1→ form the branched chain. The molecular aggregation of CQSG-2 with high molecular weight (Mw) (1.4 × 106 Da) was strong compared with CQSG-1 and CQSG-3. This is the first systematic elucidation of the structure of Chinese quince seed gum, and it provides the basis for developing applications for this gum in the food and pharmaceutical industries.