Short linear maltodextrin (SLMD) was synthesized from starch via the combined action of branching and debranching enzymes. The number-average degree of polymerization and number-average chain length of SLMD were 8.49 ± 0.21 and 8.52 ± 0.60, respectively, indicating that it consists of linear chains. In gel permeation chromatography analyses, SLMD showed a single peak at a molecular weight of 1,200. SLMD consisted mainly of linear saccharides with a degree of polymerization of 6-12, without high molecular weight α-glucans or small malto-oligosaccharides. SLMD had a much higher blue value and a longer λmax compared with those of commercial dextrose equivalent (DE) 13 maltodextrin. While the DE 13 maltodextrin solution remained clear, an SLMD solution became turbid upon cooling, with the turbidity reversing upon heating. This interconversion was reproducible. SLMD absorbed moisture only to a limited extent, even under high relative humidity, and remained solid without noticeable viscousness. These results demonstrate the novelty and distinct properties of SLMD compared with those of other maltodextrins available on the market, implying its potential for various applications in the food industry.

Because of the complicated hierarchical structure of starch, starch retrogradation is usually evaluated by combining several structural analysis methods covering various spatial scales. However, structural analyses are typically performed individually, making correlating the structural changes at different spatial scales challenging. Therefore, this study used a simultaneous measurement system comprising small-angle neutron scattering (SANS)/Fourier-transform infrared (FTIR)-attenuated total reflection (ATR) to record multiple structural changes in potato starch during retrogradation. In the SANS patterns, the shoulder-like peak became more pronounced with time. The peak intensity, I_max, representing the amount of ordered semicrystalline structures, increased over time, revealing the orderly reassembly of starch on the nanoscale upon retrogradation. In the FTIR-ATR spectra, the ratio of absorptions (R_1042/1016) at 1,042 and 1,016 cm⁻¹, indicating the short-range ordered structure in starch, increased during retrogradation. Therefore, the double-helix structures were reformed during retrogradation. The rate constant of the kinetic change for R_1042/1016 was larger than for I_max; thus, changes in the short-range ordered structure of starch converged before the changes in the semicrystalline structure. These results suggest that the formation of double-helix structures of the amylopectin side chain and the structural change of its ordered arrangement could occur in stages during retrogradation.

Water sorption reduces the glass transition temperature (T_g) of amorphous carbohydrate powders due to water plasticization. Caking of amorphous powder occurs when T_g decreases below the storage temperature (T), that is, when the glass-to-rubber transition occurs. Although glass-to-rubber transition also occurs when T is greater than T_g, knowledge regarding the caking of amorphous powders induced by T elevation is limited. Thus, caking properties were investigated using amorphous carbohydrate powders with varying water activity (a_w) values prepared at 25 °C, stored at a higher temperature, and then returned to 25 °C (T-cycled samples) for storage. Maltodextrin and glucose mixtures at weight ratios of 0, 0.1, and 0.2 glucose were employed. The caking behavior of T-cycled powders with high a_w values was similar to that of a_w-cycled samples (dried powders were stored under various a_w conditions and then returned to the dry condition via vacuum-drying) reported previously. T-cycled powders with a low a_w value, by contrast, were resistant to caking even in the rubbery state. This suggests that water molecules support the progression of caking as the binder under high-a_w conditions. To analyze the hydration level at which water molecules begin to act as a binder for caking, determination of the multilayer adsorbed water content and multilayer adsorbed a_w values is proposed. The fracture stress increased with increases in T − T_g, depending on the sample. The binding effect of water also contributed to the formation of a harder cake.

In this study, we developed a method to synthesize sophorose using three enzymes―sucrose phosphorylase from Leuconostoc mesenteroides, 1,2-β-oligoglucan phosphorylase from Enterococcus italicus, and exo β-1,2-glucooligosaccharide sophorohydrolase from Parabacteroides distasonis―in a one-pot reaction, employing inexpensive starting materials. After optimization, a reaction was carried out using 5 mM glucose, 250 mM sucrose, 10 mM inorganic phosphate, and enzyme concentrations of 5 µg/mL sucrose phosphorylase, 20 µg/mL 1,2-β-oligoglucan phosphorylase, and 50 µg/mL exo β-1,2-glucooligosaccharide sophorohydrolase at 30 °C for 48 h, yielding 108 mM sophorose. Following yeast treatment, sophorose was purified by size-exclusion chromatography with a final yield of 45 % based on the amount of sucrose used as the donor substrate.

Isoprimeverose [α-D-xylopyranosyl-(1→6)-D-glucose] is produced from xyloglucan using the cooperative action of glycoside hydrolases including isoprimeverose-producing oligoxyloglucan hydrolase and β-galactosidase in Aspergillus oryzae. This study investigated A. oryzae strains and culture conditions suitable for isoprimeverose production from xyloglucan. Each strain of A. oryzae had a different ability to degrade xyloglucans. When an A. oryzae strain with high xyloglucan-degradation activity was cultured in a medium containing partially degraded xyloglucan as the carbon source, the production of glycoside hydrolases that degrade xyloglucan into isoprimeverose was highly induced. Our procedure efficiently produced isoprimeverose from xyloglucan without any genetically modified microorganisms or purification of enzymes.

Different forms of plant biomass have been utilised for various applications in daily life and have gained increasing attention as replacements for fossil fuel-based products in the pursuit of a sustainable society. Plant cell walls, the primary carbon sink of plant biomass, have a high-order polysaccharide architecture consisting of cellulose, hemicelluloses, pectins, lignin and some proteins. Hemicelluloses are a group of polysaccharides that interact with cellulose, which is fundamental to the different properties and functionality of the plant cell walls. However, for industrial applications, the complex polysaccharide architecture poses a barrier to their efficient use. Understanding the molecular basis of plant cell walls - especially cellulose-hemicellulose interactions - is therefore critical to improving the utilisation of plant biomass. Recent research has revealed that the detailed structures, modification patterns, and conformation of hemicelluloses play an influential role in their interaction with cellulose. In this review, we discuss the latest insights into hemicelluloses across different forms of plant biomass and how their structures affect cell wall assembly. Additionally, we explore recent findings on how alterations in hemicellulose structure and modification patterns affect the usability of plant biomass, including the extractability of polysaccharides and the digestibility of biomass by glycoside hydrolases for biofuel production. Furthermore, we address unsolved questions in the field and propose future strategies to maximize the potential of plant biomass.