Digestion kinetics of low, intermediate and highly branched maltodextrins produced from gelatinized starches with various microbial glycogen branching enzymes

Maltodextrin vitamin E succinate: A novel antioxidant emulsifier for formulating functional nanoemulsions

A new multifunctional emulsifier was synthesized by coupling maltodextrin with a dextrose equivalent of 19 to vitamin E succinate. Two emulsifiers with varying degrees of vitamin E succinate substitution were prepared based on different mass ratios of vitamin E succinate to maltodextrin. The molecular structure and purity of these emulsifiers were analyzed. Nanoemulsions were prepared using octenyl succinic anhydride modified starch as a control to investigate the physical stability, antioxidant capacity, oxidative stability, and in vitro simulated digestive properties of the nanoemulsions. The emulsifying and antioxidant activity of the maltodextrin-vitamin E succinate conjugate was significantly superior to that of octenyl succinic anhydride modified starch, demonstrating good physical and oxidative stability. Additionally, they were rapidly digested under simulated small intestinal conditions. This new emulsifier shows broad application potential for the encapsulation, protection, and delivery of hydrophobic bioactive substances in the fields of medicine, food, and healthcare products.

Development of Saccharomyces cerevisiae accumulating excessive amount of glycogen and its effects on gut microbiota in a mouse model

Saccharomyces cerevisiae accumulates glycogen, a hyperbranched glucose polymer with multiple bio-functionalities. In this study, mutants of S. cerevisiae that accumulate excessive amounts of glycogen were developed through UV mutagenesis. From over 30,000 mutants, the mutant strain CEY1, which exhibited the highest glycogen production, was selected using iodine vapor screening. The glycogen structures of wild type (WT) and CEY1 were analyzed and found to be relatively similar in molecular weight, hydrodynamic diameter, and side-chain distribution. The glycogen from CEY1 contained long branches (DP >12) 23.6 % greater than those in Escherichia coli TBP38. In addition, WT and CEY1 glycogen showed 32 %-34 % digestibility, which is significantly lower than E. coli glycogen. The glycogen content in dried CEY1 cells was increased to 21.7 % during laboratory-scale fed-batch fermentation. Glycogen with a homogeneous structure was accumulated to 17.5 % (w/w dried cell), and the total glucan content was increased by 33.2 % during large-scale fed-batch fermentation. In a mouse model, a diet containing 30 % CEY1 increased the production of butyrate and populations of beneficial bacteria, including Bacteroides and Parabacteroides. Therefore, glycogen from CEY1 exhibits a distinct structure from other polysaccharides, with notably slow and low digestibility, thereby indicating its potential application as a dietary supplement.

α-Glucan-type exopolysaccharides with varied linkage patterns: Mitigating post-prandial glucose spike and prolonging the glycemic response

Microbial exopolysaccharides (EPSs) are traditionally known as prebiotics that foster colon health by serving as microbiota nutrients, while remaining undigested in the small intestine. However, recent findings suggest that α-glucan structures in EPS, with their varied α-linkage types, can be hydrolyzed by mammalian α-glucosidases at differing rates. This study explores α-glucan-type EPSs, including dextran, alternan, and reuteran, assessing their digestive properties both in vitro and in vivo. Notably, while fungal amyloglucosidase - a common in vitro tool for carbohydrate digestibility analysis - shows limited efficacy in breaking down these structures, mammalian intestinal α-glucosidases can partially degrade them into glucose, albeit slowly. In vivo experiments with mice revealed that various EPSs elicited a significantly lower glycemic response (p < 0.05) than glucose, indicating their nature as carbohydrates that are digested slowly. This leads to the conclusion that different α-glucan-type EPSs may serve as ingredients that attenuate post-prandial glycemic responses. Furthermore, rather than serving as mere dietary fibers, they hold the potential for blood glucose regulation, offering new avenues for managing obesity, Type 2 diabetes, and other related-chronic diseases.

Reduction of amylose-amylopectin ratio in low-protein diets: impacts on growth performance and intestinal health in weaned pigs

Improving the synchrony between amino acids (AAs) and glucose appearance in the blood can support the growth performance of weaned pigs fed a low crude protein (CP) diet. This can be achieved using a diet with a low amylose-to-amylopectin ratio (AM/AP). The aim of this experiment was to evaluate whether reducing the AM/AP by using a corn variety characterized by a high amylopectin content, in the weaning diet can sustain growth performance and improve the intestinal health of pigs fed a low-CP diet. At weaning (25 ± 2 d), 90 pigs were assigned to 3 treatment groups: 1) control group (CTR), fed a standard diet with a medium-high CP content and high AM/AP (days 0 to 13: 18.0% CP, 0.13 AM/AP; days 14 to 27: 16.6% CP, 0.30 AM/AP; days 28 to 49: 16.7% CP, 0.15 AM/AP); 2) a group fed a low-CP diet with a high AM/AP (LP) (days 0 to 13: 16.0% CP, 0.17 AM/AP; days 13 to 27: 14.7% CP, 0.17 AM/AP; days 28 to 49: 14.5% CP, 0.25 AM/AP); 3) a group fed a low CP and a low AM/AP diet (LPLA) (days 0 to 13: 16.0% CP, 0.09 AM/AP; days 14 to 27: 14.7% CP, 0.05 AM/AP; days 28 to 49: 14.5% CP, 0.09 AM/AP). Pigs were weighted weakly until day 49. Fecal samples were collected on days 10 and 42 (12 samples/group/timepoint) for ammonia and calprotectin content and microbiota profile characterization. Until day 28, body weight (BW) of pigs from CTR was not different from pigs of the LPLA group, whereas it was higher from pigs of the LP group (P < 0.05). Thereafter, CTR group had greater BW compared with LP and LPLA groups for all the other timepoints considered (P < 0.05). From days 0 to 7 LPLA group had a lower incidence of diarrhea than the LP group (P = 0.04). On day 10, LPLA group had a greater alpha diversity (Shannon and InvSimpson indices), than the CTR (P = 0.03) and LP (P = 0.04) groups. On day 42, LPLA group had significantly greater InvSimpson diversity than LP group (P = 0.028). On day 10, LP group was characterized by greater abundance of Lactobacillus (LDA score = 5.15, P = 0.02), Clostridium-sensu-stricto-1 (LDA score = 4.90, P = 0.02) and Oscillospiraceae NK4A214-group (LDA score = 4.87, P = 0.004), whereas LPLA group was characterized by greater abundance of Prevotella (LDA score = 5.04, P = 0.003) and Agathobacter (LDA score = 4.77, P = 0.05). In conclusion, while reducing CP levels may negatively impact growth performance, when combined with higher amylopectin levels, it can reduce the incidence of diarrhea and increase fecal microbial diversity.

Designing a Specific Pretreatment on Corn Starch to Facilitate Enzymatic Rearrangement of Glycosidic Bonds for Efficiently Reducing Starch Digestibility

Bacterial 1,4-α-glucan branching enzymes (GBEs) provide a viable strategy for glycosidic bond rearrangement in starch and regulation of its digestion rate. However, the exponential increase in paste viscosity during starch gelatinization has a detrimental effect on the catalytic action of GBEs, thereby limiting productivity and product performance. Here, we designed an enzymatic treatment on corn starch granules by the GBE from Rhodothermus obamensis STB05 (Ro-GBE) prior to the glycosidic bond rearrangement of gelatinized starch catalyzed using the GBE from Geobacillus thermoglucosidans STB02 (Gt-GBE). Specifically, a moderate amount of Ro-GBE was required for the pretreatment stage. The dual GBE modification process enabled the treatment of more concentrated starch slurry (up to 20%, w/w) and effectively reduced starch digestibility. The resulting product contained a rapidly digestible starch fraction of 66.0%, which was 11.4% lower than that observed in the single Gt-GBE-modified product. The mechanistic investigation showed that the Ro-GBE treatment promoted swelling and gelatinization of starch granules, reduced starch paste viscosity, and increased the mobility of water molecules in the starch paste. It also created a preferable substrate for Gt-GBE. These changes improved the transglycosylation efficiency of Gt-GBE. These findings provide useful guidance for designing an efficient process to regulate starch digestibility.

Production of highly branched α-limit dextrins with enhanced slow digestibility by various glycogen-branching enzymes

α-Limit dextrins (α-LDx) are slowly digestible carbohydrates that attenuate postprandial glycemic response and trigger the secretion of satiety-related hormones. In this study, more highly branched α-LDx were enzymatically synthesized to enhance the slowly digestible property by various origins of glycogen branching enzyme (GBE), which catalyzes the transglycosylation to form α-1,6 branching points after cleaving α-1,4 linkages. Results showed that the proportion of branched α-LDx in starch molecules increased around 2.2-8.1 % compared to α-LDx from starch without GBE treatment as the ratio of α-1,6 linkages increased after different types of GBE treatments. Furthermore, the enzymatic increment of branching points enhanced the slowly digestible properties of α-LDx at the mammalian α-glucosidase level by 17.3-28.5 %, although the rates of glucose generation were different depending on the source of GBE treatment. Thus, the highly branched α-LDx with a higher amount of α-1,6 linkages and a higher molecular weight can be applied as a functional ingredient to deliver glucose throughout the entire small intestine without a glycemic spike which has the potential to control metabolic diseases such as obesity and type 2 diabetes.

Biosynthesis of maltodextrin-derived glucan dendrimer using microbial branching enzyme

Glucan dendrimers were developed with microbial branching enzyme (BE) treated maltodextrin. The molecular weight (M_w) of recombinant BE was 79.0 kDa, and its optimum activity was observed at pH 7.0 and 70 °C. BE converted different maltodextrins with dextrose equivalent value of 6 (MD6), 12 (MD12), or 19 (MD19) into the given glucan dendrimers, along with the marked increment of the molecular density (approximately 30-60 folds) and α-1,6 linkage percentage (up to 7.3-9.7%). Among three glucan dendrimers, the enzyme-treated MD12 showed a more homogeneous M_w distribution with the maximum M_w of 5.5 × 10⁶ g/mol, indicating that higher substrate catalytic specificity of BE for MD12 substrate. During transglycosylation with MD12 for 24 h, the shorter chains (degree of polymerization, DP < 13) increased from 73.9% to 83.0%, accompanying by a reduction of medium chains (DP13-24) and long chains (DP > 24). Moreover, the slowly digestible and resistant nutritional fractions were increased by 6.2% and 12.5%, respectively. The results suggested that the potentiality of BE structuring glucan dendrimer with tailor-made structure and functionality for industrial application.

Microencapsulates of Blue Maize Polyphenolics as a Promising Ingredient in the Food and Pharmaceutical Industry: Characterization, Antioxidant Properties, and In Vitro-Simulated Digestion

An anthocyanin-rich blue maize waste product was used for anthocyanin extraction. To preserve bioactive phenolic compounds, a spray-drying technique was employed using conventional wall material maltodextrin (MD), with novel one, hydroxypropyl-β-cyclodextrin (HPBCD). The obtained spray-dried maize extract (SME) and microencapsulates were analyzed based on physicochemical powder properties, chemical analysis, antioxidant activity, and digestibility. The examined microencapsulates demonstrated good powder properties, exhibited a high powder yield (up to 83%), and had a low moisture content (less than 5%). HPBCD and MD + HPBCD combinations demonstrated superior powder properties in the terms of decreasing the time necessary for rehydration (133.25 and 153.8 s, respectively). The mean average particle diameter ranged from 4.72 to 21.33 µm. DSC analyses signified high powder thermal stability, around 200 °C, related to the increasing preservation with biopolymer addition. The total phenolic and anthocyanin compounds ranged from 30,622 to 32,211 mg CE/kg (CE-catechin equivalents) and from 9642 to 12,182 mg CGE/kg (CGE-cyanidin 3-glucoside equivalents), respectively, associated with good bioactive compound protection. Microencapsulates with both carriers (15% MD and 15% HPBCD) had the highest digestibility (73.63%). Our results indicated that the microencapsulates created with the active ingredient and the wall materials (MD and HPBCD) could protect phenolic compounds/anthocyanins against ABTS radicals (63.53 and 62.47 mmol Trolox Eq/kg, respectively).

Maillard reaction-based conjugation of Spirulina protein with maltodextrin using wet-heating route and characterisation of conjugates

Spirulina protein concentrate (SPC) was extracted from Spirulina biomass and its structure and technofunctional properties were modified through Maillard reaction with maltodextrin (MD). Wet-heating route was adapted and Maillard reaction was controlled within initial to intermediate stage by avoiding or minimising the formation of melanoidins. A glycation degree of up to 29.1 % was achieved after reaction between SPC and MD, and molecular weight of the SPC increased accordingly. The solubility of SPC was improved only in the pH range around its isoelectric point after conjugation. The antioxidative property of the SPC-MD conjugate was also improved as the DPPH radical scavenging activity increased 19.7 to 30.2 %. Oil-in-water emulsion stabilised by SPC-MD conjugate produced at 6 h had significantly reduced droplet size, increased surface charge, and higher physical stability in temperature range 25-60 °C. The outcome of this research will help broaden the application of SPC in food as emulsifier and encapsulating shell material.

Two 1,4-α-glucan branching enzymes successively rearrange glycosidic bonds: A novel synergistic approach for reducing starch digestibility

Enzymatically rearranging α-1,4 and α-1,6 glycosidic bonds in starch is a green approach to regulating its digestibility. A two-step modification process successively catalyzed by 1,4-α-glucan branching enzymes (GBEs) from Rhodothermus obamensi STB05 (Ro-GBE) and Geobacillus thermoglucosidans STB02 (Gt-GBE) was investigated as a strategy to reduce the digestibility of corn starch. This dual GBE modification process caused a reduction of 25.8 % in rapidly digestible starch fraction in corn starch, which were more effective than single GBE-catalyzed modification with the same duration. Structural analysis indicated that the dual GBE modified product contained higher branching density, more abundant short branches, and shorter external chains than those in single GBE-modified product. These results demonstrated that a moderate Ro-GBE treatment prior to starch gelatinization caused several suitable alterations in starch molecules, which promoted the transglycosylation efficiency of the following Gt-GBE treatment. This dual GBE-catalyzed modification process offered an efficient strategy for regulating starch digestibility.