A Critical Review on Immobilized Sucrose Isomerase and Cells for Producing Isomaltulose.

Isomaltulose is a novel sweetener and is considered healthier than the common sugars, such as sucrose or glucose. It has been internationally recognized as a safe food product and holds vast potential in pharmaceutical and food industries. Sucrose isomerase is commonly used to produce isomaltulose from the substrate sucrose in vitro and in vivo. However, free cells/enzymes were often mixed with the product, making recycling difficult and leading to a significant increase in production costs. Immobilized cells/enzymes have the following advantages including easy separation from products, high stability, and reusability, which can significantly reduce production costs. They are more suitable than free ones for industrial production. Recently, immobilized cells/enzymes have been encapsulated using composite materials to enhance their mechanical strength and reusability and reduce leakage. This review summarizes the advancements made in immobilized cells/enzymes for isomaltulose production in terms of refining traditional approaches and innovating in materials and methods. Moreover, innovations in immobilized enzyme methods include cross-linked enzyme aggregates, nanoflowers, inclusion bodies, and directed affinity immobilization. Material innovations involve nanomaterials, graphene oxide, and so on. These innovations circumvent challenges like the utilization of toxic cross-linking agents and enzyme leakage encountered in traditional methods, thus contributing to enhanced enzyme stability.

Impaired Carbohydrate Metabolism among Women with Chronic Low Back Pain and the Role of Dietary Carbohydrates: A Randomized Controlled Cross-Over Experiment.

Background: Impaired glucose regulation is suggested to be related to chronic low back pain (CLBP), although it is not clear how they interact with each other. Thus, the primary aim of this study was to investigate differences in postprandial glycemic responses (PPGRs) (the first sign of impaired glucose metabolism) to high- (sucrose) and low-glycemic index (GI) (isomaltulose) beverages in normoglycemic women with CLBP and healthy controls (HCs) and explore whether any group that showed greater PPGRs to high-GI beverage intake would benefit when the high-GI beverage was replaced with a low-GI beverage. Secondly, this study aimed to explore the association between PPGR and pain in patients with CLBP. Methods: This study was registered at clinicaltrials.org (NCT04459104) before the start of the study. In this study, 53 CLBP patients and 53 HCs were recruited. After 11-12 h of fasting, each participant randomly received isomaltulose or sucrose. Blood glucose levels were measured during the fasting state and 15, 30, 45, 60, 90, and 120 min after the beverage intake, and each participant underwent experimental pain measures. Results: Compared to the HCs, the CLBP group showed significantly higher PPGRs to sucrose (p < 0.021). Additionally, the CLBP group showed a significantly higher decrease in PPGR (p = 0.045) when comparing PPGR to sucrose with PPGR to isomaltulose. Correlation analysis revealed a positive association between self-reported pain sensitivity and PPGR to sucrose, while there was no association found between any experimental pain measures and glycemic responses. Conclusions: Overall, these findings suggest that normoglycemic CLBP patients might have a higher risk of developing impaired glucose tolerance than the HCs and might benefit more when high-GI foods are replaced with low-GI ones.

Efficient production of isomaltulose using engineered Yarrowia lipolytica strain facilitated by non-yeast signal peptide-mediated cell surface display.

BACKGROUND: Isomaltulose is a 'generally recognized as safe' ingredient and is widely used in the food, pharmaceutical and chemical industries. The exploration and development of efficient technologies is essential for enhancing isomaltulose yield. RESULTS: In the present study, a simple and efficient surface display platform mediated by a non-yeast signal peptide was developed in Yarrowia lipolytica and utilized to efficiently produce isomaltulose from sucrose. We discovered that the signal peptide SP1 of sucrose isomerase from Pantoea dispersa UQ68J (PdSI) could guide SIs anchoring to the cell surface of Y. lipolytica, demonstrating a novel and simple cell surface display strategy. Furthermore, the PdSI expression level was significantly increased through optimizing the promoters and multi-site integrating genes into chromosome. The final strain gained 451.7 g L-1 isomaltulose with a conversion rate of 90.3% and a space-time yield of 50.2 g L-1 h-1. CONCLUSION: The present study provides an efficient way for manufacturing isomaltulose with a high space-time yield. This heterogenous signal peptide-mediated cell surface display strategy featured with small fusion tag (approximately 2.2 kDa of SP1), absence of enzyme leakage in fermentation broth and ample room for optimization, providing a convenient way to construct whole-cell biocatalysts to synthesize other products and broadening the array of molecular toolboxes accessible for engineering Y. lipolytica. © 2024 Society of Chemical Industry.

Isomaltulose Enhances GLP-1 and PYY Secretion to a Mixed Meal in People With or Without Type 2 Diabetes as Compared to Saccharose.

SCOPE: Secretion of the gut hormones glucagon-like peptide (GLP-1) and peptide YY (PYY) are induced by nutrients reaching the lower small intestine which regulate insulin and glucagon release, inhibit appetite, and may improve ß-cell regeneration. The aim is to test the effect of a slowly digested isomaltulose (ISO) compared to the rapidly digested saccharose (SAC) as a snack given 1 h before a standardized mixed meal test (MMT) on GLP-1, PYY, glucose-dependent insulinotropic peptide (GIP), and metabolic responses in participants with or without type 2 diabetes (T2DM). METHODS AND RESULTS: Fifteen healthy volunteers and 15 patients with T2DM consumed either 50 g ISO or SAC 1 h preload of MMT on nonconsecutive days. Clinical parameters and incretin hormones are measured throughout the whole course of MMT. Administration of 50 g ISO as compared to SAC induced a significant increase in GLP-1, GIP, and PYY responses over 2 h after intake of a typical lunch in healthy controls. Patients with T2DM showed reduced overall responses of GLP-1 and delayed insulin release compared to controls while ISO significantly enhanced the GIP and almost tripled the PYY response compared to SAC. CONCLUSION: A snack containing ISO markedly enhances the release of the metabolically advantageous gut hormones PYY and GLP-1 and enhances GIP release in response to a subsequent complex meal.

Safety of isomaltulose syrup (dried) as a novel food pursuant to Regulation (EU) 2015/2283.

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on isomaltulose syrup (dried) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF consists of a mixture of mono- and disaccharides in powder form, mainly composed of isomaltulose (≥ 75%) and trehalulose (< 13%). The applicant intends to use the NF as a replacement for sucrose already on the market. The information provided on the manufacturing process, composition and specifications of the NF is sufficient and does not raise safety concerns. No absorption, distribution, metabolism and excretion (ADME) or toxicological data were provided for the NF. Instead, the safety of the NF was assessed based on literature data available on isomaltulose and mixtures of isomaltulose and trehalulose. In addition, considering the nature, compositional characterisation and production process of the NF, the Panel considered that such data were sufficient to conclude that the NF is as safe as sucrose.

Habitual isomaltulose intake reduces arterial stiffness associated with postprandial hyperglycemia in middle-aged and elderly people: a randomized controlled trial.

Endothelin-1 (ET-1), produced by vascular endothelial cells, plays a pivotal role in the regulation of vascular tone. Isomaltulose, a naturally occurring sweetener and structural isomer of sucrose, reduces postprandial hyperglycemia, but its effect on arteriosclerosis due to hyperglycemia is unknown. The effects of 12 weeks of isomaltulose administration on ET-1 levels, a peptide that regulates arterial stiffness, blood pressure, and vascular tone, were tested before and after an oral glucose tolerance test. Fifty-four healthy middle-aged and older adults (30 men and 24 women) were divided into two groups: (1) a 25 g isomaltulose jelly drink intake group (Group I, 27 participants, mean age 55 ± 1 years) and (2) a sucrose jelly drink intake group (Group S, 27 participants, mean age 55 ± 1 years), each consuming isomaltulose or sucrose daily for 12 weeks, and a randomized, controlled study was conducted. Participants visited the laboratory before the intervention and 4, 8, and 12 weeks after the intervention to measure carotid-femoral (cf) and brachial-ankle (ba) pulse wave velocity (PWV), systolic blood pressure (BP), plasma glucose (PG), insulin, and ET-1 levels before and 60 and 120 min after a 75-g OGTT. baPWV, and ET-1 levels before intervention were significantly increased after 75-g OGTT compared to before 75-g OGTT in both groups (p < 0.05). The post-intervention baPWV, and ET-1 levels were significantly increased after 75-g OGTT in Group S compared to before 75-g OGTT (p < 0.05), whereas no significant changes were observed in Group I. These results suggest that consumption of isomaltulose, which has a lower GI than sucrose, is more effective in preventing the increases in systemic arterial stiffness associated with postprandial hyperglycemia in healthy middle-aged and older adults.

Brush border enzyme hydrolysis and glycaemic effects of isomaltulose compared to other saccharides in dogs.

Digestible carbohydrates differ in glycaemic response, therewith having the potential to influence metabolic conditions such as insulin resistance and diabetes mellitus. Isomaltulose has been proven to lower the glycaemic response in humans, which to date has not been studied in dogs. Therefore, the aim of the present study was to characterise the digestibility, as well as the physiological effects of isomaltulose in dogs, in comparison to other saccharides. To this end, three studies were performed. Study 1 was an in vitro study, evaluating the small intestinal hydrolysis of isomaltulose compared to other relevant carbohydrate sources. Three of these saccharides, having close and low-moderate degrees of hydrolysis by brush border enzymes, were also evaluated in vivo for their glycaemic effects by measuring plasma levels of glucose, insulin and glucagon-like peptide 1 (GLP-1) 0-180 min after administration of a single dosage after an overnight fast (i.e., isomaltulose, sucrose and maltodextrin in a 3 × 3 Latin-square design, in 9 dogs, Study 2). To understand if digestive enzymes, underlying glycaemic responses for isomaltulose and sucrose can be upregulated, we exposed dogs to these saccharides for 2 weeks and repeated the measurements after an overnight fast in 18 dogs (Study 3). Isomaltulose was hydrolysed by intestinal enzyme preparation from all three dogs, but the degrading activity was low (e.g., 3.95 ± 1.03 times lower vs. sucrose), indicating a slower rate of hydrolysis. Isomaltulose had a low glycaemic response, in line with in vitro data. In vitro hydrolysis of sucrose was comparable or even higher than maltodextrin in contrast to the more pronounced glycaemic response to maltodextrin observed in vivo. The numerically higher blood glucose response to sucrose after continuous consumption, might indicate an adaptive response. In conclusion, the current work provides valuable insights into the digestion physiology of various saccharides in dogs. Further investigations on related benefits are thus warranted.

Pre-exercise isomaltulose intake affects carbohydrate oxidation reduction during endurance exercise and maximal power output in the subsequent Wingate test.

BACKGROUND: Ingestion of low-glycemic index (GI) isomaltulose (ISO) not only suppresses subsequent carbohydrate (CHO) oxidation but also inversely retains more CHO after prolonged endurance exercise. Therefore, ISO intake may affect anaerobic power output after prolonged endurance exercise. This study aimed to clarify the time course of CHO utilization during endurance exercise after a single intake of ISO or sucrose (SUC) and the anaerobic power output at the end of endurance exercise. METHODS: After an intake of either ISO or SUC, 13 athletes were kept at rest for 60 min. Thereafter, they performed a 90-min of treadmill running at their individual target level of % [Formula: see text]max. During the experimental session, the expired gas was recorded, and the energy expenditure (EE) and CHO oxidation rate were estimated. Immediately after 90 min of running, a 30-s Wingate test was performed, and the maximal anaerobic power output was compared between the ISO and SUC conditions. RESULTS: The percentage of CHO-derived EE increased rapidly after CHO intake and then decreased gradually throughout the experiment. The slopes of the regression lines calculated from the time course in the CHO-derived EE were significantly (negatively) larger in the SUC condition (-19.4 ± 9.6 [%/h]) than in the ISO condition (-13.3 ± 7.5 [%/h]). Furthermore, the maximal power output in the Wingate test immediately after the endurance exercise was significantly higher in the ISO condition than in the SUC condition (peak power: 12.0 ± 0.6 vs. 11.5 ± 0.9 [W/kg]). CONCLUSION: Compared with SUC intake, ISO intake does not produce an abrupt decline in the percentage of CHO-derived EE during prolonged endurance exercise; it remains relatively high until the final exercise phase. Additionally, anaerobic power output at the end of the exercise, largely contributed by anaerobic glycolysis, was greater after ISO intake than after SUC intake.

Thermostability improvement of sucrose isomerase PalI NX-5: a comprehensive strategy.

OBJECTIVE: To increase the thermal stability of sucrose isomerase from Erwinia rhapontici NX-5, we designed a comprehensive strategy that combines different thermostabilizing elements. RESULTS: We identified 19 high B value amino acid residues for site-directed mutagenesis. An in silico evaluation of the influence of post-translational modifications on the thermostability was also carried out. The sucrose isomerase variants were expressed in Pichia pastoris X33. Thus, for the first time, we report the expression and characterization of glycosylated sucrose isomerases. The designed mutants K174Q, L202E and K174Q/L202E, showed an increase in their optimal temperature of 5 °C, while their half-lives increased 2.21, 1.73 and 2.89 times, respectively. The mutants showed an increase in activity of 20.3% up to 25.3%. The Km values for the K174Q, L202E, and K174Q/L202E mutants decreased by 5.1%, 7.9%, and 9.4%, respectively; furthermore, the catalytic efficiency increased by up to 16%. CONCLUSIONS: With the comprehensive strategy followed, we successfully obtain engineered mutants more suitable for industrial applications than their counterparts: native (this research) and wild-type from E. rhapontici NX-5, without compromising the catalytic activity of the molecule.

Implication of sugar, protein and incretins in excessive glucagon secretion in type 2 diabetes after mixed meals.

AIMS: Amino acids powerfully release glucagon but their contribution to postprandial hyperglucagonemia in type 2 diabetes remains unclear. Exogenously applied GIP stimulates, while GLP-1 inhibits, glucagon secretion in humans. However, their role in mixed meals is unclear, which we therefore characterized. METHODS: In three experiments, participants with type 2 diabetes and obese controls randomly received different loads of sugars and/or proteins. In the first experiment, participants ingested the rapidly cleaved saccharose (SAC) or slowly cleaved isomaltulose (ISO) which is known to elicit opposite profiles of GIP and GLP-1 secretion. In the second one participants received test meals which contained saccharose or isomaltulose in combination with milk protein. The third set of participants underwent randomized oral protein tests with whey protein or casein. Incretins, glucagon, C-peptide, and insulin were profiled by specific immunological assays. RESULTS: 50 g of the sugars alone suppressed glucagon in controls but slightly less in type 2 diabetes patients. Participants with type 2 diabetes showed excessive glucagon responses within 15 min and lasting over 3 h, while the obese controls showed small initial and delayed greater glucagon responses to mixed meals. The release of GIP was significantly faster and greater with SAC compared to ISO, while GLP-1 showed an inverse pattern. The glucagon responses to whey or casein were only moderately increased in type 2 diabetes patients without a left shift of the dose response curve. CONCLUSIONS: The rapid hypersecretion of glucagon after mixed meals in type 2 diabetes patients compared to controls is unaffected by endogenous incretins. The defective suppression of glucagon by glucose combined with hypersecretion to protein is required for the exaggerated response. CLINICAL TRIALS NUMBERS: NCT03806920, NCT02219295, NCT04564391.

Acute effect of fructose, sucrose, and isomaltulose on uric acid metabolism in healthy participants.

Fructose is associated with hyperuricemia and gout development. Focusing on fructose and fructose-containing disaccharides, we investigated the effects of three different types of carbohydrates (fructose, sucrose, and isomaltulose) on uric acid metabolism and gene expression profiling in peripheral white blood cells. In a randomized crossover study, ten healthy participants ingested test drinks of fructose, sucrose, and isomaltulose, each containing 25 g of fructose. Plasma glucose, serum and urine uric acid, and xanthine/hypoxanthine concentrations were measured. Microarray analysis in peripheral white blood cells and real-time reverse transcription polymerase chain reaction were examined at 0 and 120 in after the intake of test drinks. Serum uric acid concentrations for group fructose were significantly higher than group sucrose at 30-120 min and were significantly higher than those for group isomaltulose at 30-240 min. Several genes involved in the "nuclear factor-kappa B signaling pathway" were markedly changed in group fructose. No significant differences in the mRNA expression levels of tumor necrosis factor, nuclear factor-kappa B, interleukin-1ß, and interleukin-18 were noted. This study indicated that fructose intake (monosaccharide) elevated serum uric acid concentrations compared with disaccharide intake. Differences in the quality of carbohydrates might reduce the rapid increase of postprandial serum uric acid concentrations.

Engineering cyanobacteria for converting carbon dioxide into isomaltulose.

Isomaltulose is a promising functional sweetener with broad application prospects in the food industry. Currently, isomaltulose is mainly produced through bioconversion processes based on the isomerization of sucrose, the economic feasibility of which is influenced by the cost of sucrose feedstocks, the biocatalyst preparation, and product purification. Cyanobacterial photosynthetic production utilizing solar energy and carbon dioxide represents a promising route for the supply of sugar products, which can promote both carbon reduction and green production. Previously, some cyanobacteria strains have been successfully engineered for synthesis of sucrose, the main feedstock for isomaltulose production. In this work, we introduced different sucrose isomerases into Synechococcus elongatus PCC 7942 and successfully achieved the isomaltulose synthesis and accumulation in the recombinant strains. Combinatory expression of an Escherichia coli sourced sucrose permease CscB with the sucrose isomerases led to efficient secretion of isomaltulose and significantly elevated the final titer. During a 6-day cultivation, 777 mg/L of isomaltulose was produced by the engineered Synechococcus cell factory. This work demonstrated a new route for isomaltulose biosynthesis utilizing carbon dioxide as the substrate, and provided novel understandings for the plasticity of cyanobacterial photosynthetic metabolism network.

Robust and recyclable cross-linked enzyme aggregates of sucrose isomerase for isomaltulose production.

A novel cross-linked enzyme aggregates (CLEAs) catalyst was produced by precipitation and cross-linking sucrose isomerase (SIase) for isomaltulose production. The effects of precipitants and cross-linkers on the catalytic performance of the CLEAs were first evaluated. Then, bovine serum albumin (BSA) was used as additive and two immobilized enzymes, cross-linked SIase aggregates (CLSIAs) and CLSIAs-BSA were obtained. All the immobilized preparations exhibited superior thermal stability, pH tolerance, and storage stability compared to the soluble SIase, and showed excellent reusability. These samples still retained more than 61% of their initial activity after ten reuse cycles, with CLSIAs-BSA retaining up to 91.7%. The conversion ratios of sucrose into isomaltulose using CLSIAs-BSA reached 88.4 and 81.2% with sucrose and sugar cane juice as substrate, respectively. Therefore, CLSIAs are a highly effective biocatalyst for the preparation of isomaltulose with great potential for industrial applications.

Incorporation and influence of natural gums in an alginate matrix for Serratia plymuthica immobilization and isomaltulose production.

Isomaltulose (IM) is a non-cariogenic sugar and substitute for sucrose that has been widely used in candies and soft drinks. This sugar is obtained from sucrose through enzymatic conversion, catalyzed by microbial glucosyltransferases. In this study, alternative gums, namely: gum Arabic (GA), algaroba gum (AG), and cashew gum (CG) were combined with alginate (ALG) for the immobilization of Serratia plymuthica, with the aim of improving its capability for conversion of sucrose into IM. Prior to the immobilization, the gums were characterized using FTIR spectroscopy, TGA, and XRD analysis. Then, they were combined with ALG and used to immobilize a cell mass of S. plymuthica by ionic gelation. The morphology of the produced beads was visualized using SEM, and the sucrose into IM conversion using the beads was performed in batch and continuous processes. CG showed the highest thermal stability and crystallinity. The use of CG (2.0 %, w/v) combined with ALG (2.0 %, w/v) showed the highest value for isomaltulose (236.46 g/L) produced in the first batch, and high stability in the continuous conversion process; resulting in an IM production of 199.24 g/L at 72 h of reaction. In addition, this combination produced less porous beads, able to maintain the entrapped cells longer. In conclusion, the production of IM by Serratia plymuthica cells immobilized in a matrix composed of ALG and CG is recommended, due to its high conversion capacity and high stability.

Enhanced Extracellular Production and Characterization of Sucrose Isomerase in Bacillus subtilis with Optimized Signal Peptides.

Sucrose isomerase (SIase) catalyzes the hydrolysis and isomerization of sucrose into isomaltulose, which is an important functional sugar widely used in the food industry. However, the lack of safe and efficient expression systems for recombinant SIase has impeded its production and application. In this study, enhanced expression of a SIase from Klebsiella sp. LX3 (referred to as KsLX3-SIase) was achieved in Bacillus subtilis WB800N, by optimizing the signal peptides. First, 13 candidate signal peptides were selected using a semi-rational approach, and their effects on KsLX3-SIase secretion were compared. The signal peptide WapA was most efficient in directing the secretion of KsLX3-SIase into the culture medium, producing a specific activity of 23.0 U/mL, as demonstrated by shake flask culture. Using a fed-batch strategy, the activity of KsLX3-SIase in the culture medium was increased to 125.0 U/mL in a 5-L fermentor. Finally, the expressed KsLX3-SIase was purified and was found to have maximum activity at 45 °C and pH 5.5. Its Km for sucrose was 267.6 ± 18.6 mmol/L, and its kcat/Km was 10.1 ± 0.2 s-1mM-1. These findings demonstrated an efficient expression of SIase in B. subtilis, and this is thought to be the highest level of SIase produced in a food-grade bacteria to date.

Sustainable isomaltulose production in Corynebacterium glutamicum by engineering the thermostability of sucrose isomerase coupled with one-step simplified cell immobilization.

Sucrose isomerase (SI), catalyzing sucrose to isomaltulose, has been widely used in isomaltulose production, but its poor thermostability is still resisted in sustainable batches production. Here, protein engineering and one-step immobilized cell strategy were simultaneously coupled to maintain steady state for long-term operational stabilities. First, rational design of Pantoea dispersa SI (PdSI) for improving its thermostability by predicting and substituting the unstable amino acid residues was investigated using computational analysis. After screening mutagenesis library, two single mutants (PdSIV280L and PdSIS499F) displayed favorable characteristics on thermostability, and further study found that the double mutant PdSIV280L/S499F could stabilize PdSIWT better. Compared with PdSIWT, PdSIV280L/S499F displayed a 3.2°C-higher T m , and showed a ninefold prolonged half-life at 45°C. Subsequently, a one-step simplified immobilization method was developed for encapsulation of PdSIV280L/S499F in food-grade Corynebacterium glutamicum cells to further enhance the recyclability of isomaltulose production. Recombinant cells expressing combinatorial mutant (RCSI2) were successfully immobilized in 2.5% sodium alginate without prior permeabilization. The immobilized RCSI2 showed that the maximum yield of isomaltulose by batch conversion reached to 453.0 g/L isomaltulose with a productivity of 41.2 g/l/h from 500.0 g/L sucrose solution, and the conversion rate remained 83.2% after 26 repeated batches.

Quantification of Isomaltulose in Food Products by Using Heteronuclear Single Quantum Coherence NMR-Experiments.

Isomaltulose is a commonly used sweetener in sports nutrition and in products intended for consumption by diabetics. Because previously established chromatographic methods for quantification of isomaltulose suffer from long analysis times (60-210 min), faster quantitative approaches are required. Here, an HSQC (heteronuclear single quantum coherence) experiment with reduced interscan delay was established in order to quantify isomaltulose next to potential additional sugars such as d-glucose, d-fructose, d-galactose, sucrose, lactose, and maltose in 53 min. By using HSQC coupled to non-uniform sampling (NUS) as well as ASAP-HSQC (acceleration by sharing adjacent polarization), analysis times were reduced to a few minutes. Application of NUS-HSQC with reduced interscan delay takes 27 min, resulting in accurate and precise data. In principle, application of ASAP-HSQC approaches (with analysis times as low as 6 min) can be used; however, precision data may not suffice all applications.

Blood Glucose Response of a Low-Carbohydrate Oral Nutritional Supplement with Isomaltulose and Soluble Dietary Fiber in Individuals with Prediabetes: A Randomized, Single-Blind Crossover Trial.

A high-energy-type oral dietary supplement (ONS), with a low proportion of available carbohydrate (LC-ONS), which contains a slowly digestible carbohydrate, isomaltulose, and is fortified with soluble dietary fiber, was newly developed for individuals with diabetes or prediabetes. This study aimed to evaluate the impact of LC-ONS on blood glucose levels after ingestion in individuals with prediabetes. A single-blind, randomized crossover clinical trial was performed on 20 individuals with prediabetes. After overnight fasting, all subjects ingested one serving (200 kcal/125 mL) of either LC-ONS (40% energy proportion of available carbohydrates) or standard ONS (ST-ONS, 54% energy proportion of available carbohydrates) on two separate days. The incremental area under the curve of blood glucose levels for 120 min was significantly lower after LC-ONS ingestion compared to ST-ONS (2207 ± 391 mg/dL·min (least mean square value ± standard error) and 3735 ± 391 mg/dL·min, respectively; p < 0.001). The LC-ONS showed significantly lower blood glucose levels than the ST-ONS at all time points, except at baseline. Similarly, the incremental area under the curve of plasma insulin was significantly lower after LC-ONS ingestion. These results suggest that LC-ONS is useful as an ONS for energy supply in individuals with postprandial hyperglycemia.

Effect of Isomaltulose on Glycemic and Insulinemic Responses: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

Evidence regarding the effect of isomaltulose on glycemic and insulinemic responses is still conflicting, which limits isomaltulose's application in glycemic management. The purpose of this study was to comprehensively evaluate its effectiveness and evidence quality. We systematically searched PubMed, Embase, and the Cochrane Library for randomized controlled trials (RCTs) prior to October 2021. RCTs were eligible for inclusion if they enrolled adults to oral intake of isomaltulose or other carbohydrates dissolved in water after an overnight fast and compared their 2-h postprandial glucose and insulin concentrations. The DerSimonian-Laird method was used to pool the means of the circulating glucose and insulin concentrations. Both random-effects and fixed-effects models were used to calculate the weighted mean difference in postprandial glucose and insulin concentrations in different groups. Subgroup, sensitivity, and meta-regression analyses were also conducted. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to assess the certainty of evidence. Finally, 11 RCTs (n = 175 participants) were included. The trials were conducted in 4 countries (Japan, Brazil, Germany, and the Netherlands), and all of the enrolled participants were >18 y of age with various health statuses (healthy, type 2 diabetes, impaired glucose tolerance, and hypertension). Moderate evidence suggested that oral isomaltulose caused an attenuated glycemic response compared with sucrose at 30 min. Low evidence suggested that oral isomaltulose caused an attenuated but more prolonged glycemic response than sucrose and an attenuated insulinemic response. Low-to-moderate levels of evidence suggest there may be more benefit of isomaltulose for people with type 2 diabetes, impaired glucose tolerance, or hypertension; older people; overweight or obese people; and Asian people. The study was registered on PROSPERO (International Prospective Register of Systematic Reviews) as CRD42021290396 (available at https://www.crd.york.ac.uk/prospero/).

Tuning the catalytic performances of a sucrose isomerase for production of isomaltulose with high concentration.

Obtaining a sucrose isomerase (SIase) with high catalytic performance is of great importance in industrial production of isomaltulose (a reducing sugar). In order to obtain such SIase mutant, a high-throughput screening system in microtiter plate format was developed based on a widely used 2,4-dinitrosalicylic acid (DNS) method for determination of reducing sugar. An SIase from Erwinia sp. Ejp617 (ErSIase) was selected to improve its catalytic efficiency. After screening of ~ 8000 mutants from a random mutagenesis library, Q209 and R456 were identified as beneficial positions. Saturation mutagenesis of the two positions resulted in a double-site mutant ErSIase_Q209S-R456H that showed the highest catalytic efficiency, and its specific activity reached 684 U/mg that is 17.5-fold higher than that of the wild-type ErSIase. By employing the lyophilized Escherichia coli (E. coli) cells harboring ErSIase_Q209S-R456H, a high space-time yield (STY = 3.9 kg/(L·d)) was achieved toward 600 g/L sucrose. Furthermore, the in silico analysis suggested that the hydrogen bond network was improved and steric hindrance was reduced due to the beneficial substitutions.Key points• A sucrose isomerase mutant with high catalytic efficiency was obtained.• The highest space-time yield was achieved toward high-concentration sucrose.• The optimized H-bond network contributed to the enhanced catalytic efficiency.