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Xylitol (XYL) is a sweetener used as a food additive in the food industry. In the present study, four different genotoxicity assays (chromosomal aberration=CA, sister chromatid exchange=SCE, cytokinesis-block micronucleus cytome=CBMN-Cyt, and comet assays) were conducted to assess the potential genotoxicity of XYL in human lymphocytes. Four concentrations (125, 250, 500, and 1000 μg mL-1) of XYL were applied to lymphocytes obtained from three healthy young donors. The frequency of CA was not significantly affected by 24-h administration of XYL (except 1000 μg mL-1 for the number of CAs). 48 h treatment of XYL increased the frequency of CAs and abnormal cells. However, this increase was significant at only two highest concentrations. XYL significantly increased SCE/cell rate at the two highest concentrations at both treatment times (24 and 48h). Similarly, the frequency of MN, Nuclear buds (NBUDs), and Nucleoplasmic bridges (NPBs) significantly increased by XYL only at the high concentrations. It raised the comet parameters at the two highest concentrations. These observations showed that XYL, only at high concentrations, may have a genotoxic effect on human lymphocytes in vitro. For this reason, it can be concluded that its use at low concentrations may not cause DNA or chromosomal damage.

Lignocellulose is an abundant xylose-containing biomass found in agricultural wastes, and has arisen as a suitable alternative to fossil fuels for the production of bioethanol. Although Saccharomyces cerevisiae has been thoroughly used for the production of bioethanol, its potential to utilize lignocellulose remains poorly understood. In this work, xylose-metabolic genes of Pichia stipitis and Candida tropicalis, under the control of different promoters, were introduced into S. cerevisiae. RNA-seq analysis was use to examine the response of S. cerevisiae metabolism to the introduction of xylose-metabolic genes. The use of the PGK1 promoter to drive xylitol dehydrogenase (XDH) expression, instead of the TEF1 promoter, improved xylose utilization in ?XR-pXDH? strain by overexpressing xylose reductase (XR) and XDH from C. tropicalis, enhancing the production of xylitol (13.66 ? 0.54 g/L after 6 days fermentation). Overexpression of xylulokinase and XR/XDH from P. stipitis remarkably decreased xylitol accumulation (1.13 ? 0.06 g/L and 0.89 ? 0.04 g/L xylitol, respectively) and increased ethanol production (196.14% and 148.50% increases during the xylose utilization stage, respectively), in comparison with the results of XR-pXDH. This result may be produced due to the enhanced xylose transport, Embden?Meyerhof and pentose phosphate pathways, as well as alleviated oxidative stress. The low xylose consumption rate in these recombinant strains comparing with P. stipitis and C. tropicalis may be explained by the insufficient supplementation of NADPH and NAD+. The results obtained in this work provide new insights on the potential utilization of xylose using bioengineered S. cerevisiae strains.

Objective To assess the actual xylitol content in sugar-free chewing gums available in a market of Saudi Arabia and investigate its effect on acid production and pH change in vitro. Materials and methods: A total of 29 different brands of xylitol-containing sugar-free chewing gums were collected from five major grocery stores in Saudi Arabia. Xylitol was extracted and its concentration was determined using the D-Sorbitol/Xylitol Enzymatic Kit (Megazyme; Bray, Wicklow, Ireland). The pH of the extracts and the amount of acid production for each product was measured after 15-minute and 30-minute incubation with Streptococcus mutans. Descriptive analysis, concentrations, and one-way analysis of variance (ANOVA) with the least significant difference (LSD) as multiple comparisons were performed. Results: The xylitol content in grams was clearly stated on the labels of 16 products, while it was stated in percentages on the labels of ten products. The mean pH of most of the tested products was 5.857 ± 0.096. Significant differences in pH were recorded among 20 products (p ≤ 0.05). Highly significant differences in pH (p = 0.001) were observed in five of the products. Conclusion: The results of this study indicate, using an in vitro model, that xylitol can significantly affect salivary pH. The actual xylitol content in most brands of chewing gums currently available in the markets of Saudi Arabia is less than the concentration recommended for prevention of caries. Accurate information with proper labeling is required to enable dental professionals to take correct and informed decisions about recommending the use of these products.

Bakground: Fluoride varnish with high initial fluoride and calcium release can help patients with high-risk caries. Ample quantities of free fluoride and calcium ions in the oral cavity can enhance enamel remineralization. This study aimed to investigate the effect of dicalcium phosphate dihydrate coated with xylitol (DCPD-xylitol), in fluoride varnish, on the release of fluoride and calcium ions in the oral cavity. Materials and methods DCPD powder with xylitol was synthesized by preparing a 60% xylitol solution and mixed it with DCPD solution. The mixture was stirred for 1 h at room temperature and dried at 80 °C for 18 h to reduce the water content. Then, the powder was used in the formulation of peppermint-flavored fluoride varnish as an active agent. The amounts of fluoride and calcium ion released in deionized water at 37 °C for 6 h were assessed with an ion-selective electrode. The cumulative fluoride and calcium ion release data were analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey test with α = 0.05. Results The results showed that the addition of DCPD coated with xylitol provided better bioavailability of the ions than DCPD without coating. Peppermint-flavored fluoride varnish (PFFV) with DCPD-xylitol 1% gave the highest fluoride ion release (296.90 mg/L) compared to the varnishes with other xylitol concentrations and the positive control. In contrast, PFFV DCPD-xylitol 5% afforded the highest calcium ion release at 111.20 mg/L. Conclusions This study concluded that xylitol affects the bioavailability of free fluoride and calcium ions in varnishes. However, the efficacy of fluoride and calcium uptake in enamel and under different in vitro media conditions requires further investigation.

INTRODUCTION: EmbraceTM Varnish is a new fluoride varnish which contains xylitol-coated calcium and phosphate (XCP). This combination leads to increase the release time of fluoride in this varnish.Objective: To compare the remineralizing effect of EmbraceTM varnish with Profluoride® varnish on caries-like lesions in primary teeth regarding lesion depth and calcium and phosphate enamel content.Materials and methods: Fourty eight anterior primary teeth were coated with nail varnish, leaving squares of 4x4 mm then sectioned longitudinally in a labiolingual direction into two equal halves. Each half was considered as a specimen (96 specimens). Caries-like lesions were created in all specimens. Specimens were divided into two groups. group I (n=48) was subdivided into subgroup IA (n=24) treated with EmbraceTM varnish and subgroup IB (n=24) served as control, while groupII (n=48) was subdivided into subgroup IIA (n=24) treated with Profluoride® varnish and subgroup IIB (n=24) served as control. Specimens were subjected to pH cycling then they were examined with polarized light microscopy and energy dispersive X-ray spectrometer.Results: No significant difference in mean percent reduction in lesion depth following treatment with EmbraceTM varnish and Profluoride® varnish (49.51 and 45.11, respectively) at P= 0.58. Greater significant of calcium phosphate ratio was found for EmbraceTM varnish (2.25±0.43) than Profluoride® varnish (1.65±0.05) at P< 0.0001. Significance was set at the 5% level.Conclusions: EmbraceTM varnish had no significant difference in mean percent reduction in lesion depth than Profluoride® varnish, while it had a better remineralization effect than Profluoride® varnish in terms of higher mineral content.

Objective To investigate the effect of mogroside, palatinose, erythritol, and xylitol on the dental plaque pH of children and to compare the plaque pH change between caries-active and caries-free children caused by these sweeteners. Methods Thirty-six children (mean age 6.2 ± 2.9-year-old), caries-active and caries-free, were included. After refraining from practicing oral hygiene, the accessible plaque was collected and equally divided for challenging with 6 different solutions: mogroside, palatinose, erythritol, xylitol, 10% sucrose, and deionized water. The pH of each solution was measured using a digital pH meter at 0, 5, 10, 15, 20, 25, and 30 min. Results Mogroside, erythritol, xylitol, and water did not significantly lower the dental plaque pH, however, palatinose reduced dental plaque pH comparable to sucrose (p Conclusions Mogroside, erythritol, and xylitol did not lower the dental plaque pH in caries-active or caries-free children. However, palatinose affected the dental plaque pH similar to sucrose.

Xylitol has reported to decrease gingival inflammation and nasopharyngeal pneumonia, which indicated that xylitol may have potential application in respiratory diseases. Although some studies have reported the inhalation toxicity of xylitol, however, the longest period tested was only for 14 days. The inhalation toxicity of xylitol is insufficient. This work investigated the potential subacute toxicity of xylitol according to the OECD TG 412. Rats were randomly divided into a control group and different dosage groups (2 g/m3, 3 g/m3, 5 g/m3), and exposed for 6 hours/day, 5 days/week for 28 days. At the end of the exposure or recovery period, clinical signs, mortality, body weight, food consumption, hematology, blood biochemistry, gross pathology, organ weight, and histopathology were examined. Compared with the control group, rats of both sexes in the exposure groups exhibited no significant changes in body weight, organ mass, and food uptake. After the xylitol exposure, aspartate aminotransferase activity in the xylitol group (3 g/m3) was significantly higher than that in the control group, while other blood indicators and pathological changes of liver and the analysis of the recovery group showed no changes, suggesting that xylitol exerted no observable toxic effect on the liver. Finally, other observations including the histopathology of target organs and hematology also showed no alterations. These results indicated that xylitol had no significant inhalation toxicity at doses up to 5 g/m3. These subacute inhalation toxicity results of xylitol showed that its no-observed-adverse-effect concentration (NOAEC) in rats was determined to 5 g/m3.

Xilitol adalah gula alkohol dengan lima atom karbon. Gula ini digunakan sebagai pemanis industri pangan dan makanan, karena memiliki karakter yang menguntungkan. Meskipun xilitol diproduksi secara industri oleh reduksi kimia D-xilosa yang berasal dari hidrolisat hemiselulosa, metode produksi ini tidak ekonomis karena persyaratan untuk D-xilosa murni, suhu tinggi, dan tekanan tinggi. Oleh karena itu, produksi xilitol melalui pendekatan bioteknologi dengan bantuan mikroorganisme menjadi fokus sebagai metode yang ekonomis dan ramah lingkungan. Selain itu, untuk meningkatkan produksi bio-xilitol, strain mikroorganisme telah mengalami strategi modifikasi genetik. Review ini menjelaskan upaya produksi xilitol dari biomasa lignoselulasa, proses perlakuan biomasa, dan mikroorganisme yang berperan dalam fermentasi xilitolAbstractXylitol is a sugar alcohol with five atoms of C. This sugar is used as a sweetener in the food industry and confectionary, because it has a favorable character. Although xylitol is produced industrially by the chemical reduction of D-xylose derived from hemicellulose hydrolyzate, this production method is not economical because of the requirements for pure D-xylose, high temperature, and high pressure. Therefore, the production of xylitol with a biotechnological approach with the help of microorganisms becomes the focus as an economical and environmentally friendly method. In addition, to increase bio-xylitol production, strains of microorganisms have undergone genetic modification strategies. This review article describes the latest advances made in the production of xylitol from lignocellulase biomass, biomass treatment processes, and microorganisms that play a role in xylitol fermentation.

Debaryomyces hansenii has been employed to study, initially, the influence of the oxygen availability on D-xylose to xylitol fermentation, as this parameter is considered as one of the most critical variables for this bio alcohol accumulation. Apart from the air supplied in the fermentation process through the stirring vortex (0.0 v/v/min), additional aeration rates (0.1-2.0 v/v/min) effects were discussed. Furthermore, a change in the fermentative medium composition as well as a comparative analysis of D. hansenii behavior with respect to fermentation of D-glucose and D-xylose mixtures solutions, with the aim of producing both xylitol and ethanol bioproducts, were performed. For these purposes, specific growth rates, biomass productivities, specific substrate-uptake rates, overall biomass yields, specific xylitol formation rates and overall xylitol yields values have been calculated, applying a differential method to the kinetic data. Aeration influence was clearly evinced since a faster D-xylose metabolism, for aeration values close to 1.0 v/v/min, was noted. This yeast exhibited a sequential substrate consumption, firstly D-glucose and then D-xylose. The maximum xylitol yield (0.32 kg kg- 1) was obtained for 0.5 v/v/min airflow, remarking a significant reduction of this parameter for both above and below the quoted air supply value.

This study focused on the optimization of xylitol production from sugarcane bagasse by using response surface methodology (RSM). Xylitol was produced through a series of processes, firstly, optimization of ultrasound assisted mild alkaline pretreatment for the xylan extraction from sugarcane bagasse followed by enzymatic hydrolysis of xylan to xylose by enzyme β-1,4-xylanase and finally microbial fermentation of xylose to xylitol using yeast (Candida guilliermondii), bacteria (Corynebacterium glutamicum) and their mixed culture for different time periods (0-96 h). Maximum xylan recovery of 12.059% (w/w) was observed at pretreatment; 0.73 M NaOH, 1:38.55 solid to liquid ratio and 34.77 min ultrasonication. The enzyme concentration of 400 U/g xylan at 48 h of incubation showed the highest xylose production (81.51 mg/g bagasse). Yeast (Candida guilliermondii) resulted in the highest xylitol yield (Yp/s= 0.43 g/g) after 72 h. This bioprocess route can contribute as a suitable alternative for chemical methods of xylitol production.

У літературному огляді розглядається перспектива застосування п’ятиатомного спирту ксиліту як цукрозамінника, що є альтернативою надмірному споживанню рафінованих вуглеводів. Установлено, що використання ксиліту приводить до підвищення толерантності до глюкози, стабілізує метаболічну ситуацію в пацієнтів із нестабільним перебігом цукрового діабету. Він має антикетогенні властивості й забезпечує повільну, але стійку енергопродукцію. Використання ксиліту в парентеральному харчуванні сприяє підвищенню в печінці вмісту АТФ та інших аденілнуклеотидів, стимулює синтез білків і виділення жовчі, знижує кількість вільних жирних кислот у крові і продукцію кетонових тіл. Здатність ксиліту пригнічувати ефект Варбурга відкриває нові можливості для потенційного покращення результатів лікування хворих із злоякісними новоутвореннями.

Acid hydrolysis and hydrogenation reactions were capable to convert xylose obtained from biomass materials using heterogeneous catalysts based on Ni and Ru. Xylose was extracted from sugar cane bagasse using dilute acid sulfuric solutions, and then xylitol was obtained through xylose catalytic hydrogenation. A bimetallic catalyst (Ni 10.0 wt.% and Ru 1.0 wt.%) was prepared by the wet impregnation method, supporting the metallic phase in activated carbon. Sugarcane bagasse was delignified in a three-step pretreatment (acid, basic and organic extractions, respectively), allowing effective hydrolysis of the resulting holocellulose. The acid hydrolysis process for xylose extraction was more effective at the highest concentration of sulfuric acid in the study (2.5% v/v), obtaining a xylose-rich hydrolysate with concentration over 10 g L−1. For the xylose hydrogenation process, conversion of xylose and selectivity to xylitol was near 90 % after 1 h of reaction. Kinetic evolutions were evaluated through a mathematical model in terms of operating time and temperature, providing hydrogenation activation energy values of the order of 40.76 kJ mol−1.

The growing market demand for natural sweeteners, that can be used to replace regular sugar, can be supplied by the biotechnological production of sweetening compounds, such as syrups and polyols. In the past few years, the use of low-cost and alternative substrates for production of syrups and polyols using microbial and enzymatic processes has been reported. This review discusses the recent advances in biotechnological production of sweetening syrups and low-caloric polyol, including mannitol, sorbitol, erythritol and xylitol.

Previous study has explored dip dehydration as a novel variant of osmotic dehydration to reduce solid gain, which is the main problem of osmotic dehydration. However, this dehydration process commonly uses sucrose solution as osmotic agent which might contribute to the increase in glycaemic index and can also be linked to different diseases such as diabetes and obesity. Therefore, this study aims to investigate the effect of using alternative sweeteners as an osmotic agent on mass transfer, colour, and texture profiles during dip dehydration of apple slices. Three alternative sweeteners, i.e., erythritol, sorbitol and xylitol with 30% (w/v) concentration were used in this study. Apple slices with 1.5 mm thickness and diameter of 55 mm were dipped multiple time in the same concentrated solution every 40 minutes until 200 minutes before samples were analysed. Findings showed that different type of sweetener affect water loss and solid gain. Xylitol and sorbitol gave highest water loss about 36% and 40%, respectively. Lowest total colour different with fresh apple has been observed in sample treated with xylitol. As for texture, there is no remarkable effect of using alternative sweetener as osmotic agent at all processing times. Overall, the best alternative sweetener for sucrose is xylitol considering the mass transfer and quality of apple slices.

The article analyzes the mechanisms of development and clinical manifestations of diabetic ketoacidosis (DKA), presents an intensive care program, discusses the prospects for the use of infusions based on xylitol in the treatment of DKA. The authors presented their own experience of using a solution with a 5% xylitol. It was shown that the use of xylitol can have a positive effect on various parts of the pathological process — from the elimination of dehydration to the correction of acid-base disorders. The authors also discuss the causes of severe ketoacidosis in patients with COVID-19 and present their own experience in the treatment of 14 patients with DKA on the background of COVID-19., У статті аналізуються механізми розвитку та клінічні прояви діабетичного кетоацидозу (ДКА), надано програму інтенсивної терапії, обговорюються перспективи застосування інфузійних засобів на основі ксилітолу в лікуванні ДКА. Автори надали власний досвід застосування розчину з 5% вмістом ксилітолу. Було показано, що застосування ксилітолу дозволяє позитивно впливати на різні ланки патологічного процесу — від усунення дегідратації до корекції порушень кислотно-лужного стану. Автори також обговорюють причини виникнення тяжкого кетоацидозу у хворих на COVID-19 та наводять власний досвід лікування 14 пацієнтів із ДКА на фоні COVID-19.

This study aimed to evaluate the Cirrus high-definition (HD) spectral-domain optical coherence tomography (SD-OCT) for the remineralization of artificial enamel caries and to compare it with the comparison surface microhardness (SMH) analysis. Artificial caries lesions were produced on forty human enamel samples. Then, three different remineralization agents containing casein phosphopeptide amorphous calcium phosphate; casein phosphopeptide amorphous calcium fluoride phosphate; calcium glycerophosphate, magnesium chloride, and xylitol; and remineralization solution (control) were applied with pH cycling for six days. The optical depth of backscattered light and microhardness of enamel were measured using SD-OCT and SMH. All remineralization agents were significantly efficient in reducing optical lesion depth on enamels (p1=0.001, p2=0.002, p3=0.006, p4=0.025), and in increasing the SMH of enamels (p1-3=0.005, p4=0.017). However, the optical lesion depths of the enamel showed no correlation with the SMH in the groups. In conclusion, demineralization and remineralization of artificial lesions can be assessed with both SD-OCT and SMH.

A novel arabitol dehydrogenase (ArDH) gene was cloned from a bacterium named Aspergillus nidulans and expressed heterologously in Escherichia coli. The purified ArDH exhibited the maximal activity in pH 9.5 Tris-HCl buffer at 40 °C, showed Km and Vmax of 1.2 mg/mL and 9.1 U/mg, respectively. The ArDH was used to produce the L-xylulose and coupled with the NADH oxidase (Nox) for the regeneration of NAD+. In further optimization, a high conversion of 84.6% in 8 hours was achieved under the optimal conditions: 20 mM of xylitol, 100 µM NAD+ in pH 9.0 Tris-HCl buffer at 30 °C. The results indicated the coupling system with cofactor regeneration provides a promising approach for L-xylulose production from xylitol.

The development of a green route to obtain bioactive compounds is of great interest, contributing to the value of underused matrices such as the Soursop leaves. Deep eutectic solvents (DES) using cholinium chloride as HBA, and alcohols and sugars as HBD, were combined with the ultrasound-assisted solid–liquid extraction (UA-SLE) to obtain bioactive compounds from soursop leaves. The solvent effect, temperature, and time of the process were evaluated. The better process conditions were 45 °C and 2 h considering the total phenolic content (TPC), antioxidant activity of the extracts and process energy cost. Among all evaluated solvents, those composed of glycerol and xylitol as hydrogen bond donors presented the higher extraction indexes. The main compounds on the extracts were rutin and catechin as determined by HPLC-DAD. DES demonstrated a protective effect against the thermal degradation of the bioactive compounds. Lastly, considering the meaningful antioxidant activity of the extracts and the DES protective effect, they were applied as a natural additive in soybean crude oil resulting in a satisfactory preservation of the oil. The DES combined with the ultrasound technique allow the obtaining of natural extracts with antioxidant properties which can be applied as a natural supplement to the food industry.

The article substantiates the relevance of the development of confectionery products with a reduced content of easily digestible carbohydrates and content of calories’, including those suitable for diabetic nutrition. A comparative analysis of the technological and physiological properties of sweeteners (polyols) was carried out and showed the prospects of using sorbitol, xylitol, maltitol and maltitol syrup for the manufacture of musli-bars without added sugar, including those suitable for diabetic nutrition. The processes of heat treatment of syrups with sweeteners are studied, regression equations are selected that allow determining the dry matter content in the syrup at a certain temperature or setting the temperature to which it is necessary to boil the syrup to achieve the required dry matter content. The influence of sweeteners on the dynamic viscosity of syrups and the strength of bars is studied. The determination of the mass fraction of total sugar (in terms as sucrose) was carried out, according to the results of which the developed products were classified as specialized products of diabetic nutrition. The complex analysis allowed to determine the optimal sweetener and, based on the results obtained, developed recipes for musli-bars without added sugar: «Cereals with raspberries», «Cereals with hazelnuts», «Cereals with blueberries».

Simultaneous saccharification and fermentation (SSF) configuration offers efficient use of the reactor. In this configuration, both hydrolysis and fermentation processes are conducted simultaneously in a single bioreactor, and the overall processes may be accelerated. However, problems may arise if both processes have different optimum conditions, and therefore process optimization is required. This paper presents a mathematical model over SSF strategy implementation for producing xylitol from the hemicellulose component of lignocellulosic materials. The model comprises the hydrolysis of hemicellulose and the fermentation of hydrolysate into xylitol. The model was simulated for various process temperatures, prior hydrolysis time, and inoculum concentration. Simulation of the developed kinetics model shows that the optimum SSF temperature is 36 °C, whereas conducting prior hydrolysis at its optimum hydrolysis temperature will further shorten the processing time and increase the xylitol productivity. On the other hand, increasing the inoculum size will shorten the processing time further. For an initial xylan concentration of 100 g/L, the best condition is obtained by performing 21-hour prior hydrolysis at 60 °C, followed by SSF at 36 °C by adding 2.0 g/L inoculum, giving 46.27 g/L xylitol within 77 hours of total processing time. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Confectionery ingredients are expected to enhance the medication adherence of pediatric patients taking bitter-tasting drugs when adequate pediatric medicines are not available in practical settings. Gum is a familiar confectionery, and several drug-loaded gums are on the market as medicated chewing gums. In this study, medical gum tablets composed of confectionery xylitol gum and a drug (ibuprofen or acetaminophen) were prepared and evaluated for the purpose of potential hospital applications. The effect of the sintering process, a heating treatment, on the physical properties of the solid materials was also examined. The sintering process markedly improved the hardness of the gum tablets. The sintering temperature and time affected the hardness of both ibuprofen- and acetaminophen-loaded gum tablets, whereas heat treatment around the melting point of ibuprofen or xylitol and longer heat treatment resulted in failure of the preparation or a reduction in hardness. The sintered gum tablets exhibited a delayed drug release profile in artificial saliva after an in vitro chewing test. The current results provide basic and useful information about the preparation of gum-containing tablets in future clinical settings.

Xylose is the raw material for the synthesis of many important platform compounds. At present, xylose is commercially produced by chemical extraction. However, there are still some bottlenecks in the extraction of xylose, including complicated operation processes and the chemical substances introduced, leading to the high cost of xylose and of synthesizing the downstream compounds of xylose. The current market price of xylose is 8× that of glucose, so using low-cost glucose as the substrate to produce the downstream compounds of xylose can theoretically reduce the cost by 70%. Here, we designed a pathway for the biosynthesis of xylose from glucose in Escherichia coli. This biosynthetic pathway was achieved by overexpressing five genes, namely, zwf, pgl, gnd, rpe, and xylA, while replacing the native xylulose kinase gene xylB with araL from B. subtilis, which displays phosphatase activity toward d-xylulose 5-phosphate. The yield of xylose was increased to 3.3 g/L by optimizing the metabolic pathway. Furthermore, xylitol was successfully synthesized by introducing the xyl1 gene, which suggested that the biosynthetic pathway of xylose from glucose is universally applicable for the synthesis of xylose downstream compounds. This is the first study to synthesize xylose and its downstream compounds by using glucose as a substrate, which not only reduces the cost of raw materials, but also alleviates carbon catabolite repression (CCR), providing a new idea for the synthesis of downstream compounds of xylose.

Recent years have seen an increase in the use of lignocellulosic materials in the development of bioproduct, biorefinery technologies have focused on process integration for the production of different valuable coproducts in order to reduce the overall processing cost. In this study, agricultural wastes from rice straw were used for the co-production of bioethanol and xylitol. Where bioethanol is produced from the cellulosic fraction and xylitol from the hemicellulose fraction after elimination of lignin using chemical pretreatments. The chemical treatment was carried out with diluted acid 2.5% at a 100 °C for 30 minutes , and then exposed the cellulosic fraction of the solid phase resulting from the chemical process to the enzymatic action of the fungus Trichoderma harzianum for releas sugars and fermented at a later stage using Saccharomyces cerecvisae for bioethanol production in a simultaneous saccharification and fermentation process, The liquid phase hemicellulose fraction was exposed to action of Meyerozyma guilliermondii strain F22 (Pichia guilliermondii) for xylitol production. Resulting was accomplished yielding maximum concentrations and product yield were 32.6 g/L 0.39g/g and 20.1 g/L, 0.44g/g for bioethanol and xylitol respectively of the total glucose and xylose available in rice straw, the co-production of xylitol with ethanol in an integrated biorefinery would create economic benefits making the overall lignocellulose-based process more cost effective

Cofactor availability is often a rate-limiting factor in the bioconversion of xylose to xylitol. The overexpression of pentose phosphate pathway genes and the deletion of Embden-Meyerhof-Parnas pathway genes can modulate the glucose metabolic flux and increase the intracellular NADPH supply, enabling Escherichia coli cells to produce xylitol from corncob hydrolysates. The effects of zwf and/or gnd overexpression and pfkA, pfkB, and/or pgi deletion on the intracellular redox environment and xylitol production were examined. The NADPH-enhanced strain 2bpgi produced 162 g/L xylitol from corncob hydrolysates after a 76 h fed-batch fermentation in a 15 L bioreactor, which was 13.3% greater than the 143 g/L xylitol produced by the IS5-d control strain. Additionally, the xylitol productivity and xylitol yield per glucose for 2bpgi were 2.13 g/L/h and 2.50 g/g, respectively. Thus, the genetic modifications in 2bpgi significantly enhanced NADPH regeneration, making 2bpgi a potentially useful strain for the industrial-scale production of xylitol from detoxified corncob hydrolysates.

Summary Background The highly prevalent white spot lesions around orthodontic brackets necessitate introducing preventive materials without relying on patient compliance. Objective To evaluate the antidemineralizing effect of two concentrations of xylitol varnish. Trial design Triple-blind, four-arm, parallel-group, single-center, randomized controlled clinical trial. Methods A total of 120 orthodontic patients were randomly assigned to four groups (n = 30), using a computer-generated randomized block list. The treatment groups were: 10% xylitol, 20% xylitol, 5% fluoride, and placebo. Tooth demineralization was measured with DIAGNOdent at T1 (before treatment), followed by varnish application. At T2 (third month), the varnish was re-applied, and at the third (T2) and sixth (T3) months, and after treatment (T4), the demineralization was measured. The white spot lesion frequency was assessed visually after treatment. The participants, the clinician, and data assessors were all blinded to group assignments. Results A total of 115 patients underwent per-protocol analyses. At T2, the mean DIAGNOdent numbers in the fluoride and 10% xylitol groups were significantly lower than the placebo group (P = 0.00), with a mean difference of 0.63 (95% CI, 0.15–1.10) and 0.5 (95% CI, 0.04–0.95), respectively. At T3, the fluoride and 10% xylitol groups had significantly lower mineral loss than the placebo group (P=0.046) with a mean difference of 0.52 (95% CI, 0.14–0.89) in the fluoride and 0.45 (95% CI, 0.03–0.86) in the 10% xylitol groups, respectively. However, at T4, only the mean for the 10% xylitol group was significantly different (P=0.049) from the placebo group, with a mean difference of 1.18 (95% CI, 0.42–1.93). Visual assessment showed that after treatment, the prevalence of white spot lesions in the fluoride (P=0.03) and 10% xylitol (P=0.00) groups was less than the placebo group with the odds ratio of 0.67 (95% CI, 0.46–0.96) and 0.43 (95% CI, 0.28–0.64), respectively. Conclusion The 10% xylitol varnish short-term effects on caries control were significantly greater than 20% xylitol varnish and placebo but similar to fluoride varnish. However, the 10% xylitol long-term effect was almost better than fluoride varnish. Trial registration The protocol was registered at IRCT.ir under the code IRCT20180913041032N1.

Background and Objective: The major pneumococcal pathogenesis factor is the capsular polysaccharide. the production of polysaccharide is regulated by cpsB and cpsD genes. Thus, every agent that induce or inhibition of expression of these genes probably increased pathogenesis of bacteria, intracellular survival and vis versa. The aim of this study was to assay the effect of Xylitol on Streptococcus pneumoniae cpsB, cpsD, psaA and aroE genes expression by Real Time RT-PCR. Materials and Methods: During 2019 in Baqiyatallah university laboratories, 20 clinical isolates and a reference strain Streptococcus pneumoniae (ATCC 6305) were studied. To assay the effect of Xylitol and fructose، different concentration of these sugars were exposed to BHI Broth media. Thereafter, the bacterial suspension was added to 5% Xylitol, 5%Xylitol + 5% fructose and control medium for 3hours. RNA was extracted and cDNA synthesis was carried out. Then, the cpsB, cpsD and psaA genes expression levels were measured. Results: The mean of cpsB gene expression ratio in presence of the % 5 Xylitol treated media compared with those in the control media and % 5 Xylitol + 5% fructose were 0.022 and 0.027 respectively. The means of the cpsD and psaA genes expression ratio in the % 5 Xylitol treated media compared with those in the control media and % 5 Xylitol + 5% fructose were 1.659 and 0.056, and 0.633 and 3.294 respectively. Conclusion: Our finding revealed that, the 5% Xylitol inhibit the cpsB gene expression properly. Therefore, it is possible to use of Xylitol for reductive on cpsB gene expression and superficial pneumococcal infections control.

Polyols are poorly digestible carbohydrates present in small amounts in some fruits and vegetables. Xylitol and erythritol are used as table sweeteners. These compounds are widely used in the food industry due to their low-calorie content. Erythritol is the only noncaloric polyol. Xylitol is the sweetest of the polyols, being the only one with sweetness equivalent to sucrose, but with one third of its calories. Clinical studies have shown reductions in the number of plaques, in counts of Streptococcus mutans, and in the number of dental cavities in individuals receiving erythritol and xylitol. Xylitol is also capable of reducing the growth and adherence to the oropharynx of bacteria that cause acute otitis media, such as Streptococcus pneumoniae, and several studies have shown that it reduces the risk of this bacterial infection in children. In addition to these effects, polyols can also have beneficial effects on metabolism. Both erythritol and xylitol have been approved by the European Union for use as sweeteners for several years, and replacing sugar with polyols decreases caloric intake, which can reduce body weight and blood glucose in individuals with obesity and type 2 diabetes mellitus. The safety of polyols is recognized by the Food and Drug Administration (FDA), who classifies them as compounds generally recognized as safe (GRAS). Thus, based on available scientific data, the daily consumption of both substances is associated with several benefits and does not represent any risk to human health.

NaBH4 has been widely considered as a low-cost hydrogen storage material with high gravimetric hydrogen capacity of about 10 wt%. However, its strong thermodynamic stability severely hinders the application of NaBH4 to obtain hydrogen. In this study, multi-hydroxyl xylitol, for the first time, was chosen as a protic hydrogen carrier to destabilize and react with NaBH4. The NaBH4-xylitol composites were easily prepared through hand-milling, which leads to the fast liberation of hydrogen from moderate temperatures lower than 80 °C with more than 3.6 wt% hydrogen desorption capacity. Besides, over 80% of hydrogen could be efficiently released in NaBH4-xylitol composite. The dehydrogenation process is proved to be completely impurity-free and controllable by altering the NaBH4/xylitol ratios and operating temperatures. The reaction between NaBH4 and xylitol is investigated to be similar to an alcoholysis procedure, however no observable liquid phase takes place before and after the dehydrogenation of NaBH4-xylitol composite, showing a great potential to produce hydrogen under low temperatures through solid-state carriers.

Cookies are widely consumed bakery products having high amount of sucrose. In this study, it was aimed to reduce the amount of sucrose used in cookies by using the inhomogeneous distribution of sucrose while maintaining the perceived sweetness. Five different cookie samples were evaluated namely; control, 20% reduced sucrose cookies with Homogeneous distribution (HOM20) and Inhomogeneous distribution (INHOM20), 30% reduced sucrose cookies with Homogeneous distribution (HOM30) and Inhomogeneous distribution (INHOM30). Physical properties (diameter, height, spread ratio, L*, a*, and b*) of INHOM20 cookies were determined to be similar with control sample. Hardness value of control sample (30.43 N) was lower than HOM20 (36.59 N) and INHOM20 (33.09 N), HOM30 (41.32 N) and INHOM30 (38.23 N). Although the sucrose content was reduced 20% by inhomogeneous distribution, cookies had same sweetness and general acceptance with the control sample. The perceived sweetness of INHOM30 cookies was more than HOM30 cookies. The results obtained from this study showed that enhancement of sweetness perception and sucrose reduction could be provided using inhomogeneous sucrose distribution by changing sucrose distribution in cookies without using any sucrose substitute.

Summary Exorbitant outputs of waste xylose mother liquor (WXML) and corncob residue from commercial‐scale production of xylitol create environmental problems. To reduce the wastes, a Saccharomyces cerevisiae strain tolerant to WXML was conferred with abilities to express the genes of xylose reductase, a xylose‐specific transporter and enzymes of the pentose phosphate pathway. This strain showed a high capacity to produce xylitol from xylose in WXML with glucose as a co‐substrate. Additionally, a simultaneous saccharification and fermentation (SSF) process was designed to use corncob residues and cellulase instead of directly adding glucose as a co‐substrate. Xylitol titer and the productivity were, respectively, 91.0 g l‐1 and 1.26 ± 0.01 g l‐1 h‐1 using 20% WXML, 55 g DCW l‐1 delignified corncob residues and 11.8 FPU gcellulose‐1 cellulase at 35° during fermentation. This work demonstrates the promising strategy of SSF to exploit waste products to xylitol fermentation process.

The use of Near-Infrared Spectroscopy (NIRS) and Chemometrics in-situ or in-line monitoring of xylitol fermentation process by Candida tropicalis IEC5-ITV was investigated in a bioreactor and in a complex analytical matrix. Xylose, xylitol, biomass and glycerol determinations were performed by a transflection fiber optic probe, immersed in the culture broth and connected to a Near-Infrared (NIR) process analyzer. The NIR spectra recorded between 800 and 2,200 nm, these NIR Spectra were pretreated using Savitzky-Golay smoothing and second derivative in order to perform a partial least squares regression (PLSR) and generate the calibration models. These calibration models were tested by external validation and then used to predict concentrations of xylitol fermentations in batch culture. The standard errors of calibration (SEC) and determination coefficients (R2) for xylose, xylitol, biomass and glycerol were 0.234 (R2 = 0.991), 0.220 (R2 = 0.999), 0.234 (R2 = 0.991) and 0.015 (R2 = 0.999) g/L and standard errors of prediction (SEP) were 1.771, 0.192, 0.011, 0.503 g/L, respectively. Calibration and validation criteria were defined and evaluated in order to generate robust and reliable models of a xylitol fermentation process. For validation models, SEV and SEP were 0.96 were obtained. These results indicate that in situ NIRS probe is suitable for real-time monitoring of xylitol production.

In this study, the medium requirements to increase the production of xylitol by using Candida tropicalis (CT) have been investigated. The technique of single addition or omission of medium components was applied to determine the nutritional requirements. The addition of amino acids such as Asp, Glu, Gln, Asn, Thr, and Gly had no significant effect on CT growth. However, in the absence of other metal ions, there was a higher concentration of cell growth and xylitol production when only Zn(2+) was present in the medium. The analysis of various vitamins unveiled that biotin and thiamine were the only vitamins required for the growth of CT. Surprisingly, when only biotin was present in the medium as a vitamin, there was less growth of CT than when the medium was complete, but the amount of xylitol released was significantly higher. Overall, this study will increase the xylitol production using the single omission or addtion technique.

Xylitol (C 5 H 12 O 5 ) is a non-carcinogenic polyalcoholic sugar. Xylitol is beneficial for diabetics because it can be metabolized without insulin. Corn cobs contain 30% xylose which can be fermented into xylitol by microorganisms. Xylitol can be produced by fermentation of xylose and few microorganisms. Meyerozyma caribbica is a yeast that has been proven to produce xylitol and inhibitor’s resistant. The aim of this research is to test the xylitol productivity by Meyerozyma caribbica InaCC Y67 using corn cobs hydrolyzate and the effect of the volume of fermentation media on xylitol productivity by Meyerozyma caribbica InaCC Y67. The method was carried out by culturing Meyerozyma caribbica InaCC Y67 as a starter on YPD media. Fermentation using 100 mL Erlenmeyer with the variation of fermentation volume is 10 ml and 75 ml, agitation 175 rpm and 30 o C. Parameters were measured based on the dry weight of cells, xylose and xylitol. Data were analyzed using fermentation kinetics. The results of analysis showed that the higher xylitol production was found in the fermentation volume 75 ml with an efficiency value of 7,171%. The highest xylitol production was at the 48th hour with production value of 2.050 g/L. Results from research shows that Meyerozyma caribbica InaCC Y67 can produce xylitol with corn cobs hydrolyzate. The right volume of fermentation in the fermentation process can also increase the productivity of xylitol.

Co-production systems are a strategy used to diversify production chains and to enable more profitable processes. In addition, the valorization of the sugar-and-alcohol industry through by-product conversion into value-added products is environmentally friendly and enhances their competitiveness to other products available in the market. Thus, the aim of the current study is to evaluate xylitol and ethanol co-production by Candida tropicalis deriving from sugarcane by-products, such as bagasse and straw, supplemented with molasses. Sugarcane bagasse and straw hemicellulosic hydrolysate was obtained through dilute-acid hydrolysis with H2SO4; next, it was concentrated and detoxified with activated charcoal. Different commercial sucrose concentrations (5, 25 and 50 gL−1) were added to the bagasse and straw hemicellulosic hydrolysate in semi-defined medium. In addition, hydrolysate supplementation with sugarcane molasses was evaluated based on sucrose content (10 and 50 gL−1) adjustment. Batch fermentations were carried out in 125-mL Erlenmeyer flasks filled with 50 mL of medium, at 30 °C, 200 rpm, pH 5.5, for 48 h. Molasses supplementation adjusted to 50 gL−1 sucrose in sugarcane bagasse and straw hemicellulosic hydrolysate recorded the maximum xylitol (30.61 gL−1) and ethanol (47.97 gL−1) concentrations observed in the current study. Besides, volumetric xylitol (0.64 gL−1h−1) and ethanol (1.00 gL−1h−1) productivity was observed under the very same condition. Results have shown the likelihood of co-producing xylitol and ethanol through C. tropicalis by using sugarcane by-products to compose the fermentation medium as strategy to intensify and integrate these bioprocesses in sugarcane biorefineries.

Copolymerization of xylitol usually yields cross-linked materials. In this work, microwave-assisted polyesterification of xylitol and succinic acid produced materials with diverse molecular weights and different branching degrees, and more importantly, no cross-linking was observed, as supported by the solubility behavior and spectroscopic data. Reactions were carried out for short times, less than 20 min, which is not common for production of industrial polyesters. Control over the branching degree was achieved by tuning the reaction conditions, such as temperature, time of exposure, and monomer ratio, during microwave irradiation. No solvent or catalyst was employed during the step-growth polymerization.

L-Xylulose is a rare ketose with potential applications in the pharmaceutical and food industries. This metabolic intermediate can be synthesized by xylitol 4-dehydrogenase (XDH) using xylitol as substrate and NAD+ as a cofactor. A novel XDH from Erwinia aphidicola SK47.001 was expressed in food-grade Bacillus subtilis and biochemically characterized. The purified enzyme exhibited an optimal temperature of 45 °C, an optimal pH of 11, a Km of 18.71 mM, and a Vmax of 0.52 μmol/(min mg). To improve XDH activity, another B. subtilis strain was constructed to co-express XDH and the water-forming enzyme NADH oxidase (NOX), an efficient recycler of NAD+. In this case, the XDH activity was 3.4-fold higher than that of the single enzyme. The putative structure and probable catalytic active sites of XDH were explored by homology modeling and molecular docking. The amino acids Ser149, Tyr162, and Lys166 were identified as potential XDH catalytic active sites for xylitol and NAD+.