Computational design towards a boiling-resistant single-chain sweet protein monellin

Sweet proteins offer a promising solution as sugar substitutes by providing a sugar-like sweetness without the negative health impacts linked to sugar or artificial sweeteners. However, the low thermal stability of sweet proteins has hindered their applications. In this study, we took a computational approach utilizing ΔΔG calculations in PyRosetta to enhance the thermostability of single-chain monellin (MNEI). By generating and characterizing 21 variants with single mutation, we identified 11 variants with higher melting temperature (Tm) than that of MNEI. To further enhance the thermal stability, we conducted structural analysis and designed an additional set of 14 variants with multiple mutations. Among these variants, four exhibited a significant improvement in thermal stability, with an increase of at least 20 °C (Tm > 96 °C) compared to MNEI, while maintaining their sweetness. Remarkably, these variants remained soluble even after being heated in boiling water for one hour. Moreover, they displayed exceptional stability across alkaline, acidic and neutral environments. These findings highlight the tremendous potential of these variants for applications in the food and beverage industry. Additionally, this study provides valuable strategies for protein engineering to enhance the thermal stability of sweet proteins.

Synthesis of Sucrose-Mimicking Disaccharide by Intramolecular Aglycone Delivery

Rare sugars are known for their ability to suppress postprandial blood glucose levels. Therefore, oligosaccharides and disaccharides derived from rare sugars could potentially serve as functional sweeteners. A disaccharide [α-d-allopyranosyl-(1→2)-β-d-psicofuranoside] mimicking sucrose was synthesized from rare monosaccharides D-allose and D-psicose. Glycosylation using the intermolecular aglycon delivery (IAD) method was employed to selectively form 1,2-cis α-glycosidic linkages of the allopyranose residues. Moreover, β-selective psicofuranosylation was performed using a psicofuranosyl acceptor with 1,3,4,6-tetra-O-benzoyl groups. This is the first report on the synthesis of non-reducing disaccharides comprising only rare d-sugars by IAD using protected ketose as a unique acceptor; additionally, this approach is expected to be applicable to the synthesis of functional sweeteners.

Study on the Thermal Stability of the Sweet-Tasting Protein Brazzein Based on Its Structure-Sweetness Relationship

Brazzein (Brz) is a sweet-tasting protein composed of 54 amino acids and is considered as a potential sugar substitute. The current methods for obtaining brazzein are complicated, and limited information is available regarding its thermal stability. In this study, we successfully expressed recombinant brazzein, achieving a sweetness threshold of 15.2 μg/mL. Subsequently, we conducted heat treatments at temperatures of 80, 90, 95, and 100 °C for a duration of 2 h to investigate the structural changes in the protein. Furthermore, we employed hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) to analyze the effect of heating on the protein structure-sweetness relationships. Our results indicated that the thermal inactivation process primarily affects residues 6-14 and 36-45 of brazzein, especially key residues Tyr8, Tyr11, Ser14, Glu36, and Arg43, which are closely associated with its sweetness. These findings have significant implications for improving the thermal stability of brazzein.

Rethinking Sweetener Discovering: Multiparameter Modeling of Molecular Docking Results between the T1R2-T1R3 Receptor and Compounds with Different Tastes

Molecular docking has been widely applied in the discovery of new sweeteners, yet the interpretation of computational results sometimes remains difficult. Here, the interaction between the T1R2-T1R3 sweet taste receptor and 66 tasting compounds, including 26 sweet, 19 bitter, and 21 sour substances was investigated by batch molecular docking processes. Statistical analysis of the docking results generated two novel methods of interpreting taste properties. Quantitative correlation between relative sweetness (RS) and docking results created a multiparameter model to predict sweetness intensity, whose correlation coefficient r = 0.74 is much higher than r = 0.17 for the linear correlation model between sweetness and binding energy. The improved correlation indicated that docking results besides binding energy contain undiscovered information about the ligand-protein interaction. Qualitative discriminant analysis of different tasting molecules generated an uncorrelated linear discriminant analysis (UDLA) model, which achieved an overall 93.1% accuracy in discriminating the taste of molecules, with specific accuracy for verifying sweet, bitter, and sour compounds reaching 88.0%, 92.1%, and 100%. These unprecedented models provide a unique perspective for interpreting computational results and may inspire future research on sweetener discovery.

Stevia rebaudiana Bertoni, an American plant used as sweetener: Study of its effects on body mass control and glycemia reduction in Wistar male and female rats

Stevia rebaudiana Bertoni water extracts have been used as a natural sweetener and customary medicine by the indigenous inhabitants of South America for several hundred years. This plant was sent to Europe in the 16th century and was described by Peter Jacob Esteve in Spain. Recently the food industry has started to employ S. rebaudiana as sweetener using its glycosides after purification. Advertisement claims that Stevia glycosides is good for controling body mass and reducing glycemia. This study's objective was to evaluate the effect of S. rebaudiana leaf extract on Wistar rats as animal model to prove its effectiveness on body mass control, glycemia reduction, and other biochemical parameters. Three groups were randomly formed with 24 males and 24 females: A blank group without any sweetener, a control group drinking water with 10% glucose, and the test group ingesting a 0.94% water extract of S. rebaudiana. Body mass measurements as well as food and drink consumption were daily performed. The experiment lasted 120 days after the specimens were weaned and got used to eating solid food. Euthanasia was done and blood serum was collected to evaluate the following biochemical parameters: Glucose, triglycerides, cholesterol, insulin, glucagon, leptin, ghrelin, and glucose-dependent insulinotropic peptide, GIP. Results indicated that only female rats had statistical differences in body mass gain. No relevant effects either positive or negative were found in the biochemical parameters measured. The crude extracts of S. rebaudiana did not show any relevant changes in biochemical and hormonal profiles, changes nor body mass with respect to the blank and control groups of young and healthy rats in the age range of infancy to youth. According to the results obtained, the therapeutic properties that have been associated to S. rebaudiana consumption especially for body mass control and glycemia reduction, did not occur in young and healthy male and female rats in equivalent age to infants, young children, and youths.

Modeling the structure of the transmembrane domain of T1R3, a subunit of the sweet taste receptor, with neohesperidin dihydrochalcone using molecular dynamics simulation

Neohesperidin dihydrochalcone (NHDC) is a sweetener, which interacts with the transmembrane domain (TMD) of the T1R3 subunit of the human sweet taste receptor. Although NHDC and a sweet taste inhibitor lactisole share similar structural motifs, they have opposite effects on the receptor. This study involved the creation of an NHDC-docked model of T1R3 TMD through mutational analyses followed by in silico simulations. When certain NHDC derivatives were docked to the model, His7345.44 was demonstrated to play a crucial role in activating T1R3 TMD. The NHDC-docked model was then compared with a lactisole-docked inactive form, several residues were characterized as important for the recognition of NHDC; however, most of them were distinct from those of lactisole. Residues such as His6413.33 and Gln7947.38 were found to be oriented differently. This study provides useful information that will facilitate the design of sweeteners and inhibitors that interact with T1R3 TMD.

Sweet Taste Receptors and Associated Sweet Peptides: Insights into Structure and Function

Long-term consumption of a high-sugar diet may contribute to the pathogenesis of several chronic diseases, such as obesity and type 2 diabetes. Sweet peptides derived from a wide range of food sources can enhance sweet taste without compromising the sensory properties. Therefore, the research and application of sweet peptides are promising strategies for reducing sugar consumption. This work first outlined the necessity for global sugar reduction, followed by the introduction of sweet taste receptors and their associated transduction mechanisms. Subsequently, recent research progress in sweet peptides from different protein sources was summarized. Furthermore, the main methods for the preparation and evaluation of sweet peptides were presented. In addition, the current challenges and potential applications are also discussed. Sweet peptides can stimulate sweetness perception by binding sweet taste receptors T1R2 and T1R3 in taste buds, which is an effective strategy for reducing sugar consumption. At present, sweet peptides are mainly prepared artificially by synthesis, hydrolysis, microbial fermentation, and bioengineering strategies. Furthermore, sensory evaluation, electronic tongues, and cell models have been used to assess the sweet taste intensity. The present review can provide a theoretical reference for reducing sugar consumption with the aid of sweet peptides in the food industry.

Evaluation of DNA damage induced by acesulfame potassium: spectroscopic, molecular modeling simulations and toxicity studies

Acesulfame potassium (Ace-K) is a widely used artificial sweetener that has been reported to interact with DNA and cause important genetic damage. However, the type of interaction mechanism is unknown. This study provides an approach to understanding the in vitro mechanism of Ace-K interaction with Ct-DNA using spectroscopic methods combined with molecular simulations. The hypochromic effect as obtained from UV-Vis spectra indicated the formation of the DNA-Ace-K complex in the minor groove. Further evidence for groove binding mode comes from the decrease in Hoechst-DNA fluorescence caused by increasing Ace-K concentrations, alongside no detectable change in MB-DNA emission band intensity. A negative value of ΔH and ΔS represents the hydrogen bonds and van der Waals forces between Ace-K and DNA. Based on the molecular docking, Ace-K was located between the guanine10 and 16 in DNA minor groove and stabilized by two hydrogen bonds and one π-Sulfur interaction. In vitro cell culture results showed that about 5 mg/mL of Ace-K caused the death of 85% of HUVEC cells after 48 h. Communicated by Ramaswamy H. Sarma.

The effect of alginate as an elicitor on transcription of steviol glycosides biosynthesis pathway related key genes and sweeteners content in in vitro cultured Stevia rebaudiana

BACKGROUND

Stevia rebaudiana is a medicinal herb that accumulates non-caloric sweeteners called steviol glycosides (SGs) which are approximately 300 times sweeter than sucrose. This study used alginate (ALG) as an elicitor to increase steviol glycosides accumulation and elucidate gene transcription in the steviol glycosides biosynthesis pathway.

METHODS AND RESULTS

To minimize the grassy taste associated with stevia sweeteners, plantlets were grown in complete darkness. ALG was applied to stevia plants grown in suspension culture with a Murashige and Skoog (MS) medium to determine its effect on SGs' content and the transcription profile of SG-related genes using the HPLC and RT-qPCR methods, respectively. Treatment with alginate did not significantly affect plantlet growth parameters such as shoot number, dry and fresh weight. Rebaudioside A (Reb A) content increased approximately sixfold in the presence of 1g L^-1 alginate and KS, KAH, and UGT74G1 genes showed significant up-regulation. When the concentration was increased to 2g L^-1, the transcription of KO and UGT76G1, responsible for the conversion of stevioside to Reb A, was increased about twofold.

CONCLUSIONS

The current study proposes that adding alginate to the MS suspension medium can increase Reb A levels by altering the SG biosynthesize pathway's transcription profile. The present experiment provides new insights into the biochemical and transcriptional response mechanisms of suspension-cultured stevia plants to alginate.

Maple Syrup: Chemical Analysis and Nutritional Profile, Health Impacts, Safety and Quality Control, and Food Industry Applications

Maple syrup is a delicacy prepared by boiling the sap taken from numerous Acer species, primarily sugar maple trees. Compared to other natural sweeteners, maple syrup is believed to be preferable to refined sugar for its high concentration of phenolic compounds and mineral content. The presence of organic acids (malic acid), amino acids and relevant amounts of minerals, such as potassium, calcium, zinc and manganese, make maple syrup unique. Given the growing demand for naturally derived sweeteners over the past decade, this review paper deals with and discusses in detail the most important aspects of chemical maple syrup analyses, with a particular emphasis on the advantages and disadvantages of the different analytical approaches. A successful utilization on the application of maple syrup in the food industry, will rely on a better understanding of its safety, quality control, nutritional profile, and health impacts, including its sustainability issues.

Structure of thaumatin under acidic conditions: Structural insight into the conformations in lysine residues responsible for maintaining the sweetness after heat-treatment

Thaumatin is an intensely sweet-tasting protein. Its sweetness persists when heated under acidic conditions, but disappears when heated at a pH above 7.0. To clarify how the structural features of thaumatin resist insoluble aggregation during heating under acidic conditions, we analysed its crystal structure obtained at pH 4.0, 6.0, and 8.0. Simultaneously, the melting temperature (Tm) at these pH levels was determined using differential scanning fluorimetry. At pH 4.0, the Tm of thaumatin was substantially lower and the overall B-factor value of its structure was higher than those at pH 6.0. Interestingly, the relative B-factor values for most lysine residues decreased as the pH reduced. These results suggest that the overall structure at pH 4.0 becomes flexible but the relative flexibility of some regions is lower than that at pH 6.0. Thus, the reduction in relative flexibility might play an important role in preventing thermal aggregation, thereby maintaining the sweetness.

Bioprospecting and biotechnological insights into sweet-tasting proteins by microbial hosts-a review

Owing to various undesirable health effects of sugar overconsumption, joint efforts are being made by industrial sectors and regulatory authorities to reduce sugar consumption practices, worldwide. Artificial sweeteners are considered potential substitutes in several products, e.g., sugar alcohols (polyols), high-fructose corn syrup, powdered drink mixes, and other beverages. Nevertheless, their long-standing health effects continue to be debatable. Consequently, growing interest has been shifted in producing non-caloric sweetenersfrom renewable resources to meet consumers' dietary requirements. Except for the lysozyme protein, various sweet proteins including thaumatin, mabinlin, brazzein, monellin, miraculin, pentadin, and curculin have been identified in tropical plants. Given the high cost and challenging extortion of natural resources, producing these sweet proteins using engineered microbial hosts, such as Yarrowia lipolytica, Pichia pastoris, Hansenula polymorpha, Candida boidinii, Arxula adeninivorans, Pichia methanolica, Saccharomyces cerevisiae, and Kluyveromyces lactis represents an appealing choice. Engineering techniques can be applied for large-scale biosynthesis of proteins, which can be used in biopharmaceutical, food, diagnostic, and medicine industries. Nevertheless, extensive work needs to be undertaken to address technical challenges in microbial production of sweet-tasting proteins in bulk. This review spotlights historical aspects, physicochemical properties (taste, safety, stability, solubility, and cost), and recombinant biosynthesis of sweet proteins. Moreover, future opportunities for process improvement based on metabolic engineering strategies are also discussed.

Quantification and cytotoxicity of degradation products (chloropropanols) in sucralose containing e-liquids with propylene glycol and glycerol as base

Electronic cigarettes (e-cigarettes) have gained increasing popularity in recent years, mostly because they are supposed to be less harmful than regular cigarettes. Therefore, it is highly imperative to investigate possible noxious effects to protect the consumers. E-liquids consist of propylene glycol, glycerol, aroma compounds and sweeteners. One of these sweeteners is a chlorinated version of sucrose, namely sucralose. The aim of this work was to investigate degradation products of sucralose in the presence of propylene glycol and glycerol at different temperatures of commercially available e-cigarettes. Chemical analysis and biological tests were simultaneously performed on e-liquid aerosol condensates. The results of the chemical analysis, which was executed by employing GC-MS/GC-FID, demonstrated high amounts of various chloropropanols. The most abundant one is extremely toxic, namely 3-chloropropane-1,2-diol, which can be detected at concentrations ranging up to 10,000 mg/kg. Furthermore, a cytotoxicity investigation of the condensates was performed on HUVEC/Tert2 cells in which metabolic activity was determined by means of resazurin assay. The cellular metabolic activity significantly decreased by treatment with e-liquid aerosol condensate. Due to the results of this study, we advise against the use of sucralose as sweetener in e-liquids.

Stevia Genus: Phytochemistry and Biological Activities Update

The Stevia genus (Asteraceae) comprises around 230 species, distributed from the southern United States to the South American Andean region. Stevia rebaudiana, a Paraguayan herb that produces an intensely sweet diterpene glycoside called stevioside, is the most relevant member of this genus. Apart from S. rebaudiana, many other species belonging to the Stevia genus are considered medicinal and have been popularly used to treat different ailments. The members from this genus produce sesquiterpene lactones, diterpenes, longipinanes, and flavonoids as the main types of phytochemicals. Many pharmacological activities have been described for Stevia extracts and isolated compounds, antioxidant, antiparasitic, antiviral, anti-inflammatory, and antiproliferative activities being the most frequently mentioned. This review aims to present an update of the Stevia genus covering ethnobotanical aspects and traditional uses, phytochemistry, and biological activities of the extracts and isolated compounds.

Phenolic contents, antioxidant potential and associated colour in sweet sorghum syrups compared to other commercial syrup sweeteners

BACKGROUND

Knowledge of the bioactive content of sweet sorghum syrups compared to other common food-grade syrups will expand their utilisation as a food source. Total phenolic content (TPC), phenolics evaluated by high-performance liquid chromatography, antioxidant 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activities and oxygen radical absorbance capacity (ORAC), as well as colour of high-fructose corn syrup (HFCS), corn, honey, maple, agave, rice and grain sorghum syrups, were compared to 10 commercial sweet sorghum syrups.

RESULTS

Sweet sorghum syrups contained markedly higher (P ≤ 0.05) TPC (6471 ± 1823 mg L^-1 ) compared to the other syrups (596 ± 497 mg L^-1 ). HFCS, corn, white grain sorghum and rice syrups had negligible and low DPPH radical scavenging activities and ORAC values, respectively. DPPH activities, ORAC and colour values of the sweet sorghum syrups were also markedly (P ≤ 0.05) higher than other syrups and highly related. The predominant phenolic components identified in sweet sorghum syrups were phenolic acids. Ellagic acid and protocatechuic acid were found in sorghum syrups ranging in concentration from 335-1177 and 53-485 μg g^-1 , respectively. Sinapic acid was detected in several sorghum syrups, ranging in concentrations between 21 and 3654 μg g^-1 .

CONCLUSION

HFCS, corn, white grain sorghum and rice syrups demonstrated low bioactivity with negligible and low DPPH activities and ORAC values, respectively. The TPC, DPPH, ORAC and colour values of the sweet sorghum syrups were related to each other and markedly (P ≤ 0.05) higher compared to the other syrups. Phenolic acids were the predominant phenolic compounds identified in sorghum syrups and represent potential for health benefits. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.

High-Yield Synthesis of Transglycosylated Mogrosides Improves the Flavor Profile of Monk Fruit Extract Sweeteners

Luo Han Guo fruit extract (Siraitia grosvenorii), mainly composed of mogroside V (50%), could be considered a suitable alternative to free sugars; however, its commercial applications are limited by its unpleasant off-notes. In the present work, a central composite design method was employed to optimize the transglycosylation of a mogroside extract using cyclodextrin glucosyltransferases (CGTases) from three different bacteriological sources (Paenibacillus macerans, Geobacillus sp., and Thermoanaerobacter sp.) considering various experimental parameters such as maltodextrin and mogroside concentration, temperature, time of reaction, enzymatic activity, and pH. Product structures were determined by liquid chromatography coupled to a diode-array detector (LC-DAD), liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Sensory analysis of glucosylated mogrosides showed an improvement in flavor attributes relevant to licorice flavor and aftereffect. Consequently, an optimum methodology was developed to produce new modified mogrosides more suitable when formulating food products as free sugar substitutes.

Food and Beverage Ingredients Induce the Formation of Silver Nanoparticles in Products Stored within Nanotechnology-Enabled Packaging

Nanotechnology-based packaging may improve food quality and safety, but packages manufactured with polymer nanocomposites (PNCs) could be a source of human dietary exposure to engineered nanomaterials (ENMs). Previous studies showed that PNCs release ENMs to foods predominantly in a dissolved state, but most of this work used food simulants like dilute acetic acid and water, leaving questions about how substances in real foods may influence exposure. Here, we demonstrate that food and beverage ingredients with reducing properties, like sweeteners, may alter exposure by inducing nanoparticle formation in foods contacting silver nanotechnology-enabled packaging. We incorporated 12.8 ± 1.4 nm silver nanoparticles (AgNPs) into polyethylene and stored media containing reducing ingredients in packages manufactured from this material under accelerated room-temperature and refrigerated conditions. Analysis of the leachates revealed that reducing ingredients increased the total silver transferred to foods contacting PNC packaging (by as much as 7-fold) and also induced the (re)formation of AgNPs from this dissolved silver during storage. AgNP formation was also observed when Ag⁺ was introduced to solutions of natural and artificial sweeteners (glucose, sucrose, aspartame), commercial beverages (soft drinks, juices, milk), and liquid foods (yogurt, starch slurry), and the amount and morphology of reformed AgNPs depended on the ingredient formulation, silver concentration, storage conditions, and light exposure. These results imply that food and beverage ingredients may influence dietary exposure to nanoparticles when PNCs are used in packaging applications, and the practice of using food simulants may in certain cases underpredict the amount of ENMs likely to be found in foods stored in these materials.

Potential improvement of the thermal stability of sweet-tasting proteins by structural calculations

The low thermal stability of the sweet-tasting proteins limited their applications in food industry. Improve their thermal stability is the key to developing their applications in food processing. In the present study, saturation mutagenesis was performed on 4 sweet-tasting proteins, brazzein (988 mutations), curculin (2109 mutations), monellin (1824 mutations) and thaumatin (3933 mutations), using structural calculations in order to find more thermal stable mutations. The obtained results indicated that our calculated ΔΔG value (ΔΔG < 0 stabilizing, ΔΔG > 0 destabilizing) was a good predictor for predicting changes in thermal stability caused by mutations. Moreover, mutating the negatively charged residues to the other non-negatively charged amino acids was an efficient way to improve the thermal stability of the investigated sweet-tasting proteins. In addition, some promising mutations sites were identified for improving thermal stability using mutagenesis. This study provides useful information for future protein engineering to improve the thermal stability of the sweet-tasting proteins.

Confirmative Structural Annotation for Metabolites of (R)-7,3'-Dihydroxy-4'-methoxy-8-methylflavane, A Natural Sweet Taste Modulator, by Liquid Chromatography-Three-Dimensional Mass Spectrometry

Flavonoids occupy the largest family of natural products and possess a broad spectrum of health benefits. Their metabolites are sometimes the truly effective molecules in vivo. It is still challenging, however, to unambiguously identify flavonoid metabolites using conventional LC-MS/MS. Herein, we aimed to pursue auxiliary structural clues to m/z values in both MS¹ and MS² spectra through LC coupled to three-dimensional MS (LC-3D MS). MS¹, as the first dimension, was in charge of suggesting theoretical molecular formulas, MS², the as second dimension, was responsible for offering substructures, and exactly, online energy-resolved MS (ER-MS), as the third dimension, provided optimal collision energies (OCEs) that reflected the linkage manners among the substructures. Metabolic characterization of a natural sweet taste modulator, namely, (R)-7,3'-dihydroxy-4'-methoxy-8-methylflavane (DHMMF), was conducted as a proof-of-concept. Extensive efforts, such as full MS¹ and MS² scans on IT-TOF-MS and predictive selected-reaction monitoring mode on Qtrap-MS, were made for in-depth metabolite mining. Seventeen metabolites (M1-M17) were captured from DHMMF-treated biological samples, including 17 (M1-M17), 10 (M4-M9, M11, M13, M14, and M16), and 2 (M5 and M10) metabolites from urine, plasma, and feces, respectively. Their structures were configured by integrating MS¹, MS², and OCE information. Except M10, all metabolites were new compounds. LC-MS/MS-guided chromatographic purification yielded three glucuronyl-conjugated metabolites (M5, M8, and M11), and NMR spectroscopic assays consolidated the structures transmitted from LC-3D MS. Demethylation, glucuronidation, and sulfation occurred as the primary metabolic pathways of DHMMF. Above all, LC-3D MS bridged LC-MS/MS from putatively structural annotation toward confidence-enhanced identification, beyond the metabolite characterization of flavonoids.

An in-silico layer-by-layer adsorption study of the interaction between Rebaudioside A and the T1R2 human sweet taste receptor: modelling and biosensing perspectives

The human sweet taste receptor (T1R2) monomer-a member of the G-protein coupled receptor family that detects a wide variety of chemically and structurally diverse sweet tasting molecules, is known to pose a significant threat to human health. Protein that lack crystal structure is a challenge in structure-based protein design. This study focused on the interaction of the T1R2 monomer with rebaudioside A (Reb-A), a steviol glycoside with potential use as a natural sweetener using in-silico and biosensing methods. Herein, homology modelling, docking studies, and molecular dynamics simulations were applied to elucidate the interaction between Reb-A and the T1R2 monomer. In addition, the electrochemical sensing of the immobilised T1R2-Reb-A complex with zinc oxide nanoparticles (ZnONPs) and graphene oxide (GO) were assessed by testing the performance of multiwalled carbon nanotube (MWCNT) as an adsorbent experimentally. Results indicate a strong interaction between Reb-A and the T1R2 receptor, revealing the stabilizing interaction of the amino acids with the Reb-A by hydrogen bonds with the hydroxyl groups of the glucose moieties, along with a significant amount of hydrophobic interactions. Moreover, the presence of the MWCNT as an anchor confirms the adsorption strength of the T1R2-Reb-A complex onto the GO nanocomposite and supported with electrochemical measurements. Overall, this study could serve as a cornerstone in the development of electrochemical immunosensor for the detection of Reb-A, with applications in the food industry.

Encapsulation of β-Glucosidase within PVA Fibers by CCD-RSM-Guided Coelectrospinning: A Novel Approach for Specific Mogroside Sweetener Production

Siamenoside I is a rare mogroside in Siraitia grosvenorii Swingle and has become one of the target ingredients in natural sweetener production. However, the complex structure of siamenoside I has hindered its production in various ways. Here, a yeast cell that produces a specific β-glucosidase for siamenoside I conversion from mogroside V was constructed, and the enzymes were coelectrospun with poly(vinyl alcohol) followed by phenylboronic acid cross-linking to provide potential usage in the batch production process of Siamenoside I. A central composite design (CCD)-response surface methodology (RSM) was used to find the optimum coelectrospinning parameters. The pH stability and sodium dodecyl sulfate tolerance increased for the entrapped enzymes, and positive correlations between the fiber diameter and enzymatic activity were confirmed. The batch process showed an average siamenoside I production rate of 118 ± 0.08 mg L^-1 h^-1 per gram of fiber. This is the first research article showing specific siamenoside I production on enzyme-loaded electrospun fibers.

The physiological functions and pharmaceutical applications of inulin: A review

Inulin (IN), a fructan-type plant polysaccharide, is widely found in nature. The major plant sources of IN include chicory, Jerusalem artichoke, dahlia etc. Studies have found that IN possessed a wide array of biological activities, e.g. as a prebiotic to improve the intestinal microbe environment, regulating blood sugar, regulating blood lipids, antioxidant, anticancer, immune regulation and so on. Currently, IN is widely used in the food and pharmaceutical industries. IN can be used as thickener, fat replacer, sweetener and water retaining agent in the food industry. IN also can be applied in the pharmaceutics as stabilizer, drug carrier, and auxiliary therapeutic agent for certain diseases such as constipation and diabetes. This paper reviews the physiological functions of IN and its applications in the field of pharmaceutics, analyzes its present research status and future research direction. This review will serve as a one-in-all resource for the researchers who are interested to work on IN.

Comprehensive investigations about the binding interaction of acesulfame with human serum albumin

In this work, the binding interaction of an artificial sweetener, acesulfame (ACS) with human serum albumin (HSA) are investigated at the molecular level by using spectral methods and molecular modeling. ACS has the ability to induce static quenching of the intrinsic fluorescence of HSA by a complex formed between HSA and ACS through weak multi-noncovalent forces including hydrophobic, hydrogen bond and van der Waals forces. ACS enters subdomain IIA of HSA to induce the tertiary structure changes of HSA and decreased the hydrophobicity of protein. In addition, ACS binding does not obviously alter the secondary structure of HSA. This study is hoped to provide some crucial information for further investigations of the biosafety of sweetener.

Enzymatic Monoglucosylation of Rubusoside and the Structure-Sweetness/Taste Relationship of Monoglucosyl Derivatives

Monoglucosylation of rubusoside not only could increase its structural diversity but may also improve its taste. To biosynthesize the monoglucosyl rubusosides, a series of glycosyltransferases and glycosynthases were screened to identify the enzymes capable of specifically glycosylating the hydroxyl groups of the 13-O-β-d-glucosyl and 19-COO-β-d-glucosyl moieties. After structural characterization, the effect of structure on sweetness and taste was established based on these rubusoside-derived analogues, including two first characterized compounds. β-Monoglucosylation of two 2-hydroxyl groups, as well as α-monoglucosylations of the 4- and 6-hydroxyl groups of the 13-glucosyl moiety, could significantly increase the relative sweetness of rubusoside to 140 while maintaining or improving the taste quality. In contrast, monoglucosylations of other hydroxyl groups in our study usually decreased the taste quality of the rubusoside. Additionally, the possibility of a negative influence of these monoglucosylated derivatives on the function of islets was preliminarily excluded, which should facilitate the development of rubusoside-derived sweeteners.

Maltitol: Analytical Determination Methods, Applications in the Food Industry, Metabolism and Health Impacts

Bulk sweetener maltitol belongs to the polyols family and there have been several dietary applications in the past few years, during which the food industry has used it in many food products: bakery and dairy products, chocolate, sweets. This review paper addresses and discusses in detail the most relevant aspects concerning the analytical methods employed to determine maltitol's food safety and industry applications, its metabolism and its impacts on human health. According to our main research outcome, we can assume that maltitol at lower doses poses little risk to humans and is a good alternative to using sucrose. However, it causes diarrhoea and foetus complications at high doses. Regarding its determination, high-performance liquid chromatography proved the primary method in various food matrices. The future role of maltitol in the food industry is likely to become more relevant as processors seek alternative sweeteners in product formulation without compromising health.

Trienzymatic Complex System for Isomerization of Agar-Derived d-Galactose into d-Tagatose as a Low-Calorie Sweetener

d-Tagatose is a rare monosaccharide that is used in products in the food industry as a low-calorie sweetener. To facilitate biological conversion of d-tagatose, the agarolytic enzyme complexes based on the principle of the cellulosome structure were constructed through dockerin-cohesin interaction with the scaffoldin. The construction of agarolytic complexes composed of l-arabinose isomerase caused efficient isomerization activity on the agar-derived sugars. In a trienzymatic complex, the chimeric β-agarase (cAgaB) and anhydro-galactosidase (cAhgA) from Zobellia galactanivorans could synergistically hydrolyze natural agar substrates and l-arabinose isomerase (LsAraA Doc) from Lactobacillus sakei 23K could convert d-galactose into d-tagatose. The trienzymatic complex increased the concentration of d-tagatose from the agar substrate to 4.2 g/L. Compared with the monomeric enzyme, the multimeric enzyme showed a 1.4-fold increase in tagatose production, good thermostability, and reusability. A residual activity of 75% remained, and 52% of conversion was noted after five recycles. These results indicated that the dockerin-fused chimeric enzymes on the scaffoldin successfully isomerized d-galactose into d-tagatose with synergistic activity. Thus, the results demonstrated the possibility of advancing efficient strategies for utilizing red algae as a biomass source to produce d-tagatose in the industrial food field that uses marine biomass as the feedstock.

Stevia Rebaudiana Bertoni, a Source of High-Potency Natural Sweetener-Biochemical and Genetic Characterization

Stevia rebaudiana is a natural sweetener herb that is increasingly used in herbal medicines in the food and cosmetics industries. Molecular methods can be combined with morphological techniques to identify stevia genotypes as a starting material to produce more reliable bioproducts. This study evaluated the level of the genetic and biochemical diversity in various stevia genotypes using HPLC (high performance liquid chromatography) analysis and random amplified polymorphic DNA (RAPD) markers. Stevia genotypes collected from different locations of the world showed clear variations at the biochemical and genetic level in Polish climate conditions. The influence of the genotypes on the content of steviol glycosides, antioxidants, phenols, flavonoids, and tannins was analyzed using phytochemical assays. Genotypes from Morocco, Poland, Egypt, and Nigeria can be defined as samples of higher quality compared to other genotypes analyzed in terms of the amount of steviol glycosides. Considering the rebaudioside A/stevioside ratio as a selection criterion, genotypes from Australia, China, India, and Pakistan should be considered to be valuable in terms of suitability for obtaining new varieties. The present results of RAPD marker analysis indicated differential banding pattern and considerable polymorphism among all ten stevia genotypes. Genotypes from Morocco, Egypt, Poland, Nigeria, China, and India, as genetically different, can be selected for further stevia breeding programs.

Low Calorie Sweeteners Differ in Their Physiological Effects in Humans

Low calorie sweeteners (LCS) are prevalent in the food supply for their primary functional property of providing sweetness with little or no energy. Though tested for safety individually, there has been extremely limited work on the efficacy of each LCS. It is commonly assumed all LCS act similarly in their behavioral and physiological effects. However, each LCS has its own chemical structure that influences its metabolism, making each LCS unique in its potential effects on body weight, energy intake, and appetite. LCS may have different behavioral and physiological effects mediated at the sweet taste receptor, in brain activation, with gut hormones, at the microbiota and on appetitive responses. Further elucidation of the unique effects of the different commercially available LCS may hold important implications for recommendations about their use for different health outcomes.

Highly sweet compounds of plant origin: From ethnobotanical observations to wide utilization

ETHNOPHARMACOLOGICAL RELEVANCE

Ethnobotanical studies have been of very great importance in recognizing plants that contain substances that modulate the heterodimer T1R2-T1R3 sweet taste receptor, inclusive of Stevia rebaudiana (Asteraceae) and Siraitia grosvenorii (Cucurbitaceae).

AIM OF THE REVIEW

In addition to reviewing relevant ethnobotanical literature, inclusive of original field work conducted, the authors have provided a progress report on the ultimate regulatory acceptance of highly sweet ent-kaurane (steviol) diterpene glycosides from S. rebaudiana leaves ("stevia") and cucurbitane triterpene glycosides (mogrosides) from the fruits of S. grosvenorii (popularly known as "monk fruit"). Despite their relatively high prices relative to that of sucrose, the steviol glycosides and mogrosides are of current great interest for further more extensive utilization on the market as sweet-tasting non-caloric food additives, due to increases in the rates of obesity and diabetes all over the world. Recent phytochemical work on the sweet principles of these two species is highlighted, including the important "next-generation" sweetener, rebaudioside M, from S. rebaudiana.

RESULTS

Initial observations on the ethnobotany of both S. rebaudiana and S. grosvenorii have proved crucial to indicating the presence of their sweet-tasting principles to the wider scientific community.

CONCLUSIONS

Ethnobotanical observations have been pivotal in enabling the discovery of many sweet-tasting plant constituents, with those of S. rebaudiana and S. grosvenorii both being examples. Extractives prepared from these species are now commercially used widely in the U.S. as additives for the sweetening of foods and beverages.

Interaction studies of sodium cyclamate with DNA revealed by spectroscopy methods

The interaction between sodium cyclamate (SC) and calf thymus DNA in simulated physiological buffer (pH 7.4) using ethidium bromide (EB) as fluorescence probe was investigated by UV-vis spectrometry (UV), fluorescence, resonance light scattering (RLS) and Fourier transform infrared (FT-IR) spectroscopy, along with DNA melting studies and cyclic voltammetric (CV) measurements. The results indicate that SC can not only bind into the minor groove of DNA, but also intercalate into the DNA Base pairs. Based on UV data, the binding constant K and binding sites n of the formed DNA/SC complex were estimated to be 2.83 × 10³ mol/L and 2.0, respectively. Fluorescence results demonstrate that the quenching of DNA/EB induced by SC can mainly be attributed to static procedure. The melting studies and CV analysis further confirm that the interaction mechanism between the SC and DNA is similar to that of DNA intercalator.The results of FT-IR spectra show that a specific interaction mainly exist between SC and adenine and guanine bases of DNA, which resulting in potential damage due to some change in the information structure. The DNA saturation binding value estimated to be 1.67 based on the RLS data also indicated that SC may cause damage of DNA.

Co-expression of anti-miR319g and miRStv_11 lead to enhanced steviol glycosides content in Stevia rebaudiana

BACKGROUND

miRNAs are major regulators of gene expression and have proven their role in understanding the genetic regulation of biosynthetic pathways. Stevioside and rebaudioside-A, the two most abundant and sweetest compounds found in leaf extract of Stevia rebaudiana, have been used for many years in treatment of diabetes. It has been found that the crude extract is more potent than the purified extract. Stevioside, being accumulated in higher concentration, imparts licorice like aftertaste. Thus, in order to make the sweetener more potent and palatable, there is a need to increase the intrinsic concentration of steviol glycosides and to alter the ratio of rebaudioside-A to stevioside. Doing so would significantly increase the quality of the sweeteners, and the potential to be used on a wider scale. To do so, in previous report, miRNAs associated with genes of steviol glycosides biosynthetic pathway were identified in S. rebaudiana. In continuation to that in this study, the two miRNAs (miR319g and miRStv_11) targeting key genes of steviol glycosides biosynthetic pathway were modulated and their impact was evaluated on steviol glycosides contents.

RESULTS

The over-expression results showed that miRStv_11 induced, while miR319g had repressive action on its target genes. The knock-down constructs for miR319g and miRStv_11 were then prepared and it was demonstrated that the expression of anti-miR319g produced inhibitory effect on its target miRNA, resulting in enhanced expression of its target genes. On the other hand, anti-miRStv_11 resulted in down-regulation of miRStv_11 and its target gene. Further miRStv_11 and anti-miR319gwere co-expressed which resulted in significant increase in stevioside (24.5%) and rebaudioside-A (51%) contents.

CONCLUSION

In conclusion, the role of miR319g and miRStv_11 was successfully validated in steviol gycosides biosynthetic pathway gene regulation and their effect on steviol gycosides contents. In this study, we found the positively correlated miRNA-mRNA interaction network in plants, where miRStv_11 enhanced the expression of KAH gene. miRNAs knock-down was also successfully achieved using antisense precursors. Overall, this study thus reveals more complex nature and fundamental importance of miRNAs in biosynthetic pathway related gene networks and hence, these miRNAs can be successfully employed to enhance the ratio of rebaudioside-A to stevioside, thus enhancing the sweetening indices of this plant and making it more palatable.

Sweet As Sugar-Efficient Conversion of Lactose into Sweet Sugars Using a Novel Whole-Cell Catalyst

Lactose, the sugar contained in milk, has a low sweetness. We have constructed an efficient whole-cell catalyst (WCC) that can be grown on dairy waste and that is able to convert lactose into a mixture of sugars as sweet as sucrose. The WCC is based on Corynebacterium glutamicum ATCC13032, which has been engineered to metabolize lactose, to express xylose and arabinose isomerase, and to eliminate byproduct formation. When introduced in concentrated cheese whey permeate, its content of 98 g/L lactose was completely hydrolyzed and the liberated sugars partially isomerized into 23.5 g/L fructose and 20.4 g/L tagatose, which corresponds to a 49% conversion of the glucose and a 44% conversion of galactose. The latter is similar to what can be obtained using purified enzymes. The new technology enables better resource utilization and allows for dairy waste to be converted into a valuable food sweetener with many potential uses.

Self-Assembly of Artificial Sweetener Aspartame Yields Amyloid-like Cytotoxic Nanostructures

Recent reports have revealed the intrinsic propensity of single aromatic metabolites to undergo self-assembly and form nanostructures of amyloid nature. Hence, identifying whether aspartame, a universally consumed artificial sweetener, is inherently aggregation prone becomes an important area of investigation. Although the reports on aspartame-linked side effects describe a multitude of metabolic disorders, the mechanistic understanding of such destructive effects is largely mysterious. Since aromaticity, an aggregation-promoting factor, is intrinsic to aspartame's chemistry, it is important to know whether aspartame can undergo self-association and if such a property can predispose any cytotoxicity to biological systems. Our study finds that aspartame molecules, under mimicked physiological conditions, undergo a spontaneous self-assembly process yielding regular β-sheet-like cytotoxic nanofibrils of amyloid nature. The resultant aspartame fibrils were found to trigger amyloid cross-seeding and become a toxic aggregation trap for globular proteins, Aβ peptides, and aromatic metabolites that convert native structures to β-sheet-like fibrils. Aspartame fibrils were also found to induce hemolysis, causing DNA damage resulting in both apoptosis and necrosis-mediated cell death. Specific spatial arrangement between aspartame molecules is predicted to form a regular amyloid-like architecture with a sticky exterior that is capable of promoting viable H-bonds, electrostatic interactions, and hydrophobic contacts with biomolecules, leading to the onset of protein aggregation and cell death. Results reveal that the aspartame molecule is inherently amyloidogenic, and the self-assembly of aspartame becomes a toxic trap for proteins and cells, exposing the bitter side of such a ubiquitously used artificial sweetener.

Effects of natural copigment sources in combination with sweeteners on the stability of anthocyanins in sour cherry nectars

Effects of various co-pigment sources [gallic acid (GA), rose leaf extract (RLE), cherry stem extract (CSE), pomegranate rind extract (PRE) and green tea extract (GTE)] on anthocyanin content, colour, and turbidity in sour cherry nectar (SCN), sweetened with sucrose (SCNS), maltose syrup (SCNM) or honey (SCNH), were investigated during storage at 20 °C. Co-pigment sources were associated with increases in λ_max (up to 4.1 nm), colour density (up to 22%), and polymeric colour (up to 1.7 times). Among the co-pigment sources, GA and PRE were associated with the greater anthocyanin stabilities in SCNS and SCNH. Moreover, the lowest turbidity, at the beginning of storage, and turbidity formation rate, throughout storage, were observed in SCNS, SCNM and SCNH containing PRE. When the changes in A_max, λ_max, polymeric colour, colour density, and turbidity were considered together, PRE was the best co-pigment source, regardless of the sweetener used.

Natural Ingredients-Based Gummy Bear Composition Designed According to Texture Analysis and Sensory Evaluation In Vivo

The increased interest in functional materials of natural origin has resulted in a higher market demand for preservative-free, “clean label”, or natural ingredients-based products. The gummy bear food supplements are more acceptable to consumers and have fewer limitations compared to other dosage forms. The aim of our study was to produce natural ingredients-based gummy bear composition, and evaluate the influence of the selected ingredients on the product’s textural properties, its acceptance in vivo, and the gummy bear’s quality. The optimal base composition was determined using a surface response design: gelatin 4.3 g and agave syrup 6.3 g. The investigated sweeteners did not affect the textural properties (p > 0.05). However, further studies demonstrated that a 100% increase of agave results in up to 27% higher flexibility (p < 0.05). The addition of calcium and cholecalciferol reduced firmness by 59.59 ± 1.45% (p < 0.05). On the other hand, acai berry extract had no significant effect. The presence of calcium resulted in a decreased smell and taste; however, the data indicated that experimental texture analysis is a more accurate technique than in vivo evaluation. The acai berry extract did not improve all of the tested sensory properties. We can conclude that the suggested gummy bear base can be supplemented with various active ingredients and commercialized, though further studies are needed to investigate the other natural sources to mask the unpleasant taste of active ingredients and avoid water loss.

Inactivation of Soybean Bowman-Birk Inhibitor by Stevioside: Interaction Studies and Application to Soymilk

In this work, the interaction of the soybean Bowman-Birk inhibitor (BBI) with stevioside (STE) was studied by stopped-flow-fluorescence and molecular docking. STE's inactivation of protease-inhibitor activities in soymilk and the influence of STE addition on the sensory character of soymilk were also evaluated. The results indicate that STE binds BBI with a binding constant ( Ka) of 3.38 × 105 L mol-1 to form a 1:1 complex. The docking study reveals that two hydrogen bonds are formed between the side-chain of Lys16 (reactive site 1) of BBI and the glucose-ring hydroxyl groups of STE, which may block BBI from contacting trypsin and thus deactivate the trypsin-inhibitor activity (TIA) of BBI. Moreover, the residual TIA in soymilk could also be inactivated by STE. A mixture of 159 mg/L STE and 60 g/L sucrose could be used for sweetening soymilk without affecting the sensory characteristics when compared to a reference product sweetened with 9% sucrose.

Ecotoxicity and environmental fates of newly recognized contaminants-artificial sweeteners: A review

Artificial sweeteners (ASs) are used in countless application in daily life. ASs are newly recognized as pollutants due to their high detection frequency in various environmental media, which has aroused great concern. This review presents the current knowledge of AS ecotoxicity and possible elimination routes in the environment. The obtained results indicate that the negative impacts of ASs are more severe than previously expected. More attention should be paid to the chronic and metabolite toxicities of ASs. Moreover, numerous processes (physical, chemical and biological) have been reported to be able to degrade ASs. However, the elimination efficiency varies greatly depending on the specific AS and the particular experimental conditions. Cyclamate and saccharin are easily removed, while sucralose and acesulfame are generally persistent. Additionally, there is a large gap in the ASs removal efficiency between bench tests and full-scale studies. The potential for microbial degradation of persistent ASs was reported in some regions, but clarification of the underlying mechanisms is necessary to increase the likelihood of using this approach in wide applications with a satisfactory performance.

Redox mediators and irradiation improve fenton degradation of acesulfame

Widely recognized as a promising approach to degrading recalcitrant pollutants, Advanced Oxidation Processes (AOPs) have drawn much attention for their effectiveness and efficiency. Among all the AOPs, the Fenton system has been widely applied for oxidation and mineralization of micropollutants due to its ease of implementation and high catalytic efficiency. However, the necessity of preceding acidification, together with rapid consumption and slow regeneration of Fe(II) resulting in deterioration of reactivity, has reduced its competitiveness as a practical option for water treatment. Acknowledging the above drawbacks, this study investigates the potential viable option to enhance the Fenton system. Acesulfame was chosen as the model compound due to its ubiquitous occurrence and persistence in the environment. UV-assisted photo-Fenton treatment was found to remove the parent compound effectively; the transformation profile of acesulfame was identified and elucidated with the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Prolonged UV photo-Fenton treatment was effective for mineralization of the majority of the transformation products, without increasing the overall toxicity as indicated by Vibrio fischeri bioluminescence assay. The positive effects of the addition of redox mediators to Fenton systems at neutral pH were confirmed in this study. The results could be the basis for further development of homogeneous catalytic degradation techniques for the oxidation of environmental contaminants at circumneutral pHs to neutral pHs.

Enzymatic Synthesis and Characterization of a Novel α-1→6-Glucosyl Rebaudioside C Derivative Sweetener

Zero-calorie high-intensity sweeteners from natural sources perform very well in the market place. This has encouraged food scientists to continue the effort to search for novel natural ingredients to satisfy consumer demand. Rebaudioside C (reb C) is the third most prevalent steviol glycoside in the leaves of the Stevia rebaudiana Bertoni plant, but has limited applications in food and beverage products due to its low sweetness and high lingering bitterness compared to other major steviol glycosides, such as rebaudioside A (reb A). Here we present a new enzyme modification strategy to improve the taste profile of reb C by using Cargill's propriety enzyme and sucrose as a glucose donor. A novel α-1→6-glucosyl reb C derivative was produced and its structure was elucidated by mass spectrometry and NMR spectroscopy. Sensory analysis demonstrated that this new reb C derivative has improved sweetness, reduced bitterness, and enhanced solubility in water.

Binding mechanism of five typical sweeteners with bovine serum albumin

In this work, the interactions between bovine serum albumin (BSA) and five sweeteners including aspartame (APM), acesulfame (AK), sucralose (TGS), sodium cyclamate (SC), and rebaudioside-A (REB-A) have been studied by multispectroscopic techniques, and molecular simulation in order to provide much useful information for the application of new and safer artificial sweeteners. Fluorescence quenching assays indicated that the formation of complexes between sweeteners and BSA mainly induced the fluorescence quenching of protein and the binding site number were about 1 indicting that there is one mainly binding site of APM, AK, TGS, SC, or REB-A in domain of BSA with relatively weak interactions. Molecular modeling results indicated that hydrogen bonding interactions were the mainly binding forces of sweeteners with BSA. Circular dichroism spectra indicated that APM and REB-A obviously induced the secondary structure changes of BSA. The presence of APM increased the fraction of α-Helix of BSA from 65.4% to 73.8%, while the presence of REB-A resulted in decreasing the fraction of α-helix of BSA from 65.4% to 51.2%. The melting temperature studies showed that these five sweeteners except REB-A act as stabilizers to increase the thermal stability of BSA during the thermal denaturation process. In addition, AK, TGS, and SC obviously increased the esterase-like activity of BSA, and such loss of activity of BSA induced by APM and REB-A.

New Sweet-Tasting C21 Pregnane Glycosides from the Roots of Myriopteron extensum

To investigate the sweet-tasting components in the roots of Myriopteron extensum, the phytochemical study of its roots was conducted, which led to the discovery of 12 new C21 pregnane glycosides (extensumside M-X, 1-12) and two known ones (extensumside C and extensumside E, 13-14). Their chemical structure elucidation was accomplished by means of spectroscopic methods: IR, UV, ESI-MS, and NMR (¹H NMR, ¹³C NMR, HSQC, ¹H-¹H COSY, HMBC, HSQC-TOCSY, and ROESY), as well as the chemical evidence. Sensory analysis of these compounds revealed that nine of them (1, 3, 4, 5, 6, 7, 8, 13, and 14) are highly sweet-tasting compounds. Their sweetness intensities are 25 to 400 times greater than that of sucrose. Analysis of the structure-activity relationship (SAR) indicated that the sweet intensities of the isolated compounds are closely related to the aglycone 3β,16α-dihydroxy-pregn-5-en-20-one, the number and type of the monosaccharide in the sugar chain linked to C-3 and C-16 and the position of the mBe group.

Removal of pharmaceuticals, perfluoroalkyl substances and other micropollutants from wastewater using lignite, Xylit, sand, granular activated carbon (GAC) and GAC+Polonite® in column tests - Role of physicochemical properties

This study evaluated the performance of five different sorbents (granular activated carbon (GAC), GAC + Polonite^® (GAC + P), Xylit, lignite and sand) for a set of 83 micropollutants (MPs) (pharmaceuticals, perfluoroalkyl substances (PFASs), personal care products, artificial sweeteners, parabens, pesticide, stimulants), together representing a wide range of physicochemical properties. Treatment with GAC and GAC + P provided the highest removal efficiencies, with average values above 97%. Removal rates were generally lower for Xylit (on average 74%) and lignite (on average 68%), although they proved to be highly efficient for a few individual MPs. The average removal efficiency for sand was only 47%. It was observed that the MPs behaved differently depending on their physicochemical properties. The physicochemical properties of PFASs (i.e. molecular weight, topological molecular surface area, log octanol water partition coefficient (K_ow) and distribution coefficient between octanol and water (log D)) were positively correlated to observed removal efficiency for the sorbents Xylit, lignite and sand (p < 0.05), indicating a strong influence of perfluorocarbon chain length and associated hydrophobic characteristics. In contrast, for the other MPs the ratio between apolar and polar surface area (SA/SP) was positively correlated with the removal efficiency, indicating that hydrophobic adsorption may be a key feature of their sorption mechanisms. GAC showed to be the most promising filter medium to improve the removal of MPs in on-site sewage treatment facilities. However, more studies are needed to evaluate the removal of MPs in field trials.

Origin of Xylitol in Chewing Gum: A Compound-Specific Isotope Technique for the Differentiation of Corn- and Wood-Based Xylitol by LC-IRMS

The sugar replacement compound xylitol has gained increasing attention because of its use in many commercial food products, dental-hygiene articles, and pharmaceuticals. It can be classified by the origin of the raw material used for its production. The traditional "birch xylitol" is considered a premium product, in contrast to xylitol produced from agriculture byproducts such as corn husks or sugar-cane straw. Bulk stable-isotope analysis (BSIA) and compound-specific stable-isotope analysis (CSIA) by liquid-chromatography isotope-ratio mass spectrometry (LC-IRMS) of chewing-gum extracts were used to determine the δ¹³C isotope signatures for xylitol. These were applied to elucidate the original plant type the xylitol was produced from on the basis of differences in isotope-fractionation processes of photosynthetic CO₂ fixation. For the LC-IRMS analysis, an organic-solvent-free extraction protocol and HPLC method for the separation of xylitol from different artificial sweeteners and sugar-replacement compounds was successfully developed and applied to the analysis of 21 samples of chewing gum, from which 18 could be clearly related to the raw-material plant class.

Investigation of the photocatalytic transformation of acesulfame K in the presence of different TiO2-based materials

The photocatalytic transformation of acesulfame K - an artificial sweetener that has gained popularity over the last decades for being a calorie-free additive in food, beverages and several pharmaceutical products - was studied using three different photocatalysts, the benchmark TiO₂-P25 and two other forms of synthetized titanium oxides named TiO₂-SG1 and TiO₂-SG2. The two latter materials were synthesized by a sol gel process in which the hydrolysis rate of titanium n-butoxide was controlled by the water formed in situ through an esterification reaction between ethanol and acetic acid. The investigation included monitoring the sweetener disappearance, identifying its intermediate compounds, assessing mineralization and evaluating toxicity. The analyses were carried out using high-performance liquid chromatography (HPLC) coupled with a LTQ-Orbitrap analyzer via an electrospray ionization (ESI) in the negative ion mode. This is a powerful tool for the identification, characterization and measurement of the transformation products (TPs); overall 13 species were identified. The use of several semiconductors has pointed out differences in terms of both photocatalytic efficiency and mechanism: the assessment of the evolution kinetics of each species (TPs, total organic carbon and inorganic ions) has brought to the elaboration of a general transformation pathway of acesulfame K. TiO₂-SG2 proved to be the most efficient material in degrading the artificial sweetener and leads to the complete mineralization within 6 h of irradiation, while up to 16 h are required for TiO₂-P25.

Fate of artificial sweeteners through wastewater treatment plants and water treatment processes

Five full-scale wastewater treatment plants (WWTPs) in China using typical biodegradation processes (SBR, oxidation ditch, A²/O) were selected to assess the removal of four popular artificial sweeteners (ASs). All four ASs (acesulfame (ACE), sucralose (SUC), cyclamate (CYC) and saccharin (SAC)) were detected, ranging from 0.43 to 27.34μg/L in the influent. Higher concentrations of ASs were measured in winter. ACE could be partly removed by 7.11–50.76% through biodegradation and especially through the denitrifying process. The A²/O process was the most efficient at biodegrading ASs. Adsorption (by granular activated carbon (GAC) and magnetic resin) and ultraviolet radiation-based advanced oxidation processes (UV/AOPs) were evaluated to remove ASs in laboratory-scale tests. The amounts of resin adsorbed were 3.33–18.51 times more than those of GAC except for SUC. The adsorption ability of resin decreased in the order of SAC > ACE > CYC > SUC in accordance with the pKa. Degradation of ASs followed pseudo-first-order kinetics in UV/H₂O₂ and UV/PDS. When applied to the secondary effluent, ASs could be degraded from 30.87 to 99.93% using UV/PDS in 30 minutes and UV/PDS was more efficient and economic.

Investigation of ozonation kinetics and transformation products of sucralose

Sucralose is one of widely used artificial sweeteners, which has been ubiquitously detected in various water sources, such as wastewater and randomly in reservoir water. It is also reported to be persistent to various water treatment techniques. Although there are some studies on removal of sucralose by advanced oxidation process, limited information, in terms of reaction kinetics, transformation products and degradation pathway etc., was reported in its ozonation process. In this study, the reaction kinetics, removal efficiency, influence of pH, humic acid and carbonate on sucralose degradation by ozone, have been studied systematically. The results demonstrated that ozonation of sucralose was initiated by the formation of OH radical. Sucralose could be completely removed with excess O₃ at neutral and basic conditions in ultrapure water. The rate of degradation decreased significantly in acidic condition and in the presence of carbonate and OH radical scavenger (e.g. tert-butanol). The acidity was the key factor affecting the degradation of sucralose. The rate constant was about 500 times higher at pH7 than that at pH4. Transformation products study indicated that the ozonation of sucralose were more complex than that in photolysis reaction. Although ozonation of sucralose was initiated by OH radical, both OH radical and O₃ might be involved in the formation of transformation products and total organic carbon (TOC) removal. Various transformation products, such as aldehydes, carboxylic acids and probable chloride containing products, were identified and characterized in details. An ozonation degradation pathway of sucralose was proposed as well.

Contaminants of emerging concern in surface waters in Barbados, West Indies

Contaminants of emerging concern (CECs), including pharmaceuticals, artificial sweeteners, steroid hormones, and current-use pesticides have been detected in surface waters around the world, but to date, there have been no reports in the peer-reviewed literature on the levels of these classes of contaminants in freshwater resources in the Caribbean region. In the present study, multi-residue solid phase extraction (SPE) and liquid chromatography with tandem mass spectroscopy (LC-MS/MS) were used to analyze grab samples of surface waters collected from five different watersheds in Barbados, West Indies. The artificial sweeteners (AS), acesulfame, cyclamate, saccharin, and sucralose were widely detected in the watersheds, indicating contamination from domestic wastewater, and the concentrations of these chemical tracers in water were correlated with the concentrations of the non-prescription pharmaceutical, ibuprofen (R ² values of 0.4-0.6). Surprisingly, the concentrations of another chemical tracer of domestic wastewater, caffeine were not correlated with ibuprofen or AS concentrations. Several other prescription pharmaceuticals and the steroid hormones, estrone and androstenedione, were detected in selected watersheds at low ng/L concentrations. The fungicide, chlorothalonil was widely detected in surface waters at low (< 10 ng/L) concentrations, but the levels of this pesticide were not correlated with the concentrations of the other target analytes, indicating that the source of this pesticide is not domestic wastewater. An informal survey of disposal practices for out of date or unused drugs by pharmacies in Barbados indicated that disposal into trash destined for the landfill and flushing down the sink might be significant sources of contamination of water resources by pharmaceuticals.

Formation of Polyphenol-Denatured Protein Flocs in Alcohol Beverages Sweetened with Refined Cane Sugars

The sporadic appearance of floc from refined, white cane sugars in alcohol beverages remains a technical problem for both beverage manufacturers and sugar refiners. Cane invert sugars mixed with 60% pure alcohol and water increased light scattering by up to ∼1000-fold. Insoluble and soluble starch, fat, inorganic ash, oligosaccharides, Brix, and pH were not involved in the prevailing floc-formation mechanism. Strong polynomial correlations existed between the haze floc and indicator values (IVs) (color at 420 nm pH 9.0/color at pH 4.0-an indirect measure of polyphenolic and flavonoid colorants) (R² = 0.815) and protein (R² = 0.819) content of the invert sugars. Ethanol-induced denaturation of the protein exposed hydrophobic polyphenol-binding sites that were further exposed when heated to 80 °C. A tentative mechanism for floc formation was advanced by molecular probing with a haze (floc) active protein and polyphenol as well as polar, nonpolar, and ionic solvents.

Effects of rare sugar d-allulose on heat-induced gelation of surimi prepared from marine fish

BACKGROUND

d-Allulose (Alu), the C3-epimer of d-fructose, is a non-caloric sweetener (0.39 kcal g^-1 ) with a suppressive effect on postprandial blood glucose elevation. The aim of this study was to investigate the effects of Alu used as a sweetener and gel improver instead of sucrose on heat-induced gelation of surimi.

RESULTS

The puncture test of a heat-induced surimi gel showed that with 50 g kg^-1 Alu the gel had 15% and 6% higher gel strength than the corresponding gel with sucrose (Suc) and with sorbitol (Sor), respectively. In addition, Alu-gel had 26% and 25% higher water-holding capacity (WHC) than Suc- and Sor-gel. Heating of myofibrillar protein with Alu, unlike Suc and Sor, facilitated the formation of both disulfide and non-disulfide crosslinks that might be associated with the mechanical properties and WHC of Alu-gel.

CONCLUSION

Alu improves the mechanical properties and WHC of the heat-induced surimi gel. Furthermore, Alu is low in calories compared with Suc (4.0 kcal g^-1 ) and Sor (3.0 kcal g^-1 ). Thus Alu will be an alternative of Suc or Sor for developing surimi-based products with health benefits. © 2017 Society of Chemical Industry.

Comparison of reduced sugar high quality chocolates sweetened with stevioside and crude stevia 'green' extract

BACKGROUND

The demand for zero and reduced-sugar food products containing cocoa is expanding continuously. The present study was designed to evaluate the feasibility of producing high-quality chocolate sweetened with a crude extract of Stevia rebaudiana (Bertoni) prepared by a green microwave-assisted water-steam extraction procedure. Seven approximately isosweet chocolate formulations were developed, mixing cocoa paste, sucrose, commercial stevioside, crude green extract and maltitol in different proportions. All samples were analyzed for the determination of polyphenol and flavonoid content, antioxidant activity, and sensory acceptability.

RESULTS

The use of a crude stevia extract allowed low-sugar, high-quality chocolates to be obtained that were also acceptable by consumers and had a significant increased antioxidant activity. Moreover, consumers' segmentation revealed a cluster of consumers showing the same overall liking for the sample with 50% sucrose replaced by the stevia crude extract as that obtained with the commercial stevioside and the control sample (without sucrose replacement).

CONCLUSION

The results provide information that can contribute to promoting the development of sweet food products, with advantages in terms of an improved nutritional value (reduced sugar content and increased antioxidant activity) and a reduced impact of the production process on the environment. © 2016 Society of Chemical Industry.