Dynamic characteristics of sweetness and bitterness and their correlation with chemical structures for six steviol glycosides

Dietary Guidance, Sensory, Health and Safety Considerations When Choosing Low and No-Calorie Sweeteners

The growing global focus on the adverse health conditions associated with excessive sugar consumption has prompted health and policy organizations as well as the public to take a more mindful approach to health and wellness. In response, food and beverage companies have proactively innovated and reformulated their product portfolios to incorporate low and no-calorie sweeteners (LNCSs) as viable alternatives to sugar. LNCSs offer an effective and safe approach to delivering sweetness to foods and beverages and reducing calories and sugar intake while contributing to the enjoyment of eating. The objective of this paper is to enhance the understanding of LNCSs segmentation and definitions, dietary consumption and reduction guidance, front-of-package labeling, taste and sensory perception and physiology, metabolic efficacy and impact, as well as the overall safety of LNCSs and sugar.

Correlation analysis of taste phenotype and Gynostemma pentaphyllum saponins using computer virtual screening and UPLC-(HR)MS/MS metabolomics

Gynostemma pentaphyllum, a popular tea ingredient, can be categorized into bitter, sweet, and tasteless varieties based on flavor. However, the metabolic causes of these disparities remain unclear. In this paper, sensory evaluation, untargeted metabolomic analysis using UPLC-QTOF-MS/MS, molecular docking and e-tongue testing were conducted to reveal and verify the structural characteristics and mechanisms underlying these different flavor substances. Component analysis indicated sweet saponins were characterized by glucose chains and protopanaxadiol-type aglycones featuring diagnostic ions m/z 459/475/491 in MS2- spectra; whereas bitter saponins typically featured at least one terminal rhamnose and the higher unsaturated sapogenins with diagnostic ions m/z 473/489/521. Virtual screening on T2R14 and e-tongue testing consistently validated gypenosides with more terminal rhamnoses or higher unsaturated aglycone tended to be more bitter. Docking analysis revealed PHE 172, TYR 159 and ALA 77 were the key amino residue sites in bitterness conduction via hydrophobic and hydrogen bonding interactions.

Dietary steviol glycosides mixture supplementation modulates the gene expression of gut chemoreceptors and enhances the antioxidant capacity in weaned piglets

BACKGROUND

Stevia glycosides (SGs) have been widely used as an ideal sugar alternative in the food industry. However, the potential application of SGs mixture in the diets of weaned piglets remains unexplored. This study aimed to investigate the effect of dietary SGs mixture supplementation on growth performance, gene expression of gut chemoreceptors, and antioxidant capacity in weaned piglets.

METHODS

A total of 216 weaned piglets (Duroc × Landrace × Yorkshire, 7.36 ± 0.04 kg body weight) were randomly assigned to 6 groups (6 pens/group with 6 piglets/pen), and were fed with the basal diet supplemented with 0, 100, 150, 200, 250, or 300 mg/kg SGs mixture for 42 days. The serum, liver, longissimus thoracis, and jejunal samples were collected on day 43.

RESULTS

The results showed that inclusion the SGs mixture in the diet did not have a significant impact on growth performance from days 1 to 28 (P > 0.05). But increasing the concentration of SGs mixture tended to linearly decrease the average daily gain from days 1 to 42 (P = 0.052). However, 150 mg/kg SGs mixture supplementation significantly increased the mRNA expression of taste receptor family 1 member 2 (T1R2) and glucose transporters 2 (GLUT2) in the jejunum (P < 0.05), while 150 and 200 mg/kg SGs mixture supplementation significantly increased T1R3 mRNA expression (P < 0.05). Moreover, 150 mg/kg SGs mixture supplementation significantly reduced serum malondialdehyde content (P < 0.05). Increasing the concentration of SGs mixture linearly and quadratically increased serum total superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activity, as well as hepatic T-SOD, GSH-Px activity, and muscle total antioxidant capacity contents (P < 0.05). Furthermore, piglets fed a diet supplemented with 100 mg/kg SGs mixture had higher serum T-SOD, CAT, and GSH-Px activities compared with the other treatments (P < 0.05).

CONCLUSIONS

Therefore, our results suggest that dietary 100 ~ 150 mg/kg SGs mixture supplementation modulates gene expression of sweet taste recognition receptors and glucose transporters, while also enhancing the antioxidant capacity of weaned piglets.

An exploratory study on the development of a sensory wheel affiliated with the emotional lexicon for chrysanthemum infusion

Chrysanthemum infusion has gained popularity outside of the East Asian market in recent years. However, despite the growing international demand, standardized methods to evaluate the sensory attributes of chrysanthemum tea, which are essential for guiding consumers and ensuring quality control, remain underdeveloped. In this study, a trained panel conducted a quantitative descriptive analysis (QDA®) of eight chrysanthemum samples, successfully distinguishing between them. Additionally, consumer emotional responses to chrysanthemum infusion were assessed using the Check-All-That-Apply (CATA) method. By mapping the descriptive sensory data with emotional response data through Partial Least Squares Regression (PLSR), we identified sensory drivers that elicit specific emotional responses. For this analysis, the emotion lexicon from EsSense25 was clustered into six dimensions: pleasant, tame, warm, active, negative, and bored. Our findings indicate that attributes such as smoothness and chrysanthemum-cucumber flavour induce calm and reassuring emotions (e.g., secure, understanding, calm, and tame). Conversely, sweetness and floral flavour are associated with positive emotions such as happiness, joy, and general well-being, suggesting that floral sweet beverages can mitigate negative emotions. However, sensory attributes such as bitterness, astringency, and vegetal aroma were linked to negative emotions and were sometimes associated with feelings of activity. The development of a sensory wheel, integrated with the emotional lexicon for chrysanthemum infusion, provides a tool for identifying sensory drivers behind emotional experiences. This tool offers valuable insights for market applications and product development, enhancing consumer satisfaction by aligning product attributes with desired emotional outcomes.

Structure, Properties, and Biomedical Activity of Natural Sweeteners Steviosides: An Update

Stevioside is a natural sweetener with the characteristics of low calorie and high sweetness. It comprises a diverse range of monomers that play crucial roles in numerous biological processes. Due to these attributes, it has gained widespread application in agriculture, food, and pharmaceutical industries. As a substitute for sugar, stevioside also shows good pharmacological activities on glucose metabolism, bodyweight keeping, blood pressure maintenance, and shows anti-inflammatory, anti-oxidation, anti-tumor, antibacterial, and immune regulation activities. This review summarized the update on the food safety, sweet structure-activity relationship, pharmacological activity of stevia glycosides recently, and discussed the limitations of its application in food and medicine.

Cleaner preparation of N-lauroyl theanine with taste-enhancing properties and deciphering its taste-presenting mechanism

With the improvement of people's living standards and health awareness, reducing salt, sugar, and fat is gradually becoming the mainstream trend. In this work, we delved into the development of an innovative taste enhancer, N-lauroyl theanine (NLT), and its taste presentation mechanism. NLT was synthesized in the aqueous phase by enzyme-catalyzed and direct-heating methods using food-grade enzymes in yields of up to 64.33 % and 49.11 %, respectively. Sensory evaluation and molecular docking techniques revealed the potential of NLT to enhance salty, umami, sweet, and kokumi taste sensations and its taste presentation mechanism. Results revealed significant taste enhancement of saltiness, umami, sweetness, and kokumi and prolonged their duration in the oral cavity by 0.25-1 mg/L NLT. Molecular docking analyses showed that NLT had a strong binding affinity for a variety of taste receptors. These findings highlight the potential of NLT as a potent taste enhancer for the development of healthier salt/sugar-reduced foods.

Application of multiple dynamic sensory techniques to N-lauroyl amino acids: Exposing the relationship between taste-enhancing properties and chemical structure

This study investigated the taste enhancing effects of N-lauroyl amino acids, including N-lauroyl-phenylalanine, N-lauroyl-tryptophan and N-lauroyl-tyrosine. Sensory results obtained through TDS, TCATA, and TI assessments indicated that all N-Lau-AAs significantly increased the umami intensity and duration of solutions such as simulated chicken broth. Moreover, these compounds masked bitter taste, with LTR showing the most pronounced reduction of bitterness. LP had the effect of enhancing saltiness, whereas LTR and LTY diminished saltiness. Structural analysis revealed a correlation between the chemical structure of N-Lau-AAs and their sensory properties. The presence of carbon‑carbon double bond (CC) was positively correlated with umami intensity and negatively correlated with bitter and salty parameters. Phenolic hydroxyl groups (OH) were negatively correlated with umami intensity and positively correlated with a decrease in bitterness intensity and duration. Overall, this study provides valuable insights into the taste enhancement potential of N-Lau-AAs as taste enhancers in the food industry.

Semirational Design of a UDP-Glycosyltransferase from Nicotiana tomentosiformis for Efficient Biosynthesis of Rebaudioside M2

Rebaudioside M2 (RebM2) is characterized as 13-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[(2-O-β-d-glucopyranosyl-6-O-β-d-glucopyranosyl-β-d-glucopyranosyl) ester], an isomer of rebaudioside M with a 1 → 6 sugar linkage. The product was found in the biotransformation of rebaudioside D (RebD) catalyzed by a glycosyltransferase from Nicotiana tomentosiformis (NtUGT). Herein, guided by consensus engineering and molecular dynamics simulations, a variant NtUGTF72L/L123P/L157P with enhanced activity and thermostability was obtained. It exhibits a strikingly reduced Km (22.47 mM to 0.15 mM) toward RebD, and the catalytic efficiency was over 5000-fold higher than that of the wildtype. When an Arabidopsis sucrose synthase AtSuSy was used for UDP-glucose recycling, NtUGTF72L/L123P/L157P effectively converted 80 g/L RebD to 90.14 g/L RebM2. In a one-pot three-enzyme reaction involving an engineered glycosyltransferase UGTSL2N358F, which catalyzed the conversion of RebA into RebD, 78.8 g/L of RebM2 (with a yield of 84.56%) was produced from 70 g/L of RebA, avoiding the use of the naturally rare and poorly soluble RebD as the starting material. This work will provide a promising biocatalyst for RebM2 biosynthesis on a large scale and create an opportunity to accelerate the exploration of the biological activity of RebM2 and its potential as a candidate for superior SG sweeteners.

Fabrication and Encapsulation of Soy Peptide Nanoparticles Using Ultrasound Followed by Spray Drying

Peptide aggregation inevitably occurs during hydrolysis, and insoluble peptide aggregates (ISPA) are used as feed for animals due to their poor water solubility and unpleasant bitter flavor. Ultrasound was used to fabricate soy peptide nanoparticles by reassembling ISPA, followed by spray-drying encapsulation to develop low-bitterness peptide microcapsules with soluble soybean polysaccharide (SSPS) and stevioside (STE) as wall materials. Powder properties, bitter taste, and the morphology of the microcapsules were evaluated. The formation of soluble peptide nanoparticles (<200 nm) was observed after ultrasound due to the reassembly of ISPA through the disruption of non-covalent intermolecular interactions. A gradual reduction in bitter taste was observed with increasing ultrasonic time. Moreover, spray-drying encapsulation with STE could effectively improve the flowability and wettability of the microcapsule powder owing to the rapid migration of surface-active STE to the atomized droplet surface, as evidenced by the lower angle of repose and wettability time. Peptide microcapsules with STE (spherical particles with smooth surfaces) exhibited lower density and reduced bitterness because STE (0-0.1%, w/w) exhibited an excellent bitter-masking effect. With high STE concentrations (>0.5%, w/w), microcapsules exhibited a higher bitter taste than unencapsulated peptides due to the increased surface distribution of STE on the microcapsules. These results provide an effective technique to improve the physicochemical properties of ISPA.

A review on rebaudioside M: The next generation steviol glycoside and noncaloric sweetener

So far, the use of artificial low-calorie sweeteners, like sucralose, saccharin, and so on, to replace the conventional-based sugars has not succeeded due to the long-term adverse health effects, for example, hypertension, and not well-known safety stand. In this review, we discussed the next generation SvGl (rebaudioside M [Reb M]), their biosynthetic pathway in plant, high-yield production via microbial fermentation and enzyme engineering, physicochemical properties, taste modification, kinetic metabolism, application in food and beverages, safety and toxicological evaluation, regulation and dosage recommendation, and health benefits. In stevia, the biosynthesis of stevia glycosides, especially Reb M, is derived from the bifurcation of the pathway leading to gibberellin, followed by subsequent enzymatic modification of rubusoside. Reb M is more economically produced via microbial fermentation of modified yeast Yarrowia lipolytica and enzymatic bioconversion of rebaudioside A (Reb A) or Reb E. Reb M can serve as a suitable alternative to the conventional-based sugars.

Investigation of the multiple taste enhancement properties of N-succinyl-amino acids and their relationship to chemical structure using dynamic sensory techniques

The present study aimed to explore the similarity and difference in taste enhancement properties of N-succinyl-L-phenylalanine (N-Suc-Phe), N-succinyl-L-tryptophan (N-Suc-Trp), and N-succinyl-L-tyrosine (N-Suc-Tyr) using temporal dominance of sensations (TDS), temporal check-all-that-apply (TCATA), and time-intensity (TI) techniques. Meanwhile, leading taste enhancers in the market, such as N'-[(2,4-dimethoxyphenyl)methyl]-N-(2-pyridin-2-ylethyl) oxamide (DE) was chosen to conduct a comparative analysis with the aforementioned three compounds. Findings from TDS and TCATA revealed that all compounds under investigation notably enhanced umami and saltiness while reducing bitterness in a concentration-dependent fashion (0.25-1 mg/L). Additionally, the TI results indicated that the duration of umami was extended by 50-75%, and the duration of bitterness was decreased by 20-40% upon addition of DE, N-Suc-Phe, N-Suc-Trp, and N-Suc-Tyr (1 mg/L). Among these, N-Suc-Trp was identified as the most effective in augmenting umami and mitigating bitterness, whereas N-Suc-Tyr excelled in enhancing saltiness intensity. Partial least squares regression (PLSR) pinpointed the carbon‑carbon double bond as the important structure influencing the enhancement of umami and reduction of bitterness, whereas the phenolic hydroxyl group was identified as critical for enhancing saltiness. This investigation provided insights into the different characteristics of taste enhancement of N-Suc-AAs and the impact of chemical structure on such specificity.

Raman Spectroscopic Analysis of Steviol Glycosides: Spectral Database and Quality Control Algorithms

Besides all sharing an extraordinary high (i.e., up to ~450 times) sweetening power as compared to sucrose and while presenting strong similarities in their molecular structures, molecules belonging to the family of diterpene glycosides (i.e., the secondary metabolites of Stevia rebaudiana) differ in specific structural details that strongly impact on their levels of sweetness and bitter aftertaste. Given the nutritional and pharmacological benefits of steviol secondary metabolites as natural dietetic and anti-diabetic remedies, extraction and purification of steviol glycosides from plant material are nowadays widely spread among many countries. However, an unpleasant bitter aftertaste, which is linked to a genetic variation in human bitter taste receptors, hampers the full exploitation of such benefits and calls for a prompt improvement in organoleptic property control of stevia products. A deeper understanding of the molecular structure of different steviol glycosides and the consequent development of promptly measurable criteria for the organoleptic performance of their mixtures will support processing optimization and control of taste profiles within desired yields. The present research aimed at establishing Raman spectroscopic algorithms for quantitative characterizations of raw stevia-based sweetener products. First, a series of twelve high-purity diterpene glycosides were analyzed by high spectrally resolved Raman spectroscopy and their spectra analyzed in order to establish a complete Raman library of molecular structures. Then, quantitative spectroscopic parameters were built up and applied to characterize the organoleptic property of five different commercially available samples including the recently developed Rebaudioside M isoform. Raman spectroscopy was confirmed as a versatile analytical technique that could be used for quantitative quality control tasks on the production line and for prompt in situ characterizations of purchased products.

A Novel Compound with Kokumi Properties: Enzymatic Preparation and Taste Presentation Evaluation of N-Lauroyl Phenylalanine

To satisfy the demands of the food industry, innovative flavor enhancers need to be developed urgently to increase the food flavor. In our work, N-lauroyl phenylalanine (LP) was prepared from phenylalanine (l-Phe) and lauric acid (Lau) in water through the use of commercial enzymes (Promatex, Sumizyme FP-G, and Trypsin), and its flavor-presenting properties and mechanism were investigated. The highest LP yields obtained under one-factor optimized conditions were 61.28, 63.43, and 77.58%, respectively. Sensory assessment and an e-tongue test revealed that 1 mg/L LP enhanced the kokumi, saltiness, and umami of the simulated chicken broth solution and attenuated the bitterness of the l-isoleucine solution. The molecular simulation results suggested that the mechanisms of LP enhancement of kokumi and umami were related to hCaSR and hT1R1-hT1R3, and that hydrophobic forces and hydrogen bonds were involved in the binding of LP to taste receptors. The results implied that LP is a potential flavor enhancer for food applications.

Taste and its receptors in human physiology: A comprehensive look

Increasing evidence shows that food has significance beyond traditional perception (providing nutrition and energy) in maintaining normal life activities. It is indicated that the sense of taste plays a crucial part in regulating human life activities. Taste is one of the basic physiological sensations in mammals, and it is the fundamental guarantee for them to perceive, select, and ingest nutrients in order to survive. With the advances in electrophysiology, molecular biology, and structural biology, studies on the intracellular and extracellular transduction mechanisms of taste have made great progress and gradually revealed the indispensable role of taste receptors in the regulation and maintenance of normal physiological activities. Up to now, how food regulates life activities through the taste pathway remains unclear. Thus, this review comprehensively and systematically summarizes the current study about the sense of taste, the function of taste receptors, the taste–structure relationship of gustatory molecules, the cross‐talking between distinctive tastes, and the role of the gut–organ axis in the realization of taste. Moreover, we also provide forward‐looking perspectives on taste research to afford a scientific basis for revealing the scientific connotation of taste receptors regulating body health.

Microbial synthesis of terpenoids for human nutrition - an emerging field with high business potential

Because of their complicated biosynthesis and hydrophobic nature, fermentative production of terpenoids did not play a significant role on a commercial scale until a few years ago. Driven by technological progress in metabolic engineering and process biotechnology, terpene-based food ingredients such as flavors, sweeteners, and vitamins produced by fermentation have now become viable and commercially competitive options. In recent years, several companies have developed microbial platforms for commercial terpene production. Impressive progress has been made in the fermentative production of sesquiterpenes used in flavorings. The development of sweeteners, such as steviol glycosides and mogrosides, and the production of vitamins A and E based on fermentation are also being explored. The production of monoterpenes remains challenging due to their antimicrobial effects.

A Pharmacological perspective on the temporal properties of sweeteners

Several non-caloric sweeteners exhibit a delay in sweetness onset and a sweetness linger after sampling. These temporal properties are thought to be the result of non-specific interactions with cell membranes and proteins in the oral cavity. Data and analysis presented in this report also support the potential involvement of receptor affinity and binding kinetics to this phenomenon. In general, affected sweeteners exhibit distinctly higher binding affinity compared to carbohydrate sweeteners, which do not have temporal issues. In addition, binding kinetic simulations illustrate much slower receptor binding association and dissociation kinetics for a set of non-caloric sweeteners presenting temporal issues, in comparison to carbohydrate sweeteners. So, the higher affinity of some non-caloric sweeteners, dictating lower use levels, and affecting binding kinetics, could contribute to their delay and linger in sweetness perception. Simple pharmacology principles could explain, at least in part, some of the temporal issues of sweeteners.

Efficient Conversion of Stevioside to Rebaudioside M in Saccharomyces cerevisiae by a Engineering Hydrolase System and Prolonging the Growth Cycle

Rebaudioside (Reb) M is an important sweetener with high sweetness, but its low content in Stevia rebaudiana and low catalytic capacity of the glycosyltransferases in heterologous microorganisms limit its production. In order to improve the catalytic efficiency of the conversion of stevioside to Reb M by Saccharomyces cerevisiae, several key issues must be resolved including knocking out endogenous hydrolases, enhancing glycosylation, and extending the enzyme catalytic process. Herein, endogenous glycosyl hydrolase SCW2 was knocked out in S. cerevisiae. The glycosylation process was enhanced by screening glycosyltransferases, and UGT91D2 from S. rebaudiana was identified as the optimum glycosyltransferase. The UDP-glucose supply was enhanced by overexpressing UGP1, and co-expressing UGT91D2 and UGT76G1 achieved efficient conversion of stevioside to Reb M. In order to extend the catalytic process, the silencing information regulator 2 (SIR2) which can prolong the growth cycle of S. cerevisiae was introduced. Finally, combining these modifications produced 12.5 g/L Reb M and the yield reached 77.9% in a 5 L bioreactor with 10.0 g/L stevioside, the highest titer from steviol glycosides to Reb M reported to date. The engineered strain could facilitate the industrial production of Reb M, and the strategies provide references for the production of steviol glycosides.

Fine-Scale Characterization of Plant Diterpene Glycosides Using Energy-Resolved Untargeted LC-MS/MS Metabolomics Analysis

Plant diterpene glycosides are essential for diverse physiological processes. Comprehensive structural characterization proved to be a challenge due to variations in glycosylation patterns, diverse aglycone structures, and the absence of comprehensive reference databases. In this study, a method for fine-scale characterization was proposed based on energy-resolved (ER) untargeted LC-MS/MS metabolomics analysis using steviol glycosides as a demonstration. Energy-dependent fragmentation patterns were unveiled by a series of model compounds. Distinct glycosylation sites were discerned by leveraging varying fragmentation energies for the precursor ions. The sugar moiety linkage at C19OOH (R1) exhibited facile and intact cleavage at low collision energies, while the sugar moiety at C13-OH (R2) demonstrated consecutive cleavage with increasing energy. Aglycone ions exhibited a higher relative intensity at NCE 50, with relative intensities ranging from 95% to 100%. Subsequently, aglycone candidates, R1 sugar composition, and R2 sugar sequence were deduced through ER-MS/MS analysis. The developed method was applied to Stevia rebaudiana leaves. A total of 91 diterpene glycosides were unambiguously identified, including 16 steviol glycosides with novel acetylglycosylation patterns. This method offers a rapid alternative for glycan analysis and the structural differentiation of isomers. The developed method enhances the understanding of diterpene glycosides in plants, providing a reliable tool for the in-depth characterization of complex metabolite profiles.

Selective synthesis of rebaudioside M2 through structure-guided engineering of glycosyltransferase UGT94D1

Rebaudioside M2 (Reb M2), a novel steviol glycoside derivative, has limited industrial applications due to its low synthetic yield and selectivity. Herein, we identify UGT94D1 as a selective glycosyltransferase for rebaudioside D (Reb D), leading to the production of a mono β-1,6-glycosylated derivative, Reb M2. A variant UGT94D1-F119I/D188P was developed through protein engineering. This mutant exhibited a 6.33-fold improvement in catalytic efficiency, and produced Reb M2 with 92% yield. Moreover, molecular dynamics simulations demonstrated that UGT94D1-F119I/D188P exhibited a shorter distance between the nucleophilic oxygen (OH6) of the substrate Reb D and uridine diphosphate glucose, along with an increased Ophosphate-C1-Oacceptor angle, thus improving the catalytic activity of the enzyme. Therefore, this study provides an efficient method for the selective synthesis of Reb M2 and paves the way for its applications in various fields.

Computational simulations on the taste mechanism of steviol glycosides based on their interactions with receptor proteins

Steviol glycoside (SG) is a potential natural sugar substitute. The taste of various SG structures differ significantly, while their mechanism has not been thoroughly investigated. To investigate the taste mechanism, molecular docking simulations of SGs with sweet taste receptor TAS1R2 and bitter taste receptor TAS2R4 were conducted. The result suggested that four flexible coils (regions) in TAS1R2 constructed a geometry open pocket in space responsible for the binding of sweeteners. Amino acids that form hydrogen bonds with sweeteners are located in different receptor regions. In bitterness simulation, fewer hydrogen bonds were formed with the increased size of SG molecules. Particularly, there was no interaction between RM and TAS2R4 due to its size, which explains the non-bitterness of RM. Molecular dynamics simulations further indicated that the number of hydrogen bonds between SGs and TAS1R2 was maintained during a simulation time of 50 ns, while sucrose was gradually released from the binding site, leading to the break of interaction. Conclusively, the high sweetness intensity of SG can be attributed to its durative concurrent interaction with the receptor's binding site, and such behavior was determined by the structure feature of SG.

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.

Efficient Bioconversion of Stevioside and Rebaudioside A to Glucosylated Steviol Glycosides Using an Alkalihalobacillus oshimesis-Derived Cyclodextrin Glucanotransferase

The enzymatic transglycosylation of steviol glycosides can improve the edulcorant quality of steviol glycosides. Cyclodextrin glucanotransferase (CGTase) is one of the most popular glucanotransferases applied in this reaction. Herein, the CGTase-producing strain Alkalihalobacillus oshimensis CGMCC 23164 was isolated from Stevia planting soil. Using mass spectrometry-based secretome profiling, a high-efficiency CGTase that converted steviol glycosides to glucosylated steviol glycosides was identified and termed CGTase-13. CGTase-13 demonstrated optimal transglycosylation activity with 10 g/L steviol glycoside and 50 g/L soluble starch as substrates at <40 °C. Under the above conditions, the conversion rate of stevioside and rebaudioside A, two main components of steviol glycosides, reached 86.1% and 90.8%, respectively. To the best of our knowledge, this is the highest conversion rate reported to date. Compared with Toruzyme® 3.0 L, the commonly used commercial enzyme blends, glucosylated steviol glycosides produced using CGTase-13 exhibited weaker astringency and unpleasant taste, faster sweetness onset, and stronger sweetness intensity. Thus, CGTase provides a novel option for producing high-quality glucosylated steviol glycoside products and has great potential for industrial applications.

Highly efficient synthesis of mono-β-1,6-Glucosylated Rebaudioside A derivative catalyzed by glycosyltransferase YjiC

Steviol glycosides have attracted great interest because of their high levels of sweetness and safety, and absence of calories. Improvement of their sensory qualities via glycosylation modification by glycosyltransferase is a research hotspot. In this study, YjiC, a uridine diphosphate-dependent glycosyltransferase from Bacillus subtilis 168, was found with the ability to glycosylate rebaudioside A (Reb A) to produce a novel mono β-1, 6-glycosylated Reb A derivative rebaudioside L2 (Reb L2). It has an improved sweetness compared with Reb A. Next, a cascade reaction was established by combining YjiC with sucrose synthase AtSuSy from Arabidopsis thaliana for scale-up preparation of Reb L2. It shows that Reb L2 (30.94 mg/mL) could be efficiently synthesized with an excellent yield of 91.34% within 12 h. Therefore, this study provides a potential approach for the production and application of new steviol glycoside Reb L2, expanding the scope of steviol glycosides.

Natural and low-caloric rebaudioside A as a substitute for dietary sugars: A comprehensive review

For health and safety concerns, traditional high-calorie sweeteners and artificial sweeteners are gradually replaced in food industries by natural and low-calorie sweeteners. As a natural and high-quality sugar substitute, steviol glycosides (SvGls) are continually scrutinized regarding their safety and application. Recently, the cultivation of organic stevia has been increasing in many parts of Europe and Asia, and it is obvious that there is a vast market for sugar substitutes in the future. Rebaudioside A, the main component of SvGls, is gradually accepted by consumers due to its safe, zero calories, clear, and sweet taste with no significant undesirable characteristics. Hence, it can be used in various foods or dietary supplements as a sweetener. In addition, rebaudioside A has been demonstrated to have many physiological functions, such as antihypertension, anti-diabetes, and anticaries. But so far, there are few comprehensive reviews of rebaudioside A. In this review article, we discuss the physicochemical properties, metabolic process, safety, regulatory, health benefits, and biosynthetic pathway of rebaudioside A and summarize the modification methods and state-of-the-art production and purification techniques of rebaudioside A. Furthermore, the current problems hindering the future production and application of rebaudioside A are analyzed, and suggestions are provided.