Search Results (162)

Stevia (Stevia rebaudiana Bertoni) is an important source of natural sweeteners. Since its commercial value depends on steviol glycosides, quality assessment primarily involves quantifying these compounds in leaves and shoots. While chromatography is the standard analytical method, it is labor-intensive and time-consuming; it involves multiple processing steps that may cumulatively introduce errors and remains relatively expensive. Although chromatography remains the most accurate method, this exploratory study evaluates the potential of using spectroscopy as an auxiliary method for the approximate assessment of steviol glycoside content. Leaf reflectance spectroscopy could be a simpler and more cost-effective approach. However, relationships between leaf reflectance and steviol glycoside content are indirect and mediated by physiological processes. To account for these indirect dependencies, cumulative UVB exposure was included as an additional feature because it influences both leaf optical properties and plant metabolic processes. A low-cost spectrometer was utilized as the measuring instrument. The study was conducted over a period of three months on 77 S. rebaudiana clones, divided into four groups based on their level of UVB irradiance (control without irradiation, 400, 600, and 800 μW m⁻²). Based on the collected data, linear and polynomial regression, Random Forest, XGBoost, PLSR, and ElasticNetCV models were trained. Cumulative UVB exposure was found to be the most important feature. Of the spectral features, the most informative for assessing the content of steviol glycosides were spectral indicators in the far-red and near-infrared (NIR) ranges. Our results indicate a detectable relationship, with Random Forest being the best-performing model and achieving a moderate predictive performance (R² = 0.66). Despite their limited predictive performance, the models demonstrate that leaf reflectance spectra combined with cumulative UVB exposure contain information related to steviol glycoside content. These findings support further investigation of remote sensing approaches for crop quality assessment. Full article

Background/Objectives: Stevia rebaudiosides represent a class of compounds extracted from the Stevia rebaudiana Bertoni plant or produced via yeast fermentation, which provide a sweet taste with little to no calories. These compounds are commercially referred to as stevia and are used in the food industry to reduce sugar in foods and beverages. Stevia is a non-nutritive sweetener (NNS), which is a class of ingredients which represent both artificial and plant-based sweeteners. NNSs are widely used and have been well studied. However, their effects on efficacy for weight management as a sugar reduction tool and overall metabolic effects are inconsistent. Of the approved NNSs for use, stevia is relatively new and one of the least studied. However, recent human clinical research has provided insights into stevia’s metabolic effects, effects on the gut microbiome and effects on weight management when used to replace sugar. The objective of this narrative review of human clinical studies is to provide an overview of the effects of stevia rebaudiosides (largely rebaudioside A) on glucoregulatory and cardiometabolic functions, as well as their effects on gut microbiome and weight management. These studies were typically short term (acute to three months) and heterogeneous by design, and they contained stevia rebaudiosides as lone sweeteners and as part of a binary blend with other NNSs. The majority of metabolic studies on stevia rebaudiosides have evaluated the effects on glucose homeostasis and, to a lesser extent, the effects on cardiometabolic function, the gut microbiome, and weight management. These studies suggest that stevia rebaudiosides have no statistically significant effects on glycemia, insulinemia, blood lipids, appetite hormones, or the gut microbiome. Limited studies suggest that, particularly when compared to sucrose, stevia produces very modest body weight and BMI changes, while studies on subjective appetite and food intake have had inconsistent results. Conclusions: Longer-term studies are needed, with more consistent and rigorous design protocols across various populations. However, current human clinical studies suggest that stevia rebaudiosides have a limited impact on metabolic functions, and the observed effects on gut microbiome and changes in body weight, particularly when used to replace sugar, warrant further study. Full article

The molecular management of elite-relevant lines in clonally exploited crops requires more than broad genetic structure alone. In Stevia rebaudiana, breeding materials derived from cv. ‘Morita II’ may retain useful variation while also concentrating molecularly similar lines, increasing redundancy within selection pipelines. This study assessed whether a reduced five-locus SSR dataset could provide an operational molecular-affinity framework for redundancy screening and breeding-context interpretation of previously identified elite-relevant lines in a ‘Morita II’-derived breeding collection. A curated five-locus SSR dataset comprising 85 genotypes from a tropical breeding programme was analysed using the Wang relatedness estimator, operational molecular-affinity classes, UPGMA clustering based on Wang-derived dissimilarity and permutation-based assessment of mean Wang relatedness. The collection combined a broad fraction of comparisons showing no detectable positive molecular affinity with a relevant high-affinity component, and this pattern differed between the two reference molecular strata. One subset showed a compact high-affinity profile and higher mean Wang relatedness than expected under random reassignment, whereas the other was dominated by comparisons with no detectable positive molecular affinity. Importantly, the five-locus SSR framework is interpreted here as an operational, locally validated decision-support tool rather than as genome-wide or pedigree-level relatedness inference. These findings suggest that reduced SSR-derived molecular-affinity information can complement phenotypic, physiological and clonal evaluations by providing redundancy context for line retention, clonal advancement, and parental-diversification decisions in tropical stevia breeding. Full article

Rebaudioside M (Reb M) is a high-value steviol glycoside responsible for the most desirable sensorial profile among stevia-derived sweeteners, owing to its intense sweetness and near absence of bitter aftertaste. However, its extremely low natural abundance in Stevia rebaudiana leaves has driven the development of alternative production strategies, including microbial fermentation and enzyme-assisted bioconversion. In this work, Raman spectroscopy is employed as a rapid, non-destructive, and label-free analytical tool to discriminate Reb M obtained from three distinct sources: (i) naturally occurring leaf extracts, (ii) fermentation-derived products, and (iii) enzymatically bioconverted products. Distinct vibrational fingerprints are identified that reflect differences in glycosylation patterns, residual steviol glycoside populations, matrix components, and process-related byproducts. The results demonstrate that Raman spectroscopy enables prompt authentication of Reb M origin and provides a powerful platform for real-time quality control. Importantly, the technique allows near-zero-cost screening, thus offering a decisive advantage over conventional chromatographic methods. These findings highlight Raman spectroscopy as a key method enabling a swift procedure for ensuring transparency, safety, and consistency in next-generation Stevia sweeteners. Full article

Stevia rebaudiana Bertoni is a strategically important perennial crop because it is the main botanical source of steviol glycosides, a group of high-intensity, non-caloric sweeteners increasingly demanded by the global food and beverage industry. Despite the rapid expansion of stevia cultivation, commercial production remains strongly dependent on a narrow genetic base, particularly on clonally propagated cultivars such as ‘Morita II’, which has long served as the industrial benchmark because of its favourable rebaudioside A profile and processing consistency. This dependence has raised concerns about limited adaptive capacity, genetic erosion and restricted long-term breeding progress. In this review, we provide an integrated and critical synthesis of current knowledge on the genetic diversity of S. rebaudiana, the biosynthetic and regulatory architecture of steviol glycosides, and the conventional and emerging strategies available for crop improvement. Unlike previous reviews, this article explicitly connects domestication-driven genetic bottlenecks, wild germplasm mobilisation, metabolic pathway regulation, advanced analytical phenotyping and precision breeding into a single systems-oriented framework. We examine the roles of wild germplasm, somaclonal variation, polyploidy, molecular markers, omics-assisted approaches and transgene-free genome editing as complementary tools to broaden the stevia breeding base while preserving industrial quality standards. We finally propose an integrative roadmap for the sustainable genetic improvement of stevia, positioning ‘Morita II’ not as an endpoint, but as a benchmark within a broader diversification strategy. Full article

Improving meat quality using safe phytogenic feed additives is of practical interest in yellow-feathered broiler production. This study aimed to evaluate the effects of dietary Stevia rebaudiana Bertoni extract (SBE) supplementation on meat quality traits. A total of 510 one-day-old, female yellow-feathered broilers were randomly allocated to six dietary treatments (0, 50, 100, 200, 300, and 400 mg/kg SBE) for 63 days. Meat sensory attributes, routine physicochemical characteristics, amino acid and fatty acid composition, electronic-nose profiles, and total volatile basic nitrogen (TVB–N) during refrigerated storage were assessed. Overall, the results provide evidence that dietary SBE supplementation is associated with changes in multiple meat quality-related parameters, supporting further evaluation of SBE as a phytogenic feed additive in yellow-feathered broilers. Full article

Light availability drives Stevia rebaudiana productivity, yet how incident radiation interacts with genotype and site under tropical field conditions remains unclear. We evaluated four genotypes (L020, L102, L082, and ‘Morita II’) across three Caribbean locations in Colombia under two contrasting light levels (600 vs. 1800 μmol photons m⁻² s⁻¹) using a split-plot randomised complete block design with four replicates. Incident photosynthetic photon flux density (PPFD) was logged and, at 85 days after transplanting (DAT), net CO₂ assimilation, stomatal conductance, transpiration, and intercellular CO₂ concentration were measured alongside light-adapted chlorophyll fluorescence parameters, including the effective quantum yield of photosystem II (ΦPSII), the maximum efficiency of PSII in the light (Fv′/Fm′), photochemical quenching (qP), and electron transport rate (ETR); biomass and leaf yield were quantified at harvest. Data were analysed using factorial analysis of variance (ANOVA) and complementary multivariate approaches, including Pearson correlation analysis and principal component analysis (PCA). Radiation responses were strongly site-dependent: under 1800 μmol photons m⁻² s⁻¹, net CO₂ assimilation increased by 90.2% at El Carmen de Bolívar and 21.5% at Polonuevo but decreased by 36.4% at Montería. Leaf yield was highest in El Carmen de Bolívar (1951.46 ± 182.03 kg ha⁻¹), followed by Montería (1510.94 ± 173.75 kg ha⁻¹) and Polonuevo (576.31 ± 42.36 kg ha⁻¹). Genotype rankings shifted with environment and radiation, with L102 reaching 3256.25 ± 126.39 kg ha⁻¹ under direct radiation in El Carmen de Bolívar and ‘Morita II’ showing strong responsiveness in Montería. These results demonstrate that photosynthetic plasticity and leaf yield in S. rebaudiana depend on genotype × radiation × environment interactions, supporting location-tailored radiation management combined with targeted genotype deployment. Full article

Intraspecific phenotypic diversity in clonally propagated crops is frequently constrained by narrow domestication histories and the widespread use of a limited number of elite cultivars. In Stevia rebaudiana, commercial production has largely centred on cv. ‘Morita II’, raising concerns about reduced diversity and adaptive potential. This study characterised and structured phenotypic diversity within a segregating population derived from ‘Morita II’ under tropical field conditions. Eighty-six progeny-derived genotypes (clonally propagated) plus the commercial control (87 genotypes total) were evaluated using 25 agromorphological descriptors (qualitative and quantitative). Quantitative traits showed broad variation, including plant height (28.26–119.50 cm) and dry yield rate (0.94–28.55 g plant⁻¹). Multivariate analyses of mixed descriptors (PCA and hierarchical clustering based on Gower distance) identified plant architecture, vegetative growth, and phenology as the main sources of differentiation. The first two principal components explained 19.65% and 12.58% of total phenotypic variance, respectively (32.23% cumulative). Hierarchical clustering (UPGMA; dissimilarity cut-off = 0.25) resolved four phenotypic groups (GI–GIV) with sizes n = 3, 1, 66, and 17, respectively, enabling the definition of contrasting ideotype candidates based on recurrent trait combinations. These results provide a quantitative baseline for phenotypic structuring, prioritization of materials for further evaluation, and management of clonal stevia collections in tropical production systems. These ideotype candidates should be considered preliminary until validated across environments and linked to chemical quality traits. Full article

In recent years, the sustainable production of bio-based platform chemicals from non-lignocellulosic biomass has garnered increasing attention. In this study, Stevia rebaudiana residues were evaluated via hydrothermal liquefaction (HTL) to produce key furan derivatives, namely 5-hydroxymethylfurfural (5-HMF) and furfural. The effects of reaction temperature (160–240 °C) and pressure (0–8 MPa) on product yields were systematically investigated and statistically evaluated using Analysis of Variance (ANOVA) and regression modeling. The highest 5-HMF (93.1 mg/L) and furfural (51.2 mg/L) yields were obtained at 200 °C, while pressure was found to have no statistically significant effect on product formation. To elucidate the physicochemical transformations occurring during hydrothermal processing, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy were used to analyze the morphological and functional group evolution of the biochar and bio-oil fractions. SEM images revealed gradual structural degradation, pore formation, and carbonization with increasing temperature, while FT-IR analysis confirmed dehydration, hydrolysis of glycosidic bonds, aromatization, and the formation of carbonyl groups directly related to furan production. A validated High-Performance Liquid Chromatography (HPLC-UV) method providing analytical efficiency for the precise determination of 5-HMF and furfural in complex biomass matrices was developed. This study provides a comprehensive understanding of the thermochemical behavior of Stevia rebaudiana biomass by integrating morphological characterization, molecular-level spectroscopy, and statistical process modeling and establishes a predictive framework for optimizing furan production under hydrothermal conditions. The findings highlight the potential of Stevia rebaudiana residues as a sustainable feedstock within circular bioeconomy strategies and offer a scalable approach for converting agricultural waste into high-value platform chemicals. Full article

Two steviol glycosides containing quinovose were isolated from a biotransformation mixture of stevia extract derived from Stevia rebaudiana Bertoni leaves. These compounds were elucidated using comprehensive spectroscopic techniques, including nuclear magnetic resonance (NMR) and mass spectrometry (MS). These compounds were designated as Rebaudioside QM and the novel Rebaudioside 2QM. Based on structural similarity, we hypothesize that Stevioside E may serve as a biosynthetic precursor for Rebaudioside QM. Comprehensive LC-MS profiling also suggests potential precursors for Rebaudioside 2QM. Tentative biosynthetic pathways were proposed for both compounds. The presence of these unknown compounds further supports the notion that S. rebaudiana harbours a wide array of yet-undiscovered steviol glycosides, potentially driven by the inherent diversity of UDP-dependent glycosyltransferases (UGTs) within the plant itself. The discovery of Rebaudioside QM and Rebaudioside 2QM expands the known diversity of steviol glycosides and provides new insights into glycosylation patterns in S. rebaudiana, which may support the development and production of novel sweeteners with improved sensory and physicochemical properties. Full article

Gelling agents are widely used to solidify plant tissue culture media, yet differences among commercial products may influence the medium’s physical properties and in vitro development of explants. The aim of this study was to characterize the rheological behavior of six gelling agents (Daishin agar, Gelcarin, Gelrite, Microagar, Phytoagar, and Plant agar) and to examine it in parallel with in vitro performance in Hypericum perforatum, Mentha × piperita, and Stevia rebaudiana. Rheological measurements were performed under steady shear by recording apparent viscosity and shear stress across 5–300 s⁻¹. Daishin agar showed the highest apparent viscosity (49,028.95 ± 128 mPa·s), whereas Gelrite exhibited the lowest viscosity (7826.75 ± 98 mPa·s). Plant responses were evaluated after four weeks on PGR-free Driver and Kuniyuki Walnut (DKW) medium by assessing shoot growth, rooting parameters, and shoot water content. In H. perforatum, the longest shoots were obtained on Gelrite (3.92 ± 0.34 cm), accompanied by the highest rooting percentage (95%). In M. × piperita, Gelcarin produced the longest shoots (8.20 ± 0.55 cm) and the highest number of roots per explant (9.75). In S. rebaudiana, Gelcarin promoted superior root elongation (2.86 ± 0.16 cm) and enhanced shoot growth, while Plant agar also supported favorable shoot development. Shoot water content ranged between 74% and 90%, depending on species and gelling agent. These findings highlight the practical relevance of considering low-shear rheological properties when comparing gelling agents for improving the consistency of in vitro culture media. Full article

Microbial fermentation is an effective strategy to enhance the functional value of plant-derived ingredients. In this study, Stevia rebaudiana leaves were subjected to microbial fermentation to improve their antioxidant potential and functional properties. A composite fermentation system composed of Bacillus subtilis and Candida utilis was established through strain screening, and fermentation conditions were optimized using single-factor and orthogonal experiments, with chlorogenic acid (CA) content and antioxidant activity as evaluation indices. The optimal conditions were determined to be a fermentation temperature of 34 °C, a duration of 36 h, a microbial ratio (Bs:Cu) of 2:1, a moisture content of 55%, and an inoculum level of 3%. Under these optimal conditions, fermentation significantly increased CA content, total phenolic and flavonoid levels, and antioxidant capacity compared with unfermented material. Untargeted metabolomic analysis revealed extensive fermentation-induced remodeling of secondary metabolites, particularly phenolic acids, flavonoids, and terpenoids, including the generation of multiple newly formed bioactive compounds. Functional validation using a laying hen model demonstrated that fermented S. rebaudiana exhibited enhanced antioxidant and anti-inflammatory status and favorable modulation of physiological indicators compared with unfermented samples. Overall, this study demonstrates that microbial consortium fermentation effectively transforms S. rebaudiana from a sweetener-oriented plant into a multifunctional, fermentation-derived functional ingredient. This research is significant as it provides a dual-purpose strategy for developing antioxidant-enriched functional foods for humans and health-promoting natural feed additives for the livestock industry. Full article

A novel steviol glycoside, Rebaudioside D17, was identified from the leaf extract of Stevia rebaudiana Bertoni. This compound features a rare β-1→4 glycosidic linkage between two glucose units at the C19 position, distinguishing it from its structural isomer, Rebaudioside D. The aim of this study was to isolate and characterize Rebaudioside D17 and investigate its biosynthetic origin. The compound was isolated and structurally characterized using comprehensive NMR spectroscopy including ¹H, ¹³C, COSY, NOESY, Heteronuclear Single Quantum Coherence–Distortionless Enhancement by Polarization Transfer (HSQC-DEPT), Heteronuclear Multiple Bond Correlation (HMBC), Heteronuclear Single Quantum Coherence–Total Correlated Spectroscopy (HSQC-TOCSY), along with mass spectrometry analysis. A tentative biosynthetic pathway is proposed, involving Rebaudioside E19, a putative intermediate bearing the same β-1→4 glycosidic linkage at C19. Rebaudioside E19 may serve as a common precursor to both Rebaudioside D17 and Rebaudioside U3, a minor steviol glycoside previously reported in Stevia rebaudiana leaf extract, which also contains the same β-1→4 glycosidic linkage. The discovery of Rebaudioside D17 expands the known diversity of steviol glycosides and provides new insights into glycosylation patterns in Stevia rebaudiana, which may support the development and production of novel sweeteners with improved sensory and physicochemical properties. Full article

Salt stress is one of the most harmful abiotic stresses that strongly affects plant growth and crop yield, limiting agricultural production across the Mediterranean area. Consequently, there is a growing need to identify resilient crops capable of adapting to saline conditions and enhancing desirable qualitative traits through a wide spectrum of physiological, biochemical, and molecular mechanisms. Therefore, this study aimed to investigate the effects of four different NaCl concentrations (0, 12.5, 25, and 50 mM) on the growth rates, biometric and productive characteristics, leaf gas exchange, and biochemical traits of Stevia rebaudiana Bertoni plants grown hydroponically (in a floating raft system) in a glasshouse. The results showed that NaCl-treated plants exhibited reduced growth parameters and productivity and a lower content of photosynthetic pigment content compared to the control. On the other hand, an increase in antioxidant capacity was observed due to the significant accumulation of total phenols and flavonoids, especially when stevia plants were treated with 50 mM NaCl. Similarly, the leaf concentration of ascorbic acid and glutathione remarkably increased. This provides new insight into the antioxidant defense strategy of S. rebaudiana under salt stress, demonstrating that stevia plants rely mainly on non-enzymatic mechanisms to counter oxidative stress. Although the highest salinity level (50 mM NaCl) resulted in the lowest content of steviol glycosides (stevioside + rebaudioside A), plants treated with 25 mM NaCl showed both the highest rebaudioside A content and Reb A/Stev ratio, which are desirable properties for the production of high-quality natural sweeteners. Overall, these findings underline that stevia can be considered a moderately salt-tolerant species, and mild stress conditions are able to promote the biosynthesis of interesting secondary metabolites, such as polyphenols and rebaudioside A. Full article

The Cutting Development Chamber (CDC) design is presented as an innovative solution to crucial human challenges, such as food and plant medicinal production. Unlike conventional propagation chambers, the CDC is a much more comprehensive research tool, specifically designed to optimize plant reproduction from cuttings. It maintains precise control over humidity, temperature, and lighting, which are essential parameters for plant development, thus maximizing the success rate, even in difficult-to-propagate species. Its modular design is one of its main strengths, allowing users to adapt the chamber to their specific needs, whether for research studies or for larger-scale propagation. The most distinctive feature of this chamber is its ability to collect detailed, labeled data, such as images of plant growth and environmental parameters that can be used in artificial intelligence tasks, which differentiate it from chambers that are solely used for propagation. A study that validated and calibrated the chamber design using cuttings of various species demonstrated its effectiveness through descriptive statistics, confirming that CDC is a powerful tool for research and optimization of plant growth. In validation experiments (Aloysia citrodora and Stevia rebaudiana), the system generated 6579 labeled images and 67,919 environmental records, providing a robust dataset that confirmed stable control of temperature and humidity while documenting cutting development. Full article