Stevia Glycosides Research Articles

The Influence of Sucrose on Biomass and Glycosides Content of Callus Cultured from the Leaves of Stevia rebaudiana Bertoni

Stevia rebaudiana Bertoni contains diterpenoid steviol glycosides that have no adverse impact on blood sugar levels despite being 300 times sweeter than sugar. This study aimed to investigate the rate of callus induction from stevia leaves and the content of glycosides when changing the sucrose percentage in the culture medium.. Murashige and Skoog (MS) culture medium supported by 4.0 mg/l naphthalene acetic acid (NAA) and 1.0 mg/l benzyl adenine (BA) was used, and different concentrations of sucrose (2, 3, 4, 5 and 6%) were tested .The extraction of glycosides from leaf and callus tissues was performed by using methanol. Extracted glycosides were analyzed by high-performance liquid chromatography (HPLC). The results showed significant influences of sucrose on callus initiation. The concentration of 3% sucrose had the highest fresh and dry weight. No callus was induced in the MS medium with a high concentration of sucrose (5% and 6%). However, the highest glycoside content, stevioside and rebaudioside were obtained from callus treated with 4% concentration followed by 3% sucrose the treatment . The highest fresh and dry weight average was obtained with a 3% concentration of sucrose, this treatment also increased the concentration of glycosides in the callus twice as much as in the leaves, and concentrations of 3% and 4% of sucrose gave very similar concentrations of glycosides in callus in terms of being double what was found in the leaves something which may aid in the development of a stevia glycosides based industry.

Immunomodulatory effects of Stevia rebaudiana leaves and commercial stevia on rats: a comparative study

Stevia is herbal native to South-America that is renowned for its natural sweet leaves containing stevia glycosides. Our study aimed at examining and comparing the immunomodulatory effects of the Stevia rebaudiana leaf extract and of commercially-available stevia products in rats. Our experiment involved the preparation of Stevia rebaudiana leaf extract and the use of market-available stevia obtained from the local-market. Stevia rebaudiana leaf extraction was meticulously performed, and 60 healthy adult male rats were randomly separated into three groups: untreated control, commercial stevia treatment (25 mg/kg), and Stevia rebaudiana leaf extract treatment (25 mg/kg). The rats were orally administered the treatments for 60 days, after which blood samples were collected for analysis. Our results revealed a significant rise in interleukin-1 beta (IL-1β) levels in rats treated with the Stevia rebaudiana leaf extract and the commercially-available stevia when compared to the control group. Additionally, immunoglobulin A (IgA) levels exhibited a notable increase in both stevia-treated groups, with the Stevia rebaudiana leaf extract-receiving group showing higher IgA levels than the commercially-available stevia-treated one. Our findings suggest that stevia may influence the immune response, particularly the regulation of the pro-inflammatory cytokine IL-1β and the IgA levels. This study contributes valuable insights into stevia’s effects on the immune system.

Covalent organic framework adsorption separation of the mother liquor sugars from industrial steviol: A combination of experimental and theoretical analysis

Mother liquor sugar (MLS) is considered a by-product of the industrial production of stevia glycosides. In this work, an efficient purification strategy for separating Steviol glycosides (SvGls) from MLS was developed. A β-ketenamine covalent organic framework (TPAQ-COFs) was prepared by a surfactant (sodium dodecyl sulfate (SDS)) assisted Schiff base reaction. The adsorption capacity for Rebaudioside A (RA), Rebaudioside D (RD), and Stevioside (ST) was studied. The research indicated that after adding SDS, the aggregation phenomenon of TPAQ-COFs was reduced, and the total adsorption of RA, RD, and ST increased by 338.94 mg/g. According to Langmuir model, the adsorption of RA, RD, and ST by TPAQ-COFs were 423.73, 253.16, and 381.68 mg/g, respectively. In addition, density functional theory and electrostatic potential elucidate the adsorption mechanism of SvGls on TPAQ-COFs. In TPAQ-COFs molecules β-ketenamine forms hydrogen bonds with SvGls, as well as abundant Π-Π interaction site is the main reason for its efficient adsorption of SvGls. After 9 cycles, the reuse rates of ST, RA, and RD in TPAQ-COFs were 96.26 %, 96.90 %, and 94.77 %, respectively, demonstrating high reusability and stability. This study lays the foundation for the practical application of a covalent organic framework in the separation and purification of MLS.

Sports foods are not all they shake up to be. An audit of formulated supplementary sports food products and packaging in Australian retail environments.

To determine store availability, total number of products, and types of Formulated Supplementary Sports Foods in Australia, along with their stated nutrition content, sweeteners added, total number, and type of claims displayed on the packaging. A cross-sectional, visual product audit of mainstream retailers. Supermarkets, pharmacies, health food stores, and gym/fitness centres. A total of 558 products were captured in the audit, 275 of which displayed the correct mandatory packaging attributes. Three categories of products were identified, based on the dominant nutrient. Only 184 products appeared to display the correct energy value based on the listed macronutrient content (protein, fat, carbohydrate, dietary fibre). The stated nutrient content was highly variable across all product subcategories. Nineteen different sweeteners were identified, with most foods containing only one (38.2%) or two (34.9%) types. The predominant sweetener was stevia glycosides. Packages displayed multiple claims, with a maximum of 67 and minimum of 2 claims. Nutrition content claims were most frequently displayed (on 98.5% of products). Claims included regulated, minimally regulated and marketing statements. Sports food consumers should be provided with accurate and detailed on pack nutrition information, to ensure informed choices are made. However, this audit showed multiple products which did not conform to current standards, appeared to provide inaccurate nutrition information, contained multiple sweeteners, and displayed an overwhelming number of on-pack claims. The increase in sales, availability, and products available in mainstream retail environments, could be impacting both intended consumers (athletes), and general non-athlete population. The results indicate underperformance in manufacturing practices which preference marketing over quality and stronger regulatory approaches are needed to protect consumer health and safety, and to prevent misleading consumers.

Screening UDP-Glycosyltransferases for Effectively Transforming Stevia Glycosides: Enzymatic Synthesis of Glucosylated Derivatives of Rubusoside.

Five plant-derived uridine diphosphate glycosyltransferases (UGTs) that catalyzed the glucosylation of stevia glycosides (SGs) were uncovered as the result of sequence mining considering the catalytic residues and conserved motifs of the known UGTs. Thereinto, LbUGT from Lycium barbarum with high activity toward rubusoside has been enzymatically characterized. The recombinant LbUGT was demonstrated to catalyze the β-1,6-glucosylation at C19 of rubusoside, producing a monoglucosyl derivative 13-[(O-β-d-glucopyranosyl) oxy] ent-kaur-16-en-19-oic acid-[(6-O-β-d-glucopyranosyl-β-d-glucopyranosyl) ester], which was then submitted to a β-1,2-glucosylation by LbUGT, resulting in a diglucosyl derivative 13-[(O-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]. The di-glycosylated product of rubusoside showed an obvious increase in sweetness intensity (134 times sweeter than 5% sucrose) and almost eliminated the unpleasant bitter taste. This work will provide a reference for the taste improvement of SGs.

Optimization of encapsulation of stevia glycosides through electrospraying and spray drying

Stevia rebaudiana represents a promising, natural sweetener. Stevia's sweet ingredients are called steviol glycosides and although they are absolutely safe for consumption, their bitter and metallic aftertaste acts as inhibitory agent for the widespread use of the sweetener. In this study, two encapsulation methods, spray drying and electrohydrodynamic method (electrospraying) were applied in Stevia in order to improve its quality and limit the unpleasant aftertaste of its glycosides. Maltodextrin-inulin (50:50) at concentrations of 5 and 10% for spray drying and zein at concentrations of 10 and 15% for electrospraying were used as matrices. Various operating parameters were examined during each method and their effect on the quality of the produced structures was evaluated so that the encapsulation process is optimised. HPLC showed that spray drying showed satisfactory encapsulation efficiency with a maximum value of 66.37%, while electrospraying achieved 67.47% as the best yield. SEM analysis of electrosprayed and spray dried products showed spherical particles with mean diameters of 1.35 μm and 6.02 μm, respectively. DSC analysis demonstrated that glass transition temperature ( T g ) of the encapsulated structures was lower than that of the pure matrices and was highly affected by the process conditions. The encapsulation of stevia by both techniques and the development of no chemical bonds between the matrices and stevia glycosides were confirmed in the ATR-FTIR spectra of the encapsulated particles. The success of stevia glycosides encapsulation by electrospraying and spray drying is a possible alternative to masking Stevia's bitter taste and finally to its introduction into innovative products. • The encapsulation of steviol glycosides into the polymer matrices is successful. • The operating parameters significantly affect the particle size and EE. • Spray drying using maltodextrin: inulin results in EE of 73.81%. • Electrospraying using zein achieves slightly higher EE equal to 75.87%. • The produced particles can be used as functional ingredient for food systems.

Effect of different sweeteners on the quality, fatty acid and volatile flavor compounds of braised pork.

This study aimed to assess how several sweeteners (white sugar, Siraitia grosvenorii fruit, mogrosides, and stevia glycoside) affected the flavor, fatty acid composition, and quality of braised pork. The findings indicated that braised meat prepared with sweeteners differed from typical braised pork. When simmered for 60 min, the typical braised pork with white granulated sugar exhibited a significant cooking loss (CL) and little water content. Significantly more than in the group containing Siraitia grosvenorii, mogroside, and stevia glycoside, the Thiobarbituric acid (TBARS) value increased by 14.39% (P < 0.05). The sample in the group that included mogroside had a low CL rate. After 40 min of stewing, the lean pork has the highest L* value, but the 60-min stew sample is nicely colored and stretchy. Mogroside can prevent protein, and lipid oxidation, is thermally stable and reduces CL during stewing. Additionally, Siraitia grosvenorii and stevia glycosides help prevent oxidation from intensifying during stewing. When Siraitia grosvenorii is added, lipid oxidation is significantly inhibited, and stevia glycosides are more beneficial for enhancing meat color. With an increase in heating time, the fatty acids in braised pork reduced; the unsaturated fatty acid (UFA) of the Siraitia grosvenorii fruit (SF) and mg group also fell somewhat, and the UFA: SFA ratio was higher than that of the white sugar (WS) group. The SFA content of the braised meat in the stevia glycoside group was higher than that of the WS group. In all, 75 volatile flavor elements in braised pork were discovered by Gas chromatography-ion mobility spectrometry (GC-IMS). The sweetener increased alcohols, esters, and acids in the braised pork. As stewing time increased, ketones decreased, but aldehydes and esters increased. The pork formed antioxidant peptides with great nutritional value after cooking. Braised pork with mogroside and stevia glycoside additions primarily have some protein color protection and antioxidant effects. This study may offer fresh perspectives on applying natural sweeteners and enhancing braised pork’s flavor.

A UV/Vis spectrophotometric methodology for quality control of stevia-based extracts in the food industry

This study established a methodology for quality control of stevia extracts in food industry where one, or a mixture of major stevia glycosides, rebausioside A and stevioside, are present. The methodology relies on pre-treatment to eliminate glucose that may be already present, prior to acid hydrolysis of stevia glycosides toward isosteviol plus glucose and ensuing released glucose quantification using the glucose oxidase/peroxidase coupled assay. Subsequent isosteviol isolation and concentration assessment using UV spectroscopy, permits the quantification of an average number of glucose molecules released per a generated molecule of isosteviol. The latter increases the assay specificity, allowing confirmatory assessment of stevia glycoside identity and purity. Favorable technical characteristics, satisfying international specifications for method validation, were determined for each individual assay (glycoside quantification by acid hydrolysis and isosteviol quantification) for rebaudioside A and stevioside: Standard curves were linear (R2 ≥ 0.993 [R2 ≥ 0.984 for the glucose/isosteviol quantification assay]) over a concentration range from approximately 10−1 mg/mL for the acid assay and 3.0 mg/mL for the glucose/isosteviol assay up to at least 10 mg/mL glycoside. The CV% on all quality control levels was ≤6.33% for repeatability and ≤12.03% for intermediate precision. Bias was ≤±5.00% in all cases. Upon comparison with the gold standard LC/UV method for rebA quantification, we demonstrated a very good agreement and acceptable bias (slope: 1.02, y-intercept: −0.73, R2: 0.994). Acid hydrolysis was tested successfully on commercial products, stevia extracts and commodity sweeteners, containing either of the two major glycosides. We demonstrated that the proposed methodology was able to distinguish between commercial samples containing pure rebaudioside A or stevioside alone and samples containing additional steviol glycosides in combination. When verifying glycoside content in binary mixtures of rebaudioside A and stevioside, bias was sufficiently low (<10%). The proposed methodology requires minimal equipment and expertise and is applicable to a significant percentage (approximately 50%) of all commercial stevia extracts and sweeteners. Our findings should provide a useful tool for stevia quality control, thus allowing an increase in the frequency and extent of testing, even in minimally equipped settings, while containing cost.

Effect of defatted soy and peanut flour obtained by new aqueous method on quality of gluten‐free cookies

Gluten-free cookies (GFCs) are promoted for avoiding gluten-related celiac disease. Requirement of protein/lysine enhancement in rice GFCs encouraged this study. Partly substituting rice flour by defatted peanut (DPF) or soy (DSF) and their mixture (1+1) significantly increased protein/lysine content in GFCs. DSF had the most effect of increasing lysine content. Adding DPF or DSF and their mixture significantly improved GFCs hardness and hedonic score. The hedonic score of overall acceptability, taste, crispiness, texture/grain, flavor, and appearance/color of all cookies studied were within very-like scale. Adding DPF or DSF or their mixture produced GFCs with deeper/darker color while DSF had the greatest effect. DPF or DSF or their mixture had dosage-dependent effect of increasing GFCs antioxidant capacity while DSF had the greatest effect. DPF, DSF or DPSFM was also good ingredient to make gluten-free and sugar-free cookies sweetened by meso-erythritol blended with stevia glycosides.

Ultrasound-assisted Extraction Process of Glycosides from Stevia Rebaudiana Bertoni Leaves

Stevia Rebaudiana Bertoni leaves contain glycosides that have a sweetening power of 100 to 300 times greater than sucrose. These glycosides are increasingly used as natural sweetener, mainly to replace aspartame, in order to reduce daily caloric intake. The two major glycosides are Stevioside and Rebaudioside A, which represent about 90 % [w/w] of total Steviol. The Rebaudioside A is the most interesting since it has the advantage of not having a bitter aftertaste, unlike stevioside. In recent years, the cultivation of organic stevia is growing in the Occitanie region in France. Thus, the valorization of this production chain is of economic interest for this region. It’s known that conventional extractions to obtain these glycosides are time consuming and the extensive use of organic solvents may be harmful for human health and environment. Thus, the objective of this work was to develop a green extraction process suitable for industrial purposes, using water as solvent and ultrasound technique to obtain high yield of glycosides in the Stevia extract. The extractions are carried out in batch with recirculation and continuous assemblies at 45 °C. The effects of ultrasound power (at 20kHz), experience time/ residence time, and leaves concentration are studied. The soluble solids and stevia glycosides concentration are analyzed respectively by °Bx and HPLC. With the continuous assembly the experiments were carried out at 64 W and 144 W, which represents 50 % and 100 %, respectively, of the generator capacity. A low flowrate (or high residence time) is detrimental to the use of ultrasound, leaves sedimentation and their accumulation prevents probably the ultrasound diffusion in the medium, harming the steviol extraction. The extraction ultrasound-assisted allowed to increase in 9-10 % °Bx concentration for batch and continuous assembly, compared to extraction without ultrasound under the same conditions. Soluble species other than steviols are extracted with ultrasound. The HPLC results showed that the ultrasound favored lightly the extraction of stevioside.Key-words: continuous extraction, green extraction, sweeteners.

STEVIA (STEVIA REBAUDIANA BERTONI): BIOCHEMICAL COMPOSITION, THERAPEUTIC PROPERTIES AND USE IN THE FOOD INDUSTRY (REVIEW)

The review presents the current state of the science for stevia (Stevia rebaudiana Bertony), its biochemical composition, therapeutic properties and using in the food industry. Interest in this plant, a source of natural low-calorie sweeteners, is associated with increased consumption of dietary sweeteners, caused by an increase in the number of patients with diabetes, metabolic syndrome, and with many negative effects from the use of synthetic sweeteners. Diterpene glycosides from stevia have a high sweetness (50-350 times sweeter than sucrose), low calorie content, safe for human health. In addition to them, a number of biologically valuable compounds (mineral elements, vitamins, proteins, amino acids, oligosugars, fiber, polyphenols) were found in the leaves of stevia. High antioxidant properties of stevia leaf extracts has been shown, which allows them to be used in the food industry in the production of functional products. Numerous data have been obtained on the various therapeutic properties of stevia. It has been revealed that regular use of stevia glycosides reduces blood glucose and cholesterol levels, promotes cell regeneration, inhibits the growth of tumor cells and strengthens blood vessels. Components from stevia leaves have a choleretic, diuretic effect, normalize blood pressure, prevent diseases of the gastrointestinal tract, and have a beneficial effect on kidney function. Stevia extracts also have antibacterial, antiviral, anti-inflammatory and immunomodulatory effects. The safety and stability of stevia sweet glycosides in an acidic environment and at high temperatures allows them to be widely used in the production of products such as diet drinks, teas, sauces, marinades, seafood, ice cream, yogurts, pastries, culinary products and sweets.

Molecular insight on the binding of stevia glycosides to bovine serum albumin

The interaction of the steviol and its glycosides (SG), steviolbioside, and rebaudioside A, with bovine serum albumin (BSA) was studied by absorption and fluorescence spectroscopy techniques alongside molecular docking. The stevia derivatives quenched the fluorescence of BSA by a dynamic quenching mechanism, indicating the interaction between the stevia derivatives and BSA. The binding constant (Kb) of steviol was 100-1000-fold higher than those of SG. The stevia derivative/BSA binding reaction was spontaneous and involved the formation of hydrogen bonds and van der Waals interactions between steviol and steviolbioside with BSA, and water reorganization around the rebaudioside A/BSA complex. Molecular docking pointed out the FA1 and FA9 binding sites of BSA as the probable binding sites of steviol and SG, respectively. In conclusion, steviol enhanced hydrophobicity and small size compared to SG may favor its binding to BSA. As steviol and its glycosides share binding sites on BSA with free fatty acids and drugs, they may be competitively displaced from plasma albumin under various physiological states or disease conditions. These findings are clinically relevant and provide an insight into the pharmacokinetics and pharmacodynamics of the stevia glycosides.

Potential medicinal effects and applications of stevia constituents

The application of stevia glycosides in the food industry has grown steadily in the last two decades. Besides the use of its constituents as natural sweeteners, increasing attention has been given to their potential health benefits and therapeutic applications. Whereas in some cases clinical studies have been realized (prominently, to investigate its hypoglycemic and antihypertensive activity) many of them have failed to cover the expectations from preclinical investigations. Here, we review current knowledge on stevia constituents’ pharmacokinetics (both in rodents and in humans) and some of the most profusely investigated potential medical/health-related applications: i.e. diabetes and metabolic syndrome, hypertension, antimicrobial and anticancer activity. The outcome of available clinical studies and the perspectives of Stevia therapeutic uses are discussed in connection with pharmacokinetics knowledge.

Phytochemical and Pharmacological Importance of Stevia: A Calorie-Free Natural Sweetener

Stevia, a natural sweetener, comprises of 200 species of herbs and shrubs from the family Asteraceae (Composite). The most common species of this genus and family with sweetening potential are Stevia dianthoidea, S. phlebophylla, S. anisostemma, S. bertholdii, S. crenata, S. enigmatica, S. eupatoria, S. lemmonii, S. micrantha, S. plummerae, S. rebaudiana, S. salicifolia, S. serrata and S. viscida but among these only S. rebaudiana exhibits the highest level of sweetness. It is cultivated in China, Taiwan, Thailand, Korea, Brazil, Malaysia, Canada, Hawaii and California. Rajasthan, Maharashtra, Kerala and Haryana are the main Stevia growing states in India. Stevia contains ent-kaurene, a diterpene glycoside commonly known as stevioside which is 150–300 times than more sweeter sugar. In addition to its interesting sweetening property, Stevia plant shows many pharmacological properties. Its leaves also contains good amount of protein, amino acid, lipids, vitamins and minerals. Phytochemical screening showed that tannins are also present in higher concentrations followed by alkaloids, glycosides, saponins, sterols, and triterpenes, anthraquinones, and other reducing compounds. Stevia glycosides possess many pharmaceutical properties viz; anti-hyperglycemic, antihypertensive, antioxidant, antimicrobial activity, anticancer effect, anti-inflammatory and immune-modulatory effect etc. Stevia has potential qualities of a sweetener and also constituting a source of many substances with a nutritional effect on the human beings. Among different chemical constituents, stevioside has a potential mode of actions in controlling type 2 diabetes. Stevia-enriched food products bring several benefits to human society. Commercial marketing of products stevia in different form such as leaf powder, liquid and fresh leaves has become a potential adventure for many biotechnological companies because of its large demand.

STEVIA PLANT - ALTERNATIVE SWEETNER IN FOOD TECHNOLOGY

Food and Agricultural Organization as a “sweeteners” consider products used for sweetening derived from sugar crops, cereals, fruits or milk, or that are produced by insects. Sweeteners, as an additive, have important role for technological functions of food, especially in providing texture, bulk and color, and also as preservative agents. Regardless the numerous sweeteners, alternative sweeteners to sucrose are in main focus for implementation in food industry. Nowadays Food and Agricultural Organization and World Health Organization Food standards, Codex Alimentarius Commission (2018) accepted list of 27 food additives that have the functional class “sweetener”. Nowadays, alternative sweeteners and their application in food technology are in main focus of scientist. Stevia plant stands for one of the most important natural intense sweetener, since stevia glycosides are almost 400 times sweeter than sucrose. Extracts of stevia represents a powerful tool for reducing sugars in food and beverages, which can be acceptable substitutes to full sugar versions of this products. Regarding the data of Euromonitor international, new food products containing stevia grew 10% from 2016 to 2017. The biggest increment in stevia use was noticed in categories of snacks, juice drinks, dairy, carbonated soft drinks and confectionery. Barriocanal et al. (2008) highlighted that safety studies reported no negative side effects of stevia use. Can be expected that in recent future use of S. rebaudiana as sweetener would be extended to almost all the world’s countries, regarding all discovered beneficial health effects.

Elicitation of Stevia Glycosides Using Salicylic Acid and Silver Nanoparticles Under Callus Culture

Development of biosynthesis of phytochemicals, especially medicinal products, is highly important due to their broad bioactivity properties. In this study, optimization of callus growth was initially carried out using various combinations of plant growth regulators. Callus with the highest fresh weight was produced on Murashige and Skoog (MS) medium containing 1 (mg/l) naphthalene acetic acid + 0.5 (mg/l) benzyl aminopurine. The effect of different concentrations of salicylic acid (SA) (0.25, 0.5 and 0.75 mg/l) and silver nanoparticles (Ag NPs) (15, 30, 45 and 60 mg/l) on callus growth as well as the possibility of stevia glycosides (SGs) production in callus culture was subsequently evaluated. The SA elicitation, at a concentration of 0.75 (mg/l), resulted in the highest level of callus growth rate (0.1 cm/day), callus diameter (0.79 cm) and relative callus fresh weight (0.085). Likewise, 45 (mg/l) of Ag NPs led to the highest amount of stevioside (32.34 mg/g dry weight callus). The addition of 0.25 (mg/l) of SA to the MS medium led to production of the highest amount of rebaudioside A (3.40 mg/g dry weight callus). The results of this study may enhance the commercial application of important glycosides prevalent in Stevia by highlighting that the nano-elicitors and SA should be utilized at optimized concentrations.

Evaluation of the risk of fungal spoilage when substituting sucrose with commercial purified Stevia glycosides in sweetened bakery products

The objectives of this study were to compare the effect of different Stevia-based sugar substitutes (S1–S3), sucrose alone and a mixture of sucrose+S1 on: (a) humectant properties, (b) relative colonisation rates of sponge cake slices at 0.90 aw by strains of Aspergillus flavus, Eurotium amstelodami, Fusarium graminearum and Penicillium verrucosum at 20 and 25°C and (c) shelf-life periods in days prior to visible growth. Results showed that sucrose, S1 commercial sugar substitute and the mixture of sucrose+S1 in water solutions were able to reach water activity levels similar to those of glycerol and glucose mixtures. The S2 and S3 commercial sugar substitutes were unable to reduce aw levels significantly. At 25°C, colonisation of sponge cake slices by E. amstelodami, A. flavus and P. verrucosum occurred in all the treatments. Growth of F. graminearum only occurred on sponge cake slices containing S2 and S3 Stevia-based products at both temperatures. The best control of growth (30days) was achieved in cake slices modified with sucrose or S1 Stevia treatments inoculated with A. flavus and in the sucrose treatment for E. amstelodami at 20°C. F. graminearum growth was completely inhibited when sucrose alone, S1 or sucrose+S1 treatments were used at both temperatures. This study suggests that, as part of a hurdle technology approach, replacing sucrose with low calorie sugar substitutes based on Stevia glycosides needs to be done with care. This is because different products may have variable humectant properties and bulking agents which may shorten the potential shelf-life of intermediate moisture bakery products.

Stevia Glycosides: Chemical and Enzymatic Modifications of Their Carbohydrate Moieties to Improve the Sweet-Tasting Quality.

Stevia glycosides, extracted from the leaves of the plant Stevia rebaudiana Bertoni, display an amazing high degree of sweetness. As processed plant products, they are considered as excellent bio-alternatives for sucrose and artificial sweeteners. Being noncaloric and having beneficial properties for human health, they are the subject of an increasing number of studies for applications in food and pharmacy. However, one of the main obstacles for the successful commercialization of Stevia sweeteners, especially in food, is their slight bitter aftertaste and astringency. These undesirable properties may be reduced or eliminated by modifying the carbohydrate moieties of the steviol glycosides. A promising procedure is to subject steviol glycosides to enzymatic glycosylation, thereby introducing additional monosaccharide residues into the molecules. Depending on the number and positions of the monosaccharide units, the taste quality and sweetness potency of the compounds will vary. Many studies have been performed already, and this review summarizes the structures of native steviol glycosides and the recent data of modifications of the carbohydrate moieties that have been published to provide an overview of the current progress.

The influence of stevia glycosides on the growth of Lactobacillus reuteri strains

Use of stevia-derived sweeteners was recently officially approved by the European Commission, and their application in the food industry has increased, especially in functional foods. However, there are scarce data about the influence of stevia on probiotic bacteria, which are important both as an inhabitant of the human gut and as a functional food additive. Taking into consideration the broad application of Lactobacillus reuteri in functional foods, the aim of the research was to evaluate the influence of stevia glycosides on its growth. Six Lact.reuteri strains were tested for their ability to grow in the presence of stevioside and rebaudioside A (0·2-2·6gl(-1) ). The effect of stevia glycosides on biomass concentration, cell count, pH and lactic and acetic acid synthesis was analysed. Both glycosides impaired the growth of analysed strains. However, the inhibitory effect was strain specific, and the concentration-dependent effect was not observed for all parameters. The most pronounced concentration-dependent effect was on lactic and acetic acid production. Taking into account the observed strain-specific inhibitory effect of stevia glycosides, it could be suggested to evaluate the influence of them on each strain employed before their simultaneous application in functional foods. The study showed that the growth of Lactobacillus reuteri strains was inhibited in the presence of stevia sweeteners stevioside and rebaudioside A. Probiotics, for example Lact.reuteri strains, are often used as functional additives in health foods and are an important natural inhabitant of the human gastrointestinal tract. Stevia glycosides application in food is increasing; yet, there are no data about the influence of stevia glycosides on Lact.reuteri growth and very few data on growth of other lactobacilli, either in probiotic foods or in the gastrointestinal tract. This research shows that it is necessary to evaluate the influence of stevia glycosides on other groups of micro-organisms in further research.

Large-scale profiling of diterpenoid glycosides from Stevia rebaudiana using ultrahigh performance liquid chromatography/tandem mass spectrometry

The plant Stevia rebaudiana accumulates a suite of diterpenoid metabolites that are natural sweeteners finding increased use as sugar substitutes. To guide breeding of stevia plants that accumulate substances with desirable flavor in high yield, rapid and accurate methods are needed to profile these substances in plant populations. This report describes an 8-min ultrahigh performance liquid chromatography-tandem mass spectrometry method for separation and quantification of seven stevia glycosides including steviolbioside; stevioside; rebaudiosides A, B, and C; rubusoside; and dulcoside as well as aglycones steviol and isosteviol. This negative mode electrospray ionization/multiple reaction monitoring method yielded low limits of detection <1 ng/mL for steviol, 6 ng/mL for isosteviol, and <15 ng/mL for all stevia glycosides. Stevioside and Reb A, B, and C were quantified in more than 1,100 extracts from stevia leaves as part of a large-scale profiling exercise. Leaf tissue levels in this population spanned about two orders of magnitude for stevioside (2-125 mg/g dry weight), Reb A (2.5-164 mg/g), Reb B (0.5-50 mg/g), and Reb C (1.5-125 mg/g), but levels of individual metabolites exhibited independent variation. The wide spread of metabolite levels highlights the utility and importance of performing targeted metabolic profiling for large plant populations.