Academic literature on the topic 'Steviosideo'

The knowledge of water requirement of crops in the different growing phases elicits higher crop yield and rational use of water resource. The aim of this work was to estimate the water consumption of stevia using two constant watertable microlysimeters. The research was conducted in San Piero a Grado, Pisa, Italy. The data were collected daily from June, 1st, to October, 22th, 2000. Reference evapotranspiration was determined by the Penman-Monteith-FAO method, in the same period. Microlysimeters watertables level were maintained at the 35 cm depth. Crop evapotranspiration for the total cicle (80 days) was 464 mm. For the most water consuming phase, crop average evapotranspiration was 5.44 mm day-1. The crop coefficient values were 1.45 for the first 25 days, 1.14 for the next period (26 to 50 days), and 1.16 for the latest period (51 to 80 days). The stevia leaf yield of the microlysimeters was 4.369 kg ha-1 and their steviosideo content 6.49%.

Macroporous resin was the most common method for the separation and purification of steviosides. But the purity was only 90% influenced by less selectivity of the resin. And Rebaudioside A could not be separated from other steviosides at the same time. Purity of total glycosides could be up to 99% and Rebaudioside A could be enriched efficiently by section desorption after one-dimensional chromatography of macroprous resins. The content of Rebaudioside A increased from 39.46% to 63.70% gradually in each desorption solution of the 4 resin columns. Moreover, the resolution between Rebaudioside A, Rebaudioside C and stevioside, and the number of theoretical plates for them were detected meanwhile. These results could provide theoretical foundation for the separation of high purity steviosides and enrichment of Rebaudioside A.

It was established analytical parameters for steviosides standard, besides the obtainment and purification of theses paramters. The metodology for quantitative determination was proposed for the stevioside analysis in spectrofotometry U.V. The quantitative analysis by spectrofotometry was in 208nm, in ethilic alcool. The curve of calibration presented good relative precision, with analytical error 1.5%. The parameters established in caracterization of standars was: m.p: 197-200 ºC; Rf around of 0.58; maximum absorption in 208nm and molar absortivity higher 4000 in 208nm.

The objective of this study was to evaluate the effects of dietary inclusion of tevioside on feed intake, feeding behavior, nutrient digestion, rumen fermentation, and serum biochemical parameters in goats. Nine male Xiangdong black goats (21.8 ± 1.5 kg of body weight) were used in a replicated 3 × 3 Latin square. All goats were fed a basal diet including concentrate and forage (chopped rice traw). The three treatments were 0, 400, or 800 mg stevioside per kg chopped rice traw on a dry matter (DM) basis. Dry matter intake of forage and total diet linearly increased (p = 0.03 and p = 0.04) with increasing stevioside in the diet. There was no effect (p > 0.05) of stevioside inclusion in the diets on eating time, rumination time, or total mastication time for the goats. Total volatile fatty acid (VFA) concentration in the rumen responded quadratically (p < 0.01), decreasing from 0 to 400 mg/kg stevioside inclusion and increasing thereafter. The inclusion of steviosid in the diets promoted a quadratic increase in the apparent total tract digestibilities of neutral detergent fiber (NDF) (p = 0.02) and acid detergent fiber (ADF) (p = 0.01). Based on the results of this experiment, it could be concluded that supplementing goat diets with stevioside at 400 mg/kg to 800 mg/kg forage (about 270 to 541 mg/kg diet) resulted in increased dry intake of forage and total diet, suggesting that stevioside has positive potential as a feed additive to improve feed intake.

Summary Introduction: Steviol stevioside, which has been used in the production of food products as a low-calorie sweeten, is one of the main glycoside groups in the leaves of the Stevia plants. It is useful for human health. Objective: The main objection of the present study was to find out some major chemical compositions of the dried Stevia rebaudiana Bertoni leaves and an effective, affordable, and environmentally friendly method to reach the high extraction yield of total steviosides from them. Therefore, a novel extraction, ultrasound-assisted extraction (UAE), was carried out to extract total steviosides from dried leaves of S. rebaudiana plant with ethanol of 70% (v/v) as a solvent. Methods: Some major chemical compositions of the dried S. rebaudiana leaves were analyzed according to the AOAC (Association of Official Analytical Chemists) and total steviosides content (TSC) was measured by anthrone-sulphuric acid colorimetric assay with main influencing factors including material/solvent ratio, extraction temperature, and extraction time. Results: The results referred that some chemical compounds such as protein, lipid, fibre, sugar, etc. existed in this material. The best extraction conditions were the sample/solvent ratio of 1:100 (g/ml), extraction temperature of 75oC, and extraction time of 30 min. Conclusion: The highest amount of total steviosides content of 8.894 % was obtained at the optimal extraction condition. Consequently, these results demonstrated that the parameters of UAE were applied successfully for producing total glycosides.

Stevioside, a diterpenoid glycoside, is widely used as a natural sweetener; meanwhile, it has been proven to possess various pharmacological properties as well. However, until now there were no comprehensive evaluations focused on the anti-inflammatory activity of stevioside. Thus, the anti-inflammatory activities of stevioside, both in macrophages (RAW 264.7 cells, THP-1 cells, and mouse peritoneal macrophages) and in mice, were extensively investigated for the potential application of stevioside as a novel anti-inflammatory agent. The results showed that stevioside was capable of down-regulating lipopolysaccharide (LPS)-induced expression and production of pro-inflammatory cytokines and mediators in macrophages from different sources, such as IL-6, TNF-α, IL-1β, iNOS/NO, COX2, and HMGB1, whereas it up-regulated the anti-inflammatory cytokines IL-10 and TGF-β1. Further investigation showed that stevioside could activate the AMPK -mediated inhibition of IRF5 and NF-κB pathways. Similarly, in mice with LPS-induced lethal shock, stevioside inhibited release of pro-inflammatory factors, enhanced production of IL-10, and increased the survival rate of mice. More importantly, stevioside was also shown to activate AMPK in the periphery blood mononuclear cells of mice. Together, these results indicated that stevioside could significantly attenuate LPS-induced inflammatory responses both in vitro and in vivo through regulating several signaling pathways. These findings further strengthened the evidence that stevioside may be developed into a therapeutic agent against inflammatory diseases.

Stevioside, a non-caloric sweetening agent, is used as a sugar substitute. An influence of stevioside on renal function has been suggested, but little is known about its effect on tubular function. Therefore, the present study was designed to explore the direct effect of stevioside on transepithelial transport of p-aminohippurate (PAH) in isolated S2 segments of rabbit proximal renal tubules using in vitro microperfusion. Addition of stevioside at a concentration of 0.45 mM to either the tubular lumen, bathing medium, or both at the same time had no effect on transepithelial transport of PAH. Similarly, a concentration of 0.70 mM (maximum solubility in the buffer) when present in the lumen, had no effect on PAH transport. However, this concentration in the bathing medium inhibited PAH transport significantly by about 25-35%. The inhibitory effect of stevioside was gradually abolished after it was removed from the bath. Addition of 0.70 mM stevioside to both lumen and bathing medium at the same time produced no added inhibitory effect. Stevioside at this concentration has no effect on Na+/K+-ATPase activity as well as cell ATP content. These findings suggest that stevioside, at a pharmacological concentration of 0.70 mM, inhibits transepithelial transport of PAH by interfering with the basolateral entry step, the rate-limiting step for transepithelial transport. The lack of effect of stevioside on transepithelial transport of PAH on the luminal side and its reversible inhibitory effect on the basolateral side indicate that stevioside does not permanently change PAH transport and should not harm renal tubular function at normal human intake levels.Key words: stevioside, p-aminohippurate, renal proximal tubule.

Stevioside is very potential to be an antidiabetic pro-drug. In processing, the active ingredient may be degraded. This research conducted a study of the degradation of stevioside on several stress factors such as acid and base hydrolysis; exposure to UV rays, thermal heating and oxidation using RP-HPLC. The degradation products were identified using ESI-MS/MS. Hydrolysis of acid-base solution and exposure to UV254 nm rays caused the breakdown of glycoside bonds in the analyte. Stevioside was unstable in dry heating at 105oC for 48 hours due to degradation of 91%. Stevioside was oxidized under H2O2 oxidation for 48 hours. Based on the ESI-MS/MS analysis, the identified stevioside degradation products were [M-H] ̶ with m/z = 803 as stevioside; [M-H] ̶ with the value of m/z = 641 as steviolbioside; [M-H] ̶ with m/z = 479 as steviolmonoside; [M-H] ̶ with m/z = 317 as steviol. Termination of glucose was characterized by fragmentation [M-162] ̶.Our study provides a basic view on the stability and degradation characteristics of stevioside, and demonstrates the formation of degradation products.

Stevioside is a natural sweetener from Stevia leaf, which is 300 times sweeter than sugar. It helps to reduce blood sugar levels dramatically and thus can be of benefit to diabetic people. Tissue culture is a very potential modern technology that can be used in large-scale disease-free stevia production throughout the year. We successfully produced stevia plant through in vitro culture for identification of stevioside in this experiment. The present study describes a potential method for identification of stevioside from tissue culture-derived stevia leaf. Stevioside in the sample was identified using HPLC by measuring the retention time. The percentage of stevioside content in the leaf samples was found to be 9.6%. This identification method can be used for commercial production and industrialization of stevia through in vitro culture across the world.

Made available in DSpace on 2014-10-09T12:37:34Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:03:32Z (GMT). No. of bitstreams: 1 05177.pdf: 1071515 bytes, checksum: 549d323670762fe6597fcda6cf7ea4fc (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientador: Helena Maria Andre Bolini
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-12T13:31:07Z (GMT). No. of bitstreams: 1 Melo_LauroLuisMartinsMedeirosde_D.pdf: 959944 bytes, checksum: ee44eced3d2acbc8900f5441b96782b5 (MD5) Previous issue date: 2008
Resumo: Atualmente, há um interesse crescente de consumidores do mundo todo por alimentos e bebidas com menores quantidades de calorias. Neste contexto, a Análise Sensorial é a única forma de se determinar a aceitação e o perfil em relação à aparência, aroma, sabor e textura de alimentos e bebidas, sendo, portanto, uma ferramenta insubstituível. Com base nestes fundamentos, o objetivo do presente projeto foi realizar a determinação de doçura ideal, doçura equivalente de diferentes edulcorantes, análise descritiva quantitativa (ADQ) e análise de aceitação (com mapas de prerência interno, extendido e análise de regressão de mínimos quadrados parciais, Partial Least Squares - PLS) de chocolates adoçados com diferentes edulcorantes (estévia e sucralose) e sacarose (convencional), e com substituto de gordura (concentrado de soro de leite, WPC), comparando seus comportamentos sensoriais, para a obtenção de uma formulação de alta qualidade sensorial. Também foi incluída ao estudo uma amotra diet (em sacarose) comercial. A ADQ e a análise de aceitação foram conduzidas ao longo da estocagem dos chocolates a 20 °C em 0, 3, 6 e 9 meses. A análise de aceitação foi conduzida tanto com consumidores não-diabéticos quanto com diabéticos. Também foram realizadas análises no NCSU Sensory Service Center da North Carolina State University nos Estados Unidos, incluindo análise descritiva, aceitação e conjoint analysis. Foi possível produzir chocolates ao leite diet (em sacarose) e diet (em sacarose)/light (em calorias) com sucralose e estévia como substitutos da sacarose e WPC como substituto parcial de gordura com curvas tempointensidade do gosto doce similares à curva tempo-intensidade do chocolate ao leite convencional de melhor aceitação dentre os testados (43% de sacarose). Houve poucas alterações nos chocolates desenvolvidos em relação ao chocolate convencional. A amostra de chocolate ao leite convencional adoçada com sacarose caracteriza-se mais pelos atributos aroma doce e doçura. As amostras adoçadas com sucralose e sucralose/WPC são caracterizadas, principalmente, pelo atributo sabor de leite em pó (aumentado pelos agentes de corpo lactitol/polidextrose e pelo substituto de gordura WPC). As amostras com estévia se caracterizam pelos atributos amargor e residual amargo. A amostra comercial foi caracterizada por aroma de manteiga de cacau e derretimento na boca. A maioria dos atributos sensoriais das amostras não foi significativamente alterada até o término do estudo aos 9 meses. A comparação das equipes de provadores do Brasil e dos Estados Unidos mostrou que equipes de provadores altamente treinadas usando terminologia padronizada e representativa podem fornecer resultados similares. As amostras convencional e comercial apresentaram as maiores aceitações entre consumidores não-diabéticos. As alterações observadas nos perfis sensoriais não foram suficientes para provocar mudança na aceitação das amostras durante o período de estocagem, o que garante uma vida-de-prateleira efetiva de pelo menos 9 meses. Análise de cluster dividiu os consumidores em dois grupos. As médias de aceitação das amostras convencional e comercial para o grupo 2 foram significativamente maiores. Para o grupo 1, não houve diferença entre as médias de aceitação das amostras convencional, sucralose e sucralose/WPC. As amostras produzidas com sucralose são tão bem aceitas quanto à amostra comercial entre consumidores diabéticos. Todos os chocolates desenvolvidos (diet em sacarose e diet em sacarose/light em calorias, com sucralose ou estévia) apresentaram médias de aceitação estatisticamente maiores entre diabéticos do que entre não-diabéticos. Os consumidores se dividiram principalmente para a amostra convencional e para a amostra comercial. A doçura foi o atributo mais importante para o primeiro grupo enquanto os atributos derretimento na boca e aroma de manteiga de cacau foram mais importantes para o segundo grupo. Estas tendências se mantiveram até o fim do estudo de tempo de estocagem aos 9 meses. Para consumidores dos Estados Unidos, o atributo declaração sobre açúcar é mais importante para diabéticos do que para não-diabéticos enquanto que o tipo de edulcorante e a redução calórica têm a mesma importância para ambos os grupos. Teoricamente, um chocolate com declaração ¿livre de açúcar¿, edulcorante natural e 25% de redução calórica seria a melhor combinação. Os consumidores dos Estados Unidos foram divididos em três grupos, sendo que o grupo 1 se assemelha mais aos diabéticos em geral, e os grupos 2 e 3, aos nãodiabéticos. A principal diferença entre os grupos 2 e 3 está no fato de o grupo 2 ser mais atento ao consumo de calorias. Nos Estados Unidos, convencional, sucralose e sucralose/WPC foram as amostras com melhor aceitação entre não-diabéticos e sucralose, sucralose/WPC e comercial, entre diabéticos, não confirmando o resultado teórico da conjoint analysis. Os consumidores diabéticos são mais receptivos a chocolates ao leite diet (em sacarose) e diet (em sacarose)/light (em calorias) do que consumidores não-diabéticos
Abstract: Nowadays, there is an increasing interest in foods and beverages with smaller amounts of calories. Then, Sensory Evaluation is the most important tool for evaluation of acceptance and sensory characteristics regarding appearance, aroma, flavor and texture of foods. Therefore, objective of the current study was determination of the most accepted sweetness, equi sweet concentration for different sweeteners, quantitative descriptive analysis (QDA) and acceptance testing (using internal and extended preference mappings and PLS regression) of chocolates sweetened with differente sweeteners (steviosídeo and sucralose) and sucrose (conventional), and with whey protein concentrate (WPC) as fat replacer, comparing their sensory characteristics, in order to get a high sensory quality recipe. This research also included a commercial sugra-free sample. QDA and acceptance testing were performed during storage time at 20 °C after 0, 3, 6 and 9 months. Acceptance testing was performed with both non-diabetic and diabetic consumers. In addition, some analyses were carried out at NCSU Sensory Service Center at North Carolina State University, in the USA, including descriptive analysis, acceptance testing, and conjoint analysis. Lab developed prototypes sugar-free and reduced calorie milk chocolates with sucralose or stevioside and WPC as fat replacer presented time-intensity curves similar to most accepted chocolate with sucrose (43%). There were few changes comparing lab developed prototypes to convencional chocolate. Sweet aroma and sweetness were the most important attributes for conventional milk chocolate sweetened with sucrose while milky flavor (increased by bulking agents lactitol/polydextrose and by fat replacer WPC) was the most important attribute for samples sweetened with sucralose and sucralose/WPC. Bitterness and bitter aftertaste were the most important attributes for samples sweetened with stevioside. Regarding commercial sample, cocoa butter aroma and melting rate were the most important attributes. There were not significant changes in most of sensory attributes during 9-month storage time. Comparisons with Brazilian and USA panels showed that highly trained panels using standardized, representative languages can provide comparable results. Conventional and commercial chocolates presented higher acceptance means for non-diabetic consumers. Effects of aging on some sensory characteristics of chocolates were not enough to change consumer acceptance over time, which assures a realistic shelf life for at least 9 months. Cluster analysis presented two groups. Conventional and commercial chocolates presented higher acceptance means for group 2. For group 1, there was no difference between acceptance means for conventional, sucralose, and sucralose/WPC. Diabetic consumers accept samples produced with sucralose so well as they accept commercial sample. All lab developed prototypes presented higher acceptance means among diabetics compared to non-diabetics. Consumers presented preferences especially for conventional sample or for commercial sample. Sweetness was the most important attribute for the first group while melting rate and cocoa butter aroma were the most important attributes for the second group. These results lasted until the end of storage time (9 months). For USA consumers, sugar claim attribute is more important for diabetics than for non-diabetics while sweetener type and calorie reduction attributes have the same importance for both groups. A chocolate with sugar-free claim, natural sweetener and 25% calorie reduction would be theoretically the best combination. USA consumers were segmented in 3 clusters and cluster 1 was more similar to diabetics while clusters 2 and 3 were more similar to non-diabetics. The main difference between clusters 2 and 3 is consumers in cluster 2 are more concerned about calorie consumption. In the USA, conventional, sucralose, and sucralose/WPC were the most accepted samples among nondiabetics and sucralose, sucralose/WPC, and commercial were the most accepted samples among diabetics, which did not confirm theorical results of conjoint analysis. Diabetic consumers are more accepting than non-diabetic consumers of diabetic and diabetic/reduced calorie milk chocolates
Doutorado
Consumo e Qualidade de Alimentos
Doutor em Alimentos e Nutrição

The steviolglycosides are the natural, sweet substances from Stevia rebaudiana Bertoni. It affect human health positively and its sweetness is 300x stronger than the sweetness of sucrose. That's why it's used to sweetening the commercial products. Because of its potential properties it's good to have an appropriate method to isolate it. High performance liquid chromatography ( HPLC) is based on the separation of analyte between two immiscible phases with high pressure pump and appropriately chosen stationary phase in the column. Than the analytes come out from the column in different retention times. This master´s thesis follows up selection of the best HPLC system for isolation of the main steviolglycosides and its analysis in commercial products. In the theoretical part of the thesis is described the origin, basic characteristics, botanical description, cultivation and affect to the human health of Stevia rebaudiana Bertoni and its use in food industry. There are also concisely characterized the sweet substances contained in the plant, so called steviolglycosides. Than there are given the theoretical basics of high performance liquid chromatography, HPLC instrumentation and its specific applications at sleviolglycosides with the basic chromatographic parameters. The object of the first experimental part was to research the optimum conditions for time and separation effective chromatographic analysis and select the best chromatographic system for isolation of steviolglycosides. In the second experimental part, I have compared and defined the main steviolglycosides (stevioside, rebaudioside A) in nine selected products, commercially available in Czech republic, with the best chromatographic method. In these products was the contain of the stevioside or rebaudioside A confirmed or refused.

This diploma thesis deals with sweet substances from Stevia rebaudiana and with their determination in beverages. The ambition was to adjust the separation method for major steviol glycosides (stevioside and rebaudioside A) by HPLC so as to be fast and effective enough, too. In experimental part was successfully developed the separatin method, so it is possible to determine the steviol glycosides and conservation substances, specifically benzoic and sorbic acid (eventually their sodium or potassium salts). At first, for analysis was used monolithic column, on which stevioside and rebaudioside A weren´t separated. Other analyses were performed on column Ascentis express C18 (150 x 4.6; 2.7 µm). The most suitable separation method was performed by mobile phase made up with 29:71 v/v mixture of acetonitrile and acetate buffer (with pH 4.2). The flow rate was 0.28 ml/min and the column temperature was kept constant at 50 °C. The analysis of steviol glycosides and conservation substances with these condition was verified on the samples of real beverages.

Artificiella sötningsmedel används istället för vanligt socker i tandkräm men vanligast är att de används i lättprodukter samt livsmedel utan tillsatt socker som exempelvis läsk. Användandet av sötningsmedel ökar och det beror dels på att det är lämpligt för diabetespatienter och överviktiga men det är även populärt bland den övriga befolkningen då det inte innehåller någon energi. Det första artificiella sötningsmedlet upptäcktes redan 1879 och sedan dess har flera olika artificiella sötningsmedel påfunnits. När sötningsmedlen introducerades på marknaden uppkom misstankar om att de skulle ha cancerogena bieffekter. Nu har det klargjorts vad de har för inverkan på hälsan, och nu ligger fokus på om sötningsmedel påverkar miljön och hur. De sötningsmedel som undersöks i den här studien är acesulfamkalium, aspartam, steviosid samt sukralos. Syftet med studien är att se om dessa sötningsmedel bryts ner av ultraviolett ljus för att få en uppfattning om sötningsmedlen kan ha en negativ verkan på miljön. Laborationen utfördes genom att bestråla prover med UV-ljus, efter bestrålningen undersöktes proverna för att se om mängden substans minskat, genom att använda analysinstrumentet UV-spektrofotometer. Sju mättider valdes ut och för vardera tidpunkt och ämne utfördes i tre replikat. Resultaten analyserades och redovisas med hjälp av diagram och tabeller, resultaten blev inte som jag förväntade mig. Resultaten visade inte på någon nedbrytning av sötningsmedlen då de belystes med UV-ljus i den här studien. Resultat förklaras med hjälp av andra studier på samma område och en sak alla är överens om är att det är ett viktigt område som behöver mera forskning.

Comparative studies of taste perception have found that primates may differ markedly in their sensitivity for substances perceived as sweet by humans. These findings raise questions about the reason that may underlie these differences in sweet-taste sensitivity between species. The aim of the present study was to assess the taste responsiveness of chimpanzees (Pan troglodytes verus) to seven substances tasting sweet to humans and to compare the results with those of other primate species. Using a two-bottle preference test (1 min) I found that the taste preference thresholds of the chimpanzees for five food-associated carbohydrates ranged between 20-30 mM for sucrose, 20-50 mM for fructose, 60-80 mM for glucose, 50-80 mM for maltose, and 30-80 mM for lactose. Taste preference thresholds for two steviol glycosides ranged from 0.04-0.05 mM for stevioside, and 0.03-0.05 mM for rebaudioside A. The chimpanzees displayed clear preferences for all sweet-tasting substances presented. In line with data obtained in other primates, the taste preference threshold of the chimpanzees for sucrose was lower compared to the other carbohydrates presented and the taste preference thresholds for stevioside and rebaudioside A were lower compared to sucrose. In general, the taste sensitivity of the chimpanzees fell into the range of data reported in other nonhuman primate species. Interestingly, the taste preference thresholds of the chimpanzees reported here are similar to the taste detection thresholds obtained in humans, despite the fact that the former are only a conservative approximation of an animal’s taste sensitivity. This suggests that chimpanzees may be as sweet-taste sensitive as humans.

SyfteSyftet med denna laborativa pilotstudie in vitro var att undersöka hur den mikrobiella sammansättningen och pH i den orala biofilmen påverkades vid upprepad exponering för Stevia (steviosid och rebaudiosid A), sackaros eller en kombination av reb A och sackaros. Ett ytterligare syfte var att studera om isolat av orala bakterier kunde metabolisera reb A i buljongkultur. Material och metodBiofilmer från tre personer blev exponerade för 0,025 % steviosid, 0,025 % reb A eller 10 % Todd Hewitt (TH) under 15 minuter tre gånger dagligen i fyra dagar. Artbestämning gjordes i början och slutet av försöken. Biofilmerna exponerades för 0,025 % reb A och 10 % sackaros eller en kombination av dessa varefter pH-värdet mättes. Vidare studerades 23 bakteriestammar avseende förmåga att metabolisera 0,025% respektive 0,5% reb A. ResultatStreptokocker dominerade i samtliga biofilmer vid försökets slut oavsett om de exponerats för steviosid, reb A eller enbart TH. En pH-sänkning kunde ses hos biofilmerna som enbart blivit exponerade för sackaros eller för en kombination av sackaros och reb A. Däremot kunde endast en marginell pH-sänkning observeras efter exponering för enbart reb A. Ingen av de enskilda bakteriestammar som studerades kunde metabolisera reb A.SlutsatsIngen större skillnad i biofilmens bakteriesammansättning kunde ses efter upprepad exponering för steviosid eller reb A i förhållande till TH.Upprepade exponeringar av reb A i kombination med sackaros gav en liknande pH-sänkning som enbart sackaros, dock sågs ingen pH-sänkning efter exponering för enbart reb A. Enskilda bakteriestammar kunde inte metabolisera reb A.
AimsIn this in vitro laboratory pilot study, the effect on the microbial composition and pH of the oral biofilms after repeated exposure to Stevia (stevioside and rebaudioside A), saccarose or a combination, was investigated. Another aim was to study whether isolate of oral bacteria were able to metabolise reb A in broth bacteria culture.Material and MethodBiofilms from three adult individuals were repeatedly exposed to 0,025% stevioside, 0,025% reb A or 10% Todd Hewitt (TH). Samples were taken at the beginning and at the end of the experiment for cultivation and bacterial identification.Biofilms were exposed to 0,025% reb A and 10% saccharose, either separately or combined, followed by a pH-measurement. Furthermore, 23 bacterial species were studied in regards to ability to metabolize reb A. ResultsAll biofilms were dominated by Streptococcus regardless of whether they were exposed to stevioside, reb A, or TH. A pH-decrease was seen in biofilms exposed to saccharose or a combination of saccharose and reb A. However, only minor changes were noted after exposure to reb A.None of the species studied were able to metabolize reb A.ConclusionNo major differences in the bacterial composition of the biofilms were seen after repeated exposure to stevioside or reb A compared to TH.No pH-decrease after repeated exposure to reb A was noted. Exposure to reb A combined with saccharose resulted in a pH-decrease similar to exposure to saccharose. The bacterial species tested in this study were not able to metabolise reb A.

The commercial value of stevia dehydrated leaves is related to the content of glycocides and their appearance. The present work approaches the effect of packed bed drying conditions (temperature, flow rate and solid loading) on glycosides and antioxidants activity of stevia leaves of Morita II variety. Diffusion coefficient was calculated. The drying times ranged between 34 and 160 minutes, the temperature was the most significant factor followed by solid loading and flow rate. Drying increases the concentration of antioxidants, stevioside and reduces rebaudioside A. Keywords: drying, packed bed, stevia rebaudiana, glycosides, antioxidants