Yolanda Moguel-Ordoñez

Physicochemical characterization of lima bean (Phaseolus lunatus) and Jack bean (Canavalia ensiformis) fibrous residues

Some physicochemical, physiological and functional characteristics of Jack bean (Canavalia ensiformis) and lima bean (Phaseolus lunatus) fibrous residues, obtained as a by-product during the protein and starch extraction process were evaluated. The C. ensiformis residues had higher crude fibre (22.6%), total dietary fibre (55.8%) and insoluble dietary fibre (52.4%) contents than the P. lunatus (crude fibre, 12.8%; total dietary fibre, 29.4%; insoluble dietary fibre, 28.6%). Water-holding capacities in both legume fibrous residues were higher (C. ensiformis, 39.5%; P. lunatus, 26.5%) than their oil-holding capacities (23% and 18%, respectively). The P. lunatus residue had lower emulsifying activity (8.6%) than the C. ensiformis residues (49.3%) but higher emulsifying stability (P. lunatus, 100% versus C. ensiformis, 28.25%). Neither fibrous residue was capable of bonding calcium ions, but both did bind iron ions (C. ensiformis, 31.1%; P. lunatus, 28.4%). Similar antioxidant activity values were obtained for the Jack bean (39.4%) and lima bean (35.6%) residues.

Biological activity of Stevia rebaudiana Bertoni and their relationship to health

ABSTRACT The leaves of Stevia rebaudiana Bertoni has nutrients and phytochemicals, which make it an adequate source for the extraction and production of functional food ingredients. Preclinical and clinical studies suggest therapeutic and pharmacological applications for stevia and their extracts because they are not toxic and exhibit several biological activities. This review presents the biological activity of Stevia rebaudiana Bertoni and their relationship to antidiabetic, anticariogenic, antioxidant, hypotensive, antihypertensive, antimicrobial, anti-inflammatory and antitumor activities. Consumption and adverse effects were also reviewed.

Studies on drying characteristic, nutritional composition, and antioxidant properties of Stevia rebaudiana (Bertoni) leaves

Abstract Drying characteristics of Stevia rebaudiana (Bertoni) leaves using radiation drying, convection drying, sun drying, and shade drying treatments were investigated in a convective type. Results for all treatments indicated that drying took place in the falling rate period. The chroma of the dried samples ranged between 29.66 and 23.85. Convection and shade drying samples were found better in colour and had the highest content of total pigments. The proximate and fibre composition were affected by the drying treatments. Extracts obtained from convection drying and shade drying leaves exhibited higher values of Trolox equivalent antioxidant capacities 416.89-423.64 mM mg−1 and ferric reducing power 85.19-87.97%. These extracts also showed ion chelating capacity 59.05-60.21% for Cu+2 and 55.05-59.11% for Fe+2. The results indicate that it is possible to select the drying treatment to obtain the best nutritional and biological properties. Convection drying and shade drying were the least aggressive treatments and leaf powders obtained by these drying methods could be used as sources of nutrients, fibre, and antioxidant compounds.

Validation of HPLC‐UV method for determination of minor glycosides contained in Stevia rebaudiana Bertoni leaves

Leaves of Stevia rebaudiana contain glycosides with sweetness and biological activity. However besides the major glycosides, there are other glycosides within extracts that may contribute to its activity, and therefore it is important to quantify them. In this work, an isocratic HPLC method was validated for determination of dulcoside A, steviolbioside, rebaudioside C and rebaudioside B. An HPLC method was performed using a C18 column (250 × 4.6 mm, particle size 5 µm) and a UV detector set at 210 nm. The mobile phase consisted of a 32:68 (v/v) mixture of acetonitrile and sodium phosphate buffer (10 mmol/L, pH 2.6), set to a flow rate of 1.0 mL/min. The calculated parameters were: sensitivity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision. The calibration curves were linear over the working range 25-150 µg/mL, with coefficient of correlation of ≥0.99 and coefficient of determination of ≥0.98. The LOD was 5.68-8.81 µg/mL, while the LOQ was 17.21-26.69 µg/mL. The percentage recoveries of fortified samples were 100 ± 10% and precision, relative standard deviation, was <10%. The method validation showed accuracy, linearity and precision; therefore this method can be applied for quantitative analysis of minor steviol glycosides in S. rebaudiana leaves.

EVALUACIÓN DE LA INOCUIDAD DE STEVIA REBAUDIANA BERTONI CULTIVADA EN EL SURESTE DE MÉXICO COMO EDULCORANTE DE ALIMENTOS

Stevia rebaudiana leaves and their glycosides have been recently and significantly used so important as sweeteners. However, it has been reported an antihyperglycemic effect of the extract and a glycoside. The aim of this study was to quantify S. rebaudiana glycosides, assess cytotoxicity of the extract and its acute and chronic effect on blood glucose in animal models and in human. The glycosides of the Morita II and Criolla extract were quantified by HPLC, using a C18 column (250 mm x 4.6 mm and particle size of 5 uM) with UV detection at 210 nm, mobile phase of acetonitrile/sodium phosphate buffer 10 mmol/L, pH 2.6 (32:68 v/v). Cytotoxicity study was performed in Vero cells, whereas an intraperitoneal glucose tolerance test (IPGTT) and a chronic consumption assay (4 weeks) were executed in an animal model of diabetes; finally the glycemic index (G.I.) was determined in healthy individuals. The glycoside content is higher in the Morita variety II although both had a CC50 >300 g/mL. The areas under the curve of the IPGTT and fasting glucose of the animals were not significantly different (p> 0.05) and the I.G. extract was 11.11 %, which classifies the extract as low I.G. The extract of S. rebaudiana Morita II has a low glycemic index and, in the doses tested, is not cytotoxic nor has acute or chronic effect on blood sugar, which makes it a safe sweetener.

Desarrollo de una golosina tipo "gomita" reducida en calorías mediante la sustitución de azúcares con Stevia rebaudiana B

The consumption of gummy candy is widespread among people of different ages but mainly by children. The formulation of this product requires sugar that contributes to their flavor and consistency, but with the undesirable effect of increase its glycemic index and its calories from simple sugars; it is known that consumption of products with these last two characteristics are related to childhood obesity, which is a worldwide growing disease. Stevia rebaudiana is a plant that naturally contains glycosides with high sweetening power and it is considered safe for consumption. Therefore the aim of this work was to develop a gummy candy reduced in calories by replacing sugar with Stevia rebaudiana B., and analyzes its texture and acceptability. Gummy candy were prepared with different percentage of sugar reduction (-20, -40, -60, -80 and -100%) and a product control (100% sugar); gummy elasticity was assess by displacement and maximum deformation, whereas resistance was evaluated by breaking strength; those gummies with better elasticity and resistance parameters underwent proximate analysis and sensory evaluations with a unstructured scale applied to 90 school children aged between 6 and 10 years old. A gummy candy reduced in calories with 60% sugar substitution with S. rebaudiana was developed; the level of satisfaction in school children was statistically the same respect to the gummy made of 100% sugar (p <0.05).

Nutritional, amylolytic enzymes inhibition and antioxidant properties of bread incorporated with Stevia rebaudiana

Abstract Wheat bread with sucrose content replaced with different levels of stevia extract was compared with traditional wheat bread. The ability to reduce glucose intake was highlighted by performing enzymatic assays using α-amylase and α-glucosidase. Antioxidant activity was measured by determining the scavenging effect on α,α-diphenyl-β-picrylhydrazyl radical. In comparison with the control, the bread with stevia extract was softer and had lower microbial growth during the shelf-life study. The sensory test showed that the substitution of 50% stevia extract was more acceptable when comparing with all the quality characteristics. Regarding the nutritional contribution, the content of dietary fiber and digestible carbohydrates in the bread with stevia extract was higher and lower respectively, so caloric intake was significantly reduced. The results showed that the biological properties of Stevia rebaudiana extract were retained after the bread making process and that the proposed bread could be suitable as functional food in human nutrition.

Effect of different drying methods on the composition of steviol glycosides in Stevia rebaudiana Bertoni leaves

Abstract Drying techniques can modify the composition of certain plant compounds. Therefore, the aim of the study was to assess the effect of different drying methods on steviol glycosides in Stevia rebaudiana Bertoni leaves. Four different drying methods were applied to Stevia rebaudiana Bertoni leaves, which were then subjected to aqueous extraction. Radiation or convection drying was performed in stoves at 60°C, whereas shade or sun drying methods were applied at 29.7°C and 70% of relative humidity. Stevioside, rebaudioside A, rebaudioside B, rebaudioside C, rebaudioside D, dulcoside A, and steviolbioside were quantified by a validated HPLC method. Among steviol glycosides, the content (g 100 g−1 dry basis) of stevioside, rebaudioside A, rebaudioside B, and rebaudioside C varied according to the drying method. The total glycoside content was higher in sun-dried samples, with no significant differences compared to shade or convection drying, whereas radiation drying adversely affected the content of rebaudioside A and rebaudioside C (p <0.01) and was therefore a method lowering total glycoside content. The effect of the different drying methods was also reflected in the proportion of the sweetener profile. Convection drying could be suitable for modern food processing industries while shadow or sun drying may be a low-cost alternative for farmers.

Antioxidant Capacity of Capsicum chinense Genotypes

The fruits of seven Capsicum chinense Jacq. genotypes grown in Yucatan, Mexico, were studied to determine their phenolic compounds, carotenoids, and ascorbic acid contents, as well as their free radical scavenging (ABTS assay) and antioxidant activities (s-carotene/linoleic acid assay). Phenolics, carotenoids, and ascorbic acid contents varied between genotypes. ABTS radical scavenging activity was highest in a yellow genotype, and antioxidant activity was most stable in a red genotype. Fruits from all seven studied genotypes are good antioxidant sources. Many of these benefits originate in peppers’ wide array of phytochemicals and high contents of vitamin C and carotenoids, which are vital nutritional antioxidants in the human diet.