Development of nopal-pineapple marmalade formulated with stevia aqueous extract: effect on physicochemical properties, inhibition of alpha-amylase, and glycemia response / Desarrollo de mermelada de piña-nopal formulado con extracto acuoso de estevia: efecto sobre las propiedades fisicoquímicas, inhibición de alpha-amilasa y respuesta glicémica

Introduction: Stevia rebaudiana extracts can be used as a sweetener due to their glycoside content: specifically stevioside and rebaudioside. Both compounds have adequate pharmacological characteristics for human consumption. Objective: the aim of this study was to standardize the formulation of marmalades using nopal-pineapple-stevia aqueous extract ratios. Methods: the products were evaluated to determine their physicochemical properties, in vitro inhibition of α-amylase and glycemia in healthy volunteers. Storage study was conducted for 20 days at room temperature 23-30 °C and relative humidity 80-85%. Results: incorporation of stevia significantly modified physicochemical properties like °Brix, color and flow index. After storage, the presence of molds and bacteria were not detected. Sensory evaluation indicated that marmalade with 50% stevia replacement was equally accepted as marmalade with sucrose. Marmalade with 50 and 100% of stevia inhibited 35.89 and 38.50% of the α-amylase activity. After an intake of 30 g, it seems that marmalades with stevia had a significant effect on the glycemia of the volunteers. Conclusions: however, further studies with larger doses of nopal-pineapple-stevia marmalade and consumed for longer in both healthy volunteers and patients with diabetes are needed to achieve results that are more precise

Introducción: los extractos de Stevia rebaudiana pueden ser utilizados como edulcorante debido a su contenido de glucósidos: específicamente esteviósido y rebaudiósido. Ambos compuestos presentan características farmacológicas adecuadas para el consumo humano. Objetivos: el objetivo del presente trabajo fue estandarizar formulaciones de mermeladas con diferentes proporciones de nopal-piña-extracto acuoso de stevia. Métodos: se estudiaron las propiedades fisicoquímicas de las mermeladas, su capacidad de inhibir in vitro a la enzima α-amilasa y la glicemia en voluntarios sanos. Los estudios de vida de anaquel se efectuaron durante 20 días a temperatura ambiente 23-30 °C y humedad relativa 80-85%. Resultados: la incorporación de estevia modificó significativamente los grados Brix, el color y el índice de flujo de las mermeladas. Concluido el estudio de anaquel, no se observó la presencia de hongos o bacterias. La evaluación sensorial indicó que la mermelada con 50% de estevia fue aceptada con el mismo nivel de agrado que la mermelada con sacarosa. Las mermeladas con 50 y 100% de estevia inhibieron la actividad de la α-amilasa con valores de 35.89% y 38.50%, respectivamente. Posterior a una ingesta de 30 g de mermelada se observó un efecto significativo en la glicemia de voluntarios sanos. Conclusiones: deberán efectuarse estudios de consumo prolongado y de mayores cantidades de mermelada tanto en voluntarios sanos como con diabetes para obtener resultados más precisos

Cognitive Performance and Morning Levels of Salivary Cortisol and alfa-Amylase in Children Reporting High vs. Low Daily Stress Perception

The aim of the present study was to assess the effects of daily stress perception on cognitive performance and morning basal salivary cortisol and alpha-amylase levels in healthy children aged 9-12. Participants were classified by whether they had low daily perceived stress (LPS, n = 27) or a high daily perceived stress (HPS, n = 26) using the Children Daily Stress Inventory (CDSI). Salivary cortisol and alpha-amylase were measured at awakening and 30 minutes later. Cognitive performance was assessed using the Cognitive Drug Research assessment system. The HPS group exhibited significantly poorer scores on speed of memory (p < .05) and continuity of attention(p < .05) relative to the LPS group. The HPS group also showed significantly lower morning cortisol levels at awakening and at +30 minutes measures in comparison with the LPS group (p < .05), and mean morning cortisol levels were negatively correlated with speed of memory (p < .05) in the 53 participants. No significant differences were observed between both groups in alpha-amylase levels. These findings suggest that daily perceived stress in children may impoverish cognitive performance via its modulating effects on the HPA axis activity (AU)

El objetivo del presente estudio fue evaluar los efectos de la percepción de estrés diario sobre el rendimiento cognitivo y los niveles matutinos basales de cortisol y alfa-amilasa salivar en niños sanos de edades entre los 9y los 12 años. Los participantes fueron clasificados en función de si su nivel de percepción de estrés diario era bajo (LPS, n = 27) o alto (HPS, n = 26), empleando el Children Daily Stress Inventory (CDSI). Se midió el cortisol y la alfa-amilasa salivar al despertar y 30 minutos más tarde. El rendimiento cognitivo se evaluó mediante el sistema de evaluación Cognitive Drug Research. El grupo HPS obtuvo puntuaciones significativamente más bajasen velocidad de memoria (p < .05) y continuidad de la atención (p < .05) con respecto al grupo LPS. El grupo HPS también mostró niveles significativamente más bajos de cortisol matutino al despertar y a los 30 minutos en comparación con el grupo LPS (p < .05), y sus niveles medios de cortisol matutino correlacionaron negativamente con la velocidad de la memoria (p < .05) en los 53 participantes. No se observaron diferencias significativas entre los grupos en los niveles de alfa-amilasa. Estos resultados sugieren que la percepción de estrés diario en niños puede disminuir su ejecución cognitiva a través de sus efectos moduladores en la actividad del eje HPA (AU)

Influencia del amaranto en la producción de alpha-amilasa empleando Aspergillus niger NRRL 3112 / Influence of amaranth on the production of alpha-amylase using Aspergillus niger NRRL 3112

In this paper the influence of the amaranth seed meal and the aeration conditions on the alpha-amylase production by Aspergillus niger NRRL 3112 were studied. The assays of selection of culture medium were carried out in a rotary shaker at 250 rpm and 2.5 cm stroke. The aeration conditions were studied in a mechanically stirred fermentor New Brunswick type. A concentration of alpha-amylase of 2750 U.Dun/ml was achieved at 120 h with a dry weight of 8.0 g/l, using a base medium with 5.0 g/l Amaranthus cruentus seed meal. In the experiment performed in a New Brunswick fermentor, the highest value was 2806 U.Dun/ml. This result was obtained after 120 h, operating at 300 rpm and an airflow of 1 l/l. min. in a limited dissolved oxygen concentration. It was determined that the increase in the agitation rate was not favorable to the enzyme production, despite that an increase was verified in the dissolved oxygen. The morphology of the microorganism, in long and ramified hyphae, was the critical factor to obtain higher levels of alpha-amylase.(AU)

Production of amylases by Aspergillus tamarii

A strain of Aspergillus tamarii, a filamentous fungus isolated from soil, was able to produce both Ó-amylase and glucoamylase activities in mineral media supplemented with 1(per cent) (w/v) starch or maltose as the carbon source. Static cultivation led to significantly higher yields than those obtained using shaking culture. The production of amylases was tolerant to a wide range of initial culture pH values (from 4 to 10) and temperature (from 25 to 42degree C). Two amylases, once Ó-amylase and one glucoamylase, were separated by ion exchange chromatography. Both partially purified enzymes had optimal activities at pH values between 4.5 and 6.0 and were stable under acid conditions (pH 4.0-7.0). The enzymes exhibited optimal activities at temperatures between 50(degree) and 60(degree) C and wete stable for more than ten hours at 55(degree) C.

Production of alph-amylase in acid cheese whey culture media with automatic pH control

The influence of aeration and automatic pH control on the production of alpha-amylase by a strain of "Bacillus subtilis" NRRL 3411 from acid cheese whey was studied. Tests were carried out in a rotary shaker and in mechanically stirred ferments. Alpha-maylase was analysed according to DUN's method. Oxygen absorption rate was determined by Cooper's method. Cell oxygen demand was determined as oxygen consumption in a Warburg respirometer. The level of dissolved oxygen was mesured by means of a galvanic silver-lead electrode. Results suggest the possibility of industrial use of acid cheese whey as a carbon source for alpha-amylase production, since the yiels was similar to that produced with lactose. The highest alpha-amylase levels 100,000 DUN/ml units were not attained at highr aeration rates -431 mLO2/L.h-. The indicated value correspond to a 96 h process with automatic pH enzyme production was directly related to growth in the form of cell aggregates.

Obtención de *-amilasa bacteriana: influencia del shock térmico y de los nutrientes del medio / Isolation of baceterial *-amylase: effect of heat shock and media nutrients

Se estudió la producción de alfa-amilasa empleando una cepa de Bacillus subtilis NRRL 3411. Las variables estudiadas incluyeron shock término, concentración y naturaleza de la fuente de carbono, nitrógeno y factores. Además se realizaron experiencias sobre estabilización de los caldos enzimáticos libres de células. Se determinó que utilizando esporos sometidos a un shock térmico de 100-C de 10 min, en un medio con lactosa, caseína, extracto de levadura y minerales, se alcanzaron valores de 140 unidades de alfa-amilasa en 72 h de proceso. También se demostró que el agregado de 20% de glicerol y 1% de benzoato de sodio aseguran caldos estabilizados a 20-C, por un período de 30 días (AU)

Obtención de *-amilasa bacteriana: influencia del shock térmico y de los nutrientes del medio / Isolation of baceterial *-amylase: effect of heat shock and media nutrients

Se estudió la producción de alfa-amilasa empleando una cepa de Bacillus subtilis NRRL 3411. Las variables estudiadas incluyeron shock término, concentración y naturaleza de la fuente de carbono, nitrógeno y factores. Además se realizaron experiencias sobre estabilización de los caldos enzimáticos libres de células. Se determinó que utilizando esporos sometidos a un shock térmico de 100-C de 10 min, en un medio con lactosa, caseína, extracto de levadura y minerales, se alcanzaron valores de 140 unidades de alfa-amilasa en 72 h de proceso. También se demostró que el agregado de 20% de glicerol y 1% de benzoato de sodio aseguran caldos estabilizados a 20-C, por un período de 30 días

Produçäo de *-amilase: características morfofisiológicas do B. amyloliquefaciens visando ao melhoramento genético / Production of *-amylase: morphophysiological characteristics of B. amyloliquefaciens in view to genetic improvement

Foram estudadas algumas características morfológicas e fisiológicas do B. amyloliquefaciens ATCC 23842 visando ao melhoramento genético da linhagem para o aumento da produçäo de alfa-amilase. A linhagem mostrou bom crescimento em meio ágar nutriente, apresentando tempo de geraçäo de 49,2 minutos. Neste meio, o Bacillus apresentou menor secreçäo de muco e cadeia contendo de 4 a 6 células, independentemente da fase de crescimento. Em meio mínimo, contendo amido solúvel como substrato, a produçäo de enzima iniciou-se após quatro horas de incubaçäo, coincidindo com a fase logarítmica de crescimento. De 8 a 12 horas de incubaçäo observou-se um aumento na concentraçäo da enzima enquanto a concentraçäo de açúcares redutores permanecu constante. Verificou-se que a luz ultravioleta näo se mostrou adequada para a obtençäo de mutantes com maior capacidade de síntese da enzima, provavelmente em virtude das características morfológicas apresentadas pela linhagem, que dificultaram uma absorçäo uniforme da radiaçäo. Estudo realizados para detecçäo de plasmídos, por meio de eletroforese em gel de agarose a 1% revelaram a ausência desses elementos

Melhoramento de Bacillus amyloliquefaciens por DNA transformante e fusäo de protoplastos para produçäo de amilase e proteases / Improvement of Bacillus amyloliquefaciens by DNA transformation and protoplasts fusion for amylase and proteases production

Utilizando-se Bacillus amyloliquefaciens ATCC 2342 e o B. natto, isolado do produto comercial "natto", respectivamente, bons produtores de alfa-amilase e proteases, conseguiu-se aumentar os níveis de produçäo destas enzimas através das técnicas de DNA transformante e fusäo de protoplastos. O melhoramento genético por transformaçäo foi mais eficiente do que aquele por fusäo de protoplastos