Abstract Consumption of tropical fruits is growing around the world, not only due to their flavor and appearance but also for their nutritional value. In addition to the content in macro and micronutrients, tropical fruits contain substantial amounts of bioactive compounds in peels and seeds, which constitute an underexploited source of bioactive compounds such as phenolic acid, polyphenols, carotenoids, vitamin C and polysaccharides. Polysaccharides have attracted growing interest, particularly for their bioactive characteristics such as antioxidants as well as antiinflammatory, antimicrobial, anticoagulant, hepatoprotective and immunomodulatory properties. Therefore, obtaining functional ingredients from tropical fruits and by-products is feasible, and could be used to develop functional and nutraceutical foods to elaborate products of the pharmaceutical industry and food preservation. The present review provides the most relevant information published the last ten years (2010-2020) on bioactive polysaccharides extracted with hot water reported in tropical fruits and by-products and their relationship with potential beneficial health effects.

Resumen El consumo de frutas tropicales está creciendo en todo el mundo, no solo por su sabor y apariencia, sino también por su valor nutricional. Además del contenido en macro y micronutrientes, las frutas tropicales contienen cantidades sustanciales de compuestos bioactivos en cáscaras y semillas, que constituyen una fuente subexplotada de compuestos bioactivos como ácido fenólico, polifenoles, carotenoides, vitamina C y polisacáridos. Los polisacáridos han atraído un interés creciente, especialmente por sus características bioactivas como antioxidantes y propiedades antihipoglucemiantes, antiinflamatorias, antimicrobianas, anticoagulantes, hepatoprotectoras e inmunomoduladoras. Por tanto, la obtención de ingredientes funcionales a partir de frutas tropicales y subproductos es factible y podría utilizarse para desarrollar alimentos funcionales y nutracéuticos para elaborar productos de la industria farmacéutica y conservación de alimentos. La presente revisión proporciona la información más relevante publicada durante los últimos diez años (2010-2020) sobre polisacáridos bioactivos extraídos con agua caliente reportados en frutas tropicales y subproductos y su relación con posibles efectos beneficiosos para la salud.

Abstract The effect of thin-layer drying temperature on color, phenolic content and antioxidant capacity of noni slices was investigated. Noni slices were air-dried at 50, 60 and 70 °C under natural convection conditions. Drying curves were fitted to thin-layer drying models in order to evaluate the drying characteristics of the product. In addition, an unsteady-state diffusion equation was numerically solved considering both product shrinkage and a variable mass Biot number in boundary condition to accurately estimate water diffusivity in a process with external resistance to mass transfer. Results revealed that the Aghbashlo model accurately reproduced the experimental behavior. As expected, water diffusivities, corrected for shrinkage, increased with the use of higher drying temperatures, with values in the range of 1.80-3.19 to ×10-9 m2/s. On the other hand, while drying caused a reduction in product lightness (24-31%) and total phenolic content (20-28%), the antioxidant capacity of dried noni was high (82-93% DPPH inhibition), which is advantageous for the further storage or processing of this fruit.

Abstract: The cheese industry uses different coagulants to curdle the milk, outstanding among which are rennet (extracted from the calf abomasum), enzymes from genetically modified microorganisms (Mucor miehei, M. pusillus and Endothia parasitica), plant enzymes from Cirsium spp. (thistle) and enzymes from other animals (pigs and chickens). The stomachs of animals for slaughter, such as rabbits, can be used to produce milk coagulants mainly in traditional cheese-making that produces fresh and slightly aged cheeses. In this study, the proteolytic activity and curdling strength of the extract from rabbit (Oryctolagus cuniculus) stomach supplemented with NaCl and ethanol were analyzed in milk. The study had two phases. In the first, the effect of salt on stomach drying, curdling strength following the method of Chazarra and collaborators, and proteolytic activity was evaluated. Stomachs from recently sacrificed rabbits were used. The treatments were: 1) submersion in saturated brine (NaCl), 2) superficial saturation, and 3) no NaCl. Afterwards, the stomachs were dried by insufflation. In the second stage, the effect of the NaCl concentration in combination with ethanol on curdling strength and proteolytic activity was determined. To this end, six levels of added ethanol and six levels of NaCl were utilized. In the first stage the experimental design was completely randomized, and in the second it was completely randomized with a 6×6×4 factorial array, with six levels of NaCl, six levels of ethanol and four storage times. Means were compared with the Tukey test (p≤0.05). In the first stage, the stomachs without NaCl exhibited more enzyme activity and, with saturated brine or superficial saturation there was greater curdling strength. In the second stage, the concentration of ethanol did not affect curdling strength. The best results were obtained with 1 to 5 % NaCl, which were different (p≤0.05) from those obtained without NaCl. The rabbit stomachs supplemented with NaCl and ethanol coagulated milk. Thus, this organ, suitably treated, can be used in the cheese industry.

Resumen: La industria quesera emplea coagulantes diversos para la elaboración de quesos, y destacan los cuajos naturales (abomasos de becerro), las enzimas de microorganismos genéticamente modificados (Mucor miehei, M. pusillus y Endothia parasítica), enzimas vegetales de Cirsium spp. (cardo) y enzimas de origen animal (cerdos y pollos). Los estómagos de animales de abasto, como el conejo, se podrían usar para la producción de coagulantes de leche, principalmente en queserías de tipo tradicional que elaboran quesos frescos y semi madurados. Por lo anterior, se evaluó la actividad proteolítica y la fuerza de cuajado del extracto de estómago de conejo (Oryctolagus cuniculus) adicionados con NaCl y etanol en leche. La investigación se realizó en dos etapas. En la primera se evaluó el efecto de la sal en el secado de los estómagos, la fuerza de cuajado mediante el método de Chazarra y colaboradores y la actividad proteolítica, para esto se usaron estómagos de conejos recién sacrificados. Los tratamientos fueron: 1) inmersión en salmuera saturada (NaCl), 2) saturación superficial y, 3) sin NaCl. Depués los estómagos se secaron por insuflación. En la segunda etapa se determinó el efecto de la concentración de NaCl en combinación con etanol sobre la fuerza de cuajado y actividad proteolítica; para esto se usaron seis niveles de adición de etanol y seis niveles de NaCl. En la primera etapa el diseño fue completamente al azar, y en la segunda fue completamente al azar con un arreglo factorial 6×6×4, con seis niveles de NaCl, seis niveles de etanol y cuatro tiempos de almacenamiento. La comparación de medias se realizó con la prueba de Tukey (p≤0.05). En la primera etapa los estómagos sin NaCl mostraron actividad enzimática mayor, y con salmuera saturada o saturación superficial tuvieron fuerza mayor de cuajado. En la segunda etapa, la concentración de etanol no cambió la fuerza del cuajado. Los resultados mejores fueron con 1 a 5 % de NaCl y diferentes (p≤0.05) a los obtenidos sin NaCl. Los estómagos de conejos adicionados con NaCl y etanol mostraron actividad coagulante de leche. Así, esta víscera tratada adecuadamente se puede usar en la industria quesera.

The onion (Allium cepa L.) has been cultivated for thousands of years and is an important component of human diet. Recent studies suggest that onion can be used to reduce or prevent health problems such as asthma, cardiovascular diseases and diabetes due to its high antioxidant effect. Extract aqueous and ethanolic from three (purple, yellow and white) varieties of onion were studied for their total phenolic content, capacity and inhibitory activity against α-glucosidase and α- amylase. The total phenolic content varied between 6.59 to 9.25 mg/100 g and 24.3 a 42.7 mg/100 g the antioxidant capacity expressed as the percentage of inhibition of DPPH- radical ranged from 46.8 to 89.2% and 20.4% to 39.6% for ethanolic and aqueous extracts respectively. All ethanolic extracts showed capacity of inhibition for α-glucosidase y α-amylase from 58% to 34% and 33% to 22% respective while the aqueous extracts showed less effectiveness. Among the extracts, ethanolic extract of purple onion have the maximum concentration of total phenolic compounds, the highest antiradical capacity and α-glucosidase inhibition. Differences in free-radical scavenging and inhibition appeared to be dependent on the unique profile of phenolic compounds in each variety.

La cebolla (Allium cepa L.) ha sido cultivada durante miles de años y es utilizada como un componente importante en la dieta del ser humano. Estudios recientes sugieren que su consumo puede reducir o prevenir problemas de salud como asma, enfermedades cardiovasculares y diabetes, debido a sus efectos antioxidantes. En este estudio se determinó el contenido de compuestos fenólicos totales, la capacidad antiradical y la inhibición de las enzimas α-glucosidasa y α-amilasa de extractos acuosos y etanólicos de tres variedades de cebolla (blanca, amarilla y morada). El contenido de compuestos fenólicos totales varió de 6.59 a 9.25 mg/100 g y la actividad antiradical expresada como % DPPH- se encontró entre 20.4% a 39.6% y de 46.8 a 89.2% para los extractos acuosos y etanólicos respectivamente. Todos los extractos etanólicos fueron capaces de inhibir la actividad α-glucosidasa y α-amilasa de 58% a 34%% y 33 y 22% respectivamente, mientras que los extractos acuosos fueron menos efectivos. Entre los extractos estudiados, el extracto etanólicos de cebolla morada presenta la mayor concentración de compuestos fenólicos totales y la mayor actividad antiradical e inhibidora de α-glucosidasa. Las diferencias encontradas entre la concentración de compuestos fenólicos y las distintas actividades estudiadas parecen depender del perfil único de compuestos fenólicos que posee cada variedad de cebolla.

Soft Independent Modeling of Class Analogy (SIMCA) e Regressão por Mínimos Quadrados Parciais foram usados nesse trabalho para a identificação e quantificação de tiamina, riboflavina, nicotinamida e piridoxina, por espectrofotometria UV-Vis, sem realizar os procedimentos analíticos de separação e pré-concentração. Para a quantificação, os intervalos de trabalho estabelecidos foram 1-14 mg L-1 para riboflavina, 2-26 mg L-1 para tiamina, 2-30 mg L-1 para nicotinamida, e 2-22 mg L-1 para piridoxina. Os resultados de recuperação obtidos foram superiores a 95% em todos os casos, para a análise de amostras sintéticas e comerciais. Na busca de cada vitamina alvo, foi construído um modelo de classificação com duas categorias: (i) com a vitamina de interesse e (ii) sem a vitamina de interesse. A capacidade discriminatória de cada modelo de classificação foi avaliada para aprendizagem, para um conjunto de amostras teste e para amostras comerciais, com resultados satisfatórios, com exceção da riboflavina. Assim, um método simples e confiável é proposto para a estimativa simultânea desses compostos.

Soft Independent Modeling of Class Analogy and Partial Least Squares Regression were used in this work for the identification and quantification of thiamine, riboflavin, nicotinamide and pyridoxine by UV-Vis spectrophotometry, without separation or preconcentration steps in the analytical procedure. For quantitative purposes, the working range established was 1-14 mg L-1 for riboflavin, 2-26 mg L-1 for thiamine, 2-30 mg L-1 for nicotinamide, and 2-22 mg L-1 for pyridoxine. Recovery results higher than 95% were obtained in all cases during the analysis of synthetic and commercial samples. In the screening of each target vitamin, a classification model was built with two classes: (i) with the vitamin of interest, and (ii) without it. The discriminate capability of each classification model was evaluated for learning, independent testing and commercial samples, resulting in satisfactory findings with exception of riboflavin. Thus, a simple and reliable method is proposed for the simultaneous estimation of these compounds.

The pale yellow complex formed between Cu(II) and thiosemicarbazone of 4-carboxy benzaldehyde (4CBTSC) was studied spectrophotometrically. The use of 4CBTSC as an analytical reagent in photometric estimation of Cu(II) is described. The method is suitable in the range between 0.4 and 3.0 ppm of Cu(II) (λmáx = 357 nm, ε = 3.2 x 104 L*mol-1*cm−1) with a relative error of 2.2 %. The interferences caused by numerous ions have been studied. The stoichiometry of the complex originated by the 4CBTSC with the ion Cu(II) has been determined by spectrophotometric methods and it is 1:1 (reagent:cation). The method was applied to the determination of cooper in drinking water and powder chocolate with satisfactory results.

Se estudia espectrofotométricamente la formación del complejo amarillo pálido formado entre el ión Cu(II) y la tiosemicarbazona del 4-carboxibenzaldehido (4CBTSC), desarrollándose un nuevo método fotométrico de determinación de cobre. El intervalo útil de trabajo del método desarrollado esta comprendido entre 0.4 y 3.0 ppm del ión Cu(II) (λmáx = 357 nm, ε = 3.2 × 104 L*mol-1*cm−1) con un error relativo de 2.21 % (para 1.5 ppm de Cu(II), n=11, p=0.05). Se han estudiado las interferencias de numerosos iones. La estequiometría del complejo formado resultó ser 1:1 (4CBTSC:Cu), determinado por métodos espectrofotométricos. El método se aplicó al análisis de cobre en agua potable y chocolate en polvo con buenos resultados.