Selection of starter cultures for the production of sour cassava starch in a pilot-scale fermentation process

ABSTRACT Sour cassava starch (Polvilho azedo) is obtained from a spontaneous fermentation conducted by microorganisms from raw materials and fermentation tanks. This product is traditionally used in the baking industry for the manufacture of biscuits and Brazilian cheese breads. However, the end of fermentation is evaluated empirically, and the process occurs without standardization, which results in products of inconsistent quality. Predominant microbiota from a cassava flour manufacturer was isolated in order to select starter cultures for the production of sour cassava starch in a pilot-scale fermentation process. Lactic acid bacteria and yeasts were isolated, enumerated and grouped by Restriction Fragment Length Polymorphism, and PCR fingerprinting, respectively. One isolate of each molecular profile was identified by sequencing of the rRNA gene. LAB were prevalent throughout the entire process. Lactobacillus brevis (21.5%), which produced the highest values of acidity, and Lactobacillus plantarum (13.9%) were among the most frequent species. Pichia scutulata (52.2%) was the prevalent yeast and showed amylolytic activity. The aforementioned species were tested as single and mixed starter cultures in a pilot-scale fermentation process for 28 days. L. plantarum exhibited better performance as a starter culture, which suggests its potential for the production of sour cassava starch.

Efficient production of pullulan by Aureobasidium pullulans grown on mixtures of potato starch hydrolysate and sucrose

Abstract Pullulan is a natural exopolysaccharide with many useful characteristics. However, pullulan is more costly than other exopolysaccharides, which limits its effective application. The purpose of this study was to adopt a novel mixed-sugar strategy for maximizing pullulan production, mainly using potato starch hydrolysate as a low-cost substrate for liquid-state fermentation by Aureobasidium pullulans. Based on fermentation kinetics evaluation of pullulan production by A. pullulans 201253, the pullulan production rate of A. pullulans with mixtures of potato starch hydrolysate and sucrose (potato starch hydrolysate:sucrose = 80:20) was 0.212 h−1, which was significantly higher than those of potato starch hydrolysate alone (0.146 h−1) and mixtures of potato starch hydrolysate, glucose, and fructose (potato starch hydrolysate:glucose:fructose = 80:10:10, 0.166 h−1) with 100 g L−1 total carbon source. The results suggest that mixtures of potato starch hydrolysate and sucrose could promote pullulan synthesis and possibly that a small amount of sucrose stimulated the enzyme responsible for pullulan synthesis and promoted effective potato starch hydrolysate conversion effectively. Thus, mixed sugars in potato starch hydrolysate and sucrose fermentation might be a promising alternative for the economical production of pullulan.

Enamel and dentine demineralization by a combination of starch and sucrose in a biofilm - caries model

Abstract Sucrose is the most cariogenic dietary carbohydrate and starch is considered non-cariogenic for enamel and moderately cariogenic for dentine. However, the cariogenicity of the combination of starch and sucrose remains unclear. The aim of this study was to evaluate the effect of this combination on Streptococcus mutans biofilm composition and enamel and dentine demineralization. Biofilms of S. mutans UA159 were grown on saliva-coated enamel and dentine slabs in culture medium containing 10% saliva. They were exposed (8 times/day) to one of the following treatments: 0.9% NaCl (negative control), 1% starch, 10% sucrose, or 1% starch and 10% sucrose (starch + sucrose). To simulate the effect of human salivary amylase on the starch metabolization, the biofilms were pretreated with saliva before each treatment and saliva was also added to the culture medium. Acidogenicity of the biofilm was estimated by evaluating (2 times/day) the culture medium pH. After 4 (dentine) or 5 (enamel) days of growth, biofilms (n = 9) were individually collected, and the biomass, viable microorganism count, and polysaccharide content were quantified. Dentine and enamel demineralization was assessed by determining the percentage of surface hardness loss. Biofilms exposed to starch + sucrose were more acidogenic and caused higher demineralization (p < 0.0001) on either enamel or dentine than those exposed to each carbohydrate alone. The findings suggest that starch increases the cariogenic potential of sucrose.

Efeitos da modificação por ácidos orgânicos e do processo de secagem sobre as propriedades de expansão do amido de mandioca / Effects of modification by organic acids and the drying process on the expansion properties of cassava starch

O amido fermentado de mandioca, polvilho azedo, possui ampla aplicação em produtos de panificação, devido à propriedade de expansão, sem fermento e sem glúten, o que alavancou a comercialização dos amidos substituintes modificados por ácido. O polvilho azedo é fermentado e seco ao sol, com a geração de ácidos: acético, butírico, lático e propiônico, enquanto os amidos modificados por ácido não são fermentados. Neste trabalho foi produzido o polvilho azedo, seco ao sol e em estufa e amidos modificados pelos ácidos prevalentes na fermentação, secos em UVC. Todos os amidos foram comparados, quanto aos ácidos orgânicos, dos amidos secos em diferentes condições e apenas fermentados, sem secagem, bem com quanto às características físico-químicas e reológicas. Ficou comprovado que a secagem solar favorece um produto mais ácido e de maior expansão. O maior volume específico foi observado para a amostra fermentada seca ao sol, seguida das modificadas por ácido lático 0,5 % e ácido acético 0,5 % e ácido lático 1 %. A baixa expansão da amostra fermentada e seca em estufa (E) mostrou que apenas a presença dos ácidos orgânicos não é suficiente para expansão e que a radiação UV (artificial ou solar) influencia diretamente nessa característica.

The fermented cassava starch, polvilho azedo, has wide application in bakery products, due to expansion property without yeast and gluten, which leveraged the marketing of starches modified by acid. The cassava starch is fermented and sun dried, with the generation of acids: acetic, butyric, lactic and propionic, while starches modified by acid are not fermented. In this work was produced cassava starch, dried in the sun and under oven, and modified by the acids of cassava starch fermentation, dried in UVC. All starches were compared, as the organic acids, dry starches in different conditions and only fermented without drying, as well as with the physicochemical and rheological characteristics. It was proven that solar drying favors a more acidic product and expansion property. The higher specific volume was observed for the sample fermented sun dried, followed by modified by 0.5 % lactic acid and 0.5 % acetic acid and lactic acid 1 %. The low expansion of the fermented sample and dried in an oven showed that only organic acids is not sufficient for expansion and that UV radiation (solar or artificial) directly influences this characteristic.

Symbiotic potential and survival of native rhizobia kept on different carriers

Native rhizobia are ideal for use as commercial legume inoculants. The characteristics of the carrier used to store the inoculants are important for the survival and symbiotic potential of the rhizobia. The objective of this study was to investigate the effects of peat (PEAT), perlite sugarcane bagasse (PSB), carboxymethyl cellulose plus starch (CMCS), and yeast extract mannitol supplemented with mannitol (YEMM) on the survival, nodulation potential and N₂ fixation capacity of the native strains Sinorhizobium mexicanum ITTG R7^T and Rhizobium calliandrae LBP2-1^T and of the reference strain Rhizobium etli CFN42^T. A factorial design (4 × 3) with four repetitions was used to determine the symbiotic potential of the rhizobial strains. The survival of the strains was higher for PEAT (46% for strain LBP2-1^T, 167% for strain CFN42^T and 219% for strain ITTG R7^T) than for the other carriers after 240 days, except for CFN42^T kept on CMCS (225%). All the strains kept on the different carriers effectively nodulated common bean, with the lowest number of nodules found (5 nodules) when CFN42^T was kept on CMCS and with the highest number of nodules found (28 nodules) when ITTG R7^T was kept on PSB. The nitrogenase activity was the highest for ITTG R7^T kept on PEAT (4911 μmol C₂H₄ per fresh weight nodule h⁻¹); however, no activity was found when the strains were kept on YEMM. Thus, the survival and symbiotic potential of the rhizobia depended on the carrier used to store them.

Shock séptico en unidad de cuidados intensivos: Enfoque actual en el tratamiento / Septic shock in intensive care units: Current focus on treatment

Los pilares terapéuticos del niño con shock séptico se mantienen en el tiempo, sin embargo, se han incorporado nuevos conceptos, siendo importante que el pediatra y el intensivista tengan conocimiento a cabalidad de ellos. La reanimación con fluidos es una intervención fundamental, no obstante, aún no se ha establecido un tipo de fluido ideal, presentando cada uno limitaciones específicas, no existiendo evidencia sobre la superioridad de un tipo de fluido. Si a pesar de una adecuada resucitación con fluidos persiste el shock, el inicio de inótropos y/o vasopresores está indicado. En caso de refractariedad al uso de vasopresores, nuevos fármacos vasoactivos pueden ser empleados y el uso de hidrocortisona debe considerarse en niños con sospecha de insuficiencia suprarrenal. Existe controversia respecto a la transfusión de glóbulos rojos o el nivel óptimo de glucemia, no existiendo consenso en el valor umbral para el uso de estos hemocomponentes o el inicio de insulina, respectivamente. Asimismo, la utilización de la hemofiltración de alto volumen (HFAV)aún permanece controversial, requiriendo mayores estudios para su recomendación en forma rutinaria en el curso de un shock séptico refractario. El soporte nutricional es primordial, ya que la desnutrición es una grave complicación que debe ser prevenida y tratada adecuadamente. El objetivo de la presente revisión es entregar una actualización en los más recientes avances en tratamiento del shock séptico en la población pediátrica.

Essential therapeutic principles in children with septic shock persist over time, although some new concepts have been recently incorporated, and fully awareness of pediatricians and intensivists is essential. Fluid resuscitation is a fundamental intervention, but the kind of ideal fluid has not been established yet, as each of these interventions has specific limitations and there is no evidence supportive of the superiority of one type of fluid. Should septic shock persists despite adequate fluid resuscitation, the use of inotropic medication and/or vasopressors is indicated. New vasoactive drugs can be used in refractory septic shock caused by vasopressors, and the use of hydrocortisone should be considered in children with suspected adrenal insufficiency, as it reduces the need for vasopressors. The indications for red blood cells transfusion or the optimal level of glycemia are still controversial, with no consensus on the threshold value for the use of these blood products or the initiation of insulin administration, respectively. Likewise, the use of high-volume hemofiltration is a controversial issue and further study is needed on the routine recommendation in the course of septic shock. Nutritional support is crucial, as malnutrition is a serious complication that should be properly prevented and treated. The aim of this paper is to provide update on the most recent advances as concerns the treatment of septic shock in the pediatric population.

O trabalho no cárcere: reflexões acerca da saúde do agente penitenciário / El trabajo en la prisión: reflexiones sobre la salud del guardia penitenciário / The work in prison: reflections on the health of prison officers

RESUMO Objetivo: conhecer as condições de trabalho de agentes penitenciários e os reflexos do exercício da atividade laboral em sua saúde. Método: pesquisa descritiva, qualitativa. Os dados foram coletados por meio de entrevista aberta com agentes de um presídio regional e submetidos a análise de conteúdo na modalidade temática. Resultados: os resultados revelaram condições de trabalho insatisfatórias por deficiência de recursos materiais e descaso do poder público com as questões inerentes à ressocialização do apenado, resultando em exposição aos riscos psicossociais, insatisfação e desgaste emocional dos trabalhadores. Conclusão: investimentos na segurança dos trabalhadores podem contribuir para a promoção de sua saúde. .

RESUMEN Objetivo: conocer las condiciones laborales de guardias de prisión y las consecuencias del ejercicio de la actividad laboral en su salud. Método: investigación cualitativa y descriptiva. Los datos fueron recolectados a través de entrevistas abiertas con agentes de una cárcel regional y se sometieron a análisis de contenido en la modalidad temática. Resultados: los resultados mostraron condiciones insatisfactorias por la falta de recursos materiales y el abandono por parte del gobierno en los asuntos relacionados con la rehabilitación del condenado, lo que resulta en la exposición a riesgos psicosociales, la insatisfacción y el agotamiento emocional de los trabajadores. Conclusión: las inversiones en la seguridad de los trabajadores pueden contribuir a la promoción de su salud. .

ABSTRACT Objective: to understand the working conditions of prison offi cers and the repercutions of labor activity on their health. Method: qualitative and descriptive research. Data were collected through open interviews with the prison offi cers of a regional prision and the speeches were submitted to content analysis. Results: the results showed unsatisfactory working conditions due to poor material resources and neglect of governmental regarding rehabilitation of convicts, resulting in workers’ exposure to psychosocial risks, dissatisfaction, and emotional distress. Conclusion: investments on the security of workers may contribute to their health promotion. .

Estrutura dos grânulos de amido e sua relação com propriedades físico-químicas: [revisão] / Starch granules structure and its regards with physicochemical properties: [review]

Devido aos escassos trabalhos brasileiros sobre a estrutura dos grânulos de amido, o objetivo desta revisão foi demonstrar os avanços atuais na elucidação da arquitetura e da estrutura química desse polímero. Muitas pesquisas sobre a avaliação da relação existente entre a estrutura molecular do amido e seu comportamento em algumas propriedades físico-químicas sugerem que diversas características estruturais, tais como teor de amilose, distribuição de comprimento das cadeias de amilopectina e grau de cristalinidade no grânulo, estejam intimamente relacionadas a eventos associados à gelatinização e retrogradação, como inchamento do grânulo, lixiviação de amilose e/ou amilopectina, perda da estrutura radial (birrefringência), supra-molecular (cristalinidade) e molecular e recristalização. O foco principal desta revisão foi a compilação de estudos a fim de obter melhor entendimento da estrutura e das características dos componentes do amido e sua relação com propriedades físico-químicas, principalmente no que diz respeito à gelatinização e retrogradação, as quais apresentam grande importância nutricional e tecnológica.

Due to poor Brazilians work on the structure of starch granules, the purpose of this review was to demonstrate the advances in current understanding of architecture and chemical structure of this polymer. Many studies evaluating the relationship between the molecular structure of starch and its behavior in some physicochemical properties, suggest that several structural features, such as amylose content, amylopectin chain length distribution and the degree of crystallinity in the granule, are closely related to the events associated with gelatinization and retrogradation as starch granule swelling, amylose and/or amylopectin leaching, loss of radial structure (birefringence), supra-molecular (crystallinity) and molecular order, and recrystallization. The main focus of this review was to make a compiler of studies in order to gain better understanding of the granule structure and characteristics of starch components and physicochemical properties (gelatinization and retrogradation) that could play a significant role in improving the quality of different food products.

Relación entre la respuesta glicémica del almidón y su estado microestructural / Relationship between glycemic response of starch and its microstructural state

Se ha observado que alimentos que contienen almidón en cantidades similares pueden generar respuestas glicémicas diferentes. En este trabajo se realizó una revisión bibliográfica tendiente a estudiar uno de los factores que modelaría estas diferencias: el estado físico del almidón contenido en el alimento. Los resultados expuestos indican que el estado físico (que llamaremos microestructura) del almidón es uno de los factores principales a considerar, ya que determinaría cómo y qué fracción del total será digerida, lo cual a su vez determina cómo y cuánto será absorbido para su uso metabólico. Estudios tendientes a una mejor cuantificación, tanto de la microestructura como de la respuesta glicémica y efectos fisiológicos, parecen ser necesarios si se tiene como objetivo el poder diseñar alimentos que cumplan con requerimientos nutricionales específicos.

It has been observed that foods with similar amount of starch can generate different glycemic responses. In the present paper we review the one factor that probably determines these differences: the physical state of starch in food. The literature support the idea that the physical state (called microstructure) of starch is a very important factor because determine the rate and the total amount of glucose that will be released (in the digestion process) for absorption and metabolic use. Many studies relating the microstructure and glycemic response, and its physiological effects, are still needed to make new carbohydrate foods with specific nutritional requirements.

Aspecto físico-químicos e fisiológicos do amido resistente / Physical-chemical and physiological aspects of resistant starch

A presente revisão teve por objetivo estudar os fatores que influem na formação do amido resistente (AR) e sua proporção nos alimentos, visando auxiliar os profissionais da área de saúde no estabelecimento de recomendações dietéticas. O termo amido resistente é definido como a soma do amido e produtos da sua degradação que não são digeridos pelas enzimas humanas de indivíduos saudáveis. O amido e produtos foi abordado quanto a sua classificação e formação, bem como seus efeitos fisiológicos sobre o metabolismo intestinal, glicídico e lipídico. Verificou-se que não obstante comprovação das propriedades prebióticas do AR, os mecanismos sistêmicos dos ´´acidos graxos de cadeia curtos produzidos durante a fermentação e os efeitos sobrre as respostas glicêmicas e lipídicas ainda são conflitantes

Características químicas, físicas y reológicas de la harina y el almidón nativo aislado de Ipomoea batatas Lam / Chemical, physical and rheological characteristics of flour and native starch isolated from sweet potato (Ipomoea batatas Lam)

Se caracterizó la composición química y las propiedades físicas y reológicas de la harina y almidón, ambos obtenidos de la pulpa comestible de la batata (Ipomoea batatas Lam), a fin de mostrar el potencial de estos derivados como ingredientes en la formulación de productos alimenticios. Para lograr este objetivo, se evaluaron los siguientes parámetros: rendimiento y eficiencia de la extracción, composición proximal, contenido de amilosa, azúcares totales, azúcares reductores y no reductores, contenido de minerales, índice de absorción de agua (IAA) y de solubilidad en agua (ISA), separación de fases, pH, acidez titulable, parámetros reológicas y color. Se obtuvo una harina con un buen potencial nutricional: alto contenido de carbohidratos totales (59,80 por ciento) y con relativo aporte de fibra dietética total (7,33 por ciento) y fósforo (21,92 mg/100 g) a través de un proceso muy eficiente (97 por ciento). Asimismo, se obtuvo un almidón de alta pureza (99,25 por ciento), con relativo bajo contenido de amilosa aparente (16,40 por ciento). Los resultados mostraron diferencias significativas (p 0,05) en las propiedades reológicas del almidón, comparadas con las de la harina. Tanto el almidón como la harina presentaron características para ser usados en la industria de alimentos como ingredientes en una gama de productos alimenticios, tales como productos horneados, mezclas para tortas, mezclas para sopas y pastas de untar, entre otros.

This study characterized the chemical, physical and functional properties of the flour and starch obtained and starch isolated from the edible portion of sweet potato (Ipomoea batatas Lam). In order to fulfill the objectives, the following parameters were evaluated: extraction efficiency and yield, proximal composition, total sugar , reducing and non reducing sugars, starch and its relative amylose content, pH, titratable acidity and absolute density; water absorption index (WAI) and water solubility index (WSI), phase separation, rheological properties and color. Results pointed out that both highly pure starch (99.25 percent) and good nutritional quality flour may be easily obtained from sweet potato, with high total carbohydrate content (59.80 percent), and a relatively good dietary fiber (7.33 percent) and phosphorous (21.92 mg/100g) contents. Statistical significant differences (p<0.05) in the rheological properties of the starch and flour were also registered. Both starch and flour have excellent potential as ingredients for new product development.

Cambios físico-químicos del almidón durante la nixtamalización del maíz en variedades con diferente dureza de grano / Physicochemical changes in starch during corn alkaline-cooking in varieties with different kernel hardness

Changes in starch characteristics caused by alkaline-cooking in two corn genotypes (hard and soft) were studied in the present work. Color, pH, pasting properties (Brabender viscoamylograph), water sorption, solubility, swelling power and thermal analysis (Differential scanning calorimetry) were determined in starches previously extracted, from raw and alkaline-cooked hard and soft corns. A reduction in maximum viscosity peak, temperature at the endothermic peak and swelling power at 90 degrees C, and an increase in solubility was observed in starches obtained from both hard and soft corn after alkaline-cooking. Starch from hard corn showed an increment in initial pasting temperature after alkaline-cooking. Alkaline-cooking induced higher modifications in hard than in soft corn starch, probably as a result of its endosperm type and grain hardness, although optimum cooking times were used for each corn genotype.

Evaluacion de las caracteristicas quimicas y propiedades fisicas y reologicas del almidón extraído de dos especies de amaranto (Amaranthus cruentus y Amaranthus hypochondriacus) / Evaluation of the chemical characteristics and physical and rheological properties of the starch isolated from 2 amaranth species (Amaranthus cruentus y Amaranthus hypochondriacus)

En el presente trabajo se evaluaron algunas características químicas, propiedades físicas y el comportamiento reológico del almidón extraído de granos provenientes de cultivos experimentales de tres variedades de dos especies de amaranto granífero (Amaranthus cruentus y Amaranthus hypochondriacus). Para ello, en la primera fase del estudio se determinó el contenido de almidón en los granos de amaranto de las tres variedades por dos métodos: por diferencia y por el método hidrolítico. Posteriormente, se extrajo el almidón de las tres variedades de amaranto y se evaluaron sus características químicas (humedad, proteína cruda, grasa cruda, ceniza y amilosa), propriedades físicas (densidad y valor azul) y reológicas (viscosidad aparente, consistencia del gel, y corrido amilográfico). Los almidones extraídos presentaron alta pureza, con un contenido de proteína que varió en el intervalo de 0,90-0,93 por ciento, mientras que el almidón extraído de A. cruentus mostró el mayor contenido de grasa (2,63 por ciento). El contenido de amilosa de A. cruentus y A. hypochondriacus varió entre 12,47 y 12,61 por ciento, mientras que el almidón extraído de A. cruentus x A. cruentus presentó mayor contenido de amilosa (27,34 por ciento). Las propriedades reológicas de los almidones extraídos de las especies A. cruentus y A. hypochondriacus, presentaron curvas amilográficas y de viscosidad semejantes.

Properties of starch recovered from effuent of snack factories

Snack factories produce effluents, which are high in starch and suspended solids. The recovery of starch from effluent shows, besides a significant improvement of the effluent quality, a very promising substrate. Analysis for chemical composition, microscopic examination, colour measurements and viscosity of recovered starch paste were carried out. The result of analysis revealed that, the recovered starch met the Egyptian standards for edible starch. The colour quality was promising and just needs little purification. Recovered potato starch has several interesting, desirable characteristics. These include swelling power that results in high viscosity of the pastes. The excellent colloidal properties of recovered starch suggest a high spreading industrial potentiality in the near future for local market. Microscopic examination supported some of these findings

Production of extracellular protease by Streptomyces fradiae.

A new strain of Streptomyces fradiae, isolated and identified in our laboratory, was found to be a potential producer of protease enzyme. An enzyme yield of 285 P.U./ml. was obtained prior to optimization in a synthetic medium containing potato starch, potassium nitrate and trace salts by shake flask method. The carbon and nitrogen compounds play prominent role in the protease production. The maximum enzyme yield of 930 P.U./ml. (about 3-fold increase) was obtained with all optimum parameters such as pH. 7.0, with 3% jowar starch, 0.5% tryptone, 28 degrees C incubation temperature, with 1:20 medium to flask volume ratio and with 48 hrs. inoculum.

Immobilization of amyloglucosidase.

Enzymatic hydrolysis of starch for the production of glucose syrups of various compositions has assumed considerable commercial significance due to the extensive application of these syrups in food and beverage industries. Hydrolysis of starch to glucose involves liquefaction of the gelatinized starch with acid or thermostable alpha-amylase followed by saccharification to glucose by amyloglucosidase. Large scale saccharification of liquefied starch to glucose using soluble enzyme is time consuming and requires 48-72 hr at pH 4.5 and 55-60 degrees C. Since, by replacing soluble amyloglucosidase with immobilized enzyme, it is possible to reduce the conversion time, several methods have been tried to obtain a highly active and stable immobilized preparation capable of converting high concentrations of liquefied starch to glucose. However, till today, immobilized amyloglucosidase has not found industrial application as no immobilized system has shown high temperature stability and conversion efficiency comparable to that of the soluble enzyme.