Growth of Myriangium sp. in sabouraud medium: a new approach to the definition of kinetic parameters / Crescimento de Myriangium sp. em meio sabouraud: uma nova abordagem para a definição de parâmetros cinéticos

In this study, the yeast growth process was mathematically modeled and growth kinetic parameters were defined for two strains of Myriangium sp. (Y6511 and Y6512) in Sabouraud medium at temperatures of 26, 30 and 34 °C at time t varying from t0 = 0 h, tf = 36 h. Maximum cell concentrations were 30.50 g/L (Y6511 at 34°C) and 34.00 g/L (Y6512 at 34°C). The maximum specific growth rates calculated for strains Y6511 and Y6512 were respectively 0.30 and 0.28 h-1 in the growth condition at 26 °C after 11.5 h of growth (for Y6511) and 9.5 h of growth (for Y6512). Maximum biomass volumetric growth rates were 2.75 and 2.63 g/L.h for strains Y6511 and Y6512, respectively, at 26 °C. For strain Y6511, the unit increase in temperature (g/L.°C) raises the cell concentration to a maximum value of 0.27 g/L.°C in the process time of 9.55 h and temperature of 29.5 °C. Similarly, for strain Y6512, the unit increase in temperature raises the cell concentration to a maximum value of 0.45 g/L.°C in the process time of 7.35 h and temperature of 26.8 °C. The observed parameters can be used for the production of cell mass, in batch or continuous process, enzymes and other bioproducts of commercial interest

Rižine (Oryza sativa) mekinje i sojina (Glycine max) sačma kao nekonvencionalni dodaci u proizvodnji medovine

Research background. Due to the lack of nitrogen in honey, fermentation of honey must is limited or delayed, in addition to stimulating the production of unpleasant sensory compounds, such as sulfur derivatives. The use of natural supplements has been investigated as low-cost alternatives mainly to correct the nutritional deficiency of nitrogen in honey must in mead production. Experimental approach. Initially, the physicochemical characterization of the rice bran and soybean meal extracts was carried out. The fermentation of three yeasts (Saccharomyces bayanus Premier Blanc, Saccharomyces cerevisiae Montrachet and Saccharomyces cerevisiae Safbrew T-58) in honey must supplemented with 30 g/L rice bran or soybean meal extracts was evaluated. The trials were compared with the fermentations of the must with commercial supplement (30 g/L) and the control trials. Fermentations were carried out in Erlenmeyer flasks containing honey must with supplements, inoculated with 106 cell/mL yeast and incubated at 30 °C for 264 h. Results and conclusions. There was significant difference in the evaluated properties of the extracts, with the exception of reducing sugars. The fermentations with soybean meal extract reached the highest cell concentrations, as well as the largest consumption of glucose, fructose and ethanol. The glycerol concentrations slightly increased when soybean meal extract and commercial supplement were used. The highest concentrations of succinic and acetic acids were registered in the control trials produced by Saccharomyces strains Premier Blanc, Montrachet and Safbrew T-58. Formic and lactic acids were not produced. Results showed that the extracts can be used as low-cost alternatives for correcting the nutritional deficiency of nitrogen in honey must since their effect was similar to that of synthetic supplement. Novelty and scientific contribution. The use of low-cost, unconventional supplements such as those used in this work, in addition to reducing the cost of the process by reducing fermentation time and providing nutrients needed to improve yeast metabolism, prevents the formation of undesirable compounds in the beverage due to prolonged fermentation time. It also makes it possible to add value to industrial by-products. Unconventional supplements have still been little tested in mead production.Pozadina istraživanja. Vrenje meda ograničava ili usporava nedostatak dušika, koji uz to pospješuje nastanak spojeva nepoželjnih senzorskih svojstava, kao npr. derivata sumpora. U radu je ispitana primjena prirodnih dodataka kao jeftinih nadomjestaka koji korigiraju nedostatak dušika u moštu tijekom proizvodnje medovine. Eksperimentalni pristup. Prvo su opisana fizikalno-kemijska svojstva ekstrakata rižinih mekinja i sojine sačme. Zatim je ispitano vrenje meda s pomoću triju sojeva kvasaca (Saccharo¬myces bayanus Premier Blanc, Saccharomyces cerevisiae Montrachet i Saccharomyces cerevisiae Safbrew T-58) u moštu obogaćenom s 30 g/L ekstrakta rižinih mekinja ili sojine sačme. Rezultati tih eksperimenata uspoređeni su s rezultatima dobivenim vrenjem mošta s dodatkom 30 g/L komercijalnog suplementa, te s kontrolnim uzorcima. Vrenje mošta inokuliranog s 106 stanica kvasca po mL meda provedeno je u Erlenmeyerovim tikvicama inkubiranima na 30 °C tijekom 264 h. Rezultati i zaključci. Opažene su bitne razlike u svojstvima ekstrakata, osim u masenom udjelu reducirajućih šećera. Najviše stanica kvasaca dobiveno je vrenjem meda s dodatkom ekstrakta sojine sačme, pri čemu su kvasci potrošili najviše glukoze i fruktoze, te je dobiven najveći volumni udjel etanola. Koncentracije glicerola neznatno su se povećale pri dodatku sojine sačme i komercijalnog ekstrakta. Najveće su koncentracije jantarne i octene kiseline proizveli sojevi kvasaca Saccharomyces Premier Blanc, Montrachet i Safbrew T-58 u kontrolnim uzorcima. Pritom nije došlo do nastanka mravlje i mliječne kiseline. Rezultati pokazuju da se dobiveni ekstrakti mogu upotrijebiti za korekciju nedostatka dušika u moštu od meda, budući da su postignuti slični rezultati kao sa sintetičkim spojevima. Novina i znanstveni doprinos. Dodatkom ovakvih jeftinih nekonvencionalnih ekstrakata smanjuju se troškovi proizvodnje jer fermentacija kraće traje, a kvasci imaju dovoljno hranjiva, čime se sprječava nastanak nepoželjnih spojeva koji nastaju tijekom duljih fermentacija. Osim toga, korišteni industrijski nusproizvodi dobili su dodanu vrijednost. Primjena nekonvencionalnih suplemenata u proizvodnji medovine još nije dovoljno ispitana

Maracujá-amarelo (Passiflora edulis f. Flavicarpa): cinética da secagem artificial e natural da casca / Yellow passion fruit (Passiflora edulis f. Flavicarpa): kinetics of artificial and natural drying of the peel

O Brasil é o maior produtor mundial de maracujá. A polpa é a parte do fruto que é normalmente consumida, enquanto que cascas e sementes são considerados resíduos do seu processamento, não sendo devidamente aproveitados pelas indústrias. O objetivo do trabalho foi avaliar o efeito da temperatura na desidratação artificial e natural da casca do maracujá-amarelo. Os ensaios de secagem artificial foram realizados em secador nas temperaturas de 30, 40, 50, 60 e 70 ºC durante 6 h. Na secagem natural as cascas foram colocadas em bandejas de aço inoxidável, cobertas com telas de náilon sendo expostas ao sol (25 a 38ºC) durante 375 h. O teor de água inicial das cascas do maracujá (aproximadamente 64,2% b.u.), sendo reduzido para 61,2; 58,9; 35,5; 7 e 30,7% b.u. nas temperaturas de secagem, respectivamente. O uso de 60 oC proporcionou a maior perda de umidade, de vitamina C e um aumento da acidez titulável e do teor de sólidos solúveis. Os modelos de Structural Transition 2 (R2 = 0,9934); Structural Transition 2 (R2 = 0,98498); Wang Sing (R2 = 0,9078); Two Term (R2 = 0,9961) e Structural Transition 3 (R2 = 0,9907) descreveram melhor os processos artificiais nas temperaturas de 30 a 70 oC. O teor de água inicial (63,2%) nas amostras submetidas à secagem natural diminuiu entre 75 e 97% nas primeiras 96 h de secagem atingindo valores próximos a 2% após 250 h. A secagem natural permitiu uma maior perda de umidade em baixas temperaturas (30 a 40 ° C) do que no processo artificial (4,8 e 8,3%). O uso de condições naturais poderiam reduzir os custos do processo e ser um método de secagem mais favorável para a agricultura familiar.  

Proposal of the Polygonal Model for Representing Biomolecules as a Tool for Teaching Metabolism

INTRODUCTION: Fischer projections are widely used for representing organic molecules, including the intermediates of metabolism. With the high number of molecules involving in metabolic processes and sometimes the relatively short time of learning of metabolism available for the students, it would be very useful an easier way to learn the structure of biomolecules and the involved reactions in metabolic pathways. OBJECTIVES: In this work it is presented the polygonal model, which consists in a new form of notation of biomolecules using geometric forms for representing the chemical groups in a biomolecule. MATERIALS AND METHODS: In this model, the carbonic chain is presented vertically using points of intersection or small black circles for carbon atoms, triangles, squares and circles represent, respectively, the hydroxyl, carbonyl and carboxyl groups, and the phosphate and amine groups are showed as, respectively, as yellow and blue circles. The stereoisomers and cis-trans isomers are clearly distinguishing as well. A form of familiarizing the student with the proposed notation can be to make an activity in class, furnishing a material which includes a short explanation of the model using examples, and some proposed activities of “transforming” molecules to polygonal model form from Fischer projections, and vice and versa. DISCUSSION AND RESULTS: It was observed that the average time necessary to complete this activity was less than 40 min. Polygonal model found to have several advantages, as no loss of information of the molecule, the simplicity to show the reactions in a metabolic pathway, good receptivity by the students, capacity to diagnostic misconceptions of the students in organic chemistry. CONCLUSION: This method is much faster to represent the molecules. This is important in the dynamics of the class

Modelagem e superfície de resposta da produção de bioetanol a partir de amido por leveduras silvestres em batelada simples

O bioetanol compreende os processos de obtenção do etanol em que a matéria-prima é a biomassa, tal como celulose, cana-de-açúcar ou milho. Este trabalho objetivou investigar o comportamento de leveduras sob fermentação em batelada simples para produção de etanol a partir de amido e analisar as condições de processo para maximizar a concentração deste álcool. O ajuste matemático foi inspirado na Equação de Transporte de Boltzmann. Na reação sem aeração, o valor máximo foi de 0,81 g/L de etanol, menos da metade do valor obtido sob aeração (1,64 g/L). As aproximações obtidas denotaram altos valores para os coeficientes de determinação calculados. A estratégia de modelagem demonstra possibilidade de estudo de variáveis de processo mesmo em condições de escassez de fatores. A equação de ajuste explica de maneira harmônica o comportamento observado em bancada e permite avaliação do processo para a produção de etanol a partir da biomassa em maiores escalas