Optimização das condições de cultura da Saccharomyces Cerevisiae e de outros fungos produtores de oligossacáridos

Este estudo envolve o controlo e a optimização das condições de culturas dos microrganismos: Saccharomyces cerevisiae CCMI 396, S. cerevisiae v. lab., Aspergillus oryzae CCMI 125, Aspergillus japonicus CCMI 443, Fusarium oxysporum CCMI 866, Aspergillus niger CCMI 296 com vista à produção de oligossacáridos. Determinaram-se os parâmetros característicos das culturas de duas diferentes estirpes de Saccharomyces com diferentes fontes de carbono e em diferentes condições ambientais. O perfil de crescimento da S. cerevisiae CCMI 396 foi semelhante nos diferentes meios de cultura estudados, sendo a velocidade específica de crescimento mais elevada no meio com glucose a pH 5 e a 30°C (0,36h-1). A S. cerevisiae v. lab. Teve velocidade específica de crescimento idêntica nas mesmas condições da outra estirpe, no entanto, o perfil de crescimento foi diferente nos outros meios de cultura. Estudou-se o efeito da adição de sumo de laranja ou de tomate ao meio de cultura com sacarose e avaliou-se a evolução glucídica no meio de cultura durante o ensaio por HPLC com detector RI. Determinou-se a frutosiltransferase no sobrenadante e na fracção intracelular e determinou-se a evolução dos oligossacáridos. Numa segunda parte deste trabalho efectuaram-se culturas dos quatro fungos filamentosos com vista a avaliar a capacidade de produção, nomeadamente, de fruto­oligassacáridos. Os resultados mostraram que a espécie Aspergillus japonicus CCMI 443 originou, nas mesmas condições de cultura, valores superiores, sendo a percentagem de produção FOStotais/GluCtotais de 61% para as enzimas intracelulares e 40% para as enzimas no sobrenadante. ABSTRACT; This study involves control and optimization of the cultures of microorganisms: Saccharomyces cerevisiae CCMI 396, S. cerevisiae v. lab., Aspergillus oryzae CCMI 125, Aspergillus japonicus CCMI 443, Fusarium oxysporum CCMI 866, Aspergillus níger CCMI 296 for oligosaccharides production. Were determined the parameters characteristic of the cultures of two different strains of Saccharomyces with different sources of carbon and in different environmental conditions. The growth profile of S. cerevisiae CCMI 396 was similar in different cultures media, but the highest specific growth was obtained in a medium with glucose, pH 5, at 30°C (0.36h-1). S. cerevisiae v. lab. had similar growth profile in a medium with glucose but with others culture media was different. We studied the effect of adding orange juice or tomato to the culture medium with sucrose and evaluated the evolution glucidic in the culture medium during the test by HPLC with RI detector. Fructosyltransferase was determined in the extracellular and the intracellular fractions and determined the evolution of oligosaccharides. ln the second part of this work were carried out cultures of four filamentous fungi in order to assess production capacity, in particular, fructoligosaccharides. The results showed that the specie Aspergillus japonicus CCMI 443 originated in the same culture conditions, higher values and the percentage of production FOStotal/Guctotal of 61% for intracellular enzymes and 40% for extracellular enzymes.

Effect of edible coatings with essential oils on the quality of red raspberries over shelf-life

The objective of the present work was to develop stategies for raising the shelf-life of red raspberries (Rubus idaeus L.). The quality of red raspberries over shelf-life after coated with alginate plus Brazilian Citrus essential oils was evaluated. Edible coatings did not significantly influence the firmness loss, soluble solids content (SCC), and brightness of fruits over time, when compared to control, nevertheless all edible coatings with essential oils induced higher weight loss than those samples in which the essential oils were not incorporated. Fruits coated with alginate plus lime essential oil (0.2%) or orange essential oil (0.1%) after 15 days of storage had less red skin, but were darker than the remaining samples. The less red colour verified in these samples was also coincident with the lower concentration of anthocyanins at the end of the experiment as well as the lower capacity for scavenging ABTS free radicals or quenching singlet oxygen. The edible coatings supplemented with the essential oil of orange either at 0.1 % or 0.2 % were very efficient to control the yeasts and moulds growth after 15 days of storage. To control the development of aerobic mesophilic bacteria the use of essential oil of lemon 0.2% and essential oil of orange 0.1% were the most efficient. The essential oils used in the edible coatings did not significantly change the sensorial properties of the fruit. Cyanidin-3-O-sophoroside, cyanidin-3-O-glucosylrutinoside, cyanidin-3-O-xylosylrutinoside, cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside, pelargonidin-3-O-sophoroside, pelargonidin-3-O-glucosylrutinoside, pelargonidin 3-O-glucoside, pelargonidin 3-O-rutinoside were found in raspberries fruits. An unknown cyanidin derivative was also found in all samples, constituting 27.4% of total anthocyanin content.