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Certification and integration of environment with quality and safety – a path t...
Santos, Gilberto; Rebelo, Manuel; Barros, Siria; Pereira, MartinhaAccording to Wright [1] certification of products and processes began during the 1960’s in the manufacturing industry, as a tool to control and assure the quality/conformity of products and services provided by suppliers to customers/consumers. Thus, the series of ISO 9000 was published first time, in 1987 and it was been created with a flexible character, to be reviewed periodically. Later, were published othe...
Purificação de uma endo-poligalacturonase, produzida por Kluyveromyces marxianu...
Pereira, MartinhaDissertação de doutoramento em Engenharia Química e Biológica. ; Com o trabalho presente nesta dissertação pretendeu-se estabelecer procedimentos para a purificação da enzima endo-poligalacturonase, produzida pela levedura Kluyveromyces marxianus. Para tal foram usados os sistemas de duas fases aquosas. As estirpes provenientes da fermentação do cacau foram estudadas para encontrar a melhor produtora de enzima...
Liquid-liquid equilibrium phase diagrams of new aqueous two-phase systems : Uco...
Pereira, Martinha; You-Ting Wu; Madeira, Pedro; Venâncio, Armando; Macedo, Eugénia; Teixeira, J. A.The phase diagrams of Ucon 50-HB-5100 (Ucon) + ammonium sulfate (NH4)2SO4 + water, Ucon 50-HB- 5100 + poly(vinyl alcohol) 10000 (PVA 10000) + water, Ucon 50-HB-5100 + hydroxypropyl starch (Reppal PES 100) + water, and poly(ethylene glycol) 8000 (PEG 8000)-PVA 10000 systems were determined at 22 °C. Measurements at 30 and 40 °C were also done for each Ucon-salt system. A linear regression was used to calculate t...
Aqueous two-phase extraction using thermoseparating polymer : a new system for ...
Pereira, Martinha; You-Ting Wu; Venâncio, Armando; Teixeira, J. A.Aqueous two-phase partitioning of endo-polygalacturonase (endo-PG) produced by Kluyveromyces marxianus strains was studied, on systems containing the thermoseparating polymer Ucon 50-HB-5100 (a random copolymer of 50% ethylene oxide (EO) and 50% propylene oxide (PO)) as one of the phase-forming compounds. Ucon 50-HB-5100 (Ucon)–polyvinyl alcohol (PVA 10,000), Ucon 50-HB-5100–hydroxypropyl starch (Reppal PES100)...
Separation of endo-polygalacturonase using aqueous two-phase partitioning
You-Ting Wu; Pereira, Martinha; Venâncio, Armando; Teixeira, J. A.The partitioning of endo-polygalacturonase (endo-PG) in polyethylene glycol (PEG)–polyvinyl alcohol (PVA10 000) and PEG–hydroxypropyl starch (Reppal PES100) aqueous two-phase systems was studied, and revealed the possibility of using aqueous two-phase extraction to purify and concentrate endo-PG from its clarified fermentation broth. For the PEG8000– PVA10 000 system, endo-PG presented in the fermentation broth...
Characterisation of new aqueous two-phase systems using thermoseparating polymers
Pereira, Martinha; Madeira, Pedro; Wu, You-Ting; Teixeira, J. A.; Macedo, EugéniaAqueous two-phase systems (ATPS) are increasingly being used for separation of proteins, cells and viruses and some small molecular weight substances since they offer a gentle and friendly environment. The use of new thermoseparating polymers opens new opportunities to develop more efficient aqueous two-phase systems as they make possible polymer recycling just by temperature control. Phase diagrams for Ucon-(N...
Recovery of endo-polygalacturonase using polyethylene glycol-salt aqueous two-p...
Wu, You-Ting; Pereira, Martinha; Venâncio, Armando; Teixeira, J. A.The partitioning behaviour of endo-polygalacturonase (endo-PG) and total protein from a clarified Kluyveromyces marxianus fermentation broth in polyethylene glycol (PEG)-ammonium sulfate and PEG-potassium phosphate (pH=7) aqueous two-phase systems was experimentally investigated. Both the enzyme and total protein partitioned in the bottom phase for these two kinds of systems. The enzyme partitioning coefficient...
Isolation, screening, and characterisation of flocculating and pectinase produc...
Pereira, Martinha; Schwan, Rosane F.; Teixeira, J. A.Eleven strains of Kluyveromyces marxianus were studied to select the best producers of extracellular endo-polygalacturonase (endo-PG), using glucose and lactose as carbon source. Flocculation ability was also assayed. Four out of eleven strains produced more enzyme when glucose was used as substrate. Only one strain was a better endo-PG producer when lactose was used as carbon source, although producing less en...
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