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The purpose of this study was to examine some fundamental aspects of the particle formation during spray drying, related to particle size and density. Particles were prepared in a laboratory spray dryer from carbohydrates with different solubility and crystallization propensity, such as lactose, mannitol, and sucrose/dextran 4:1. The feed concentrations ranged from 1% w/w to saturated and the size
This study investigates to what extent an aqueous two-phase system (ATPS) can encapsulate and protect the secondary structure of a protein during spray drying. The ATPSs contained polyvinyl alcohol (PVA) and dextran solutions, in different proportions. A model protein, bovine serum albumin (BSA) and, in some experiments, trehalose were added to the ATPS prior to spray drying. Electron spectroscopy
Fat encapsulation in spray-dried protein-stabilised emulsions is known to depend on the choice of protein, the emulsion droplet size, and the melting point of the fat. However, the fat encapsulation may also depend on the fat crystal habit. Fats may crystallise in three different forms α, β′ and β, of which the β-form is thermodynamically stable. The α-form is obtained in rapidly cooled fats, and
To find means of controlling the size and density of particles intended for inhalation the relationship between droplet and particle size during spray drying was investigated. Lactose solutions were atomized with a two-fluid nozzle and dried in a laboratory spray drier. The effects of nozzle orifice diameter, atomization airflow and feed concentration on droplet and particle size were examined. Ma
Microencapsulation of fish oil was achieved by spray-drying homogenized emulsions of fish oil using 3 different types of casein as emulsifier and lactose as filler. As the degree of aggregation of the casein emulsifier increased, the vacuole volume of the microencapsulated powders decreased. The shelf life of the powders increased as the degree of aggregation of the casein emulsifier increased at
Several important technical properties of spray-dried food powders depend on particle-liquid interactions (e.g. wettability, dispersability) and particle-particle interactions (e.g. flowability). It can be assumed that the chemical composition of the surface layer of the particles to a large extent determine these properties. The present study has been aimed to investigate the relation between the
Spray-drying has been investigated as a method for preparation of dry formulations of live bacteria with high viability and high cell density. The concept used in this study has been to disperse the bacteria in an aqueous polymer containing two-phase system (ATPS), compatible with the micro-organisms. The cells partition to one phase, which is separated from the other phase in a droplet dispersion
This investigation describes a novel concept in the formulation of carrier systems for the spray-drying of biological materials. As carrier material a system composed of poly(vinyl pyrrolidone) (PVP) and dextran was used. This system yields an aqueous two-phase system in which each phase is enriched in one of the polymers. By varying the composition of the system, the effective structure of a 'sti
In the present study trypsin mixed with various carbohydrates, i.e. lactose, sucrose, mannitol, α-cyclodextrin and dextrin, was spray-dried in order to investigate the effects of spray-drying on this enzyme, with particular emphasis on the effects of interactions between trypsin and the surface formed during spray-drying. The protein was strongly over-represented at the surface of the powder parti
In the present investigation freeze-drying of proteins (BSA or trypsin) together with various carbohydrates, i.e. lactose, sucrose, mannitol, α-cyclodextrin and dextrin, has been studied with particular emphasis on the surface composition of the freeze-dried powders. The proteins were found to be over-represented on the powder surface as compared to the bulk concentration of protein. The mechanism
A simple and flexible chemoenzymatic route for the preparation of a wide range of dimeric (gemini) and trimeric mono- and disaccharide-based surfactants was developed. The synthesis relies on the use of enzymes for regioselective introduction of fatty acids into carbohydrate moieties. Several structures were prepared containing xylose, glucose, galactose, and lactose, connected via different hydro
Enzymatic transglycosylation in supersaturated solutions of substrates was investigated using crude glycosidase preparations from barley, snail, and coffee beans. It was shown that the use of supersaturated glycoside solutions as media for transglycosylation reactions offers considerable advantages over conventional aqueous systems. These advantages include higher yields, more efficient use of the
The results of an initial study of enzymatic catalysis in metastable supersaturated solutions of carbohydrates are presented. It has been shown that such solutions, formed in the presence of small amounts of water and alcohol as plasticizers, are sufficiently stable under ambient conditions to enable enzymatic transformations of substrates. A partial phase diagram for a system consisting of glucos
Three ethoxylated glycosides, tetraethylene glycol β-D-glucoside, tetraethylene glycol β-D-xyloside, and methoxy triethyleneglycol β-D- glucoside, were prepared via almond β-glucoside-catalyzed (trans)glycosylation carried out in supersaturated solutions of glucose or p- nitrophenyl β-D-xyloside and the respective polyethylene glycols. The products were isolated and further modified by enzymatic e
Climate change manifests historically and spatially in uneven geographies of responsibility, vulnerability and adaptation. Urban and tourism expansion on the city’s margins in Cartagena, Colombia, has led to the criminalization and dispossession of land, water, and mangroves in Black communities who resist racism, ecological degradation, and climate vulnerability. We analyse how Black women in mar
Det finns en osäkerhet rörande rollfördelningen i samband med lärarstudenters VFU. Såväl lärarstudenter som handledare och VFU-lärare efterfrågar mer och tydligare information om vad man förväntas prestera utifrån den roll man har, enligt en ny avhandling i utbildningsvetenskap.
Unga är inte mindre politiskt engagerade i dag än tidigare. Men deras politiska handlande söker sig nya former. När Elisabeth Kring analyserar skolstrejk för klimatet med hjälp av filosofen Hanna Arendts idéer växer en komplex bild av relationen mellan vuxna och barn fram. Krings forskning gör det möjligt att tänka kring skolstrejkande elever på ett helt nytt sätt. De överger inte skola och barndo
Forskning om skolbyggnader och utbildningsmiljöer är ett växande och mångvetenskapligt område. Ord som ny, innovativ och modern är vanliga i skolbyggnadsprojekt och skapar en bild av att vi befinner oss i en brytningstid. Den upplevelsen intresserar forskningen.
I den allmänna debatten talas det ofta om skolans kris. En ny antologi undersöker varför och ger samtidigt läsaren redskap för att sätta krisutropen i ett politiskt och historiskt sammanhang.
Läraren och det litteraturdidaktiska ledarskapet spelar en större roll för elevernas intresse än vad tidigare forskning har uppmärksammat. Det visar Jonas Johansson i sin studie av gymnasiets litteraturhistorieundervisning.
