The effect of glass transition on the desired and undesired agglomeration of amorphous food powders

Palzer, Stefan

doi:10.1016/j.ces.2005.02.015

Cited by 182 publications

(115 citation statements)

References 19 publications

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“…carbohydrates and fats). When the surface reaches the sticky state, collisions with other particles (sticky or dry) could lead to agglomeration, depending on velocity, force, angle and time of contact between particles [5,11].…”

Section: Introductionmentioning

confidence: 99%

Powder agglomeration during the spray-drying process: measurements of air properties

Gianfrancesco

Turchiuli

Dumoulin

2008

Dairy Sci. Technol.

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-Instant food powders are usually produced by spray drying of formulated liquid and powder agglomeration, either into the drying chamber or in an external fluid bed. During spray drying, according to the liquid composition, the viscosity of the initial liquid drops increases more or less rapidly, until the drop surface reaches a rubbery state considered as sticky, before further drying. This sticky property may be used to produce agglomerates inside the chamber by adding dry solid particles, as fines. The present study deals with a methodology to identify regions where the drying drops are sticky in relation to drying conditions (inlet air temperature 144-159-174 • C, liquid flow rate 15 to 75 mL·min −1 ), using a co-current pilot spray dryer with rotary atomizer. Assuming that drying air properties' (temperature and humidity) evolution is representative of drop drying (drying rate, amount of evaporated water), we realized a map of temperatures and relative humidity for drying air inside the drying chamber. Trials were performed with water (feasibility) and a maltodextrin aqueous solution (40% w/w, DE12) as a model product with sticky properties during drying. The results showed that drying behavior was different for water and aqueous maltodextrin solution. For both, in the tested conditions, the percentage of evaporated water was found to vary from 57 to 89% in the top part of the chamber, close to the atomizer. That represents a possible region where dry fines could be introduced for agglomeration. Résumé -Agglomération de poudres au cours du processus de séchage par pulvérisation : mesure des propriétés de l'air. Les poudres alimentaires instantanées sont habituellement produites par séchage par pulvérisation d'une solution formulée, suivi d'une étape d'agglomération, soit dans la chambre de séchage soit dans un lit fluidisé externe. Au cours du séchage, selon la composition du liquide, la viscosité des gouttes liquides augmente plus ou moins rapidement jusqu'à ce que la surface de la goutte devienne collante, avant séchage ultérieur. Cette propriété collante peut être exploitée pour produire des agglomérats dans la chambre par introduction de particules solides sèches, les fines. Cette étude cherche à établir une méthodologie pour identifier des zones où les gouttes qui sèchent deviennent collantes en fonction des paramètres de séchage (température d'entrée d'air 144-159-174 • C, débit liquide de 15 à 75 mL·min −1 ), en utilisant un séchoir pilote co-courant équipé avec une turbine de pulvérisation. En supposant que l'évolution des propriétés de l'air (température et humidité) au cours du séchage soit représentative du séchage des gouttes (vitesse de séchage, quantité d'eau évaporée), des cartographies des températures et des humidités relatives de l'air dans la chambre de séchage ont été réalisées. Des essais ont été effectués avec pulvérisation d'eau (faisabilité), puis d'une solution de maltodextrine (40 % w/w, DE12) comme produit modèle pouvant avoir un comportement collant au cours du séchage. ...

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Section: Introductionmentioning

confidence: 99%

Powder agglomeration during the spray-drying process: measurements of air properties

Gianfrancesco

Turchiuli

Dumoulin

2008

Dairy Sci. Technol.

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“…Low temperature and low water content increase the viscosity of a liquid finally resulting in a brittle glass. Due to the high viscosity, stability of the incorporated biological compound is maintained for a long period of time (Stefan Palzer, 2005). Figure 16 shows the glass transition temperature curve for glucose syrup (dextrose syrup with a dextrose equivalent DE of 21).…”

Section: Starch and Sugar Productsmentioning

confidence: 99%

“…By this idea it is possible to guess the viscosity and the Young's modulus for a given amorphous substance while knowing their glass transition temperature in dependence on the water content. Knowing the viscosity and the Young's modulus and applying equations derived from the sintering technology or the theory of viscoelasticity it is possible to define suitable conditions for most of the agglomeration processes (Stefan Palzer, 2005).…”

Section: Starch and Sugar Productsmentioning

confidence: 99%

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The Significance of Glass Transition Temperature in Processing of Selected Fried Food Products: A Review

Abbas¹,

Lasekan²,

Khalil³

2010

MAS

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This paper emphasized the significance of the glass transition temperature (Tg) by highliting its applications in drying (hot air and freeze drying) for various food systems such as skim milk powders, rice kernels, starch and sugar products and some freeze-dried products such as strawberries and surimi. The study revealed that the major components of the specified foods (which consist of mixture of ingredients), for example lactose in skim milk powder and sucrose in sugar mixtures, will influence the glass transition temperature of the food. Moreover, Tg is an important parameters for determining the optimum processing conditions of dried products. Thus, it is used in designing drying equipment to meet the purpose. In general, Tg affects the physical properties of food such as stickiness, caking and agglomeration. The effect of moisture content on Tg was covered by almost all studies focusing on Tg of foods. Meanwhile, the effect of pressure on Tg was not well covered due to its scarce availability in the existing literature. In term of test methods for determining the Tg of foods, it seems that not all test methods are suitable for certain type of foods, accordingly, more study on the recommended test methods should be carried out.

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“…The focus is to obtain an instant drink with adequate solubility without fine powder, which can cause problems during processing and handling (Iveson et al, 2001;Knight, 2001;Palzer, 2005).…”

Section: Cocoa Beverage Powder and Steam Agglomerationmentioning

confidence: 99%

Morphological characterization with image analysis of cocoa beverage powder agglomerated with steam

Vissotto

Giarola

Jorge

et al. 2014

Food Sci. Technol (Campinas)

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In this study, the morphological characteristics of cocoa beverage powder granules under minimal, average, and maximal process conditions of a steam agglomerator were studied. a stereoscopic microscope coupled to a digital camera was used for the morphological analysis. The images were analyzed to obtain shape and size descriptors. aiming to evaluate the descriptors, 150 particles were analyzed. The results showed that there was no difference between the shape descriptors -compacity, circularity, roughness, and aspect ratio -in the operating conditions evaluated. It was observed that the cocoa beverage powder granules are elongated in shape. The size descriptors, area, perimeter, perimeter of convex bounding polygon, minimal and maximal Feret diameter, were different in the process conditions for the granules of size above 600 μm. as for the minimal process conditions, especially due to low solid feed rates, there is an increase in the size descriptor values. In addition, under the minimum process conditions, in which there is low solid feed rate (400g/min) for a steam pressure of 1.0 bar, it was obtained a good granular condition with retention of 81.1% of granules on sieves with aperture size between 300 and 1190 µm.

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The effect of glass transition on the desired and undesired agglomeration of amorphous food powders

Cited by 182 publications

References 19 publications

Powder agglomeration during the spray-drying process: measurements of air properties

Powder agglomeration during the spray-drying process: measurements of air properties

The Significance of Glass Transition Temperature in Processing of Selected Fried Food Products: A Review

Morphological characterization with image analysis of cocoa beverage powder agglomerated with steam

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