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- Walther, Bernhard, et al.
(författare)
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Flow processing and gel formation : A promising combination for the design of the shape of gelatin drops
- 2002
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Ingår i: Food Hydrocolloids. - 0268-005X .- 1873-7137. ; 16:6, s. 633-643
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Tidskriftsartikel (refereegranskat)abstract
- This investigation is a model study on how drops can be structured by a combination of flow processing and gel formation. Different drop shapes were created by subjecting gelatin drops to various flow conditions. At the same time, temperature induced gel formation of the drops fixed the shape. Elongated drops and drops of complex form were created. The flow to shape the gelatin drops was generated in a 4-Roll Mill (4RM) and silicon oil was used as the continuous phase. During processing in the 4RM, the drops were allowed to follow two different streamlines and thereby being subjected to purely elongational and a mixture of shear and elongational flow. The drop size varied between 1.5 and 2.8 mm. The gelatin drops were temperature conditioned before the experiment to 60 °C and the silicon oil to 5 °C. The drops were cooled via the cold oil phase during the flow process, and gel formation was induced. A gel strength strong enough to resist further deformation was achieved at different fixation zones in the 4RM, and this depended on the process parameters of flow type, flow rate, drop size and gelatin concentration. The shape created was directly related to the fixation zone. There was a broad freedom to combine different parameter values to fix a drop in a certain fixation zone. The mechanism behind the various drop shapes is explained in terms of elongation, relaxation, pinching and gel formation in relation to flow pattern and time in the 4RM. Elongation is a major contribution to the mechanism in the case of elongated shapes, while elongation followed by relaxation and pinching are the dominant determinants in the creation of complex shapes. © 2002 Elsevier Science Ltd. All rights reserved.
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