Impact of high pressure homogenization modification of a cellulose based fiber product on water binding properties

• Mechanical modification of a dietary fiber using high pressure homogenization.
• Porosity of the fibrous material is strongly affected by the mechanical treatment.
• Water binding is primarily linked to structural parameters like porosity.
• Water binding changes systematically on mechanical treatment.
• Increased non-freezable bound water with increased modification.

A commercial dietary fiber was mechanically modified by treating a suspension in a high pressure homogenizer. Different drying methods were applied prior to examining macroscopic and water binding properties. DSC experiments show that more water is bound non-freezable with increasing mechanical modification. Capillary suction method and centrifugation experiments confirm that the water binding capacity changes systematically on mechanical treatment. Rheological studies confirm that the modification has a profound effect on the physico-chemical properties of the fibers. Samples with higher water binding capacity result in gel-like structures relating to higher specific volumes or swelling and possibly increased mutual entanglement. The water binding is primarily linked to structural parameters, such as porosity and does not increase any further once additional mechanical treatment does not further lead to increased porosities. Electron microscope images support the experimental findings.Effects of mechanical treatment supersede the impacts of the different drying methods. However, more gentle drying methods such as freeze drying and water-ethanol-extraction-drying yield in general higher water binding capacities than spray drying and oven drying.The study documents that the profound effect of mechanical treatment on the water binding capacity of a cellulose based fibrous material is strongly related to the porosity of the dried samples.

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