The influence of the pre-treatment of apple cell wall samples on their functional properties

Apple cell wall materials (CWMs) exhibiting different degrees of cell wall degradation were prepared by the application of maceration and liquefaction enzymes (control sample without treatment), and their physico-chemical properties were investigated. Different methods were used for the determination of the water binding behaviour and the rheological properties. It was found that the standardized analysis methods gave results of limited correctness depending on the sample type and on the sample pre-treatment. Aggregates, formed during the drying of apple CWM that was treated with liquefaction enzyme, could be re-dissolved by mechanical stress (stirring) during rehydration. The stirring improved the detected functional properties (water binding and rheology) of the material to a great extent. It has to be realized that the analysis methods including the sample pre-treatment have to be adapted to the type of sample material. Furthermore the investigations showed that the water binding properties of CWMs do not simply correlate with separate parameters such as porosity, pectin content or the remaining natural grown cell structure. Probably, the functional properties are influenced mutually and multivariately by many material attributes.