Mesoscale investigation of the structural properties of unrefined cell wall materials extracted from minimally processed salads during storage

Cell walls in plants are polymeric composite systems, which determine the textural attributes of vegetal tissue. In this paper, results are presented on the investigation on the structural properties of cell wall materials (CWMs), intended for use as structuring materials in manufactured products. Specifically, CWMs were extracted from fresh and ripened minimally processed Valerianella locusta Laterr. At the tissue level, the structural resilience inferred by CWM varies with storage time, as it was evaluated both quantifying the membrane degradation and the mechanical characteristics of salads texture wilting. Mechanical spectra of the rehydrated CWM gel show the increase of the elastic character with the salad aging time. Stress relaxation spectra deduced from rheological study on water suspension of the extracted cell wall polysaccharides, showed fast and slow relaxation modes, whose ratio changed with the aging of the salad tissue. The use of unrefined cell wall materials (CWMs) in food formulations may infer naturalness to food offerings and this paper shows how CWM extraction from salad that underwent different time storage histories, can provide modulation of the functional properties of these structures in final manufactured products. (C) 2015 Elsevier Ltd. All rights reserved.