Physico-chemical and viscoelastic properties of high pressure homogenized lemon peel fiber fraction suspensions obtained after sequential pectin extraction

The viscoelastic properties of high pressure homogenized lemon peel cell wall fiber suspensions, obtained after sequential selective pectin extraction, were investigated in the current study. For comparison, a general pectin extraction was additionally performed on lemon peel under acid thermal conditions. The obtained insoluble residues and solubilized pectin fractions were characterized based on their neutral sugar and galacturonic acid content, degree of methoxylation and molar mass distribution. Subsequently, microstructure and viscoelastic characteristics of the diverse insoluble residue suspensions were investigated by means of microscopic visualization, determination of the particle size distribution and rheological properties after high pressure homogenization. Due to the use of different extraction conditions, the insoluble cell wall residues were found to have diverse pectin characteristics and contents. While homogenization of non- or moderate-depleted cell wall suspensions resulted in small viscoelastic moduli due to the disruption of the stiff microfibrillar cell wall network, extensive pectin removal was found to correlate to large viscoelastic moduli of the cell wall suspension upon high pressure homogenization. It is suggested that an extensive pectin extraction resulted in the creation of interfibrillar voids within the cellulose-hemicellulose network, increasing the cell wall flexibility and hydration of the fibers upon suspension. Due to the increased flexibility of this fiber network, the interfibrillar voids in the pectin depleted cell wall material were proposed to expand with increasing pressure level during high pressure homogenization of the generated cell wall suspensions, thereby increasing its viscoelastic properties.

Publication year:2017

BOF-keylabel:yes

IOF-keylabel:yes

BOF-publication weight:10

CSS-citation score:2

Authors from:Private, Higher Education

Accessibility:Open