Plasticizing Effects of Polyamines in Protein-Based Films

Abstract

Zeta potential and nanoparticle size were determined on film forming solutions of native and heat-denatured proteins of bitter vetch as a function of pH and of different concentrations of the polyamines spermidine and spermine, both in the absence and presence of the plasticizer glycerol. Our results showed that both polyamines decreased the negative zeta potential of all samples under pH 8.0 as a consequence of their ionic interaction with proteins. At the same time, they enhanced the dimension of nanoparticles under pH 8.0 as a result of macromolecular aggregations. By using native protein solutions, handleable films were obtained only from samples containing either a minimum of 33 mM glycerol or 4 mM spermidine, or both compounds together at lower glycerol concentrations. However, 2 mM spermidine was sufficient to obtain handleable film by using heat-treated samples without glycerol. Conversely, brittle materials were obtained by spermine alone, thus indicating that only spermidine was able to act as an ionic plasticizer. Lastly, both polyamines, mainly spermine, were found able to act as “glycerol-like” plasticizers at concentrations higher than 5 mM under experimental conditions at which their amino groups are undissociated. Our findings open new perspectives in obtaining protein-based films by using aliphatic polycations as components.

Starch-Based Coatings for Preservation of Fruits and Vegetables

“…However, they were more permeable to O 2 , which was associated with the high concentration of plasticizer in the dry coating. In fact, plasticizers are used to decrease the intermolecular attractions between adjacent polymeric chains, which in turn facilitates the molecular mobility and diffusion of the gas molecules through the polymer network [28,42].…”

Black Edible Films from Protein-Containing Defatted Cake of Nigella sativa Seeds

“…PC was obtained from NsDSC by acid base extraction method as previously described [10] with some modifications. Dry NsDSC was ground using a rotary mill (Grindomix GM200, Retsch GmbH, Haan, Germany) at a speed of 1200 rpm.…”

“…The instrument software programmer calculated the zeta potential through the electrophoretic mobility by applying a voltage of 200 mV using the Henry equation. The pH value of PC solution was adjusted at pH 12.0 by using 1.0 N NaOH and then the titration was carried out from pH 12.0 to pH 2.0 by adding 1.0, 0.5, and 0.1 N HCL as titrant solution under constant stirring at 25 • C. Z-average and zeta potential values were measured at each pH value in triplicate [10,41].…”

“…Different seeds are widely used to produce vegetable oils or animal feed. Those from soy, sesame, and bitter vetch have been shown to be potential sources of biodegradable/edible films [8][9][10][11][12]. In fact, after oil extraction, the leftover cakes may contain up to 50% recyclable proteins that may produce bio-materials.…”

Starch based coatings with thyme essential oil for fruit preservation

“…However, they were more permeable to O2, which was associated with the high concentration of plasticizer in the dry coating. In fact, plasticizers are used to decrease the intermolecular attractions between adjacent polymeric chains, which in turn facilitates the molecular mobility and diffusion of the gas molecules through the polymer network Sabbah et al, 2017).…”