Chitosan Films in Food Applications. Tuning Film Properties by Changing Acidic Dissolution Conditions

Abstract

Food contamination due to the presence of microorganisms is a serious problem. New food preservation systems are being studied to kill or inhibit spoilage and pathogenic microorganisms that contaminate food and reduce the shelf life of products. Chitosan films with potential application to food preservation have witnessed great developments during the last years. Chitosan is a cationic polysaccharide with the ability to form films and possess antimicrobial properties. It is water-insoluble but can be dissolved in acidic solutions. In the present work, three different acids (acetic, lactic and citric) were used in chitosan dissolution and both, the resultant solutions and formed films were characterized. It was observed that chitosan water-acetic acid systems show the highest antimicrobial activity due to the highest chitosan charge density, compared to the mixtures with lactic and citric acid. This system showed also the higher solution viscosity compared to the other systems. Chitosan–acetic acid films were also the ones presenting better mechanical properties; this can be attributed to the fact that lactic and citric acids remain in the films, changing their properties, which does not happen with acetic acid. Films produced from chitosan dissolved in water/acetic acid system are resistant, while very fragile but elastic films are formed when lactic acid is used. It was demonstrated that a good selection of the type of acid not only facilitates the dissolution of chitosan but also plays a key role in the properties of the formed solutions and films.

Preparation and characterization of citric acid crosslinked chitosan‐cellulose nanofibrils composite films for packaging applications

“…The 2% chitosan solution was prepared in a 2% acetic acid aqueous solution. 44 The CNF aqueous gel was added in chitosan solution and dispersed well by mixing in a magnetic stirrer for 1 h at room temperature (20 ± 2 C). The CA was added slowly to the chitosan-CNF solution and was heated at 80 C for 15 min in a hotplate magnetic stirrer plate under continuous stirring to complete the crosslinking reaction.…”

Shellfish Chitosan Potential in Wine Clarification

“…In more detail, the sample outcomes depended-only in two out of four cases-on the interaction between the sample and the dissolving acid, namely when the higher ionic strength acids (SA, HCl) were used. These findings suggest that the variations depend on the mechanism of the primary amines protonation and probably on the CTS charge density [34]. No correlation between the calculated molecular weight and the clarification capacity was found, as the two MCs with the best clarifying capacity (F2 and F3) were those with the highest (84 kDa) and the lowest (30 kDa) molecular weight, respectively.…”

“…Several works explored the effects that different solvents have on chitosan properties, testing, for example, antimicrobial activities against bacteria and mold [19,32], CTS membrane properties and hydrophobicity [33], CTS film water vapor permeability [17], resistance, and elasticity [34]. However, no studies explored whether and how the choice of the acid used for the CTS dissolution influences wine clarification.…”

A handy skin wound dressing prepared by alginate and cationic nanofibrillated cellulose derived from solid residues of herbs

“…Polyelectrolyte complexation through electrostatic interactions could play a dominant role in governing the nanostructure of the obtained hydrogel dressing at a relatively lower amount of CCNF. In this case, part of SA was incorporated into the surfaces of CCNF, but the remaining SA with a high absolute value of zeta potential (correspondingly high charge density) could tend to an extended structure, leading to more entanglement of SA chains (Melro et al 2021). To a relatively small extent, physical entanglement among the fibrous CCNF still existed (as shown in Fig.…”