Chitosan/pectin polyelectrolyte complex as a pH indicator

Abstract

A polyelectrolyte complex (PEC) matrix formed between chitosan and pectin was developed to entrap a bioactive compound (anthocyanin), obtaining an useful pH indicator device. Polysaccharides of opposite charges such as chitosan and pectin can have a very strong intermolecular interaction. The innovation lies in obtaining a new system based on natural and biodegradable compounds, which is simple to manufacture, to indicate variation in pH by visual changes in colour. This device has potential applications in food packaging. The PEC was studied using chitosan and pectin solutions at different pHs values (3.0, 4.0, 5.0 and 5.5) and pectin/chitosan molar ratios (1.0 to 10/1.0 to 5.0). PEC films were homogeneous and showed the highest yield (60.0%) at pH 5.5. Diffusion tests indicated efficient bioactive compound entrapment in the PEC matrix. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy indicate the compatibility between the polymers and bioactive compound.

Preparation of a visual pH-sensing film based on tara gum incorporating cellulose and extracts from grape skins

“…The spectrum of EGS-10 had weak adsorption at 1732 cm -1 ; and shoulder peaks at 2890-2936 and 1630 cm -1 , which became sharper with EGS addition compared with EGS-0 spectra. There were no significant band shifts in the EGS-10 spectrum, indicating the EGS had no specific interactions with the TG/NCC matrix and EGS was merely entrapped in the matrix [24]. Table 1 shows the color parameters (L*, a*, b* and ΔE ) of TG/CNC films with and without EGS at various levels.…”

Nutritional improvement of pasta with Pereskia aculeata Miller: a non-conventional edible vegetable

“…Ot was calibrated with a white plate, an observation angle of 2° and illuminant D65. Measurements were performed using the COE L* a* b* system (Maciel et al, 2015).…”

Reversible swelling behaviour of Diels–Alder clicked chitosan hydrogels in response to pH changes

“…As expected, higher roughness values were observed for CsFu:BMI 1:2 sample, supporting our previous results. The pH sensitivity of chitosan-based hydrogels through the protonation of amino groups below the pK a (6.2-6.5) [39] lead to volume changes of hydrogels (swell), whereas the opposite effect is normally observed when the pH increases (shrink) [40][41][42]. The degree of swelling at equilibrium in different media of these Diels-Alder cross-linked hydrogels was studied in our previous work [12], where this trend was clearly observed.…”