Chitosan tailor‐made films: the effects of additives on barrier and mechanical properties

Abstract

With the aim of achieving 'tailor-made' chitosan fi lms, the effects of several variables on the properties of chitosan fi lms were studied. These variables were chitosan concentration and molecular weight of thermally depolymerized chitosan, addition of lipids (palmitic acid, beeswax or carnauba wax) and plasticizer (glycerol). The water vapour transmission rate (WVTR) and mechanical properties of these fi lms were measured. The innovative feature of this study is that it provides specifi c information to support the design of tailor-made fi lms. These can only be formulated when the effects of the important variables are well understood. It was found that WVTR was reduced by 57% in fi lm made from chitosan that had been thermally treated for 7 h at 100°C (molecular mass 13.7 kDa), while in the emulsion fi lms, the WVTR was increased by incorporation of palmitic acid, beeswax or carnauba wax incorporation. The mechanical properties (tensile strength and elongation at break) were improved when glycerol was used as plasticizer, resulting in more elastic fi lms (increasing the elongation at break by 62%).

Changes in hyphal morphology due to chitosan treatment in some fungal species

“…anionic groups) and consequently, reducing their availability to a level that will not sustain growth of the pathogen form the films (Bautista-Baños et al 2006). The present results suggested that this barrier to water soluble nutrients could be most effective for chitosans of lower molar mass and low F A , since it was observed that the water permeability of chitosan films was 50% reduced when molar mass of the original chitosan was reduced from 235 kDa (DP 1,383) to approximately 13.7 kDa (DP 45), which was also reported by Yoshida et al (2008). Chitosan coating observed on the surface of the mycelia suggested that the fungal growth inhibition could be explained by a direct interaction of chitosan on the fungal cell wall as a consequence of polycationic nature of chitosan.…”

Preparo e caracterização de filmes comestíveis de quitosana

“…Para o preparo dos filmes das amostras de quitosana seguiu-se o procedimento descrito por Yoshida et al [16] . Os filmes foram preparados dissolvendo as amostras de quitosana em solução de ácido acético 1% nas concentrações 0,25, 0,5, 1,0 e 1,5%.…”

Sistemas inteligentes de embalagens utilizando filmes de quitosana como indicador colorimétrico de temperatura

“…A metodologia de produção foi adaptada de [15] . Os filmes foram produzidos por via úmida, solubilizando 2,00 g/100 g de suspensão filmogênica de quitosana, contendo o indicador colorimétrico clorofila na concentração de 0,25 g/100 g. Ácido acético foi adicionado estequiometricamente, de acordo com o grau de acetilação e massa de quitosana, para promover a protonação dos grupos NH 2 [32] .…”

“…Nesta última década, inúmeros estudos foram desenvolvidos visando a produção e caracterização de filmes biodegradáveis à base de macromoléculas naturais, como proteínas de soro de leite [6,7] , gelatina [8][9][10] , zeína [11][12][13] , quitosana [14][15][16][17] , quinoa [18] , amido de mandioca [19][20][21][22] , proteína de soja [23] , pectina [24] , alginato [25][26] , entre outros. Entretanto, a abordagem de aplicação destes materiais como sensores em embalagens inteligentes, ainda é escassa na literatura especializada.…”