Effect of the Addition of Carnauba Wax on Physicochemical Properties of Chitosan Films

Abstract

Films and edible coatings of natural polymers have been proposed as an attractive alternative for conventional plastic packaging because of their excellent biodegradability and biocompatibility. However, natural polymers, like chitosan, are hydrophilic and present poor water barrier properties. The addition of wax or other hydrophobic substances decreases water permeability of natural polymers but can increases their opacity.The objective of this work was to produce biofilms based on chitosan and different concentrations of carnauba wax and analyze their optical and barrier properties. The films were obtained by dissolving chitosan in acetic acid. Carnauba wax was incorporated into filmforming solutions at0, 15, 30, 40 and 50% (w/w). The opacity increased with higher concentrations of wax, the film with 50% of wax showed the highest value with an increase of 10.5% compared to the control film. The water vapor permeability decreased from 2.73 g.mm/kPa.m 2 .h (0% of wax) to 0.77 g.mm/h.kPa.m 2 (40% of wax). The solubility decreased to about 60% over the control films, and the contact angle increased from 53º to 83º, in film with 0 and 50% of wax, respectively.

Effects of Candelilla and Carnauba Wax Incorporation on the Functional Properties of Edible Sodium Caseinate Films

“…It is well-known that lipid-containing films show a tendency to reduced film transparency [ 36 ]. A decrease in lightness as a result of the addition of carnauba wax was also observed for chitosan films [ 39 ]. A similar tendency was reported by Zhang, Simpson, and Dumont [ 35 ] for the gelatin films incorporated with beeswax.…”

“…The authors connected the results of constant total solid values in the formulation with the reduction in the soluble matter in the films due to the incorporation of wax, and, consequently, the lowered water solubility. Dos Santos et al [ 39 ] noted a 60% reduction in water solubility of chitosan films when carnauba wax was added at 15%, but higher amounts of wax addition showed increased values, which was probably due to the higher concentration of Tween-20 and its hydrophilic effect. A decrease in water solubility as a result of wax addition was also observed for fish skin gelatin films incorporated with beeswax and carnauba wax [ 35 ], whey protein isolate/beeswax films [ 40 , 41 ], and cassava starch/carnauba wax films [ 34 , 42 ].…”

“…Bearing this in mind, better organization of lipid particles in the sodium caseinate film matrix showed an effective barrier against a visible spectrum of the UV–VIS light (600 nm), which may be a critical factor for practical application of the analyzed materials as an edible coating for specified food products. Different structural rearrangement occurs during the emulsified film drying process which may cause several mechanisms such as creaming, aggregation, or coalescence, which affect film homogeneity and visible light scattering through the films [ 39 ], thus resulting in limited film transparency. Numerous studies have previously reported a decrease in film opacity or transparency of biopolymer films as a consequence of addition of waxes [ 19 , 33 , 35 , 39 , 45 , 46 , 47 ].…”

“…It is well-known that the main reason for incorporation of lipids into biopolymer films is to improve their water barrier property, which is usually low, since most of the edible films are hydrophilic [ 22 ]. Therefore, several research groups have reported a decrease in water vapor permeability of edible films as a consequence of wax addition, including whey protein isolate [ 49 ], soy protein isolate [ 45 ], pea protein isolate [ 46 ], fish skin gelatin [ 35 ], chitosan [ 39 ], konjac glucomannan [ 47 ], cassava [ 34 , 42 ], and high-amylose starch-based films [ 33 ]. However, Brzoska et al [ 18 ] recently reported an increase in water vapor permeability of sodium caseinate films prepared with the addition of beeswax at the concentration of 1.0% without the presence of a plasticizer.…”

Filmes biopoliméricos baseados em fécula, quitosana e cera de carnaúba e suas propriedades

“…Na Os filmes contendo cera, Figura 1 (b), apresentaram, em média, TPVA 20,56% inferior em relação a seus correspondentes sem cera, Figura 1 (a). Como esperado e de acordo com a literatura [9,[19][20][21][22][23][24]35], a incorporação da cera de carnaúba resultou em melhora das propriedades de barreira dos filmes, uma vez que a matriz biopolimérica é hidrofílica e o componente lipídico, hidrófobo, atenua esta característica por dificultar o fluxo das moléculas de água. Além disso, a incorporação de tensoativo, para tornar possível a homogeneização da cera na matriz, afetou a própria coesão desta, atenuando regiões de polaridade e, consequentemente, limitando o transporte de vapor de água.…”