Effect of the degree of acetylation, plasticizer concentration and relative humidity on cassava starch films properties

Abstract

The objective of this study was to develop films with reduced hygroscopicity and improved mechanical properties from acetylated cassava starch. For that, an acetylation procedure using acetic anhydride as the esterification reagent was performed, resulting in starch acetates with degrees of substitution (DS) of 0.6 (S0.6) and 1.1 (S1.1). Twelve films formulations were studied: native cassava starch (S), starch acetate S0.6 and S1.1, with two glycerol concentrations (0.25 g.100 g-1 (25) and 0.30 g.100 g-1 (30)). The films were conditioned at the relative humidities (RH) of 58% and 75% for 96 h before characterization. Water vapor permeability, water solubility, water sorption isotherms, microstructural analyses, and mechanical properties in different relative humidity and different glycerol concentration were performed. Starch acetate films (S1.1) resulted in lower water vapor permeability (2.35 ± 0.26 × 10-7 g/m.s.Pa) and water solubility (21.2 ± 0.16 g.100 g-1) than native starch films (3.79 ± 0.26 × 10-7 g/m.s.Pa and 25.46 ± 0.12 g.100 g-1). S0.6 films showed higher tensile strength (8.42 ± 0.84 MPa) than S1.1 films (6.93 ± 0.55 MPa). The results indicated that acetylated starch can be used to produce films with improved mechanical properties, with less water solubility and permeability to water vapor, especially when starch acetate with 0.6 DS and low glycerol concentration are used. Chemical compounds used in this article: Starch, acetate

Packaging potential of Ipomoea batatas and κ‐carrageenan biobased composite edible film: Its rheological, physicomechanical, barrier and optical characterization

“…The study revealed a significant ( p < .05) decrease in the tensile strength of composite film with the increasing concentration of glycerol. The reduction of tensile strength due to plasticization effect has been widely proclaimed (Bharti, Pathak, Alam, Arya, Singh, et al, 2020; Schmidt et al., 2019; Sun et al., 2018). The disordered structural restructuring is attributed to the fact the glycerol weakened the intra and inter‐molecular interactions in the matrix and form new hydrogen bonds with the polymers, enhancing flexibility and reduction of tensile resistance.…”

Effect of hydrophobically modified extracted starch nanocrystal on the properties of LDPE/ thermoplastic starch (TPS)/PE‐g‐MA nanocomposite

“…Also, a very sharp band can be noticed at 1749 cm −1 , indicating the existence of the C═O bond related to the formation of ester in the ASNC. Also, two observed sharp bands at 1375 and 1240 cm −1 could assign stretching vibration of CH 3 and CO bond of acetate, respectively 25,33,34,32 . The schematic illustration of the molecular structure of SNC and the effect of acetylation on its chemical structure is clarified in Figure 3(b).…”

“…As shown, the starch spectrum illustrates evident bands at 3382, 2930, and 1647 cm −1 that could be assigned to hydroxyl groups, CH bond, and bending vibration of HOH groups, respectively; the latter confirmed the presence of water in the structure. There are also apparent bands in the range of 900–1250 cm −1 referred to as the CO stretching 14,29–31,32 . In the SNC spectrum, broadband was observed at 3300–3900 cm −1 corresponded to free, inter, and intra‐molecular bonds of the hydroxyl groups 22 .…”

Advantages and Disadvantages of Bioplastics Production from Starch and Lignocellulosic Components

“…Different degrees of acetylation and plasticizers can alter the mechanical properties, solubility, and water vapor barrier of starch-based bioplastics [ 89 ]. The degree of substitution (DS) of 0.6 was the most promising compared to the DS of 1.1.…”

“…While the tensile strength on the DS of 1.1 was 6.57 MPa, and the solubility and WVP did not change either. However, acetylation resulted in bioplastics with improved properties compared to native starch [ 89 ]. The improvement of bioplastics based on acetylated starch is due to the replacement of hydrophilic groups by acetyl, which results in a less flexible and hydroscopic bioplastic.…”