Characterization of rice starch-ι-carrageenan biodegradable edible film. Effect of stearic acid on the film properties

Abstract

The main aim of this study was to develop rice starch (RS), ι-carrageenan (ι-car) based film. Different formulations of RS (1-4%, w/w), ι-car (0.5-2%, w/w) was blended with stearic acid (SA; 0.3-0.9%, w/w) and glycerol (1%, w/w) as a plasticizer. The effect of film ingredients on the thickness, water vapour permeability (WVP), film solubility (FS), moisture content (MC), colour, film opacity (FO), tensile strength (TS), elongation-at-break (EAB) of film was examined. Interactions and miscibility of partaking components was studied by using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Hydrocolloid suspension solution of mix polysaccharides imparted a significant impact (p<0.05) on the important attributes of resulting edible film. TS and EAB of film were improved significantly (p<0.05) when ι-car was increased in the film matrix. Formulation F1 comprising 2% ι-car, 2% RS, 0.3% SA, Gly 30% w/w and 0.2% surfactant (tween20) provided film with good physical, mechanical and barrier properties. FT-IR and XRD results reveal that molecular interactions between RS-ι-car have a great impact on the film properties confining the compatibility and miscibility of mixed polysaccharide. Results of the study offers new biodegradable formulation for application on fruit and vegetables.

The physicochemical and structural properties of psyllium gum/modified starch composite edible film

“…Increases in MS concentration led to decreases in the films’ EB. These results were in agreement with those of Thakur et al, who reported a decrease in the EB of rice starch films with decreasing the ɩ‐carrageenan concentration (Thakur et al, ). According to Table , neat MS film showed the lowest EB (6.08%).…”

“…Generally, the incorporation of PG with MS could form more hydrogen bonds between the two polymers and reinforce the network of composite films; this has been reported in previous studies (Martins et al, ; Sukhija et al, ; Thakur et al, ).…”

“…The films' WVP is shown in Table 1. The WVP of the films examined in this study was higher than that found for rice starch/ι-carrageenan (Thakur et al, 2016), probiotic-residing pullulan/starch (Kanmani & Lim, 2013), lotus starch/whey protein concentrate/psyllium husk (Sukhija et al, 2016), corn starch/chitosan (Garcia, Pinotti, & Zaritzky, 2006), and modified starch/carboxy methyl cellulose g m −1 s −1 Pa −1 ). This may be due to interactions between the two biopolymers leading to fewer free spaces in the film matrix (Dick et al, 2015).…”

“…The mechanical properties of films, including tensile strength (TS) and elongation at break (EB), are shown in Table . Tensile strength shows the mechanical resistance of films to stretching and elongation at break shows the flexibility of films before breaking (Qiu, Hu, & Peng, ; Thakur et al, ). As shown in Table , neat PG films had the lowest (20.83 MPa) TS.…”

“…FTIR spectroscopy is considered one of the most powerful and widely applicable spectroscopic techniques (Sun, ). The FTIR spectrum shows some interactions between polymers that could lead to changes in the location, width and/or intensity of peaks (Bourbon et al, ; Marvdashti et al, ; Thakur et al, ). Figure shows the FTIR spectrum of the films examined in this study.…”