Surface Modification via Dielectric Barrier Discharge Atmospheric Cold Plasma (DBD–ACP): Improved Functional Properties of Soy Protein Film

Abstract

Atmospheric cold plasma (ACP), a novel technology, has been widely adopted as an efficient approach in surface modification of the film. The effect of ACP treatment on the physicochemical and structural properties of soy protein film were investigated. As a result, the optimal conditions for the preparation of the film were determined for soy protein (10%), glycerol (2.8%), ACP treatment at 30 kV for 3 min, on the basis of elongation at the break, and water vapor permeability. Under the optimal conditions, the ACP–treated films exhibited enhanced polarity according to the increased values of solubility, swelling index, and moisture content, compared with the untreated counterpart. An increase in the hydrophilicity is also confirmed by the water contact angle analysis, which decreased from 87.9° to 77.2° after ACP pretreatment. Thermostability was also improved by ACP exposure in terms of DSC analysis. SEM images confirmed the tiny pores and cracks on the surface of film could be lessened by ACP pretreatment. Variations in the Fourier transform infrared spectroscopy indicated that some hydrophilic groups were formed by ACP pretreatment. Atomic force microscopy data revealed that the roughness of soy protein film which was pretreated by ACP was lower than that of the control group, with an Rmax value of 88.4 nm and 162.7 nm for the ACP- treated and untreated samples, respectively. The soy protein film was characterized structurally by FT–IR and DSC, and morphological characterization was done by SEM and AFM. The soy protein film modified by ACP was more stable than the control group. Hence, the great potential in improving the properties of the film enables ACP treatment to be a feasible and promising alternative to other modification methods.

Cold atmospheric plasma‐induced protein modification: Novel nonthermal processing technology to improve protein quality, functionality, and allergenicity reduction

“…For example, the film-forming properties of zein subjected to HV-CAP generated at 60 kV for different treatment times (1-5 min) were significantly improved in terms of increased elongation at break, increased tensile strength, and decreased hydrophobicity when compared to that without HV-CAP treatment, which was attributed to the decreased aggregation of zein micelles (Dong et al, 2017c). In the recent work of Li et al (2022b), soybean protein was modified using HV-CAP at different voltages (10-50 kV) and exposure times (1-4 min) before film casting, in which treatment at 30 kV for 3 min was selected as the optimized condition yielding the highest water vapor permeability and elongation at break values. The authors reported improved polarity, hydrophilicity, and thermostability for the soybean films treated with HV-CAP at the optimized conditions compared to the control.…”

“…The thermostability of the films was improved by cold plasma exposure. (Li et al, 2022b) Zein DBD-plasma system with a current of 1 A. Zein DBD-plasma system: Intensity of 100 W (65 V, 1.5 A) for 30 s.…”

“…In the recent work of Li et al. (2022b), soybean protein was modified using HV‐CAP at different voltages (10–50 kV) and exposure times (1–4 min) before film casting, in which treatment at 30 kV for 3 min was selected as the optimized condition yielding the highest water vapor permeability and elongation at break values. The authors reported improved polarity, hydrophilicity, and thermostability for the soybean films treated with HV‐CAP at the optimized conditions compared to the control.…”

“…The improved polarity was attributed to the promoted hydration reaction via exposure of active species on the surface of soybean proteins, which was mediated by the reactive species (─OH and ─NH) produced using air as the working gas for the production of HV‐CAP. The enhanced intermolecular force via protein crosslinking most likely contributed to the improved thermostability of the soybean protein films after HV‐CAP treatment (Li et al., 2022b).…”

Biopolymer-loaded plasma-mediated multi-functional finishes of polypropylene fabrics

“…9 The main advantage of these discharges is that they modify the chemistry and morphology of the fabric surface, improving hydrophilicity and raising the susceptibility of fibre to various chemical species without affecting the fiber interior. 13 Vacuum, low-pressure, and atmospheric-pressure plasmas are the three categories into which cold plasmas fall. Low-pressure plasma and wet chemical treatments are more expensive, whereas atmospheric plasmas can process surfaces continuously and uniformly.…”