The environmental damage caused by plastic packaging and the need to reduce pollution requires actions to substitute plastic materials for more sustainable and biodegradable materials. Starch, gelatin, and bacterial cellulose films are three potential biodegradable polymeric films for use in packaging. However, these materials need improvements in their physical, chemical, and mechanical properties to be used in packaging. In this work, these films were treated with cold plasma to evaluate the effects of treatment conditions on several physical, chemical, and mechanical properties. The dielectric barrier discharge plasma technology was applied with varying treatment times (0 to 20 min) and excitation frequencies (50 to 900 Hz) at 20 kV. The optimal excitation frequency for starch films (50 Hz) was different from the optimal frequency for gelatin and bacterial cellulose films (900 Hz), indicating a high dependency on the treatment in this variable that is often neglected. Plasma treatment improved the hydrophobicity, surface morphology, water resistance, and mechanical properties of all three films, with the advantage of not recurring to chemical or biological additives.

This study evaluated the effects of dielectric barrier discharge (DBD) plasma technology on some physicochemical and structural properties of corn starch. Amylose content, solubility, water absorption index, turbidity, structural relationships, and surface morphology were measured at 100, 200, and 300 Hz excitation frequencies and at 10 and 20 min exposure times. The plasma treatment at 200 Hz and 20 min promoted the most significant modifications in amylose content, solubility, the water absorption index, and surface morphology. Turbidity did not change significantly. The surface of the granule became smoother with the presence of pores. Slight changes were observed in the ordered structure of starch. Plasma changed several physicochemical properties, significantly decreasing the amylose to amylopectin ratio. Plasma treatment at 200 Hz is recommended to increase the amylopectin content in starches.

Starch-based biodegradable films are a type of packaging material that can naturally decompose in the environment. Current challenges regarding starch-based film applications are their high solubility and low hydrophobicity. Prior studies have shown that plasma application improves the physical, chemical, and mechanical properties of these films. This work evaluates the plasma application strategy regarding the process stage in which plasma should be applied (starch granule, film-forming solution, or film). Three groups of films were produced: a film produced with the plasma-treated starch, a film produced by subjecting the film-forming solution to plasma treatment, and a plasma-treated film produced with the untreated starch. A 2² face-centered experimental design was applied to each group of films to attain the optimal film of each group. The design consisted of applying plasma at 100, 200, and 300 Hz for 0, 10, and 20 min to each group. The results showed significant differences regarding their physical-chemical and morphological properties. Most chemical changes occurred in the starch subjected to plasma prior to film formation, while the films produced with the untreated starch presented physical changes. Plasma-treated films presented reduced solubility and higher hydrophobicity.

This study explores the development of biodegradable starch-based films treated with dielectric barrier discharge (DBD) plasma and incorporated with acerola residue and grape pomace extracts. The primary aim was to enhance the films’ physicochemical properties and introduce pH-sensing capabilities. Plasma treatment at 200 Hz for 20 min modified the films’ amylose content (by 13.2%), solubility (by 13.3%), contact angle (by 12.7%), moisture content (by 14.2%), and surface morphology. The addition of the extracts changed the short-range ordered structure parameters of the films (by 111.4%), solubility (by 11.1%), moisture content (by 18.4%), and water vapor permeability (by 6.1%). The films with acerola residue and grape pomace extracts exhibited good colorimetric responses for pH indication. The films with acerola residue extract tended to intensify the yellowish color, while those with grape pomace extract showed more significant color changes varying from purple to green. Integrating natural pigments like anthocyanins from grape pomace and carotenoids from acerola improved the films’ functional properties and provided a visual indication of food freshness through pH changes.

This research has explored the development of pH-sensing starch and carrageenan films incorporated with grape pomace and acerola residue extracts. The main goal was to improve the films’ physicochemical properties and induce pH-sensing capabilities. This study has evaluated the pH-sensing capabilities of the films as well as important properties such as amylose content, moisture content, solubility, contact angle, surface morphology, and chemical group profiling. The film incorporated with grape pomace extracts presented satisfactory colorimetric pH indication, while the response of the film incorporated with acerola residue extract was less intense. Integrating natural pigments such as acerola carotenoids and grape pomace anthocyanins enhanced the functional properties of the films and enabled visual indication of food freshness through pH-sensing ability.