The aim of this study is to analyze the properties of a series of polysaccharide composite films, such as apparent density, color, the presence of functional groups, morphology, and thermal stability, as well as the correlation between them and their antimicrobial and optical properties. Natural antioxidants such as anthocyanins (from cranberry; blueberry and pomegranate); betalains (from beetroot and pitaya); resveratrol (from grape); and thymol and carvacrol (from oregano) were added to the films. Few changes in the position and intensity of the FTIR spectra bands were observed despite the low content of extract added to the films. Due to this fact, the antioxidants were extracted and identified by spectroscopic analysis; and they were also quantified using the Folin-Denis method and a gallic acid calibration curve, which confirmed the presence of natural antioxidants in the films. According to the SEM analysis, the presence of natural antioxidants has no influence on the film morphology because the stretch marks and white points that were observed were related to starch presence. On the other hand, the TGA analysis showed that the type of extract influences the total weight loss. The overall interpretation of the results suggests that the use of natural antioxidants as additives for chitosan-starch film preparation has a prominent impact on most of the critical properties that are decisive in making them suitable for food-packing applications.

Natural extracts possess several kinds of antioxidants (anthocyanins, betalains, thymol, carvacrol, and resveratrol) that have also demonstrated antimicrobial properties. In order to study these properties, extracts from cranberry, blueberry, beetroot, pomegranate, oregano, pitaya, and resveratrol (from grapes) were obtained. Growth inhibition tests of mesophilic aerobes, coliforms, and fungi were conducted in films prepared from the extracts in accordance with Mexican Official Norms (NOM). Optical properties such as transparency and opacity, mechanical properties, and pH were also analyzed in these materials. The films with beetroot, cranberry, and blueberry extracts demonstrated the best antimicrobial activity against various bacteria and fungi in comparison with unmodified chitosan–starch film. This study shows that the addition of antioxidants improved the antimicrobial performance of these films. It was also found that antimicrobial properties are inherent to the films. These polymers combined with the extracts effectively inhibit or reduce microorganism growth from human and environmental contact; therefore, previous sterilization could be unnecessary in comparison with traditional plastics. The presence of extracts decreased transmittance percentages at 280 and 400 nm, as well as the transparency values, while increasing their opacity values, providing better UV–VIS light barrier properties. Despite diminished glass transition temperatures (Tg), the values obtained are still adequate for food packaging applications.

Chitosan films were used to remove heavy oil from connate water, deionized water, and seawater. In this research, chitosan–starch films were modified with natural extracts from cranberry, blueberry, beetroot, pomegranate, oregano, pitaya, and grape. These biodegradable, low-cost, eco-friendly materials show an important oil sorption capacity from different water conditions. It was observed that the sorption capacity has a clear correlation with the extract type, quantity, and water pH. In order to understand the physical and chemical properties of the films, they were analyzed according to their apparent density, water content, solubility, and swelling degree by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), gas chromatography–mass spectroscopy (GC–MS), and the determination of surface area using the Brunauer Emmett Teller (BET) method. The results indicate that chitosan–starch films modified with natural extracts can be successfully applied for environmental issues such as oil spill remedy.

Aim The purpose of this research was to analyze the antimicrobial activity ‐against food‐borne microorganisms‐ of modified chitosan‐starch films using formic and acetic acid as chitosan solvents and Melicoccus bijugatus leaves and fruit extracts. Methods and Results The effects of the modification process on the films’ antimicrobial activity against mesophilic aerobic bacteria, total coliform, and fungi (Sclerotinia sclerotiorum, Penicillium digitatum and Aspergillus Niger) were also analyzed. The previous contamination and antimicrobial tests were carried out in accordance with the Mexican Official Norms (NOM). The pH values of the films and extracts were measured, and the volatile compounds of the extracts, as well as those of QAfF10 and QAfH10 films were determined by Gas Chromatography–Mass Spectrometry (GC‐MS) considering the relationship among the type of compounds, the type and concentration of extracts, the pH of the films, and the antimicrobial activity against bacteria and fungi. The films that were prepared with formic acid as chitosan solvent, with a concentration of 5 and 10% (v/v) of leaves and fruit extracts, demonstrated the best antimicrobial activity in comparison with untreated chitosan–starch films. Conclusions The study showed that the extracts contain several compounds that improved the films' antimicrobial capacity and inhibited the growth of microorganisms with no previous sterilization required. The antimicrobial activity is correlated to the pH of the media, the combination of solvent/extract used and its concentration. Significance and impact of study This is one of the few researches were the antimicrobial activity of Melicoccus bijugatus extracts are studied. It was found that the presence of these extracts are capable of improve the antimicrobial activities of chitosan‐starch films. The performance of the modified films suggests their potential application as novel food packaging materials and encourages further research.