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Aim: Analysing 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 films' antimicrobial activity against mesophilic aerobic bacteria, total coliform and fungi were also analysed, in accordance with the Mexican Official Norms (NOM-092-SSA1-1994, NOM-111-SSA1-1994 and NOM-113-SSA1-1994. The pH values of the films and extracts were measured, and the volatile compounds of the extracts and two films were determined by Gas Chromatography-Mass Spectrometry (GC-MS) considering the relationship among the type of compounds, extracts concentration, films' pH and the antimicrobial activity against bacteria and fungi. The best results are obtained by films with formic acid and 10% (v/v) of leaf and fruit extracts, in comparison with untreated chitosan-starch films. Conclusions: The extracts' compounds improved the films' antimicrobial capacity and inhibited the growth of micro-organisms with no previous sterilization required. It is correlated to the pH of the media, the combination of solvent/extract used and its concentration. Significance and Impact of the study: This is one of the few researches where the antimicrobial activity of M. bijugatus extracts is studied. It was found that the presence of these extracts is capable of improving 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.

BACKGROUND: The difficulty of separating fiber from polyolefin coatings of single-use plastic (SUP) cups for cold (carbonated) or hot (coffee) drinks, has led us to investigate a recycling method to obtain new high-performance materials. The present work relates to valorization of ICEE S.A. de C.V. cups into crystalline nanocellulose (CNC), while studying the effects on the structural, thermal, morphological and particle size properties in dependence of the acid hydrolysis concentration (40 and 64% v/v) employing sulfuric acid to remove amorphous cellulose.RESULTS: On the basis of results, optimal CNC was found at 64% v/v concentration obtaining ribbon-like morphologies rich in cellulose types I⊍ (27%) and II (45.1%) of triclinic and monoclinic structures, respectively, high crystallinity percentage (91%) and nanosize scale (26.70 nm). CNC was successfully grafted through the C 2 in cellulose onto the methyl methacrylate (MMA) monomer to obtain PMMA-g-CNC, considering different concentrations (5, 10, 20 and 30 wt%) of CNC. A reduction of crystallinity % was found when CNC is grafted onto MMA owing to the amorphous nature of the poly(methyl methacrylate) (PMMA). However, this is not a limitation.CONCLUSIONS: PMMA-g-CNC samples displayed high thermal stability (345 °C) and nanometric scale (165-260 nm), which have potential to be studied as reinforcement agents for incompatible polymers such as PMMA and poly(urethane) (PU) through Interpenetrating Polymer Networks. Preliminary mechanical studies indicated that PMMA-g-CNC systems are able to reinforce the tensile properties becoming the PMMA/PU into ductile materials. Specially, the MMA 90 CNC 10 system improved the strain four-fold compared to the pure PMMA/PU IPN.