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Biopolymer-based films can be activated by the incorporation of active compounds into their matrix. Plant extracts are rich in phenolic compounds, which have antimicrobial and/or antioxidant properties. The aim of this study was to produce gelatin-based active films and nanocomposite films incorporated with "pitanga" (Eugenia uniflora L.) leaf extract (PLE) and/or crystalline nanocellulose extracted from soybean straw (CN), and to study the physicochemical, functional, microstructural, thermal, UV/Vis light barrier, and antioxidant properties of these materials. PLE enhanced some film properties, such as tensile strength (from 30.2 MPa to 40.6 MPa), elastic modulus (from 9.3 MPa to 11.3 MPa), the UV/Vis light barrier, and antioxidant activity, in addition to affecting the microstructural, surface, and color properties. These improvements were even more significant in nanocomposites simultaneously containing PLE and CN (59.5 MPa for tensile strength and 15.1 MPa for elastic modulus), and these composites also had lower moisture content (12.2% compared to 13.5–14.4% for other treatments) and solubility in water (from 48.9% to 44.1%). These improvements may be the result of interactions that occur between PLE's polyphenols and gelatin, mainly in the presence of CN, probably due to the formation of a stable PLE–CN–gelatin complex. These results are relevant for the food packaging sector, as the activated nanocomposite films exhibited enhanced active, barrier, and mechanical properties due to the presence of PLE and CN, in addition to being entirely produced with sustainable components from natural and renewable sources. [ABSTRACT FROM AUTHOR]

This study investigates how enzymatic activity (X1) and pretreated soybean straw concentration (X2) affect the production of cellulose nanofibers and reducing sugars using the Composite Central Rotational Design (CCRD). The soybean straw is subjected to alkaline pretreatment with either 5% NaOH (PT1) or 17.5% NaOH (PT2), followed by bleaching (4% H2O2) and enzymatic treatment. The mathematical model generated by Response Surface Methodology (RSM) predicts that increasing X1 and X2 simultaneously is necessary to increase the nanocellulose yield. On the other hand, to increase the sugar yield, it is necessary to increase the ratio X1:X2. The model also predicts that the lowest concentration of soybean straw (1.17%) resulted in more stable nanofiber suspensions, regardless of the enzyme activity (−25.0 and −19.4 mV for PT1 and PT2, respectively). The optimal condition for the simultaneous production of cellulose nanofibers and reducing sugars is 4.0 g of biomass and enzymatic activity of 600 CMCU, resulting for PT1 and PT2, respectively: 7.01 and 3.73 g of nanofibers/100 g of soybean straw; 11.34 and 14.30 g of reducing sugars/100 g of soybean straw. Therefore, the processing efficiency according to the pretreatment used can directly guide the production of cellulose nanofibers and reducing sugars. [ABSTRACT FROM AUTHOR]

This work investigated changes in the chemical composition and structure of soybean straw (SS) treated with alkali (NaOH 5% and 17.5%) and bleached with hydrogen peroxide (H 2 O 2 ) or sodium hypochlorite (NaOCl). Removal of the amorphous constituents increased the degree of crystallinity and the content of cellulose fibers particularly after reaction with high concentrations of alkali. Treatment with NaOH 17.5% contributed to the allomorph transition from cellulose I to II regardless of the bleaching agent, but H 2 O 2 as bleaching agent promoted more effective delignification. This work also evaluated the potential use of treated and non-treated SS as reinforcement filler in soy protein isolate film (SPI). Films added with treated SS presented higher mechanical resistance, lower elongation at break, and lower solubility in water. Addition of non-treated SS did not affect the properties of the SPI film significantly. The low solubility and the reasonable water vapor permeability of the composite films make them suitable packaging materials for fresh fruit and vegetables. [ABSTRACT FROM AUTHOR]

Mechanical properties of biopolymer films can be a limitation for their application as packaging. Soybean straw crystalline nanocelluloses (NC) can act as reinforcement load to improve these material properties, and W/O/W double emulsion (DE) as encapsulating bioactive agents can contribute to produce active packaging. DE droplets were loaded with pitanga leaf (Eugenia uniflora L.) hydroethanolic extract. The mechanical, physicochemical, and barrier properties, and the microstructure of gelatin and/or chitosan films incorporated with NC or NC/DE were determined by classical methods. Film antioxidant activities were determined by ABTS and DPPH methods. The incorporation of NC/DE in gelatin and/or chitosan films (NC/DE films) changed the morphology of these films, which presented more heterogeneous air-side surfaces and cross-sections. They presented rougher topographies, notably greater resistance and stiffness, higher barrier properties to UV/Vis light and higher antioxidant activity than the NC films. Moisture content, solubility in water and water vapor permeability decreased due to the presence of DE. Overall, the NC/DE films improved all properties, when compared to the properties of NC films or those of films with only DE, from a previously published study. In spite of not having antimicrobial activity against the studied bacteria, NC/DE films did display a great antioxidant activity. • Pitanga leaf hydroethanolic extract (PLHE) is rich in phenolic compounds. • PLHE was encapsulated in the W inner phase of a W/O/W (DE) emulsion. • Cellulosic nanofibers (NC) were extracted from soybean straw by chemical treatments. • Gelatin/chitosan nanocomposite was produced with NC and DE. • Nanocomposite presented improved mechanical properties and antioxidant activity. [ABSTRACT FROM AUTHOR]