Investigating the microbial properties of sodium alginate/chitosan edible film containing red beetroot anthocyanin extract for smart packaging in chicken fillet as a pH indicator

Tuning the structure and physiochemical properties of sodium alginate and chitosan composite films through sodium tripolyphosphate (STPP) crosslinking

Sodium tripolyphosphate (STPP), an inorganic and non-toxic polyphosphate, has potential applications as a crosslinking agent in the fabrication of edible films. This study utilized STPP in the development of sodium alginate-chitosan composite films, with a focus on their suitability for food packaging applications. The results indicate that the incorporation of STPP led to an increase in film thickness (from 0.048 ± 0.004 to 0.078 ± 0.008 mm), elongation at break (from 11.50 ± 1.49 % to 15.88 ± 2.14 %), water permeation (from 0.364 ± 0.010 to 0.521 ± 0.021 gmm/(m2h*kPa)), and moisture content (from 25.98 ± 0.20 % to 28.12 ± 0.17 %). In contrast, there was a decrease in tensile strength (from 30.23 ± 2.08 to 25.60 ± 1.22 MPa) and swelling index (from 752.9 ± 17.1 to 533.5 ± 8.9 %). Scanning electron microscopy (SEM) analysis revealed the formation of distinctive needle-like microcrystals with the incorporation of STPP. Fourier-transform infrared spectroscopy (FTIR) analysis indicated intermolecular interactions between STPP and the film-forming biopolymers. The data obtained from Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) demonstrated enhanced thermal stability of STPP-loaded films at elevated temperatures. Furthermore, the films exhibited increased DPPH scavenging activity with the addition of STPP. This study underscores the potential of STPP as a crosslinking agent for the development of composite edible films, suggesting applications in the field of food packaging.

Development and Analysis of Silver Nitroprusside Nanoparticle-Incorporated Sodium Alginate Films for Banana Browning Prevention

Banana (Musa acuminate) has been popular among consumers worldwide due to its rich nutrients and minerals. However, bananas are highly susceptible to the physical and biological factors that lead to postharvest loss during transportation and storage. In this work, novel sodium alginate (SA) films incorporated with silver nitroprusside nanoparticles (AgNNPs) were prepared to extend the shelf life of bananas through antibacterial and antioxidant coating. The results exhibited that AgNNPs were cubical and that their size was <500 nm, with metal composition being Ag and Fe. Additionally, the incorporation of AgNNPs in the SA film was seen in FE-SEM and zeta analysis, with an average size of about 365.6 nm. Furthermore, the functional and crystalline properties of AgNNPs were assessed through FTIR and XRD. Transmittance testing of the SA-AgNNPs films confirmed they have good UV barrier properties. SA-AgNNPs films exhibited excellent high antibacterial activity against foodborne pathogens including L. monocytogenes, S. enterica, and E. coli at the concentration of 500 µg/mL. Moreover, during the storage of bananas, SA-AgNNPs nanocomposite coatings act as a barrier to microbial contamination and slow down the ripening of bananas. As a result, compared with SA-coated and uncoated bananas, SA-AgNNPs-coated bananas exhibited the lowest weight loss and lowest total bacterial colonies, thus greatly extending their shelf life. Particularly when coated with SA-AgNNPs films, total bacterial colonies (TBC) in the banana peel and pulp were as low as 1.13 × 103 and 51 CUF/g on the ninth day of storage, respectively. Our work offers an efficient strategy to improve the quality of bananas during the postharvest period, with extensive applications in fruit preservation and food packing.