ADVANCEMENTS IN ANTIMICROBIAL ACTIVE PACKAGING: INNOVATION IN ENCAPSULATION PRINTING AND COATING TECHNOLOGIES

Abstract

The occurrence of recurrent "food safety incidents" has emerged as a pressing concern, adversely affecting public health and precipitating a crisis of trust within society, garnering substantial attention. Active food packaging, a dynamic, and rapidly advancing technology, integrates antibacterial or antioxidant compounds into packaging materials to enhance packaged foods' quality, safety, and shelf life, thereby impeding bacterial development and mitigating lipid oxidation. In essence, the overarching objective of this work is to contribute to advancing antimicrobial active packaging through three distinct approaches. In the present doctoral thesis work, antimicrobial active packaging materials have been developed with the aim of enhancing the shelf life of packaged food materials by inhibiting the growth of microbial contamination. Our first objective was to develop active packaging that used a vapor-phase antimicrobial agent incorporated into chitosan capsules to extend the shelf life of dry cakes. The clove essential oil (CEO) was encapsulated into chitosan capsules using an emulsion-ionic gelation crosslinking technique. CEO loading in chitosan was taken in different ratios (0.0:1, 0.25:1, 0.50:1, 0.75:1, 1:1, 1.25:1, 1.50:1) and validated using Fourier Transform-Infrared (FT-IR) spectra and a Field-Emission Scanning Electron Microscope (FE-SEM). The thermal stability of the capsules was evaluated using thermogravimetric analysis (TGA). Differential Scanning Calorimetry (DSC) was used to assess the oxidative thermal stability of the compounds. The encapsulation efficiency and loading capacity were 12.01 and 8.01 for 1.50:1 (CEO: Chitosan) loaded samples. The antimicrobial activity of active capsules was performed in the vapor phase. It completely prevented the development of E. coli and S. Aureus when CEO was used with chitosan in more than a 1:1 ratio. Finally, the dry cakes were packed with active capsules, and bacterial growth was reduced until the 10th day of packing. In another study, the second objective was to formulate a water-based ink with antimicrobial properties for packaging applications. Two distinct types of inks were developed, one with synthetic yellow color pigment and the other with curcumin, as an antimicrobial and a natural yellow pigment. The resulting two inks were then printed on polyethylene terephthalate (PET) films, and the physiochemical characteristics of the ink were thoroughly examined. The coated inks had an average thickness of 10 microns for both the inks. The viscosity of the water-based and antimicrobial water-based ink were determined to be 54cp and 30cp, respectively, and the drying time of the inks was 10 sec. At the same time, the gloss value increased from 30% to 50% in the case of antimicrobial ink. The antimicrobial efficacy of the antimicrobial water-based ink, as demonstrated against S. aureus and E. coli, surpassed that of the conventional water-based ink. These findings showed that the antimicrobial water-based ink had a good drying time, increased gloss, and favourable storage stability. Using curcumin as a pigment in water-based ink may be significant for printing applications of active food packaging materials. It can also help lower the risk of contamination of the food components with microbes. Further, the third objective was planned to develop active antimicrobial paper sheets from bagasse fiber pulp. Bagasse is a waste material collected from Saharanpur. After the development of the bagasse sheets these sheets were coated with an antimicrobial solution. Silver-exchanged zeolite was used as an antimicrobial and dispersed in a PVA solution; the resulting antimicrobial solution was applied to the paper sheets using a laboratory rod coater, followed by oven drying at a temperature of 80° C for a duration of 5 minutes. Subsequently, the thermal stability, water vapor barrier, and antimicrobial efficacy against E. Coli and S. Aureus of the coated paper were studied. The PVA-coated paper was smooth and covered all the fibers. Moreover, SEZ greatly influenced the thickness of the antimicrobial sugarcane bagasse paper sheet. WVTR decreased with the addition of SEZ to a concentration of 4%, showing a better water barrier. SEZ incorporated PVA increased the tensile index of paper. The coated and uncoated paper's burst index also followed the tensile index trend. The folding endurance of SEZ-incorporated PVA paper decreased, highlighting that the control sample proved to be the most folding resistant. The zone of inhibition increased with an increase in SEZ concentration in PVA against both E. coli and S. Aureus. Therefore, SEZ incorporated PVA coated Paper can be used as an antimicrobial paper-based packaging.