SYNTHESIS AND CHARACTERIZATION OF ECO-FRIENDLY SMART PACKAGING MATERIALS FOR EDIBLES

Abstract

In today’s world, new food packaging technologies are developing as a response to the consumer demands or industrial production trends towards mildly preserved, fresh and convenient food products with prolonged shelf-life and controlled quality. In addition, the changes in retailing practices, or consumer’s busy lifestyles present major challenges to the food packaging industry, and act as driving forces for the development of new and improved packaging concept, that extend the shelf-life of the packaged foodstuff, while maintaining and monitoring its safety and quality. Unfortunately, all sort of packaging ends-up in garbage and dumping sites, hence, resulting in the piling up of the non-recyclable waste. The food packaging films that show post-consumer biodegradability are rarely explored by the researchers. The present study was carried out with an aim to develop an environment friendly qualitatively responsive film for the food packaging. The ethyl cellulose (EC) was used as the base material for the development of these food packaging films. Ethyl cellulose films were plasticized with different percentage of polyethylene glycol (PEG) and the samples of standard dimensions were subjected to different testing, such as, soluble matter content, moisture content, oil permeability, surface morphology, mechanical testing etc. The films with EC to PEG ratio of 4:2 had shown the best properties among all formulations tested, with total soluble matter percentage equal to 56. 26 and the moisture content percentage equal to 50. Tensile stress analysis had shown an increase in tensile properties with increase in coalescence temperature from 30°C to 60°C, and was found maximum for EC: PEG ratio 4:2 film, equal to 0.017Mpa in the range of 50°C to 60°C. The mean value of the load carrying capacity for a varying time period was maximum for EC: PEG ratio 4:2 while minimum for the EC: PEG ratio 4:1. Further, the qualitatively responsive smart films were developed, using the best formulation of the EC films i.e. EC: PEG ratio 4:2, with an emphasis on the change in pH of the packed food stuff. These pH responsive ethyl cellulose films were developed by incorporating the azo indicators such as iii Methyl Red (MR) and Methyl Orange (MO) in the EC film formulation, by casting method. After activation in different pH range, the color variation was measured for each film, with the CIE Lab methodology. A significant L∗ [the parameter L∗ represents the lightness of color from 0 (dark) to 100 (light), in CIELAB units] variation of EC-MO was seen ranging from 59 (at 0% acid) to 32 (at 60% acid) while for EC-MR, the variation in L∗ parameter was seen ranging from 89 (at 0% acid) to 32 (at 50% acid). As evident from the results obtained, the developed bio-degradable smart films had shown remarkable sensitivity towards the pH variation, Further, these qualitatively responsive films were tested for their water absorption capacity and mechanical properties. The water absorption capacity of the EC film incorporated with indicators were observed to be low as compared to the EC standard film. The incorporation of MO resulted in a regular increase in water absorption capacity range from 34.08–47.11 while the MR incorporated films showed an irregular increase from 41.13– 42.13, during a 24 hrs interval. The film with MO also showed a good mechanical property when tested by a micro UTM. The peak load was observed at around 2.7 N. Necking was more observant in the EC film incorporated with MO as compared to other samples, thus showing good plasticity. The water vapour permeability (WVP) of the ethyl cellulose films found to be affected by the incorporation of indicators. As reported, the WVP for EC-standard film increased during initial 2 hrs from 2.29407 x10-9 gmˉ1s ˉ1Paˉ1to 3.44111 x10-9 gmˉ1s ˉ1Paˉ1, and then noted to be decreased upto 8.60277x10-10 gmˉ1s ˉ1Paˉ1 during the test duration of 24 hrs, Similar trends were show by EC-MO and EC-MR films respectively, with an initial (first 2 hrs) increase of WVP from 3.44451 x10-9 gmˉ1s ˉ1Paˉ1 to 4.99454 x10-9 gmˉ1s ˉ1Paˉ1 and from 4.57908 x10-9 gmˉ1s ˉ1Paˉ1 to 4.97975 x10-9 gmˉ1s ˉ1Paˉ1, and then, a decrease upto 1.07640 x10-9 gmˉ1s ˉ1Paˉ1and 1.23062 x10-9 gmˉ1s ˉ1Paˉ1respectively, within next 24 hrs The WVP of the film was also influenced by the temperature variation and are found to be increased, when the temperature was raised from 20°C 50°C. As ethyl cellulose is biodegradable in nature, the resulted films are also biodegradable and environment friendly. These qualitatively responsive ethyl cellulose films can be utilized as conventional food wrappings or as a small patch within the conventional transparent packaging.