* Contact email ID : nabanita@ft.utb.cz / madhu@agfe.iitkgp.ernet

1. Moisture Sorption and Isosteric Heat of Sorption properties of PVP-CMC Hydrogel based Food Packaging Material Nabanita Sahaa, Dipali S.Shindeb, Madhusweta Dasb, Petr Saha a aCentre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Tř. T. Bati 5678, Zlin 760 01, Czech Republic bDepartment of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur-721302, India * Contact email ID: nabanita@ft.utb.cz / madhu@agfe.iitkgp.ernet.in Biopolymers and Bioplastics-2015 Tuesday, August 11, 2015

2. Outline • INTRODUCTION • Polymer in packaging • Hydrogel food packaging • Unique properties of hydrogel • Application of hydrogels • Preparation techniques of hydrogel • MOTIVATION OF RESEARCH • EXPERIMEMTATION • RESULTS • Visual Images of PVP-CMC hydrogel food packaging material • AFM image of PVP-CMC hydrogel film • Water activity of PVP-CMC hydrogel at different temperature • Moisture sorption isotherm of PVP-CMC hydrogel film • Comparison of PVP-CMC hydrogel film at different temperature • Effect of temperature on moisture sorption isotherm • Isosteric heat of sorption of PVP-CMC hydrogel • CONCLUSION Biopolymers and Bioplastics-2015 Tuesday, August 11, 2015

3. Introduction Polymers in Packaging Polymeric materials play a dominate role in the food packaging industry Tuesday, August 11, 2015

4. Introduction

5. Introduction Lists of acceptable polymers for use in food packaging Global bioplastic packaging market by product type, 2010 (%) Tuesday, August 11, 2015

6. Introduction Hydrogel based food packaging Hydrogel food package Hydrogels are one kind of bio-inspired materials and devices for chemical and biological defense . Crosslinking network and pores in hydrogel • Porous internal morphology • Quite a good moisture absorption capacity • Flexible in nature for the preparation of sample in different shape, size and thickness Hydrogel Tuesday, August 11, 2015

7. Introduction Unique properties of hydrogels • Hydrogels provide suitable semiwet, three-dimensional environments for molecular-level biological interactions. • Provide inert surfaces that prevent nonspecific adsorption of proteins, a property known as antifouling • Biological molecules can be covalently incorporated into hydrogel structures using a range of well-established chemistries • Hydrogels can be designed to change properties (e.g. swelling/collapse or solution-to-gel transitions) in response to externally applied triggers, such as temperature, ionic strength, solvent polarity, electric/magnetic field, light, or small (bio)molecules. R.V.Ulijn., et al. Materialstoday, Vol 10, p-40-48, 2007 Tuesday, August 11, 2015

8. Methods for the preparation of hydrogel Based on starting materials • Monomers • Prepolymers • polymers Physical stimuli • Heat Pressure pH Ionic strength • Hydrophobic interactions • Charge interactions • Hydrogen bonding • Stereo complexation • Supramolecular chemistry Chemical stimuli • Different chemical Crosslinking agents Irradiation Technique X-ray UV-ray Gamma ray Tuesday, August 11, 2015

9. Experimental Preparation of “PVP-CMC Hydrogel” for Food Packaging Tuesday, August 11, 2015 SEM images of hydrogels: PVP/CMC (a.i) surface (a.ii) cross section Tuesday, August 11, 2015

10. MOTIVATION OF RESEARCH • It is known that macromolecular network determining the properties of biopolymer based polymeric films where this macromolecular network isdependent on moisture content. • On the other hand, moisture sorption isotherm (MSI) provides information on the moisture holding capacity of the films at variable relative humidity (water activity, aw). • Water activity (aw) is a measure of the energy status of the moisture content in a system, and controls several properties of biopolymer based materials; high water activity leads to chemical and microbial instability. • The equilibrium relationship between water activity (aw, ranging within 0.0-1.0) and the corresponding moisture content at any particular temperature is an essential tool for design of drying, packaging and storage systems of food. • TBU researcher reported that PVP-CMC hydrogel based food packaging material has capacity to absorb moisture, therefore, we are motivated to pursue the research to find the moisture sorption isotherm and isosteric heat sorption properties of PVP-CMC hydrogel. Tuesday, August 11, 2015

11. Visual images of PVP-CMC hydrogel based food packaging material • Transparent • Sealable • Printable • Able to absorb moisture • Breathable and • Biodegradable Hydrogel food package Tuesday, August 11, 2015

12. AFM (surface) images of PVP-CMC hydrogel film Front site Back site Tuesday, August 11, 2015

13. Water activity at different temperatures Water activity of each saturated solution was estimated following the equation: aw = [ΔH/R] [1/T] + c where, T=°K Tuesday, August 11, 2015

14. Moisture sorption isotherm of PVP-CMC hydrogel film Where, EMC= equilibrium moisture content of sample on percent dry basis WEq= weight of sample after attaining equilibrium moisture content WDry= weight of sample after removal of the moisture in the oven Note:#Mean of five replications ± SD. For each temperature, F test is positive (p<0.01) for variation of EMC with water activity; *within a column for a particular sample, EMCs are not significantly different (LSD test, p<0.01 or < 0.05) with change of aw; Tuesday, August 11, 2015

15. Note: #Mean of five replications ± SD. For each temperature, F test is positive (p<0.01) for variation of EMC with water activity; *within a column for a particular sample, EMCs are not significantly different (LSD test, p<0.01 or < 0.05) with change of aw; Tuesday, August 11, 2015

16. Comparison of PVP-CMC hydrogel film at different temperature using GAB, BET and Peleg models Tuesday, August 11, 2015

17. Estimation parameters and comparison criteria for PVP- CMC hydrogel film at different temperature using Modified Oswin models Tuesday, August 11, 2015

18. Effect of temperature on moisture sorption isotherm of PVP-CMC hydrogel based food packaging material Tuesday, August 11, 2015

19. Isosteric heat of sorption of PVP-CMC hydrogel based food packaging material at different moisture content Tuesday, August 11, 2015

20. Acknowledgement Authors are thankful for the financial support provided by the Ministry of Education , Youth and Sports of the Czech Republic - Program NPU I (LO1504) Tuesday, August 11, 2015

21. Thank youforyourattention!