1. 1 * Contact email ID: nabanita@ft.utb.cz / madhu@agfe.iitkgp.ernet.innabanita@ft.utb.cz Tuesday, August 11, 2015 Moisture Sorption and Isosteric Heat of Sorption properties of PVP-CMC Hydrogel based Food Packaging Material a Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Tř. T. Bati 5678, Zlin 760 01, Czech Republic b Department of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur-721302, India Nabanita Saha a, Dipali S.Shinde b, Madhusweta Das b, Petr Saha a Biopolymers and Bioplastics-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 2 Biopolymers and Bioplastics-2015 Tuesday, August 11, 2015

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

4. 4 Introduction

5. 5 Table no. Polymer TypeCode 1PolyethylenesPE 2PolypropylenesPP 3Poly(ethylene-vinyl acetates)EVA 4PolystryrenesPS 5PolyvinylchloridesPVC 6IonomersI 7Polyethylene terephthalatesPET 8Polyvinyl acetatePVAc 9PolycarbonatesPC 10PolyamidesPA 11PolyvinylalcoholsPVOH 12Polyvinylidene choliridePVDC 13OthersO Lists of acceptable polymers for use in food packaging Global bioplastic packaging market by product type, 2010 (%) Tuesday, August 11, 2015

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

7.  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 Introduction 7 Tuesday, August 11, 2015

8. 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 Methods for the preparation of hydrogel Tuesday, August 11, 2015

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

10. 10 MOTIVATION OF RESEARCH  It is known that macromolecular network determining the properties of biopolymer based polymeric films where this macromolecular network is dependent 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, a w ).  Water activity (a w ) 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 (a w, 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. 11 Hydrogel food package Tuesday, August 11, 2015 Transparent Sealable Printable Able to absorb moisture Breathable and Biodegradable Visual images of PVP-CMC hydrogel based food packaging material

12. 12 Tuesday, August 11, 2015 Front site Back site

13. 13 Tuesday, August 11, 2015 SaltsWater activity (a w ) 25354555 Sodium hydroxide, NaOH 0.0870.0650.050.039 Potassium acetate,CH 3 COOK 0.2370.2150.1970.182 Magnesium chloride, MgCl 2 0.3270.320.3110.3 Potassium carbonate, K 2 CO 3 0.4430.4360.4290.424 Magnesium nitrate,Mg(NO 3 ) 2 0.5360.5150.4970.481 Sodium nitrate, NaNO 3 0.7420.720.699 0.686 Sodium chloride, NaCl 0.7520.7480.7450.71 Potassium chloride, KCl 0.8550.8220.7910.764 Potassium sulphate, K 2 SO 4 0.97280.96720.9620.9572 Water activity at different temperatures Water activity of each saturated solution was estimated following the equation: a w = [ΔH/R] [1/T] + c where, T=°K

14. 14 Tuesday, August 11, 2015 Temperature (˚C)Water activity # EMC(%db)±SD 25˚C0.087 17.662±0.75 * 0.237 19.682±0.93 0.327 23.567±1.11 0.443 25.608±0.76 0.536 27.621±1.07 0.742 39.797±0.93 0.752 39.581±2.62 * 0.855 58.043±1.95 0.972 118.693±1.16 LSD 0.05 1.48 LSD 0.01 2.13 35 ˚C0.06519.985±1.22 * 0.21523.085±3.03 * 0.3223.286±0.85 * 0.43639.739±0.97 0.51525.33±1.13 * 0.7235.667±0.87 * 0.74839.295±0.77 * 0.82253.09±1.17 0.967119.196±26.76 LSD 0.05 11.33 LSD 0.01 16.34 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 a w ; Moisture sorption isotherm of PVP-CMC hydrogel film Where, EMC= equilibrium moisture content of sample on percent dry basis W Eq = weight of sample after attaining equilibrium moisture content W Dry = weight of sample after removal of the moisture in the oven

15. 15 Tuesday, August 11, 2015 45 ˚C0.0537.941±2.17 * 0.19711.054±0.40 0.31115.704±0.95 * 0.42932.701±4.72 * 0.49720.115±0.78 * 0.69925.925±1.68 * 0.74529.873±2.47 * 0.79136.071±0.48 * 0.968168.022±15.77 LSD 0.05 7.09 LSD 0.01 10.22 55 ˚C0.03924.237±1.66 * 0.18216.267±2.84 0.317.702±1.38 * 0.42423.090±2.12 * 0.48126.970±4.8 * 0.68627.532±3.66 * 0.7130.745±5.75 * 0.76430.504±0.85 * 0.96570.575±1.81 LSD 0.05 LSD 0.01 5.75 3.99 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 a w ; Temperature (˚C)Water activity # EMC(%db)±SD

16. 16 Tuesday, August 11, 2015 ModelParameterTemperature 25˚C35˚C45˚C55˚C GAB M0M0 14.26614.2449.77713.323 C1.30E+458.62E+44-1.05E+46-3.12E+45 K0.9030.9080.9780.841 r2r2 0.9910.9530.9380.899 RMSE2.716.3811.254.81 MRE7.3113.3823.0513.53 Residual PlotPattern BET M0M0 3.6694.4086.5963.573 C7.54E+45-2.16E+45-4.49E+46-4.10E+46 r2r2 0.5280.5890.9210.161 RMSE26.8027.6513.2412.30 MRE80.9185.8432.2433.11 Residual PlotPattern Peleg K1K1 105.292115.869211.97063.626 n1n1 8.1889.32210.8676.181 K2K2 34.34834.71423.83521.383 n2n2 0.3220.2524.68E-151.81E-14 r2r2 0.9930.9780.9710.970 RMSE2.654.778.477.66 MRE5.777.5733.7327.67 Residual PlotRandom Comparison of PVP-CMC hydrogel film at different temperature using GAB, BET and Peleg models

17. 17 Tuesday, August 11, 2015 ModelParametersValues Modified OswinA 33.748 B-0.135 x2.306 r2r2 0.921 RMSE18.99 MRE (%)29.22 Residual plotRandom Estimation parameters and comparison criteria for PVP- CMC hydrogel film at different temperature using Modified Oswin models

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

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

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

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