EFFECT OF PLASTICIZERS ON MOISTURE ABSORPTION AND MECHANICAL PROPERTIES OF AGAR FILMS

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DOI: https://doi.org/None
Issue: 
8
Year: 
2017

O.N. Pozharitskaya(1), PhD, A.N. Shikov(1), Dr.Sci., D.V. Demchenko(1), PhD, E.V. Flisyuk(2), Dr.Sci., V.G. Makarov(1), Dr.Sci. 1-Saint-Petersburg Institute of Pharmacy, Leningrad region, Vsevolozhsky district, 188663, Kuzmolovo P 245, Russia 2-Saint-Petersburg State Chemical-Pharmaceutical Academy, 197376, St. Petersburg, Prof. Popova, 14, Russia

Introduction. Polysaccharide-based polymers have a great potential of using in pharmaceutical industry and biotechnology. The advantages of agar versus other gelling agents are its higher stability at low pH values and elevated temperatures. Plasticizers increase the flexibility of the film and prevent its crack during processing and storage. Objective: to investigate the effects of different types of plasticizers and their concentration on the kinetic and static absorption of moisture and on the mechanical properties of agar films. Methods. The effect of plasticizers (glycerol, sorbitol, citric acid, sodium citrate, and mixtures thereof) and their mixtures on the absorption of moisture and the mechanical properties of agar films was investigated when the plasticizers were used at various concentrations according to the experiment design. Results. Addition of glycerol to the films increased the rate of absorption and the amount of absorbed moisture when stored under conditions of higher relative humidity. At the same time, the films containing citric acid and sodium citrate absorbed moisture more slowly and in smaller quantities, especially at a lower relative humidity. There was the thinnest water monolayer (0.035-0.036 g water/g film) on the films containing citric acid and sodium citrate as a plasticizer. When 3.6 wt.-% glycerol and 0.6 wt.-% sorbitol were added to the films, the monolayer thickness increased to 0.065 g water/g film. The highest thickness of the water monolayer (0.158 g water/g film) was observed when 4 wt.-% sorbitol was added. The addition of citric acid to the agar films lowered their strength. While the higher levels of glycerol (up to 5 wt.-%) and sodium citrate (up to 2.5 wt.-%) increased the strength of the films. The strength of agar films with sodium citrate increased by adding of citric acid. Conclusion. The results of the investigation can be used in the pharmaceutical and biotechnological industries when manufacturing agar capsules or an agar-agar pack.
Keywords: 
agar films
citric acid
glycerol
sodium citrate
sorbitol
References: 
  1. Gontard N., Guilbert S. Bio-packaging: technology and properties of edible and/or biodegradable material of agricultural origin. In Mathlouthi M (Ed) Food packaging and preservation, Blackie Academic and Professional, Glasgow; 1994
  2. Arnott S., Fulmer A., Scott W.E. The agarose double helix and its function in agarose gel structure. J. Molecular. Biol. 1974; 90(2):269–84.
  3. Phan T.D., Debeaufort F., Luu D., Voilley A. Functional properties of edible agar-based and starch-based films for food quality preservation. J. Agric. Food Chem. 2005; 53(4):973–81.
  4. Freile-Pelegrín Y., Madera-Santana T., Robledo D., Veleva L., Quintana P., Azamar J.A. Degradation of agar films in a humid tropical climate: Thermal, mechanical, morphological and structural change. Polym. Degrad. Stabil. (2007); 92(2):244–52.
  5. Phan T.D., Debeaufort F., Voilley A., Luu D. Biopolymer interactions affect the functional properties of edible films based on agar, cassava starch and arabinoxylan blends. J. Food Eng. 2009; 90(4):548–58.
  6. Tian H., Xu G., Yang B., Guo G. Microstructure and mechanical properties of soy protein/agar blend films: effect of composition and processing methods. J. Food Eng. 2011; 107(1):21–6.
  7. Giménez B., de Lacey A.L., Pérez-Santín E., López-Caballero M.E., Montero P. Release of active compounds from agar and agar–gelatin films with green tea extract. Food Hydrocoll. 2013; 30(1):264–71.
  8. Shikov A.N., Pozharitskaya O.N., Makarov V.G., Makarova M.N. New technology for preparation of herbal extracts and soft halal capsules on its base. Amer. Eur. J. Sustainable Agric. 2009; 3:130–4.
  9. Nieto M.B. Structure and function of polysaccharide gum-based edible films and coatings, In Embuscado ME, Huber KC (Eds.) Edible Films and Coatings for Food Applications. Springer, Dordrecht, Heidelberg, London, New York; 2009
  10. Haq M.A., Hasnain. A., Azam M. Characterization of edible gum cordia film: Effects of plasticizers. LWT-Food Sci. Technol. 2014; 55(1):163-9.
  11. Vieira M.G.A., da Silva M.A., dos Santos L.O., Beppu M.M. Natural-based plasticizers and biopolymer films: A review. Eur. Polym. J. 2011; 47(3):254–63.
  12. Mali S., Sakanaka L.S., Yamashita F., Grossmann M.V.E. Water absorption and mechanical properties of cassava starch films and their relation to plasticizing effect. Carbohyd. Polym. 2005; 60(3): 283–9.
  13. Cao N., Yang X., Fu Y. Effects of various plasticizers on mechanical and water vapor barrier properties of gelatin films. Food Hydrocoll. 2009; 23(3):729–35.
  14. Reddy N., Yang Y. Citric acid cross-linking of starch films. Food Chem. 2010; 118(3):702–11.
  15. Olivato J.B., Grossmann M.V.E., Bilck A.P., Yamashita F. Effect of organic acids as additives on the performance of thermoplastic starch/polyester blown films. Carbohyd. Polym. 2012; 90(1):159–64.
  16. Olsson E., Hedenqvist M.S., Johansson C., Järnström L. Influence of citric acid and curing on moisture absorption, diffusion and permeability of starch films. Carbohyd. Polym. 2013; 94(2):765–72.
  17. Cho S.Y., Rhee C. Absorption characteristics of soy protein films and their relation to mechanical properties. LWT- Food Sci. Technol. 2002; 35(2):151–7.
  18. Rhim J.W., Wang L.F. Mechanical and water barrier properties of agar/κ-carrageenan/konjac glucomannan ternary blend biohydrogel films. Carbohyd. Polym. 2013; 96(1):71–81.
  19. Rockland L.B. Satured salt solutions for static control of relative humidity between 5° and 4°C. Analytical Chem. 1960; 32(10):1375–6.
  20. Peleg M. An empirical model for the description of moisture sorption curves. J. Food Sci. 1988; 53(4):1216–7.
  21. Bizot H. Using the GAB model to construct sorption isotherms. In Jowitt R., Escher F., Hallistrom B., Meffert H.F.T., Spiess W.E.L., Vos. (Eds.), Physical properties of foods Applied Science Publishers, London; 1984
  22. Yolmeh M., Najafi M.B.H., Farhoosh R. Optimisation of ultrasound-assisted extraction of natural pigment from annatto seeds by response surface methodology (RSM). Food Chem. 2014; 155: 319–24.
  23. Turhan M., Sayar S., Gunasekaran S. Application of Peleg model to study water absorption in chickpea during soaking. J. Food Eng. 2002; 53 (2): 153–9.
  24. Sothornvit R., Krochta J.M. Plasticizer effect on mechanical properties of β-lactoglobulin films. J. Food Eng. 2001; 50(3):149–55.
  25. Leung H.K. Water activity and other colligative properties of foods. In Okos M.R. (Ed.) Physical and chemical properties of food. American Society of Agriculture Engineers, Michigan; 1986.
  26. Garcia M.A., Martino M.N., Zaritzky N.E. Microstructural characterization of plasticized starch-based films. Starch/Stärke 2000; 52(4):118–24.
  27. Timmermann E.O., Chirife J., Iglesias H.A. Water sorption isotherms of foods and foodstuffs: BET or GAB parameters? J. Food Eng. 2001; 48(1):19–31.
  28. Coupland J.N., Shaw N.B., Monahan F.J., O’Riordan E.D., Sullivan M. Modeling the effect of glycerol on the moisture sorption behavior of whey protein edible films. J. Food Engineer. 2000; 43(1):25–30.
  29. Demchenko D.V., Pozharitskaya O.N., Shikov A.N., Flisyuk E.V., Rusak A.V., Makarov V.G. Rheological study of agar hydrogels for soft capsule shells. Pharm. Chem. J. 2014; 47(10): 556–8.
  30. Olivato J.B., Grossmann M.V.E., Yamashita F., Eiras D., Pessan L.A. Citric acid and maleic anhydride as compatibilizers in starch/poly(butylene adipateco-terephthalate) blends by one-step reactive extrusion. Carbohyd. Polym. 2012; 87(4):2614–8.
  31. Shi R., Bi J., Zhang Z., Zhu A., Chen D., Zhou X., et al. The effect of citric acid on the structural properties and cytotoxicity of the polyvinyl alcohol/starch films when molding at high temperature. Carbohyd. Polym. 2008; 74(3):763–70.
  32. Choi J.S., Park W.H. Effect of biodegradable plasticizers on thermal and mechanical properties of poly(3-hydroxybutyrate). Polymer Testing 2004; 23(4):455–60.