Bourbon, A. I.

Cerqueira, M. A.

Martins, Joana

Pinheiro, A. C.

Vicente, A. A.

Universidade do Minho: RepositoriUM

Edible films-based on ț-carrageenan/Locust bean gum – effects of different polysaccharide ratios on film properties Martins, J. T., Cerqueira, M. A., Bourbon, A. I., Pinheiro, A. C., Vicente, A. A.  IBB – Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal (avicente@deb.uminho.pt)   INTRODUCTION Polysaccharides obtained from renewable sources are extensively applied in food industry due to their low cost and wide range of functional properties. In the last years, the development of edible films to extend shelf-life of food products was one of the most studied applications for polysaccharides [1]. However, when compared with commercial plastics, polysaccharide-based films present a great water sensitivity and poor mechanical properties, which have lead to a extensive number of studies with the main objective of improving their physicochemical properties. Mixed systems formed by different hydrocolloids, such as Locust bean gum (LBG), and ț-carrageenan (ț-car) have already showed extensive applications as thickening and stabilizing agents [2,3]. However, their peculiar synergic behaviour can still offer new interesting applications such as the development of edible films with particular properties.  In order to verify their synergic behaviour, edible films composed by mixtures of ț-car and LBG were developed and the effect of different ratios of these polysaccharides on films’ properties were evaluated.  MATERIALS & METHODS Films with different ț-car/LBG ratios - 100/0; 80/60; 60/40; 40/60; 20/80; 0/100 % (w/w) –and with 30 % (w/w) glycerol (as plasticizer) were prepared for this study. Moisture content, water vapor permeability (WVP), tensile strength (TS), elongation at break (EB) and optical properties were determined [4], being the chemical interaction between the two polysaccharides assessed by Fourier Transform Infrared (FTIR) spectroscopy. The relationship between moisture content, WVP, mechanical and optical properties was studied using principal component analysis (PCA) with the R software for Windows (version 2.11.1).  RESULTS & DISCUSSION The film characterization results of the ț-car and LBG films at different ratios are reported in Table 1. Results showed that water content ranged between 26.77 % and 13.69% for 80/20 % (w/w) of ț-car/LBG and 100 % (w/w) of LBG, respectively. The WVP values changed from 8.01x10-11 to 5.15x10-11 g (m s Pa)-1 for films composed by 100 % (w/w) of LBG and 40/60 % (w/w) of ț-car/LBG, respectively. Film opacity values did not show significant (p<0.05) differences for the different formulations. Edible films composed of 100 % (w/w) of LBG present simultaneously the highest value of EB (28.21 %) and the lowest value of TS (8.61MPa), while for edible films composed of 20/80 (% w/w) of ț-car/LBG and 40/60% 11th International Congress on Engineering and Food - Athens, Greece, 2011 1015(w/w) of ț-car/LBG films have exhibited the lowest value of EB (10.19 %) and the highest value of TS (27.57 MPa), respectively. The IR spectrum of ț-car/LBG films showed a shift of C-O-C band from 1162 cm-1 (100/0 % (w/w)) to 1151cm-1 (20/80 % (w/w)), a shift of C-OH band from 1023 cm-1 (0/100 % (w/w)) to 1033 cm-1 (20/80 %) and a shift of C-H band from 919 cm-1 (100/0 % (w/w)) to 926 cm-1 (20/80 %), suggesting physical entanglements of these two polysaccharides. PCA showed that edible films composed of 40/60 % (w/w) of ț-car/LBG could be the best choice to be applied on food systems due to their good water vapour barrier and mechanical properties.  Table 1. Values of thickness, moisture content (MC), water vapor permeability (WVP), elongation at break (EB), tensile strength (TS) and opacity obtained for ț-car/LBG films ț-car/LBG film % (w/w) MC (%) WVP u 10-11 (g (m s Pa)-1) EB (%) TS (MPa) Opacity (%) 100/0 19.28±0.58a 5.48±0.19 abc 16.18±1.57a 19.95±1.06a 8.90±0.09ab 80/20 26.77±1.37b 6.32±0.26 d 22.06±2.57b 20.68±1.97ab 9.61±0.32a 60/40 24.81±0.42b 6.00±0.30 ad 14.95±1.18a 22.98±1.91b 8.97±0.62ab 40/60 21.08±1.13ab 5.15±0.11 b 19.88±1.44b 27.57±1.46c 8.82±0.30b 20/80 19.25±0.21a 5.43±0.06 c 10.19±3.40c 18.19±0.83d 9.55±0.09ab 0/100 13.69±0.63c 8.01±0.40 e 28.21±2.89d 8.61±3.27e 8.90±0.69ab a-eDifferent superscript letters in the same column indicate a statistically difference (Tukey test p<0.05)  CONCLUSION The results provided useful information on the structural properties of ț-car and LGB and the structural changes in the films network induced when mixing different ratios of the two polysaccharides. This work will contribute to the establishment of an approach to optimize films’ composition based on the interactions between different polysaccharides sources, aiming at improving polysaccharide-based films’ properties when compared with other sources, namely non-edible and non-biodegradable films.  REFERENCES [1] Bourtoom T. 2008. Edible films and coatings: characteristics and properties. International Food Research Journal, 15(3), 1-12. [2] Pinheiro A.C., Bourbon A.I., Rocha C., Ribeiro C.,. Maia J.M, Gonçalves M.P., Teixeira J.A. & Vicente A.A. 2011. Rheological characterization of ț-carrageenan/galactomannan and xanthan/galactomannan gels: Comparison of galactomannans from non-traditional sources with conventional galactomannans. Carbohydrate Polymers, 83, 392–399. [3] Mikkonen K.S., Rita H., Helén H., Talja R.A., Hyvönen L. & Tenkanen M. 2007. Effect of Polysaccharide Structure on Mechanical and Thermal Properties of Galactomannan-Based Films. Biomacromolecules, 8, 3198-3205. [4] Casariego A., Souza B.W.S., Cerqueira M.A., Teixeira J.A., Cruz L., Díaz R. & Vicente A.A. 2009. Chitosan/clay films' properties as affected by biopolymer and clay micro/nanoparticles' concentrations. Food Hydrocolloids, 23(7), 1895-1902.    1016FOOD PROCESS ENGINEERING  IN A CHANGING WORLD    Proceedings of the  11th International Congress on Engineering and Food (ICEF11)   VOLUME II    Editors Petros S. Taoukis Nikolaos G. Stoforos Vaios T. Karathanos George D. Saravacos    ATHENS, GREECE 2011 11th International Congress on Engineering and Food - Athens, Greece, 2011 iiiFood Process Engineering in a Changing World Proceedings of the 11th International Congress on Engineering and Food,  May 22-26, 2011, Athens, Greece.    ICEF 11 Secretariat: Professor Petros Taoukis School of Chemical Engineering  National Technical University of Athens Athens 15780 Greece e-mail: icef11@chemeng.ntua.gr   Technical & Scientific ICEF11 Editorial Team: Dr. Efimia Dermesonluoglu, Dr. Eleni Gogou, Dr. Virginia Giannou, John Tzigounakis National Technical University of Athens  Published by:  Cosmosware, Ag. Ioannou 53, Athens, Greece, 0030 2106013922 cosmosware@ath.forthnet.gr  All papers appearing in the ICEF11 Proceedings were Peer Reviewed for acceptance by at least two independent reviewers from the Scientific Committees.  Copyright © NTUA, School of Chemical Engineering, Athens 2011 SET ISBN: 978-960-89789-6-6 ISBN: 978-960-89789-4-2 iv

Edible films-based on k-carrageenan/Locust bean gum – effects of different polysaccharide ratios on film properties

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