Studi Karakteristik dan Aplikasi Film Pelapis Kelat Logam Alkali Tanah Alginat-Kitosan

Abstract

Several types of thin films are widely used to protect foodstuff, but thin film with antimicrobial activity and edible film characteristic is still limited to develop. In this work has been performed the preparation of thin film of alkaline earth element chelate with alginate-chitosan, through reactions between 0.1 M CaCI2, 0.1 M SrCI2 and 0.1 M BaCI2 with alginate-chitosan ionic interaction. These products were characterized by physicochemical measuring of Scanning Electron Microscope (SEM), Differential Thermal Analysis (DTA), Fourier Transform Infra Red (FT-IR), load, stroke, percentage of elongation and its antimicrobial properties. Surface morphology measuring by SEM showed that the smoothness to roughness of surfaces were in order Ca alginate-chitosan, Sr alginate-chitosan and Ba alginatechitosan. This order was agree with the ionic size from large to small that is Ca2+, sr2+ and Ba2+ ions. Thermogram results of DT A showed that exothermic thermal degradations were 330; 430 and 440°C for thin film of Ba alginate-chitosan, Sr alginate-chitosan and Ca alginate-chitosan respectively. These mean that smaller ionic radius from Ba2+ ion to sr2+ and Ca2 + ions resulted larger degradation temperature. From FT-IR spectra of thin film chelates of Ca alginate-chitosan, .Sr alginatechitosan and Ba alginate-chitosan showed that there were no new added functional groups. It means that there was no reaction between alginate and chitosan, but it was only ionic interaction. From measuring of loads resulted 0.03; 0.02 and 0.09 kgf, stroke values were 15 .89; 11.95 and 9 .13 mm/minute, while percentage of elongations were 10.66; 8. 70 and 7 .04 % for Ca alginate-chitosan, Sr alginate-chitosan and Ba alginate-chitosan. These mean that the higher ionic radii of alkaline earth elements formed chelates with alginatechitosan, the lower of its elasticity. Based on characteristic measurement by physicochemical resulted that alkaline earth elements Ca, Sr and Ba which have empty d orbitals, capable to form chelates with alginate-chitosan ionic interactions. Occurrence of these thin films because of complexation between alkaline earth elements with guluronat block of alginate. In the measuring simple biochemistry toward microba in white bread which covered with each thin film were found four bacteria species and one fungi species based on types and their cell morphologies. The largest number of microbial was microbial was in white bread which covered by Ca alginate-chitosan, then followed by Ba alginatechitosan and Sr alginate-chitosan. These mean that thin film antimicrobial activity of Sr alginate-chitosan chelate was stronger than that of Ba alginate-chitosan followed by Sr alginate-chitosan. Based on characteristic measurement which has been performed by microbiological test, it was clearly that each thin film of alkaline earth alginate-chitosan was very potential to use as thin film which has antimicrobial activity. In order to know which one of these thin films of alkaline earth element alginate-chitosan that can be used as edible film, therefore it is necessary to determine the safety of the product.