Desenvolvimento de filmes biopoliméricos com base de amido de milho reforçados por Theobroma Cacao

Abstract

This work aimed to produce biopolymeric films based on thermoplastic corn starch reinforced with cocoa in order to obtain films with optimized mechanical properties, hydrophobicity and potential of microbial inhibition. Natural cacao seeds extracted of the fruit was fermented, dryed and milled (NAT-F) and results of the addition of this powder was compared to the obtained for cacao milled from comercially fermented and dried seeds (NAT-C) and industrialized cacao (IND). All samples were treated by ultrasonic bath in hydroalcoholic solution for incorporating into gelatinized starch for casting. Small changes in starch crystallinity were observed after cacao addition. Films presented increased mechanical strength (30% up to 150%) and enhancement in surface hydrophobicity (91% up to 313%). Films with NAT-F showed better strength (3.89 ± 0.15MPa) with higher fat content. By the other side, this sample presented less polyphenols (4.75 ± 0.32 mg(GAE)/g), heterogeneous particle agglomeration and did not inhibit microbial growth. The films with NAT-C, improved the hydrophobic performance, with some microbial inhibition, higher quantity of polyphenols (8.77 ± 0.09 mg(GAE)/g) and lower tensile strength (2.20 ± 0.09 MPa). The films produced from industrial cacao (IND), showed better microbial inhibition potential (IC50 = 5.9% against S.aureus and 8.6% against E. coli), due to alkalinization of the powder and high quantity of polyphenols (7.97 ± 0.05 mg(GAE)/g) and better tensile strength of films with 10% cocoa (3.72 ± 0.23 MPa) and good particle dispersibility. Overall, the films with IND cocoa showed the best performance and with NAT-C the best eco-friendy proposal.