Chemical and Physical Characteristics of Edible Films, Based on κ- and ι-Carrageenans with the Addition of Lapacho Tea Extract

Abstract

The aim of the study was to characterize antioxidant and textural property differences of edible films prepared with the addition of lapacho extract (LE). The experimentally produced edible films also contained different carrageenans (ι-and κ-carrageenan). The κand ι-carrageenan, glycerol and the different addition of LE (5%, 10%, 20%) were used as ingredients for forming films. The pH and viscosity were measured for film forming solutions (before drying). The following analyses were performed on films: the total polyphenol content (TPC), Ferric Reducing Antioxidant Power (FRAP) and 2-Diphenyl-1-Picrylhydrazyl (DPPH). Optical parameters were analyzed by the determination of UV-Vis spectra. The structure of films was characterized by scanning electron microscopy. The gained results indicated that the use of different gelling agents (ι-and κ-carrageenan) resulted in statistically significant (p < 0.05) differences in textural properties (strength and breaking strain) of produced edible films. The highest antioxidant properties and TPC had a κ film with 20% LE (DPPH: 87.63 ± 0.03%; TPC: 233.75 ± 0.104 mg gallic acid/g). According to these results, it can be concluded that edible films with the highest concentrations of added lapacho extract can serve as a good source of antioxidant compounds. Certainly, these properties can be usefully incorporated into the wrapped food commodity.Foods 2020, 9, 357 2 of 15 but there is a high demand from consumers for less processed food and natural substances that can make produced food commodities even more functional [4].Carrageenans are polysaccharides produced by red seaweeds Rhodophyceae [5]. Kappa carrageenan has about 25% to 30% of sulfate content and iota carrageenan about 28 to 30% [6]. Commercial κand ι-carrageenans are gel-forming compounds and they are water soluble [5,7,8]. The physicochemical properties of carrageenans are highly affected by their chemical structures (helical structure formation). It was observed that edible films produced with the use of kappa carrageena were clear, with advantageous mechanical and structural properties [9].The lapacho tea is the inner bark and heartwood of the tree of different botanical names such as Tabebuia avellanedae and Tecoma impetiginosa. These trees are specific to the area of South America, where lapacho is traditionally used, and this tea is well known for its antitumor properties, mainly due to the presence of polyphenolic compounds [10].Polyphenolic compounds are common in fruit and vegetables, they are secondary metabolites, and they also have high antioxidant potential and can also work as anti-inflammatory, antimicrobial, antithrombotic and cardio protective compounds [11]. In natural extracts, there can also be a lot of aromatic compounds, which can work as a UV barrier [12]. On the other side, polysaccharides can interact with the polyphenolic compounds, and they can impact the properties of matrices consisting of these compounds. Food commodities represent mainly complex matrixes, in which interactions between the...

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