Characterization of pectin and carrageenan edible films in the presence of lemon balm infusion

Abstract

The present study aimed the formation of edible films with antioxidant properties. Initially, 20 herbs were evaluated for their total phenolics content (TPC) and antioxidant activity (AA). The majority of the herbs had high AA (>80%), while lemon balm had the best TPC performance. As such, the lemon balm infusion was subsequently used in film formation, along with high and low methoxyl pectin and iota-carrageenan (on their own or in mixtures) at a concentration of 1.5% w/w. For comparison reasons, films prepared in water were also studied. Regarding the films’ properties, their weight varied from 0.74 to 0.81 g, thickness from 71 to 90 μm, density from 1.29 to 1.56 g/cm3, moisture content from 71 to 84% and WVP from 3.81 10−8 - 4.5 10−8 g mm/h cm2 Pa. Maximum force and modulus values ranged from 7.4 to 17.2 N and 186.8–397.2 kPa, respectively. According to the statistics, for the same formulation, the presence of the infusion was not statistically important for weight, thickness, density and moisture content. All infusion films showed significantly greater TPC and AA values and were more opaque and less bright than water films. The type of biopolymer was important for all measured properties. Carrageenan films had greater moisture content and were more opaque, less bright, stronger and stiffer than the remaining films. They also had the lowest TPC and AA values. Possible biopolymer-biopolymer and biopolymer –extract interactions were suggested by FT-IR.