Eficiência hidrolítica da lactase imobilizada em filmes flexíveis de quitosana

Abstract

Chitosan is a biopolymer that is biodegradable and has antimicrobial activity. In an attempt to intensify this last characteristic, some materials can be added to chitosan films, such as TiO2 nanoparticles. In dairy, products without lactose, it’s mostly used lactase in its free form. The immobilization of this enzyme is an alternative for their use in different cycles of lactose hidrolisys. The present work proposes the development of chitosan films with immobilized lactase and nanoparticles of TiO2 and the evaluation of its applicability like a package, which is capable of, hydrolyze lactose and produce milk with low or no content of lactose in different cycles of reutilization. For such, were formulated films with different concentrations of lactase (3 and 5 mL), different crosslinking agents (glutaraldehyde and genipin) and with different concentrations of TiO2 nanoparticles (0 and 1%). The films were evaluated for their antimicrobial activity. It was found that all films exhibited antimicrobial activity, and the presence of nanoparticles did not influence an increase in this activity. Therefore, only films without TiO2 nanoparticles were selected and evaluated in the subsequent analyzes. Selected films were evaluated regarding the efficiency of milk lactose hydrolysis at different temperatures, 7 °C and 25 °C, in periods of 48 and 24 hours, respectively, and its operational stability was evaluated in five cycles. It was also evaluated the films influence in increasing the acidity of the milk which were in contact with it and solubility in a milk solution. Lastly, a market research was conducted in order to meet the perception of the consumers through the food packaging innovations. All of the films were capable of hydrolyze an amount of lactose in all five cycles. The films with genipin and 5mL of lactase, hydrolyzed 100% of the lactose in all cycles and temperatures, showing excellent operational stability. All films shown an influence in acidity increasing of the milk which were in contact with it. Films with low solubility in aqueous media were obtained. The films developed in the present work can be considered as a good alternative to be applied as milk food packaging. The interviewed consumers are open to new technologies used in food packaging.